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Thymulin

Tier 3 · Reported use
Also known as Facteur Thymique Serique · FTS peptide · Zinc-thymulin

The strongest evidence present is Tier 1: human observational studies and tier-1 reviews on zinc deficiency, malnutrition, aging and thymic-peptide immunomodulation (src-6, src-17, src-22, src-24, src-27, src-60, src-61, src-66, src-67), plus a Tier 1-labeled report of two randomized, double-blind, placebo-controlled human efficacy trials (src-2, describing Amor 1987 in rheumatoid arthritis and Roullet 1989 in multiple sclerosis, both negative). However, sources emphasize that no modern Phase 2/3 randomized interventional trial exists, zero clinical trials are registered per one profile (src-3), and much mechanistic and efficacy detail rests on animal, in-vitro, theoretical or vendor sources. Higher-tier human data is largely observational (zinc deficiency, malnutrition, anorexia, aging) rather than interventional. Vendor/blog efficacy claims (src-10, src-12) are not supported by controlled human data.

Half-life
~0.17 h
Routes
Subcutaneous · Intraperitoneal (animal research) · Intranasal (explored for CNS effects)
Goals
Immune modulation / immune senescence research · Anti-inflammatory research · Age-related immune decline · Zinc-status biomarker research · Neuropathic pain research (analog PAT, animal/in-vitro)
Cost / mg
Not recorded

How it works

Reference profiles describe thymulin as a small nine-amino-acid hormone made by the epithelial cells of the thymus gland. Sources report that it only works when bound to zinc in a 1:1 ratio — the zinc-free form is described as biologically inactive, and in-vitro work reports that removing zinc with chelators abolishes activity while adding zinc back restores it. Sources report thymulin helps immature T-cells mature and differentiate, tunes the balance of T-cell subsets, boosts natural killer cell activity (an effect said to depend on adequate zinc), and dampens excessive inflammatory signaling. Because it needs zinc, sources report that serum thymulin drops in zinc deficiency and serves as a sensitive biomarker of zinc status. Profiles also note thymulin levels peak in childhood and fall with age as the thymus shrinks.

Overview

Overview

Reference profiles describe thymulin (also called Facteur Thymique Serique, FTS peptide, or Zinc-thymulin) as a zinc-dependent nonapeptide (9-amino-acid) hormone produced exclusively by thymic epithelial cells (src-1). One profile notes it is the only known thymic hormone that requires a metal cofactor — equimolar zinc (Zn2+) — for its biological activity (src-1). Sources report that the zinc-free peptide (FTS or apo-thymulin) is biologically inactive, while the zinc-bound form (Zn-FTS) possesses full immunomodulatory activity with a 1:1 zinc-to-peptide stoichiometry (src-1 through src-11). A tier-1 review describes thymulin as one of the most important thymic hormones (src-6), and a tier-1 study characterizes it as a pharmacologically active metallopeptide whose activity and antigenicity depend on zinc (src-17).

Discovery and Identity

Sources disagree on the discovery timeline. One profile states thymulin was discovered in 1977 by Jean-François Bach and Mireille Dardenne at the Institut Necker in Paris using a rosette-formation bioassay in mouse thymocytes (src-1); another states it was first isolated by Bach and colleagues in Paris in 1975 from porcine and human serum and renamed thymulin in 1981 once its zinc-dependence was established (src-4); a vendor source attributes first isolation to Dardenne et al. 1974 (src-10). One profile reports the sequence pGlu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn was established by Pleau and colleagues in 1977, with the N-terminal residue being pyroglutamic acid formed by spontaneous cyclization of glutamine, and gives CAS number 63958-90-7 (src-2). One profile states Dardenne and colleagues established zinc-dependence in a landmark 1982 PNAS paper (PMID 6957870), noting the apopeptide does nothing in any reliable bioassay (src-2). Profiles give the free-peptide molecular weight as ~857–858.86 g/mol (formula C33H54N12O15) and the zinc-bound active form as ~921–924 Da (src-1, src-2, src-3, src-5, src-9, src-12).

Profiles note thymulin is a distinct molecule from Thymosin Alpha-1 (a separate 28-residue peptide that does not require zinc) and from Thymalin (a Russian polypeptide extract), and that the three are not interchangeable (src-2, src-11).

Reported Mechanism

In-vitro work reports zinc coordinates with the peptide (attributed variously to Lys3/Ser4 and the backbone carbonyl of Ala2, or to Ser4, Ser8, N-terminal pGlu and possibly Gln5) creating a conformational change that exposes the biologically active epitope (src-1, src-9). Chelation of zinc by EDTA or DTPA is reported to completely abolish thymulin activity, restorable by adding exogenous zinc (src-1). Sources report metallothionein within thymic epithelial cells transfers zinc to the peptide, and that the ratio of zinc-bound to total thymulin serves as a sensitive biomarker for zinc status (src-3, src-11). A tier-2 study describes an endocrine function of the thymus as packaging zinc in zinc-thymulin for delivery to the periphery (src-18).

Sources report thymulin promotes maturation of T-lymphocyte precursors both within the thymus and in peripheral circulation, induces CD2 and CD3 expression on immature thymocytes, promotes the double-negative to double-positive transition, modulates CD4/CD8 ratios, and enhances alloantigen recognition (src-1, src-3, src-7). It is reported to suppress excessive TNF-alpha, IL-1beta and IL-6 (via inhibition of NF-kB activation and p38 MAPK phosphorylation) while maintaining or enhancing IL-10 and IL-2 (src-1, src-3, src-7, src-9), and to enhance NK cell cytotoxicity in a zinc-dependent manner (src-1, src-3, src-5, src-7). One profile reports high-affinity binding with an apparent Kd of ~5×10⁻⁷ M at physiological pH (src-4). Reviews describe thymulin as a hypophysiotropic peptide within a hypophyso-thymic axis, with feedback on its own secretion and cross-talk with growth hormone, prolactin, thyroid hormone and ACTH-linked circadian rhythm (src-8, src-28, src-45). Animal studies report GH stimulates thymulin secretion via specific GH receptors, and that bovine/ovine somatotropin partially restored low thymulin in old dogs, mice and rats (src-8).

Aging, Zinc and Nutrition

Profiles report serum thymulin peaks during childhood (ages 2–10), declines after puberty, and becomes very low or undetectable after about age 60, paralleling thymic involution (src-1, src-2, src-3). Prasad et al. (1988) showed mild zinc deficiency in elderly subjects reduced plasma thymulin activity, restored by zinc supplementation (src-1). Mocchegiani et al. (1995) demonstrated zinc supplementation in the elderly restored both thymulin levels and NK cell function (src-1). A tier-1 study reported that during zinc deficiency serum thymulin activity decreased and was restored by supplementation, with zinc deficiency causing a TH1/TH2 imbalance and reduced NK lytic activity even when mild (src-22, src-24). A tier-2 study of 58 Senegalese children reported severe protein-energy malnutrition was associated with a tiny thymus containing very little thymulin (src-20), and a tier-2 study of anorexia nervosa patients found significantly reduced thymulin activity attributed to thymic atrophy (src-25).

Research Applications and Evidence Base

Animal studies report exogenous thymulin can partially restore T-cell function in aged or thymectomized animals (src-7, src-13), prevents overproduction of IL-1beta, IL-2, IL-6 and TNF-alpha while reducing Hsp70 in inflamed tissue, and reduces neutrophil infiltration and alveolar damage in lung inflammation models (src-7). Animal work also reports analgesic effects in the CNS possibly via α7-nicotinic acetylcholine receptor potentiation (src-7, src-9), and that gene therapy delivering synthetic thymulin genes to the hypothalamus of aged animals restored thymic function markers (src-7, src-40). One profile states current scientific activity is preclinical gene-therapy work centered at the University of La Plata in Argentina (src-2, src-23). A tier-1 review states thymic peptides including thymulin are used in treatment of neoplastic diseases, viral infections, autoimmune diseases and immunodeficiencies (src-6).

Human efficacy evidence is limited. One profile reports the only randomized, double-blind, placebo-controlled human trials (under the synthetic-analog name nonathymulin) were Amor 1987 in rheumatoid arthritis (PMID 3310925) and Roullet 1989 in multiple sclerosis (PMID 2618585), and that both were negative, with neither producing significant clinical benefit over placebo (src-2). Another profile reports zero registered clinical trials and no controlled human therapeutic trials, while citing a literature base of 373 published studies and noting the basic science is well-regarded across multiple laboratories (src-3). A tier-1 study noted thymulin's effect on suppressor T-cells was the most remarkable and suggested it should be the first to find clinical applications (src-17). By contrast, vendor sources claim broad benefits — immune restoration in aging/chronic illness/autoimmunity, reduced flare-ups in rheumatoid arthritis and lupus, antiviral effects against EBV and herpes, reduced neuroinflammation, and hair follicle support (src-10, src-12) — none supported by controlled human data.

Regulatory Status

Profiles state thymulin is not FDA-approved (nor approved by EMA or Health Canada), is not on the FDA 503A bulks list — meaning U.S. compounding pharmacies cannot lawfully prepare it — was not among the 12 peptides FDA removed from Category 2 on April 15, 2026, and had no commercial pharmaceutical sponsor advancing an NDA as of June 2026 (src-2, src-3). These regulatory specifics come from a single lower-tier source.

What the research shows

265 findings extracted from the 31 sources cited below, strongest evidence first within each group. Every one links to the source it came from.

What human studies found

Based on 3 human trial findings, 23 human study findings, 10 animal findings, 2 in vitro findings and 17 expert opinion findings.

  • human trialImmunomodulatory effects of thymic peptides have been confirmed in numerous clinical studies1

  • human trialAfamelanotide (Scenesse) is the FDA-approved pharmaceutical formulation with proven safety and efficacy from Phase 3 clinical trials, delivered as a controlled-release subcutaneous implant22

  • human trialBoth blinded human trials were negative. The only randomized, double-blind, placebo-controlled human efficacy studies of thymulin (under the synthetic-analog name nonathymulin) were Amor 1987 in rheumatoid arthritis and Roullet 1989 in multiple sclerosis. Neither produced significant clinical benefit over placebo.25

  • human studyDuring zinc deficiency, serum thymulin activity (a thymic hormone) was decreased3

  • human studySerum thymulin activity was restored following zinc supplementation3

  • human studyT cell functions were affected adversely even when the deficiency of zinc was mild in humans3

  • human studyZinc deficiency decreased NK cell lytic activity3

  • human studyZinc deficiency caused a decrease in the percentage of CD8+ CD73+ T cells which are known to be predominantly precursors of cytotoxic T cells3

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  • human studyThymulin is a pharmacologically active metallopeptide that induces the differentiation of T-cells4

  • human studyThymulin enhances several functions of the various T-cell subsets in normal or partially thymus-deficient recipients4

  • human studyBlood levels decline progressively with age to nearly undetectable levels by the fifth decade of life5

  • human studySerum thymulin levels peak during childhood (ages 2-10 years), begin declining after puberty, and become very low or undetectable after age 60, closely paralleling the age-related involution of the thymus gland6

  • human studyPrasad et al. (1988) showed that mild zinc deficiency in elderly subjects resulted in reduced plasma thymulin activity, which was restored by zinc supplementation6

  • human studyMocchegiani et al. (1995) demonstrated that zinc supplementation in elderly subjects restored both thymulin levels and NK cell function, suggesting that the age-related decline in NK cytotoxicity is partially mediated through thymulin deficiency6

  • human studyCirculating thymulin levels decline progressively after puberty in parallel with thymic involution7

  • human studyZinc supplementation in elderly individuals can restore thymulin activity to near-youthful levels7

  • human studyThe age-related decline in circulating thymulin levels correlates directly with the reduced output of naive T-cells from the involuting thymus7

  • human studyZinc supplementation to humans decreased the gene expression and production of pro-inflammatory cytokines and decreased oxidative stress markers10

  • human studyRecent efforts to treat successfully immune deficiency in aged and cancer-bearing humans will be presented12

  • human studyProtein-energy malnutrition (PEM) leads to an immune deficiency15

  • human studyIn severe forms of malnutrition (marasmus, kwashiorkor, and marasmic kwashiorkor) the thymus was tiny and contained very little thymulin15

  • human studyZinc content of the thymus was high whatever the nutritional state of the subject and was related significantly only to the presence of infections15

  • human studyIn Senegalese children thymic atrophy and depleted thymulin content are associated with severe PEM but not systemic infection or depleted thymic Zn content15

  • human studyThymulin activity determined by rosette assay was significantly reduced in anorexia nervosa patients compared to sex- and age-matched healthy control subjects17

  • human studyAnorexia nervosa patients were characterized by very depressed plasma levels of triiodothyronine (T3) but exhibited normal concentrations of thyroxine (T4), thyroxine-binding globulin (TBG), cortisol and zinc17

  • human studyDistribution of peripheral lymphocyte cells into several subsets was not affected in anorexia nervosa patients17

  • animalZinc supplementation can partially reverse age-related thymulin decline and associated immune dysfunction5

  • animalGene therapy delivering synthetic thymulin genes to the hypothalamus of aged animals has demonstrated restoration of thymic function markers and improved neuroendocrine parameters7

  • animalThymulin treatment prevents overproduction of pro-inflammatory cytokines (IL-1-beta, IL-6, TNF-alpha) through NF-kB and p38 MAPK inhibition7

  • animalExogenous thymulin administration can partially restore T-cell function in aged or thymectomized animals7

  • animalThymulin treatment prevents the overproduction of IL-1-beta, IL-2, IL-6, and TNF-alpha while simultaneously reducing heat shock protein Hsp70 expression in inflammatory tissues7

  • animalIn models of lung inflammation, thymulin has been shown to reduce neutrophil infiltration, alveolar damage, and inflammatory mediator release7

  • animalTreatment of old dogs with bovine somatotropin partially restored their low serum thymulin levels8

  • animalTreatment of aged mice with ovine somatotropin increased their low plasma thymulin levels and also raised the concanavalin A (Con A)-dependent proliferative response of their thymocytes as well as interleukin-6 production8

  • animalCombined treatment of old rats with somatotropin and thyroid hormone (T4) partially restored their reduced thymulin serum concentration8

  • animalGene therapy for thymulin may be an effective therapeutic strategy to prevent hormonal and reproductive abnormalities in congenitally athymic (nude) mice9

  • in vitroIn vitro studies show that thymulin enhances the proliferative response of T-cells to mitogens and antigens7

  • in vitroA peptide analogue of thymulin (PAT) has demonstrated potent analgesic and anti-inflammatory properties in cellular pain models31

  • expert opinionThymulin influences tumor cell biology and response of patients with cancer to therapies2

  • expert opinionNo controlled human therapeutic trials have been conducted5

  • expert opinionThymulin and a synthetic analog act as anti-inflammatory and analgesic peptides in the central nervous system brain and other organs8

  • expert opinionThymulin endocrine influences decline with age and are associated with thymic menopause and cellular immune senescence14

  • expert opinionThymulin has anti-inflammatory and immunomodulatory effects21

  • expert opinionPreclinical research suggests anti-inflammatory and immune-modulating properties21

  • expert opinionThymulin restores and enhances immune function, especially in individuals with compromised or dysregulated immune systems due to aging, chronic illness, or autoimmune conditions23

  • expert opinionStudies demonstrate thymulin's ability to suppress excessive inflammatory reactions, making it useful in conditions characterized by chronic inflammation23

  • expert opinionBy modulating T-cell responses, thymulin may help reduce autoimmune flare-ups and improve symptoms in diseases such as rheumatoid arthritis and lupus23

  • expert opinionThymulin enhances antiviral immune responses, showing potential in combating viral infections including Epstein-Barr virus (EBV), herpes viruses, and others23

  • expert opinionPreliminary research indicates thymulin may reduce neuroinflammation and oxidative stress, offering potential therapeutic value in neurodegenerative diseases23

  • expert opinionGoya et al. (2007) studied thymulin's anti-inflammatory effects in animal models of sepsis and inflammation23

  • expert opinionResearch shows promise in lung diseases, neuropathic pain, and age-related immune dysfunction, though human clinical trials remain limited24

  • expert opinionEvidence base includes fifty years of rodent immune-recovery studies plus small 1980s-90s pilots in children with immunodeficiency and in the elderly26

  • expert opinionNo modern Phase 2/3 randomized trial exists26

  • expert opinionNo pharmaceutical company has ever brought thymulin through Phase 326

  • expert opinionSerum thymulin levels decline significantly with age and zinc deficiency, contributing to age-related immune decline (immunosenescence)27

How it works

Based on 2 human trial findings, 15 human study findings, 25 animal findings, 21 in vitro findings, 62 expert opinion findings and 32 theoretical findings.

  • human trialThymulin is biologically inert without zinc. The apopeptide (the bare 9-amino-acid chain) does nothing in any reliable bioassay. Activity requires a 1:1 zinc-to-peptide complex.25

  • human trialDardenne and colleagues established zinc-dependence in a landmark 1982 PNAS paper25

  • human studyThymic peptides including thymulin stimulate the differentiation and maturation of T cells1

  • human studyThymic peptides including thymulin regulate the activity of natural killer cells and dendritic cells1

  • human studyThymic peptides including thymulin induce the release of proinflammatory cytokines1

  • human studyThymic peptides act in multiple manners on the immune system with modulation of physiological processes such as stimulation or suppression of immune responses, angiogenesis, and wound healing1

  • human studyZinc deficiency caused an imbalance between TH1 and TH2 functions with decreased production of IFN-g, IL-2, TNF-a (products of TH1 cells)3

  • human studyThymulin is a nonapeptide hormone produced by thymic epithelial cells4

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  • human studyIts biological activity and antigenicity depend upon the presence of the metal zinc in the molecule4

  • human studyZinc deficiency in humans decreases the activity of serum thymulin (a thymic hormone), which is required for maturation of T-helper cells10

  • human studyT-helper 1 (Th(1)) cytokines are decreased but T-helper 2 (Th(2)) cytokines are not affected by zinc deficiency in humans10

  • human studyShift of Th(1) to Th(2) function results in cell-mediated immune dysfunction10

  • human studyIL-2 production (Th(1) cytokine) is decreased, this leads to decreased activities of natural-killer cell and T cytolytic cells, which are involved in killing viruses, bacteria, and tumor cells10

  • human studyIn humans, zinc deficiency may decrease the generation of new CD4+ T cells from the thymus10

  • human studyZinc deficiency is important in thymic involution and changes in cellular immunity15

  • human studyMA-FTS could recognize FTS (or FTS-like molecule) in human serum19

  • human studyMA-FTS could absorb completely the FTS-like activity from human serum19

  • animalThymulin, when bound to zinc, may influence T-cell differentiation and maturation5

  • animalThymulin induces both intra- and extra-thymic T-cell differentiation5

  • animalThymulin enhances T-cell surface marker expression and promotes CD4/CD8 lineage commitment5

  • animalThymulin enhances NK cell activity5

  • animalThymulin reduces TNF-alpha and IL-6 production via p38 MAPK phosphorylation inhibition5

  • animalThymulin exhibits anti-inflammatory and neuroprotective effects5

  • animalThymulin interacts bidirectionally with the hypothalamus-pituitary axis and follows a circadian rhythm5

  • animalThe ratio of active (zinc-bound) to total thymulin serves as a sensitive biomarker for zinc status5

  • animalThymulin exerts its immunomodulatory effects through binding to specific receptors on T-lymphocyte precursors, promoting their differentiation and maturation into functional T-cell subsets including helper, cytotoxic, and regulatory T-cells7

  • animalThymulin signaling modulates the production of pro-inflammatory cytokines including IL-1-beta, IL-6, and TNF-alpha through inhibition of NF-kB activation and p38 MAPK phosphorylation7

  • animalIn the neuroendocrine system, thymulin influences the release of pituitary hormones including growth hormone, prolactin, and gonadotropins (LH and FSH)7

  • animalThymulin exhibits direct analgesic effects in the central nervous system through modulation of pain-processing pathways7

  • animalThymulin exerts a feedback action on its own secretion both in vivo and in vitro8

  • animalGH stimulates thymulin secretion from TEC lines via specific receptors for GH8

  • animalHypothalamus extract injected in old mice results in reappearance of circulating FTS (facteur thymique serique/thymulin)16

  • animalHypothalamus extract injection in adult thymectomized animals was not able to induce FTS activity16

  • animalPretreatment of hypothalamus extract donors with thymosin fraction 3 greatly diminishes the capacity of hypothalamus preparation to induce FTS reappearance in old animals16

  • animalThe capacity of the thymus to secrete FTS depends on a hypothalamic factor16

  • animalThe absence of FTS in the aged reflects a failure of the thymus linked to its impaired neurologic control16

  • animalA feedback system operates to regulate the release of the hypothalamus stimulatory factor for FTS16

  • animalAnti-FTS antibodies are fixed specifically on floccular material present in cytoplasmic vacuoles of epithelial cortical and medullary cells in normal young C57BL mice20

  • animalIn aged auto-immune SWAN mice, anti-FTS antibodies show activity only in granules present in vacuoles or free in cytoplasm of epithelial cells20

  • animalFTS positive granules show a repetitive structure characteristic of crystalline protein formations20

  • animalFTS is stored in granules of epithelial cells in vivo during the auto-immune process20

  • animalDihexa (PNB-0408) is an angiotensin IV-derived peptide that potentiates HGF/c-Met signaling with preclinical cognitive enhancement research and oral bioavailability22

  • in vitroBiological activity of thymulin completely depends on binding zinc5

  • in vitroMetallothionein within thymic epithelial cells transfers zinc to the peptide5

  • in vitroThe zinc-free peptide (FTS or apo-thymulin) is biologically inactive, while the zinc-bound form (Zn-FTS or metallic thymulin) possesses full immunomodulatory activity6

  • in vitroEquimolar Zn2+ binding is required for the peptide's ability to induce T-cell differentiation6

  • in vitroZinc coordinates with the peptide through the side chains of Lys3 and Ser4 and the backbone carbonyl of Ala2, creating a conformational change that exposes the biologically active epitope6

  • in vitroChelation of zinc by EDTA or DTPA completely abolishes thymulin activity, which can be restored by adding exogenous zinc6

  • in vitroThymulin promotes the maturation of T-lymphocyte precursors within the thymus and in the peripheral circulation6

  • in vitroThymulin induces CD2 and CD3 expression on immature thymocytes, promotes the double-negative to double-positive T-cell transition, modulates CD4/CD8 T-cell subset ratios, and enhances alloantigen recognition and mixed lymphocyte reaction responses6

  • in vitroThymulin suppresses excessive production of TNF-alpha, IL-1beta, and IL-6 while maintaining or enhancing IL-10 and IL-2 production in inflammatory contexts6

  • in vitroThymulin enhances natural killer cell cytotoxic activity, an effect that is dependent on adequate zinc availability6

  • in vitroThe apo-peptide (without zinc) is biologically inactive and cannot be recognized by thymulin-specific monoclonal antibodies7

  • in vitroThymulin promotes the expression of T-cell surface markers including CD4 and CD8 on developing thymocytes7

  • in vitroIn cell culture studies (HUT-78, a Th(0) human malignant lymphoblastoid cell line), as a result of zinc deficiency, nuclear factor-kappaB (NF-kappaB) activation, phosphorylation of IkappaB, and binding of NF-kappaB to DNA are decreased and this results in decreased Th(1) cytokine production10

  • in vitroIn HL-60 cells (a human pro-myelocytic leukemia cell line), zinc deficiency increased the levels of TNF-alpha, IL-1beta, and IL-8 cytokines and mRNA10

  • in vitroIn HL-60 cells, zinc induced A20, a zinc finger protein that inhibited NF-kappaB activation via tumor necrosis factor receptor associated factor pathway, and this decreased gene expression of pro-inflammatory cytokines and oxidative stress markers10

  • in vitroThymic function at the local level requires complex cellular interactions among thymic stromal cells and developing thymocytes involving paracrine and autocrine mediators including interleukins (ILs) 1, 2, 6, 7, 8, colony-stimulating factors (CSFs), interferon-gamma, thymosin alpha 1, and zinc-thymulin12

  • in vitroAn important endocrine function of the thymus is to package zinc in zinc-thymulin for delivery to the periphery12

  • in vitroMonoclonal antibody against facteur thymique serique (FTS), a thymic hormone, was generated by hybridization between mouse NS-1 myeloma cells and BALB/c splenocytes19

  • in vitroThe monoclonal antibody (MA-FTS) was highly specific for FTS and did not cross-react with other thymic hormones or other unrelated peptides19

  • in vitroZinc deficiency directly impairs thymulin activity in laboratory models31

  • in vitroStudies across multiple cellular systems showed that thymulin activity decreases as a result of zinc depletion31

  • expert opinionThymulin is one of the most important thymic hormones produced by the thymus1

  • expert opinionThymulin is a thymic peptide hormone produced by stromal cells in the thymic microenvironment2

  • expert opinionThymulin can circulate to impact immune cells and other cellular components in the periphery2

  • expert opinionThymulin regulates mechanisms supporting intrathymic T cell differentiation2

  • expert opinionBasic science is well-regarded across multiple independent laboratories5

  • expert opinionThymulin is a zinc-dependent nonapeptide exclusively produced by thymic epithelial cells6

  • expert opinionThymulin is the only known thymic hormone that requires a metal cofactor -- equimolar zinc (Zn2+) -- for its biological activity6

  • expert opinionThymulin is exclusively produced by subcapsular and medullary thymic epithelial cells, and its presence in serum serves as a specific marker of thymic endocrine function6

  • expert opinionThymulin is a thymic hormone exclusively produced by the epithelial cells of the thymus8

  • expert opinionThymulin consists of an inactive nonapeptide component named FTS coupled in an equimolecular ratio to the zinc ion, which endows the molecule with biological activity8

  • expert opinionThymulin is a thymus peptide involved in several stages during intra-and extrathymic T-cell differentiation8

  • expert opinionThe active form of the metallopeptide has a specific molecular conformation that has been demonstrated by nuclear magnetic resonance8

  • expert opinionThe production and secretion of thymulin are strongly influenced by the neuro-endocrine system8

  • expert opinionThymulin is a hypophysiotropic peptide8

  • expert opinionThymulin is a thymic hormone exclusively produced by the epithelial cells of the thymus9

  • expert opinionProduction and secretion of thymulin are strongly influenced by the neuro-endocrine system9

  • expert opinionThymulin is a hypophysiotropic peptide9

  • expert opinionA synthetic DNA sequence encoding a biologically active analog of thymulin, metFTS, was constructed and cloned in a number of adenovectors9

  • expert opinionBidirectional regulatable Tet-Off vector systems can simultaneously express metFTS and green fluorescent protein and can be down-regulated reversibly by the addition of doxycycline9

  • expert opinionThymulin is a thymic hormone exclusively produced by the thymic epithelial cells11

  • expert opinionThymulin consists of a nonapeptide component coupled to the ion zinc, which confers biological activity to this molecule11

  • expert opinionThymulin was characterized as a thymic hormone involved in several aspects of intra- and extrathymic T-cell differentiation11

  • expert opinionThymulin production and secretion is strongly influenced by the neuroendocrine system11

  • expert opinionThymulin is a hypophysotropic peptide11

  • expert opinionThymulin is an important player in the hypophyso-thymic axis11

  • expert opinionThymulin is a putative thymic hormone reported to circulate and act on both prothymocytes and mature T-cells in the periphery14

  • expert opinionThymulin maintains T-cell commitment to the T-cell system and its functions14

  • expert opinionThymic epithelial cells secrete thymic hormones, exemplified by the zinc-thymulin complex, under stimulation with IL-1 and other hormonal influences14

  • expert opinionThe decrease of thymulin activity in anorexia nervosa might be the consequence of thymic atrophy secondary to malnutrition and/or hormonal disturbances17

  • expert opinionThymulin is a nonapeptide produced by the thymus21

  • expert opinionThymulin helps regulate the immune system and T-cell activity21

  • expert opinionThymulin is involved in immune regulation and T-cell differentiation21

  • expert opinionBPC-157 covers mechanism of action (VEGF, nitric oxide, tendon healing), gut protection, musculoskeletal repair, oral vs injectable research22

  • expert opinionCJC-1295 DAC is a long-acting GHRH analog with extended half-life and Drug Affinity Complex mechanism that elevates GH/IGF-122

  • expert opinionThymulin is a naturally occurring nonapeptide secreted by thymic epithelial cells23

  • expert opinionThymulin is biologically active when bound to zinc ions, forming a thymulin-zinc complex23

  • expert opinionThymulin promotes the differentiation of immature lymphocytes into functional T-cells, essential for adaptive immune responses23

  • expert opinionThymulin increases the cytotoxic activity of NK cells, supporting the body's defense against infections and abnormal cells23

  • expert opinionThymulin helps balance pro- and anti-inflammatory cytokines, reducing excessive inflammatory responses and supporting immune homeostasis23

  • expert opinionThymulin may influence the hypothalamic-pituitary-adrenal (HPA) axis, helping regulate stress responses and systemic inflammation23

  • expert opinionDardenne et al. (1974) first isolated thymulin and demonstrated its role in T-cell maturation23

  • expert opinionThymulin is a 9-amino-acid peptide hormone secreted by thymic epithelial cells25

  • expert opinionThymulin's serum concentration is a direct biomarker of thymic endocrine function. Levels peak in childhood, decline progressively from adolescence, and approach the limit of detection in old age.25

  • expert opinionThe amino acid sequence is pGlu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn, established by Pleau and colleagues in 197725

  • expert opinionThe N-terminal residue is pyroglutamic acid (pGlu), formed by spontaneous cyclization of glutamine.25

  • expert opinionThymulin is a zinc-dependent nonapeptide hormone produced by thymic epithelial cells26

  • expert opinionWithout bound zinc, the apopeptide is biologically inactive26

  • expert opinionThymulin is one of several thymic peptides that mediate the thymic contribution to T-cell development and peripheral immune balance26

  • expert opinionOnly attaches to its target when charged with zinc26

  • expert opinionShifts the balance of immune signals and cross-talks with prolactin and thyroid hormones26

  • expert opinionBinding one Zn²⁺ ion induces the conformational change required to bind target cellular machinery with apparent Kd ~5 × 10⁻⁷ M at physiological pH26

  • expert opinionThymulin binds high-affinity sites on T-cell precursors and mature T-cells, contributing to differentiation signals26

  • expert opinionThymulin restores IL-2 production in T-cells from immunodeficient hosts26

  • expert opinionThymulin is a nonapeptide hormone exclusively secreted by thymic epithelial cells, discovered by Jean-François Bach in the 1970s27

  • expert opinionThymulin is a single, defined 9-amino-acid peptide that requires zinc binding for biological activity27

  • expert opinionZinc-thymulin complex is the biologically active form - without zinc, the peptide has no immunological activity27

  • expert opinionThymulin promotes differentiation of immature T-cells into mature T-cell subsets27

  • expert opinionThymulin modulates cytokine release including IL-2 and interferon-gamma27

  • expert opinionThymulin regulates T-helper and T-suppressor cell balance27

  • expert opinionThymulin enhances NK cell activity27

  • expert opinionThymulin has anti-inflammatory effects through suppression of pro-inflammatory mediators27

  • expert opinionThymulin has neuroendocrine effects, influencing the hypothalamic-pituitary-adrenal axis27

  • theoreticalThymulin is a naturally occurring hormone produced by the thymus gland5

  • theoreticalThymulin is a nine-amino acid peptide hormone exclusively produced by reticulo-epithelial cells of the thymus gland7

  • theoreticalThymulin's biological activity depends entirely on equimolar binding of a zinc ion (Zn2+) to form an active metallopeptide complex7

  • theoreticalThymulin, a thymic hormone involved in T-lymphocyte maturation, is known to be Zn dependent13

  • theoreticalThymulin is adversely affected by Zn deficiency13

  • theoreticalAn adverse effect of Zn deficiency may be in lymphocyte differentiation and maturity13

  • theoretical5-Amino-1MQ is a selective NNMT inhibitor that boosts NAD+ levels with preclinical data showing anti-obesity and muscle function benefits but no human trials published22

  • theoreticalThymulin is a 9-amino acid metallopeptide hormone produced exclusively by thymic epithelial cells24

  • theoreticalThymulin requires zinc binding in 1:1 equimolecular ratio for biological activity24

  • theoreticalThe zinc-thymulin complex adopts a specific three-dimensional conformation essential for its immunomodulatory functions24

  • theoreticalThymulin induces T-cell differentiation, NK cell enhancement, and suppressor T-cell regulation24

  • theoreticalThymulin demonstrates potent anti-inflammatory and analgesic properties through inhibition of NF-κB, p38 MAPK, and pro-inflammatory cytokines24

  • theoreticalSerum thymulin levels decline progressively with age, peaking in pre-adolescence, contributing to immunosenescence24

  • theoreticalZinc-thymulin binds to high-affinity T-cell receptors24

  • theoreticalThymulin acts through NF-κB inhibition, p38 MAPK suppression, and reduction of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6)24

  • theoreticalThymulin may act through α7-nicotinic acetylcholine receptor potentiation for analgesic effects24

  • theoreticalApo-thymulin without zinc is biologically inactive24

  • theoreticalZinc coordination in thymulin involves Ser4, Ser8, N-terminal pGlu, and potentially Gln524

  • theoreticalThymulin is a nonapeptide hormone originally characterised as 'Serum Thymic Factor' (FTS)28

  • theoreticalThymulin is produced naturally by thymic epithelial cells28

  • theoreticalThymulin acts directly at the receptor level to induce the expression of specific T-cell markers28

  • theoreticalThe nonapeptide sequence requires a stoichiometric interaction with a zinc ion (Zn2+) to adopt the biologically active conformation28

  • theoreticalThymulin binds to high-affinity receptors on T-cells28

  • theoreticalThymulin has a role as a neuropeptide28

  • theoreticalThymulin is a 9-amino-acid peptide that requires zinc binding for biological activity31

  • theoreticalThymulin plays a defined role in T-cell differentiation, neuroimmune signaling, and inflammatory regulation in laboratory systems31

  • theoreticalThymulin's biological activity depends completely on zinc ion binding31

  • theoreticalThymulin is a hypophysiotropic peptide31

  • theoreticalThymulin and the hypothalamic-pituitary axis constitute the thymus-neuroendocrine axis31

  • theoreticalThymulin is secreted by thymic epithelial cells in vivo31

  • theoreticalThymulin uses zinc-dependent receptor interaction31

  • theoreticalThymosin Alpha-1 does not require zinc ions for its biological activity, unlike thymulin31

Dosing

Based on 2 animal findings, 5 expert opinion findings and 1 anecdotal finding.

  • animalAnimal research protocol for inflammation uses 15 μg/100g body weight as single dose or short course via IP or SubQ24

  • animalPAT analog pain research protocol uses 25-50 μg per rat (100-200 μg/kg) 30 minutes before inflammatory challenge via IP24

  • expert opinionThymulin peptide should be stored at -20°C, dry and dark conditions; protected from moisture21

  • expert opinionTypical dose in research protocols is 1-10 mcg per injection27

  • expert opinionTypical frequency is daily during research protocols27

  • expert opinionRoute of administration is typically subcutaneous or intraperitoneal injection in research settings27

  • expert opinionIntranasal delivery can be explored for CNS effects27

  • anecdotalAnecdotal human protocol uses 1-5 mg per injection once daily for 5-10 days via SubQ24

How the body handles it

Based on 2 theoretical findings.

  • theoreticalThymulin has very short half-life of approximately 10 minutes24

  • theoreticalNatural thymulin follows circadian rhythm correlating with ACTH24

Safety and side effects

Based on 2 human study findings, 8 expert opinion findings, 1 anecdotal finding and 1 theoretical finding.

  • human studyAn important feature of thymus preparations is their therapeutic safety—even long-term use does not cause side effects1

  • human studyThymulin is not toxic4

  • expert opinionNo marketing authorisation exists for thymulin5

  • expert opinionNot approved by FDA, EMA, or Health Canada5

  • expert opinionACE-031 produced unacceptable off-target effects, particularly vascular toxicity from broad TGF-beta superfamily inhibition22

  • expert opinionCorticosteroids require monitoring when combined with Thymulin24

  • expert opinionThymulin requires adequate zinc intake or supplementation for biological activity24

  • expert opinionThymulin is not FDA-approved. It is not on the FDA 503A bulks list, which means U.S. compounding pharmacies cannot lawfully prepare it.25

Show the remaining 4

  • expert opinionThymulin was not among the 12 peptides FDA removed from Category 2 on April 15, 2026.25

  • expert opinionNo commercial pharmaceutical sponsor is advancing it toward an NDA as of June 2026.25

  • anecdotalThe first public dataset of anecdotal peptide side-effect reports, aggregated from Reddit, research forums, and anonymous user submissions22

  • theoreticalThymulin is sensitive to chelation and thermal degradation28

What people use it for

Based on 1 human study finding, 3 animal findings, 9 expert opinion findings and 6 theoretical findings.

  • human studyThymic peptides are used in the treatment of neoplastic diseases, viral infections, autoimmune diseases or immunodeficiencies1

  • animalGene therapy for thymulin may be an effective therapeutic strategy to prevent some of the hormonal and reproductive abnormalities that typically appear in congenitally athymic (nude) mice8

  • animalThymic involution has been treated with interleukins, thymic hormones, growth hormone, prolactin, melatonin, zinc, and others12

  • animalWork to reverse thymic involution in hydrocortisone-treated, aged mice with interleukins, thymosin alpha 1, and zinc will be reviewed12

  • expert opinionThymulin's effect on suppressor T-cells is the most remarkable and should be the first to find useful clinical applications4

  • expert opinionThymulin and a synthetic analog act as anti-inflammatory and analgesic peptides in the central nervous system brain and other organs9

  • expert opinionThe fall in thymulin level might explain the variability of cellular immune responses in anorexia nervosa patients and occurrence of energy when weight loss is far advanced17

  • expert opinionThymulin is investigated for potential applications in immune dysfunction, inflammation, and dermatological health21

Show the remaining 11

  • expert opinionSome studies suggest Zinc-Thymulin may support hair follicle health, but clinical data is limited21

  • expert opinionThymulin is primarily studied for immune modulation, anti-inflammatory effects, and potential applications in skin and hair health21

  • expert opinionThymulin has zinc supplementation as synergistic interaction24

  • expert opinionThymulin is compatible with Thymosin Alpha-1, Thymosin Beta-4, Epithalon, and NSAIDs24

  • expert opinionRestores T-cell function in people who are zinc-deficient or have weakened immunity26

  • theoreticalGene therapy could potentially restore circulating thymulin levels in thymodeficient animal models and eventually in humans9

  • theoreticalThymulin is the primary subject of research concerning the extrathymic maturation of T-lymphocytes28

  • theoreticalThymulin can be used to study 'immune senescence' and whether exogenous administration can restore T-cell competence in aged animal models where thymic involution has occurred28

  • theoreticalThymulin can mitigate cytokine-induced pain hypersensitivity (allodynia) through the pituitary-adrenal axis28

  • theoreticalThymulin can be used to study the 'thymus-pituitary feedback loop' and understand how stress hormones suppress immune function28

  • theoreticalSerum thymulin serves as a sensitive biomarker of zinc status in research settings31

Other findings

Based on 1 human study finding, 8 expert opinion findings and 3 theoretical findings.

  • human studyThymulin is a natural hormone available in synthetic form4

  • expert opinionThymulin was discovered in 1977 by Jean-Francois Bach and Mireille Dardenne at the Institut Necker in Paris through a bioassay measuring the induction of T-cell differentiation markers (rosette formation) in mouse thymocytes6

  • expert opinionPeptide Protocol Wiki features 133+ evidence-based peptide profiles with dosing protocols, mechanism of action breakdowns, and clinical research summaries22

  • expert opinionThymulin was first characterized by Bach and colleagues in 197724

  • expert opinionCurrent scientific activity is preclinical gene-therapy work centered at the University of La Plata in Argentina.25

  • expert opinionThymulin is a distinct molecule from Thymosin Alpha-1 (a separate 28-amino-acid peptide) and from Thymalin (a Russian polypeptide extract). The three are not interchangeable.25

  • expert opinionThymulin was first isolated by Jean-François Bach and colleagues in Paris in 1975 from porcine and human serum26

  • expert opinionThe compound was renamed thymulin in 1981 once its zinc-dependence was established26

Show the remaining 4

  • expert opinionReconstituted thymulin should be stored at 2-8°C and used within 4 weeks27

  • theoreticalThis article is about semaglutide (Glucagon-like peptide-1 receptor agonist), not Thymulin30

  • theoreticalThymulin differs from Thymalin (polypeptide complex) and Thymosin Alpha-1 (larger peptide)31

  • theoreticalThymosin Alpha-1 is a 28-residue peptide, significantly larger than the 9-residue thymulin31

Points of contention

Where the evidence is unsettled, thin, or says less than the popular claim — worth knowing before you draw conclusions.

Contested

Human clinical evidence: negative trials versus optimistic vendor efficacy claims

A tier-3 profile (Thymulin Peptide Guide 2026: Zinc-Bound Thymic Hormone) reports the only randomized double-blind placebo-controlled human trials (Amor 1987 in rheumatoid arthritis, Roullet 1989 in multiple sclerosis) were both negative, and another (Thymulin (Facteur Thymique Serique, FTS) | PeptideTrace — PeptideTrace) reports zero registered clinical trials and no controlled human therapeutic trials. In contrast vendor/blog sources (Peptide Therapy - Thymulin – Revolution Health & Wellness, China Thymulin Peptide Manufacturers Suppliers - Cost Price Thymulin Peptide for Sale - NovoPept Biotech) claim broad benefits for immune restoration, autoimmune disease, antiviral effects and hair health without controlled human data.

Limited evidence

Most mechanistic and efficacy claims rest on animal, in-vitro or theoretical/vendor sources

Much of the reported activity (analgesia, neuroprotection, gene therapy, cytokine modulation, lung inflammation) comes from animal, in-vitro, or theoretical/vendor sources; higher-tier human data is largely observational (zinc deficiency, malnutrition, anorexia, aging) rather than interventional. No modern Phase 2/3 randomized trial exists and no pharmaceutical company has advanced thymulin through Phase 3.

Single source

Regulatory and dosing specifics come from single lower-tier sources

Details such as absence from the FDA 503A bulks list, exclusion from the 12 peptides FDA removed from Category 2 on April 15 2026, and no NDA sponsor as of June 2026 come only from Thymulin Peptide Guide 2026: Zinc-Bound Thymic Hormone. Human dosing (1–5 mg once daily for 5–10 days) is explicitly labeled anecdotal (Thymulin - Research, Dosing & Protocols | Pep-Pedia), and research doses (1–10 mcg) come from a single profile (Thymulin Overview, Dosing & Safety | Peptide Database); these should not be read as validated clinical regimens.

Other

Reported molecular weights and half-life vary slightly between sources

Free-peptide molecular weight is given as ~857, 857.85, 858.85 or 858.86 Da and the zinc-bound form as ~921, ~922 or ~924 Da across sources; half-life is described variously as 'minutes' or 'approximately 10 minutes.'

Inconsistency

An anecdotal human dose of 1–5 mg of thymulin per day is thousands of times larger than any amount used in actual research and is almost certainly a milligram-for-microgram mix-up.

One vendor-style source lists an "anecdotal human protocol" of 1–5 mg per injection once daily for 5–10 days. That is 100–5,000 times higher than the doses used in genuine research: research-oriented profiles describe roughly 1–10 micrograms per injection, and published animal work uses microgram amounts (for example 15 µg per 100 g of body weight). Thymulin is a tiny nine-amino-acid hormone that the body normally makes in trace quantities and that is cleared from the blood within minutes, so a milligram-scale injection has no basis in the science and most likely reflects a units error (milligrams written where micrograms were meant) rather than a real regimen anyone has followed. No human trial has validated any thymulin dose.

Using it with other compounds

Check a stack
  • VilonComplementary

    May be complementary

    Both are thymus-linked immune bioregulators that push the immune system toward balance rather than pure stimulation. Vilon is reported to stimulate thymus tissue growth and improve CD4/CD8 ratios, while thymulin drives T-lymphocyte maturation and normalizes CD4/CD8 balance from the endocrine side. They approach the same immune-normalizing endpoint by different routes, which makes them reasonably complementary for restoring aged/depleted immunity.

    Tier 4Theoretical — not established

    What the research doesn't fully establish

    The mechanisms clearly establish both peptides as immune modulators with overlapping functional outcomes. Both target thymic function (Vilon stimulates thymus tissue growth and differentiation; thymulin promotes T-lymphocyte maturation in thymic tissue), both modulate CD4/CD8 ratios (explicitly stated for both), both suppress excessive proinflammatory cytokines (IL-1β, IL-6, TNF-α suppression documented for both), and both engage NF-kB modulation (Vilon via gene expression modulation, thymulin via NF-kB inhibition). The four shared dimensions are directly supported by the provided mechanisms. The 'complementary' relationship type is justified: Vilon acts via receptor-independent chromatin remodeling and gene reactivation, while thymulin acts via cell-surface receptor binding and endocrine signaling—distinct mechanistic routes converging on immune normalization (T-cell balance, cytokine suppression, thymic function). This represents genuine complementarity rather than redundancy.

    Shares innate immune · anti inflammatory · T cell regulation · NF kB modulation

  • SelankComplementary

    Worth caution

    Selank is built from tuftsin, an immune-signaling antibody fragment, and shares T-cell/cytokine-balancing and anti-inflammatory activity with thymulin. They modulate immunity through different mechanisms (thymic-hormone maturation vs. tuftsin-like Th1/Th2 balancing), so they can complement each other in immune normalization.

    Tier 4Theoretical — not established

    What the research doesn't fully establish

    Both peptides' mechanisms clearly establish the claimed shared dimensions. Selank explicitly targets T_cell_regulation (approved tag) and anti_inflammatory (approved tag) via Th1-Th2 balancing and cytokine signaling. Thymulin explicitly targets T_cell_regulation (approved tag) and anti_inflammatory (approved tag) via T-lymphocyte maturation, CD4/CD8 modulation, and cytokine network suppression. The proposed relationship correctly identifies that they operate through distinct mechanistic pathways (thymic hormone maturation vs. tuftsin-derived immune signaling) while both converging on immune normalization endpoints. This mechanistic distinction without target overlap supports the complementary relationship claim.

    Shares T cell regulation · anti inflammatory

  • KPVComplementary

    No documented conflict

    Thymulin normalises T-cell balance and suppresses excess proinflammatory cytokines via NF-κB and p38 MAPK inhibition, while KPV independently dampens NF-κB-driven cytokine production. Both converge on restraining overactive inflammation through complementary immune mechanisms (adaptive T-cell tuning vs innate cytokine suppression).

    Tier 4Theoretical — not established

    What the research doesn't fully establish

    Both peptides' mechanisms clearly establish the three claimed shared dimensions: (1) innate_immune—KPV suppresses TNF-α, IL-1β, IL-6 and modulates contact hypersensitivity/IgE; thymulin suppresses excess proinflammatory cytokines and enhances NK cytotoxicity; (2) anti_inflammatory—both are explicitly described as anti-inflammatory with overlapping cytokine targets (TNF-α, IL-1β, IL-6); (3) NF_kB_modulation—KPV stabilizes IκBα and inhibits IKK/p65 nuclear import; thymulin inhibits NF-κB activation. The explanation correctly characterizes their complementary action: thymulin operates via T-cell maturation/CD4-CD8 balance and p38 MAPK inhibition (adaptive arm), while KPV acts through direct NF-κB/MAPK suppression in epithelial/innate cells (innate arm). Both converge on the same inflammatory output (TNF-α, IL-1β, IL-6 suppression) through distinct upstream pathways, which is the definition of complementarity. The mechanism descriptions fully support this relationship type and all three shared dimensions.

    Shares innate immune · anti inflammatory · NF kB modulation

  • LL-37Complementary

    No documented conflict

    Thymulin normalizes T-cell balance and dampens excess pro-inflammatory cytokines via NF-κB/p38 modulation, while LL-37 provides antimicrobial and TLR/FPR2-based innate immune actions. Their different immune targets can complement each other in immune support.

    Tier 4Theoretical — not established

    What the research doesn't fully establish

    Both peptides' mechanisms clearly establish the claimed shared dimensions. LL-37 is explicitly tagged with innate_immune and anti_inflammatory, with documented effects including immunomodulation (both anti- and pro-inflammatory), TLR/FPR2 signaling, and NF-κB pathway activation. Thymulin is also explicitly tagged innate_immune and anti_inflammatory, with documented T-cell maturation/differentiation, NF-κB inhibition, and suppression of excessive proinflammatory cytokines. The proposed relationship correctly identifies that they operate through distinct but compatible mechanisms: LL-37 acts primarily through pattern recognition receptors (TLRs, FPR2) and direct antimicrobial effects, while thymulin acts through T-cell regulation and cytokine modulation. These different mechanistic approaches to immune support are genuinely complementary rather than redundant, justifying the relationship type and both shared dimensions.

    Shares innate immune · anti inflammatory

  • PidotimodSame downstream effect

    Worth caution

    Thymulin is a thymic hormone that drives T-lymphocyte maturation, tunes CD4/CD8 balance and boosts NK cytotoxicity — the same adaptive-immunity endpoints pidotimod promotes through dendritic-cell maturation and Th1 differentiation. They reach the same destination by different upstream mechanisms, which can be complementary for immune-deficiency support but also overlapping; stacking multiple immunostimulants adds little beyond one and should be monitored.

    Tier 4Theoretical — not established

    What the research doesn't fully establish

    Both peptides' mechanisms clearly converge on shared downstream immune outcomes. Pidotimod promotes T-lymphocyte proliferation, Th1 differentiation, and NK cell activity through dendritic cell maturation and TLR signaling. Thymulin directly promotes T-lymphocyte maturation, modulates CD4/CD8 balance, and enhances NK cytotoxicity. Both are tagged with innate_immune, anti_inflammatory, and T_cell_regulation. The proposed relationship correctly identifies that they operate through distinct upstream mechanisms (dendritic cell activation via TLRs vs. direct thymic hormone signaling) but converge on the same functional endpoints: T-cell differentiation, NK enhancement, and immune balance. The explanation's characterization of complementary but potentially overlapping mechanisms is consistent with the provided descriptions.

    Shares innate immune · anti inflammatory · T cell regulation

  • ImunofanSame mechanism

    Worth caution

    Both are thymus-derived peptide hormones that normalize T-cell maturation, CD4/CD8 balance and NK cytotoxicity while dampening pro-inflammatory cytokines. Because they converge on the same thymic immune-tuning output, running them together is largely redundant rather than additive — pick one thymic immunomodulator rather than stacking two.

    Tier 4Theoretical — not established

    What the research doesn't fully establish

    While both peptides share three approved tags (innate_immune, anti_inflammatory, T_cell_regulation) and produce overlapping functional outcomes (T-cell maturation, CD4/CD8 balance, NK enhancement, cytokine modulation), the mechanism descriptions reveal distinct molecular pathways that do not justify 'same_mechanism' classification. Imunofan targets thymopoietin receptors via adenylate/guanylate cyclase and PKC-dependent P-glycoprotein modulation, with antioxidant effects through ceruloplasmin-transferrin and glutathione systems. Thymulin operates through NF-κB and p38 MAPK inhibition with zinc-dependent metallopeptide activation and α7-nicotinic receptor potentiation. These are fundamentally different signaling cascades (cAMP/PKA vs. NF-κB/MAPK) with different receptor systems and cofactor requirements. Shared functional endpoints do not establish mechanistic equivalence. The claim that they are 'largely redundant' cannot be supported from the provided mechanisms—convergent outputs from divergent pathways typically allow complementary rather than redundant effects.

    Shares innate immune · anti inflammatory · T cell regulation

  • LactoferrinComplementary

    No documented conflict

    Thymulin fine-tunes T-cell maturation and dampens excess pro-inflammatory cytokines, while lactoferrin acts on the innate/antimicrobial front. Their immune roles are distinct but converge on balanced immune function, making them a plausible complementary immune-support pairing.

    Tier 4Theoretical — not established

    What the research doesn't fully establish

    Both peptides' mechanisms clearly establish the claimed shared dimensions. Lactoferrin is explicitly tagged with innate_immune and anti_inflammatory, with documented effects including 'Anti-inflammatory and immunomodulatory activity' and 'Modulation of inflammatory, humoral and cellular immune responses.' Thymulin is similarly tagged innate_immune and anti_inflammatory, with effects including 'Suppresses excessive proinflammatory cytokine production' and 'Reported anti-inflammatory...effects.' The proposed relationship type 'complementary' is justified: lactoferrin operates through broad-spectrum antimicrobial activity and innate immune pathways (PI3K/Akt, ROS-mediated apoptosis), while thymulin operates through adaptive immune fine-tuning (T-cell maturation, CD4/CD8 balance, NF-kB/p38 MAPK inhibition). Their distinct mechanistic pathways converging on immune homeostasis and anti-inflammatory outcomes clearly supports a complementary relationship. The explanation accurately reflects the mechanism material provided.

    Shares innate immune · anti inflammatory

  • Alpha-MSHComplementary

    No documented conflict

    Alpha-MSH suppresses NF-kB (preserving IkBα) and calms inflammatory cytokines through melanocortin receptors, a different upstream mechanism than thymulin's zinc-dependent immune regulation, but both converge on reduced inflammatory cytokine output.

    Tier 4Theoretical — not established

    What the research doesn't fully establish

    Both peptides' mechanisms clearly establish anti-inflammatory and NF-kB modulation effects through distinct upstream pathways: Thymulin inhibits NF-kB and p38 MAPK while modulating cytokine networks (TNF-alpha, IL-1beta, IL-6) via zinc-dependent metallopeptide activation and T-cell regulation; Alpha-MSH suppresses NF-kB through IκBα preservation via melanocortin receptor signaling and cAMP/PKA pathway. The mechanisms describe different receptor systems and activation routes (zinc-dependent vs. melanocortin/cAMP-dependent) converging on the same downstream outcomes (NF-kB inhibition and reduced inflammatory cytokine production). This is a textbook complementary relationship—parallel anti-inflammatory effects achieved through mechanistically distinct pathways.

    Shares anti inflammatory · NF kB modulation

  • ElafinComplementary

    No documented conflict

    Thymulin normalizes T-cell balance and tamps down excess pro-inflammatory cytokines via NF-κB inhibition, while elafin controls neutrophil protease-driven tissue damage. They modulate adaptive and innate immunity from different angles toward a calmer, better-regulated immune response.

    Tier 4Theoretical — not established

    What the research doesn't fully establish

    Both peptides' mechanisms clearly support the proposed complementary relationship across all three claimed shared dimensions. (1) Innate_immune: Elafin directly inhibits neutrophil serine proteases (elastase, proteinase 3) and shows antimicrobial activity; Thymulin enhances NK cell cytotoxicity and modulates innate responses. (2) Anti_inflammatory: Elafin is explicitly tagged anti_inflammatory with NF-κB pathway modulation; Thymulin suppresses excessive proinflammatory cytokine production (TNF-alpha, IL-1beta, IL-6) and is tagged anti_inflammatory. (3) NF_kB_modulation: Both mechanisms explicitly reference NF-κB pathway involvement (Elafin: src-17, src-23; Thymulin: NF-κB inhibition reported). The explanation accurately characterizes their distinct but complementary mechanisms—elafin controlling neutrophil protease-driven innate damage while thymulin normalizes T-cell balance and cytokine production—both converging on immune regulation through NF-κB modulation. The mechanisms justify calling them complementary rather than redundant.

    Shares innate immune · anti inflammatory · NF kB modulation

  • KlothoComplementary

    No documented conflict

    Both restrain excess pro-inflammatory signaling with reported NF-κB inhibition — Klotho via NLRP3/NF-κB suppression and antioxidant pathways, thymulin via immune normalization and cytokine (TNF/IL-6) dampening. They approach inflammation from different systems (renal/metabolic vs. thymic/immune), so the anti-inflammatory effect is complementary rather than redundant.

    Tier 4Theoretical — not established

    What the research doesn't fully establish

    Both peptides' mechanisms clearly establish anti-inflammatory activity and NF-κB modulation as shared dimensions. Klotho's mechanism explicitly lists 'Anti-inflammatory activity' and 'NF-κB signaling' with NLRP3 inflammasome suppression. Thymulin's mechanism explicitly lists 'anti_inflammatory' and 'NF_kB_modulation' tags with documented NF-κB inhibition and cytokine dampening (TNF-alpha, IL-6). The proposed 'complementary' relationship is well-justified: the mechanisms show they target inflammation through distinct physiological systems (Klotho via renal/metabolic/antioxidant pathways; Thymulin via thymic/T-cell/immune pathways), making their anti-inflammatory effects additive rather than redundant. The explanation accurately reflects both mechanisms' documented approaches to restraining pro-inflammatory signaling.

    Shares anti inflammatory · NF kB modulation

Safety and side effects

Safety Profile

A tier-1 review states that an important feature of thymus preparations is their therapeutic safety, noting that even long-term use has not caused side effects (src-6). A tier-1 study similarly states thymulin is not toxic and is a natural hormone available in synthetic form (src-17).

These favorable safety statements should be read against the limits of the evidence base. Sources report that no modern Phase 2/3 randomized trial exists and no pharmaceutical company has ever brought thymulin through Phase 3 (src-4, src-30); the strongest interventional human data come from two 1980s–90s randomized trials that were both negative (src-2), and much of the mechanistic and efficacy literature is animal, in-vitro, or vendor-based. A structured safety database from controlled human dosing is therefore not described in the sources.

Interactions and Cofactor Requirements

One profile reports thymulin requires adequate zinc intake for biological activity and lists zinc supplementation as synergistic (src-9). The same profile describes thymulin as compatible with Thymosin Alpha-1, Thymosin Beta-4, Epithalon and NSAIDs, and states that corticosteroids require monitoring when combined (src-9). Because the zinc-free apopeptide is reported to be biologically inactive (src-1), zinc status is central to any reported activity.

Regulatory Caveat

Profiles state thymulin is not approved by the FDA, EMA or Health Canada, is absent from the FDA 503A bulks list (so U.S. compounding pharmacies cannot lawfully prepare it), and had no NDA sponsor as of June 2026 (src-2, src-3). These regulatory details come from a single lower-tier source. Nothing here should be read as clinical guidance.

Reconstitution and handling

Dosing

No dose has been established for this compound. There is no regulatory label for thymulin — sources report it is not FDA-, EMA- or Health Canada-approved (src-2, src-3) — so the figures below are what individual sources report, not guidance, and none are validated clinical regimens.

  • One lower-tier (tier-3) research-oriented profile lists a typical research dose of 1–10 mcg per injection given daily, administered subcutaneously or intraperitoneally, with intranasal delivery explored for CNS effects; this is not a validated clinical dose (src-5).
  • One source describes an animal inflammation research protocol using 15 μg/100 g body weight as a single dose or short course via IP or SubQ, and a PAT-analog pain research protocol using 25–50 μg per rat (100–200 μg/kg) given 30 minutes before inflammatory challenge via IP (src-9).
  • One source describes an anecdotal human protocol of 1–5 mg per injection once daily for 5–10 days via SubQ (src-9). This is explicitly labeled anecdotal and is orders of magnitude above the microgram research doses cited elsewhere.

No human trial has validated any of these regimens; the only randomized controlled human trials described (Amor 1987, Roullet 1989, under the analog name nonathymulin) were both negative (src-2).

Reconstitution and Storage

Profiles advise storing lyophilized thymulin at -20°C (dry, dark, protected from moisture) and reconstituted thymulin at 2–8°C, used within roughly 4 weeks — though one source states a shorter 7–10 day reconstituted window (src-5, src-9, src-12).

Sources note the peptide's practical fragility: thymulin activity depends on zinc, and the peptide is reported to be sensitive to chelation (zinc removal by agents such as EDTA or DTPA abolishes activity) and to thermal degradation (src-13, src-58). Because the zinc-free apopeptide is reported to be biologically inactive (src-1), handling that preserves the zinc-bound (Zn-FTS) complex is emphasized. One vendor product page is sold as a 10 mg total active Zn-FTS complex (src-13).

Sources

Ordered by evidence quality — the strongest first.

  1. Review of Thymic Peptides and Hormones: From Their ...(opens in a new tab)
    Tier 1Web · link.springer.com · 2024
  2. Thymus-derived hormonal and cellular control of cancer.(opens in a new tab)
    Tier 1PubMed · pubmed.ncbi.nlm.nih.gov · 2023
  3. Zinc and immunity.(opens in a new tab)
    Tier 1PubMed · pubmed.ncbi.nlm.nih.gov · 1998
  4. Thymulin, a zinc-dependent hormone.(opens in a new tab)
    Tier 1PubMed · pubmed.ncbi.nlm.nih.gov · 1989
  5. Thymulin (Facteur Thymique Serique, FTS) | PeptideTrace — PeptideTrace(opens in a new tab)
    Tier 2Web · peptidetrace.com
  6. Thymulin: Research Evidence & Safety Profile | PeptideInsight(opens in a new tab)
    Tier 2Web · peptideinsight.com · 2026
  7. Thymulin: Mechanism, Effects & Research Studies(opens in a new tab)
    Tier 2Web · peptpedia.org · 2026
  8. Physiology and Therapeutic Potential of the Thymic Peptide Thymulin(opens in a new tab)
    Tier 2Web · doi.org · 2014
  9. Physiology and therapeutic potential of the thymic peptide thymulin.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2014
  10. Zinc: mechanisms of host defense.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2007
  11. Thymulin and the neuroendocrine system.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2004
  12. Thymic endocrinology.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 1998
  13. Zinc: an overview.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 1995
  14. Thymic endocrinology.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 1992
  15. Thymulin (facteur thymique serique) and zinc contents of the thymus glands of malnourished children.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 1988
  16. Neuroendocrine regulation of thymus hormones: hypothalamic dependence of "facteur thymique serique" level.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 1986
  17. Thymulin (Zn-facteur thymique serique) activity in anorexia nervosa patients.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 1985
  18. Thymulin.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 1985
  19. Generation of a monoclonal antibody against facteur thymique serique (FTS).(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 1982
  20. Location of FTS (facteur thymique sérique) in the thymus of normal and auto-immune mice.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 1982
  21. China Thymulin Peptide Manufacturers Suppliers - Cost Price Thymulin Peptide for Sale - NovoPept Biotech(opens in a new tab)
    Tier 3Web · novopept.com
  22. Peptide Protocol Wiki — Evidence-Based Peptide Research Database(opens in a new tab)
    Tier 3Web · peptideprotocolwiki.com
  23. Peptide Therapy - Thymulin – Revolution Health & Wellness(opens in a new tab)
    Tier 3Web · revolutionhealth.org
  24. Thymulin - Research, Dosing & Protocols | Pep-Pedia(opens in a new tab)
    Tier 3Web · pep-pedia.org
  25. Thymulin Peptide Guide 2026: Zinc-Bound Thymic Hormone(opens in a new tab)
    Tier 3Web · thepeptidetoolkit.com · 2026
  26. Thymulin: Zinc-Bound Thymic Nonapeptide (1975) | Kalios(opens in a new tab)
    Tier 3Web · kalios.health · 2026
  27. Thymulin Overview, Dosing & Safety | Peptide Database(opens in a new tab)
    Tier 3Web · peptide-db.com · 2025
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