Recovery ⏱ Half-life: ~15-20 minutes (serum) Experimental

Thymulin

Facteur Thymique Sérique (FTS, Serum Thymic Factor)

Updated March 30, 2026

Evidence at a Glance

Regulatory statusExperimental
Zinc-bound thymic nonapeptide; only one old human interventional trial (1982); no modern drug-development program.
Human evidenceLimited
Animal evidenceExtensive

Thymulin is a zinc-dependent thymic hormone with extensive rodent immune data but essentially no modern human clinical trials beyond small, unreplicated pilots and a serum-marker role in zinc deficiency.

What the research does not support

  • It has no modern randomized human trials supporting any therapeutic claim.
  • Its activity depends on adequate zinc, and it is not a proven immune therapy in humans.
  • The topical zinc-thymulin hair-growth pilot was small, unblinded, and not placebo-controlled.
  • It is not FDA-approved and remains a research compound.
Half-Life
~15-20 minutes (serum)
Purity
≥98%
Mol. Weight
857.9 Da
Form
Lyophilized powder

What is Thymulin?

Thymulin is a nonapeptide hormone produced by thymic epithelial cells, discovered in the 1970s by Bach and colleagues. It is unique among thymic hormones in requiring zinc as a metallic cofactor, creating a direct link between zinc nutrition and immune competence. The age-related decline in thymulin mirrors immune aging, making it a biomarker and potential therapeutic target for immunosenescence.

Dosage Information (Research Use)

Research doses: 1-10μg/kg in animal studies. No standardized human protocol. Often studied in zinc-supplemented contexts. Research compound only.

Reconstitution & Handling

Reconstitute in sterile saline. Zinc must be present for biological activity.

Half-Life & Pharmacokinetics

~15-20 minutes (serum)

Reported Observations in Literature

Limited toxicity data. Well tolerated in animal studies. Zinc-dependent — excess zinc supplementation carries its own risks.

Key Research References

  • Bach JF. “Thymulin (FTS-Zn).” Clin Immunol Immunopathol. 1983;27:1-12
  • Reggiani PC et al. “Thymulin gene therapy.” Int Immunopharmacol. 2014;23:57-62

How Thymulin Works

Thymulin is the only thymic hormone with a fully characterized molecular structure. It requires zinc for biological activity — the Zn²⁺ ion stabilizes the peptide's active conformation. Thymulin promotes T-cell differentiation by inducing expression of T-cell markers (CD2, CD3, CD4, CD8) on immature thymocytes. It also modulates cytokine production and has demonstrated anti-inflammatory effects through HPA axis interaction.

Research Applications

🔬 Immunosenescence and aging
🔬 T-cell development and function
🔬 Autoimmune disease modulation

Research Findings

Thymulin levels decline dramatically with age, correlating with thymic involution. Zinc supplementation in elderly populations partially restores thymulin activity. Intranasal administration shows neuroprotective effects in demyelination models. Current research explores thymulin gene therapy for immune reconstitution.

Dosage & Administration

Research doses: 1-10μg/kg in animal studies. No standardized human protocol. Often studied in zinc-supplemented contexts. Research compound only.

Safety & Side Effects

Limited toxicity data. Well tolerated in animal studies. Zinc-dependent — excess zinc supplementation carries its own risks.

Important: All safety information is derived from published research, primarily animal studies. No controlled human clinical trial data exists unless explicitly noted. This compound is sold for research purposes only.

Quick Facts

Sequence Glu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn
Molecular Weight 857.9 Da
Half-Life ~15-20 minutes (serum)
Purity ≥98%
Form Lyophilized powder
Storage Lyophilized: -20°C. Reconstituted: 2-8°C, use within 24 hours.

Key Research References

  • Bach JF. "Thymulin (FTS-Zn)." Clin Immunol Immunopathol. 1983;27:1-12
  • Reggiani PC et al. "Thymulin gene therapy." Int Immunopharmacol. 2014;23:57-62

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