Research Only Immune & Anti-Inflammatory

Thymulin

also known as: FTS, Facteur Thymique Sérique, Serum Thymic Factor

A zinc-dependent thymic peptide — biologically active only when zinc-saturated, making serum thymulin activity a functional readout of zinc status.

A nonapeptide thymic hormone (pGlu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn) isolated by Bach in the 1970s, requiring zinc binding for biological activity and acting primarily on T-cell differentiation and function.

Mechanism of action

Zinc-bound thymulin promotes T-cell maturation (particularly CD4+ and CD8+ differentiation from thymic precursors), enhances NK cell cytotoxicity, and modulates IL-2 production. Activity absolutely depends on zinc binding — in zinc-deficient states serum immunoreactive thymulin remains but loses biological activity.

Primary uses

Thymic function research
Zinc-status functional assessment
Community immune support (limited data)

Typical dosing

research-only varies (subcutaneous (community))

No human clinical dosing standard.

Regulatory status

Not approved. Primarily a research compound and diagnostic marker (serum thymulin activity is used as a functional zinc-status readout in nutritional research).

References

[pubmed] Dardenne M, et al. "Contribution of zinc and other metals to the biological activity of the serum thymic factor." Proc Natl Acad Sci USA, 1982;79:5370-5373.
[review] Mocchegiani E, et al. "Zinc, thymulin and aging: key-links and biological significance." Front Biosci, 2010;15:693-710.

Related peptides

Thymosin α1

The most clinically studied thymic peptide — approved in 35+ countries as Zadaxin for hepatitis B and C, with 30+ RCTs across more than 11,000 subjects. Not FDA-approved despite extensive global use.

Thymopentin

A synthetic pentapeptide fragment of thymopoietin — historically marketed as Timunox for immunodeficiency, now primarily used in research and limited European clinical practice.

Thymosin β4

The natural 44-amino-acid parent of the TB-500 research peptide — in clinical trials (as RGN-259/Lacripep) for dry eye disease, corneal wounds, and dermal healing.

Disclaimer

This entry is for educational purposes only and does not constitute medical advice. Dosing information reflects published regulatory or research data and is not a recommendation. Many compounds described here are not approved for human use in the United States. Consult a licensed medical professional before considering any peptide therapy.