Thymulin — complete EU guide.
Thymulin (formerly FTS, facteur thymique sérique) is a zinc-dependent nonapeptide hormone produced by the thymus, discovered in 1977 and among the most thoroughly characterised thymic peptides in the immunology literature.
- Zinc-dependent nonapeptide (pGlu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn) produced exclusively by thymic epithelial cells; biologically inactive without bound zinc.
- Discovered in 1977 by Bach and Dardenne at the Institut Necker, Paris — a distinct research lineage from the Russian Khavinson bioregulators (e.g. Thymalin, Vilon) covered elsewhere in this encyclopedia.
- Best-characterised role: induction of T-cell differentiation markers and modulation of T-cell subset function in animal and in vitro models.
- A synthetic peptide analogue (PAT) has been studied separately for neuroprotective and analgesic effects in animal inflammation models.
- No completed modern human clinical trials; most mechanistic work dates from the 1980s–1990s French immunology literature.
What is Thymulin?
Thymulin, originally named facteur thymique sérique (FTS, 'serum thymic factor'), is a nonapeptide hormone produced exclusively by thymic epithelial cells. It was discovered in 1977 by Jean-François Bach and Mireille Dardenne at the Institut Necker in Paris. Its defining feature is a strict requirement for zinc: the zinc-free peptide (FTS) is biologically inactive, while the zinc-bound form (thymulin, or Zn-FTS) is the active hormone. This is distinct from the Khavinson-school Russian bioregulators (Thymalin, Vilon, Thymagen) covered elsewhere in this encyclopedia, which come from a separate research tradition.
How is it proposed to work?
Once bound to zinc, thymulin adopts a specific three-dimensional conformation, confirmed by NMR, that allows it to bind receptors on lymphocytes and induce T-cell differentiation markers. Research has focused on its role in T-cell maturation, modulation of natural killer cell activity, and a feedback loop with the hypothalamic-pituitary axis — circulating thymulin follows a circadian rhythm linked to ACTH levels.
What does the research show?
Thymulin is one of the best-characterised thymic hormones in the immunology literature, with a substantial body of animal and in vitro work from the 1980s and 1990s establishing its zinc-dependent structure and T-cell effects. A separate line of research has studied a peptide analogue of thymulin (PAT) for neuroprotective and analgesic properties in animal models of inflammation. However, most of this evidence predates modern clinical-trial standards, and no completed contemporary human trials exist.
EU legal status
Thymulin is not an approved medicine in the EU or elsewhere. It is sold by research-chemical suppliers as a laboratory peptide, research use only, and is not listed on WADA's prohibited list.
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Frequently asked questions
What is Thymulin? ▾
Thymulin (formerly FTS) is a zinc-dependent nonapeptide hormone produced by thymic epithelial cells, discovered in 1977. It requires bound zinc to be biologically active.
Is Thymulin the same as Thymalin or Thymagen? ▾
No. Thymulin comes from a separate French research lineage (Bach and Dardenne, Institut Necker), distinct from the Russian Khavinson bioregulator family that includes Thymalin, Vilon and Thymagen.
What is Thymulin studied for? ▾
Its best-characterised role is inducing T-cell differentiation markers and modulating T-cell subset function in animal and in vitro immunology research. A separate peptide analogue (PAT) has been studied for neuroprotective effects.
Why does Thymulin need zinc? ▾
The zinc-free peptide (FTS) is biologically inactive. Zinc binding induces the specific three-dimensional conformation required for receptor activity — a defining and unusual feature among thymic peptides.
Is Thymulin approved as a medicine? ▾
No. It has no approved medical indication in the EU or elsewhere and is sold strictly as a research chemical.
Is Thymulin banned in sport? ▾
No. It does not appear on WADA's prohibited list.
How do I verify Thymulin quality? ▾
Require a batch-specific COA from a named third-party lab confirming identity by mass spectrometry and purity by HPLC (≥98%).
References
- Original biochemical characterisation of the serum thymic factor (later named thymulin) by Bach and colleagues at the Institut Necker. Bach JF, et al. Nature. 1977;266(5597):55–57. DOI PubMed 300146
- Review establishing the equimolar zinc requirement for thymulin's biological activity, confirmed by NMR structural studies. Dardenne M, Pléau JM. Res Immunol. 1994;145(3):233–235. DOI PubMed 18476235
- Study of a thymulin-related peptide analogue (PAT) showing analgesic and anti-inflammatory effects in a neuropathic pain model. Safieh-Garabedian B, et al. Neurosci Lett. 2019;702:61–65. DOI PubMed 30503917