Thymalin

Thymulin (Facteur Thymique Sérique, FTS) is a nonapeptide hormone produced by thymic epithelial cells that requires zinc for biological activity. The zinc-thymulin complex plays essential roles in T-cell differentiation, maturation, and immune system development. Research demonstrates thymulin modulates multiple immune functions including T-cell subset balance, cytokine production, and immune cell activation. As the thymus involutes with age, thymulin levels decline significantly, contributing to age-related immune dysfunction (immunosenescence). Studies show thymulin supplementation may restore some immune parameters in aging animal models. The peptide influences neuroendocrine-immune interactions through effects on hypothalamic-pituitary function. Research indicates potential applications for immune reconstitution, autoimmune conditions, and age-related immune decline. Thymulin has also shown analgesic and anti-inflammatory properties independent of its immune effects. The zinc dependence makes adequate zinc status essential for thymulin function. Clinical applications remain limited by the peptide's short half-life and need for specific delivery methods.

The evidence base is dominated by the Khavinson program and Russian-language studies with small samples and limited methodological reporting; no large international trials exist, the preparation is not FDA approved, and standardization of the extract is difficult.

Thymalin is a polypeptide extract of calf thymus developed as an immunomodulator in Russia, typically given by subcutaneous or intramuscular injection in short courses. As a heterogeneous biological extract it has no single defined half-life, and published pharmacokinetic data are minimal.