Thymalin

Thymalin is a polypeptide extract derived from bovine thymus glands, containing a mixture of thymic peptides including thymopoietin fragments and other low-molecular-weight immunoregulatory peptides. It was developed in the Soviet Union in the 1970s and is registered as a pharmaceutical in Russia, where it has been used clinically to restore immune function in immunodeficient states, cancer patients undergoing chemotherapy, and elderly populations with age-related immune decline. Proposed mechanisms include stimulation of T-cell maturation and differentiation, restoration of CD4/CD8 ratios, and modulation of cytokine balance, though molecular targets have not been rigorously characterized by modern standards. Most supporting evidence comes from Soviet-era and post-Soviet clinical literature with significant methodological limitations; it is not approved by the FDA, EMA, or comparable regulatory bodies outside Russia.

Evidence last reviewed: 19 Apr 2026