Thymalin

Thymalin (Thymulin; CAS 66017-93-4; MW 857.9 g/mol) is a 9-amino acid polypeptide bioregulator produced by the thymus gland, distinct from Thymosin Alpha-1 in mechanism and profile. While Thymosin Alpha-1 modulates T-cell function directly, Thymalin acts as a broader thymic bioregulator, restoring thymic microenvironment function, normalizing T-lymphocyte and B-lymphocyte counts, and reducing markers of inflammaging. Khavinson's 6-year human study using Thymalin + Epithalon showed 41% increased average lifespan vs. controls and over 75% reduction in age-related disease incidence. Thymalin fills the immune aging slot in the canonical four-target longevity stack (telomere maintenance + mitochondrial function + senescence clearance + immune aging).

This zinc-dependent nonapeptide functions as a thymic hormone essential for T-cell differentiation and immune system maturation. Unlike direct T-cell modulators, Thymalin works at the organ level to restore thymic architecture and function, addressing the age-related thymic involution that underlies immunosenescence. The peptide requires zinc for biological activity, forming a coordination complex critical for receptor binding and signal transduction.

In research applications, Thymalin demonstrates ability to normalize both T-lymphocyte and B-lymphocyte populations, restoring immune balance without overstimulation. The peptide reduces chronic low-grade inflammation characteristic of aging (inflammaging) while enhancing immune surveillance and response capacity. This dual action on immune cell populations and inflammatory tone makes it valuable for investigating immune aging, autoimmunity, and age-related disease prevention.

The landmark Khavinson clinical study provides compelling human data supporting Thymalin's role in longevity research. When combined with Epithalon in a comprehensive protocol targeting multiple aging hallmarks, the combination demonstrated unprecedented lifespan extension and disease reduction, establishing Thymalin as a cornerstone of evidence-based peptide longevity research.