A zinc-dependent thymic hormone that regulates T-cell development and declines dramatically with age.
Thymulin (formerly called Facteur Thymique Sérique or FTS) is a nonapeptide hormone produced exclusively by thymic epithelial cells. It is unique among thymic peptides in requiring zinc for biological activity — the active form is a zinc-thymulin complex. Thymulin promotes T-lymphocyte differentiation and maturation, enhances NK cell activity, and modulates inflammatory cytokine production.
Thymulin levels peak in adolescence and decline progressively with age, closely paralleling thymic involution. By age 60, circulating thymulin is often undetectable. This age-related decline correlates with reduced immune competence, increased susceptibility to infections, and impaired vaccine responses in elderly populations.
Research interest in thymulin supplementation focuses on restoring immune function in aging, enhancing vaccine efficacy, and modulating inflammatory and autoimmune conditions. Its zinc requirement also highlights the interplay between zinc status and immune function.
Animal studies demonstrate thymulin supplementation restores T-cell subsets in aged mice, improves vaccine responses, and reduces inflammatory markers associated with aging (inflammaging). Zinc-thymulin complexes show anti-nociceptive (pain-reducing) effects in inflammatory pain models.
Human observational data confirms thymulin decline with aging. Small clinical studies in elderly populations show thymulin supplementation can partially restore T-cell function markers. The zinc dependency means that zinc-deficient individuals may have compounded thymulin deficiency.
📚 Key Reference: PMID: 2474563 (thymulin aging), PMID: 8307034 (zinc-thymulin)
Limited human clinical data. Preclinical safety is favorable. As an endogenous thymic hormone, theoretical toxicity is low. Zinc supplementation should be monitored to avoid copper deficiency. Consult your provider.
NOT FDA-approved. Research use only.