Thymopentin

Thymopentin (TP-5) is a synthetic pentapeptide corresponding to residues 32–36 (Arg-Lys-Asp-Val-Tyr) of the thymic hormone Thymopoietin. It is an immunomodulator that promotes T-lymphocyte maturation and restores cell-mediated immune function. Thymopentin has been used clinically in Italy and other countries for HIV infection, atopic dermatitis, and rheumatoid arthritis, though it remains a research compound in the United States.

Thymopentin binds to thymopentin receptors on immature lymphoid precursors, inducing differentiation toward CD4+ and CD8+ T-cell phenotypes and expression of T-cell surface markers (including Thy-1). It promotes IL-2 production and T-helper cell activity, enhancing both cellular and humoral immunity. TP-5 also modulates NK cell activity and has been reported to normalize aberrant T-cell subset ratios in immunocompromised patients. Its mechanism reflects the active core of full-length Thymopoietin.

Multiple clinical trials conducted primarily in Italy and Eastern Europe have evaluated Thymopentin in HIV-infected patients, reporting CD4+ cell count stabilization and reduced infection frequency. Studies in atopic dermatitis showed immune rebalancing and reduced IgE levels. A Phase II trial evaluated TP-5 in rheumatoid arthritis with modest benefit. The compound was approved in Italy (brand: Timopentina) for HIV-associated immune deficiency. No FDA approval has been sought in the United States, where it remains classified as a research compound.

Peptides commonly paired with Thymopentin for synergistic effects.