Thymosin

Thymosin is a family of proteins originally isolated from thymic tissue (the gland behind your sternum that trains immune cells). The name covers a diverse group of peptides with different structures and very different functions. Two thymosins appear on this site in different contexts: Thymosin Alpha-1 (Tα1) is a 28-amino-acid immune modulator, approved in over 35 countries as Zadaxin for viral hepatitis. It upregulates T-cell activity and has been used as an immune adjuvant in cancer and HIV contexts. This is the "immune" thymosin. Thymosin Beta-4 (Tβ4) is an actin-sequestering protein with tissue-repair and anti-inflammatory functions. TB-500 is a synthetic fragment that mimics its activity. This is the "repair" thymosin. They are not the same compound. They don't work through the same mechanism. Grouping them under "thymosin" confuses the evidence base — the clinical history for Thymosin Alpha-1 is extensive; the evidence base for TB-500/Thymosin Beta-4 is mostly animal data. Knowing which thymosin you're reading about matters.