Thymosin Alpha-1 (Tα1) is a 28-amino acid peptide naturally secreted by the thymus gland, where it plays a central role in T-cell maturation, differentiation, and immune surveillance. It is one of the most well-characterized immunomodulatory peptides, with decades of research demonstrating its ability to enhance both innate and adaptive immune responses, increase NK cell activity, modulate dendritic cell function, and upregulate cytokine signaling including IL-2 and IFN-γ. Research has also explored its anti-tumor, antiviral, and anti-inflammatory properties, positioning it at the intersection of immune defense, repair, and healthy aging research.