Hormones that play a critical role in the immune system. They include thymosin a, (32 fraction 5, thymus humoral factor (THG-γ2), and thymopoietin.
Any of the hormones produced by the thymus that may help attract lymphoid stem cells to the thymus and stimulate their development into mature T lymphocytes. These hormones include thymulin, thymopoietin, and thymosin.