Synthetic pentapeptide corresponding to the amino acids 32-36 of thymopoietin and exhibiting the full biological activity of the natural hormone. It is an immunomodulator which has been studied for possible use in the treatment of rheumatoid arthritis, AIDS, and other primary immunodeficiencies.

Two closely related polypeptides (molecular weight 7,000) isolated from the thymus gland. These hormones induce the differentiation of prothymocytes to thymocytes within the thymus. They also cause a delayed impairment of neuromuscular transmission in vivo and are therefore believed to be the agent responsible for myasthenia gravis.