A Multifaceted Role for Thymosin and its Composite Peptides in T-Cell Regulation

Abstract

The thymus synthesizes and secretes several biochemically distinct hormone-like products. A number of these factors with thymic hormone-like activity have been isolated from thymus tissue and blood. These preparations are in various stages of characterization and include: thymosin fraction 5, thymosin α1, thymosin α7, thymosin β3 and thymosin β4, thymopoietin II (TP), thymic humoral factor (THF), facteur thymique serique (FTS), thymic factor (TF), and a number of other thymosin fraction 5-like preparations such as TFX and TP-1. Thymosin fraction 5 has been found to contain a number of active peptides with molecular weights ranging from 1,000 to 15,000. Several of these peptides have now been purified to homogeneity, sequenced, chemically synthesized and, in the case of thymosin α1, cloned.