Recently attention has been newly focused on the histocompatibility antigen, Mls, because of its profound effect on the expressed T cell receptor V-beta gene repertoire. The goal of this research is to characterize Mls-a at the molecular level in order to define the elusive Mls-a gene product. cDNA encoding Mls-a will be identified using transient expression systems that allow functional detection of Mls determinants. Although Mls-a has been described nearly twenty years ago as a single gene trait that induces strong T lymphocyte proliferative responses in mixed lymphocyte cultures matched for the major histocompatibility antigens, the nature of this antigenic determinant has remained an enigma. These studies should provide direct insights into the nature of this "universal" tissue specific ligand that is recognized by the T cell receptor in the context of a class II molecule. This recognition molecule is important because it plays a role in regulation of immune responses by leading to elimination of immature thymocytes and activation of mature peripheral T lymphocytes.
