ABSTRACT
Since the mid 1970s it has been known that helper and cytotoxic T cells recognize foreign antigenic determinants "in the context" of normal self-cell surface components, the major histocompatibility complex (MHC) encoded protein^.'.^ In the 10 years following the discovery of these basic phenomena, a vast number of studies of T cell specificity were performed which led to a rather thorough understanding of T cell recognition at the phenominological level. However, since the T cell antigen receptor molecule was not identified until the early 1980s, analysis of the molecular basis of T cell specificity was not possible until recently. In the first part of this review, I will summarize some of the recent studies of the T cell receptor a and p chain proteins, and the genes that encode them. These studies represent the initial effort at developing an understanding of the molecular basis of MHCrestricted T cell recognition. In anticipation of the conclusions of this review, I note that the current status of the studies does not allow solid conclusions to be drawn as to the structural basis of T cell specificity for MHC and antigens. Nonetheless, several models have been ruled out and the basis has been laid for the eventual solution to this problem.
