POTENTIAL ROLES OF THE B7 AND CD28 RECEPTOR FAMILIES IN AUTOIMMUNITY AND IMMUNE EVASION

Recognition of self major histocompatability complex (MHC) presented a ntigen (MHC:Ag) by the T cell antigen receptor (TCR) is by itself not sufficient to induce T cell proliferation. Rather, to be fully activat ed T cells require both a TCR-generated signal and a ''co-stimulatory' ' signal. This important costimulatory signal is not completely unders tood. Recent evidence suggests that this costimulatory signal is gener ated by the interaction of the T cell CD28 receptor with the B7 counte rreceptor found on antigen-presenting cells. Regulation of costimulati on may well prove to be more complex than was previously imagined base d on the discovery that CD28 and E7 are each members of larger gene fa milies. The present review highlights recent advances in the understan ding of the CD28 and B7 receptor families with an emphasis on controve rsies in the field. Certain forms of immunopathology that might result from the aberrant regulation of CD28 and/or B7 expression are also di scussed. (C) 1995 Academic Press, Inc.