T-lymphocyte coactivator molecules

T-cell recognition and activation occurs within a specialized area of conta ct known as the immunologic synapse, localized to areas of glycolipid-enric hed membrane microdomains. Within this area, T-cell activation is dependent not only upon specific recognition of peptide antigen embedded within mole cules of the major histocompatibility complex, but also on a variety of cos timulatory receptors and interactions. Engagement of T-cell receptor (TCR) with antigen alone will induce T-cell unresponsiveness; ligation of the cor eceptor CD28 will prevent the induction of unresponsiveness. Novel costimul atory molecules belonging to both the CD28 and TNF/TNFR superfamilies have recently been identified. These receptors appear to act at different stages of T-cell differentiation and activation, have been shown to play a role i n promoting different T-cell effector functions, and are important for B-ce ll differentiation and function. (C) 2001 Lippincott Williams & Wilkins, In c.