SLAM AND ITS ROLE IN T-CELL ACTIVATION AND TH CELL RESPONSES

Following the initial events of T cell activation, triggered by bindin g of specific peptide-MHC complex to the TCR for antigen and engagemen t of costimulatory molecules, a number of activation molecules are exp ressed on the cell surface. Many of these molecules regulate T cell fu nction, T-T cell interactions and the interaction of T cells with othe r cells. One such molecule is SLAM, a multifunctional 70 kDa glycoprot ein member of the Ig superfamily with multiple isoforms. SLAM is rapid ly induced on naive T cells and B cells following activation. Engageme nt of SLAM by a specific antibody (mAb A12) results in IL-2-independen t T cell expansion and induction/up-regulation of IFN-gamma by activat ed T cells, including Th2 cells. SLAM was found to be a high-affinity self-ligand mediating molecular and cellular hemophilic interactions. In this review we discuss SLAM as a receptor involved in T cell expans ion and in directing immune responses to a Th0-Th1 pathway.