THE ROLE OF CD40 IN THE REGULATION OF HUMORAL AND CELL-MEDIATED-IMMUNITY

The dynamic and reciprocal communication between T helper (Th) cells a nd B cells appears to rely on the provision of multiple signals. The f irst is antigen specific and is mediated by the interaction between th e T-cell receptor (TCR) and antigen bound to the major histocompatibil ity complex (MHC). The subsequent signals are provided by the binding of accessory molecules such as CD28 and CD40 to their respective ligan ds. Here, Fiona Durie and colleagues discuss the co-stimulatory role o f the interaction between CD40 on B cells and CD40 ligand (CD40L, gp39 ) on T cells, and review evidence that suggests blocking this interact ion may induce T-cell tolerance.