CD40 and its ligand: central players in B lymphocyte survival, growth, and differentiation.

This article brings together information garnered over the last 10 years on the B cell-associated CD40 surface glycoprotein. The discovery in 1992 of a natural counterstructure, the CD40 ligand (CD40L), which can be rapidly induced on T-cells has hastened research and increased interest in this area dramatically. It has become clear that CD40 and its ligand are central players in B cell responses to T-dependent antigens. The capacity of CD40 to deliver signals for B cell growth, differentiation and survival is covered together with discussion of the signal transduction pathways which operate to bring about these changes. Future issues surrounding this important receptor-ligand pair are discussed.