The role of CD40-CD154 interactions in the regulation of cell mediated immunity.

CD40 is expressed on a diverse array of cell types from the hematopoietic and non-hematopoietic compartments. Within the hematopoietic compartment, CD40 is found constitutively expressed on B cells, dendritic cells (DC) and macrophages. The function of CD40 in B cells has been documented as being essential in the control of humoral immunity. In DCs and macrophages, CD40 has been shown to be important in the induction of antigen-presenting cell (APC) maturation and effector function. CD40 is also expressed on non-hematopoietic cells like keratinocytes, epithelial cells, and vascular endothelial cells and has been shown to be functionally important on these cell types.