A member of the tumor necrosis factor receptor superfamily with specificity for cd40 ligand. It is found on mature b-lymphocytes and some epithelial cells, lymphoid dendritic cells. Evidence suggests that CD40-dependent activation of B-cells is important for generation of memory B-cells within the germinal centers. Mutations of the gene for CD40 antigen result in hyper-igm immunodeficiency syndrome, TYPE 3. Signaling of the receptor occurs through its association with TNF RECEPTOR-ASSOCIATED FACTORS.