CD40 and autoimmune disease: Current strategies for autoimmune diseases include appropriate targets for therapeutic modulation such as B cell surface antigens (CD20 and CD22), co-stimulatory molecules (CTLA-4, CD40/CD40L, ICOS/ICOSL, and BAFF/APRIL/BAFF-R/BCMA/TACI), and various intracellular signal transduction pathways (Syk and Btk) (Fig. 1) [47, 48].