Given the central role of CD40-CD40L signalling in the regulation of inflammatory processes, this dyad is involved in the pathophysiology of many autoimmune and inflammatory diseases, including inflammatory bowel disease, systemic lupus erythematosus (SLE), rheumatoid arthritis, type 1 diabetes mellitus and allograft rejection, as recently reviewed [13]. Here, CD40 is linked to systemic lupus erythematosus.