CD40 and neoplasm: When CD40L engages CD40 on the surface of B cells, it promotes germinal center formation, immunoglobulin (Ig) isotype switching, somatic hypermutation to enhance antigen affinity, and lastly, the formation of long-lived plasma cells and memory B cells [28].Various studies have been conducted to utilize gene delivery of CD40L to DCs and tumor cells for tumor immunotherapy.