IL21 and autoimmune disease: Further studies are still needed to delineate the exact mechanisms of action of IL-4 and IL-21 on the B cell differentiation and survival of autoreactive B cells in primary B cell cultures in the presence of different co-stimulatory factors and the animal models of autoimmune diseases, and how antibodies against these cytokines can modulate the phenotypes of autoreactive B cells and improve the clinical outcomes of patients with autoimmune diseases.