IL21R and Crohn disease: Studies have shown that B cells may participate in osteoclastogenesis.(46) IL21R induces the growth-promoting signals of its ligand, IL21, which might be involved in the maturation and function of myeloid cells.(47) IL21R and IL21 have been revealed to be involved in a variety of human diseases, including cancers, inflammatory bowel disease and Crohn's disease, and multiple autoimmune diseases.