Test Details: CD22, is a molecule belonging to the SIGLEC family of lectins. It is also called as B lymphocyte cell adhesion molecule (BL-CAM). It is found on the surface of mature B cells and to a lesser extent on some immature B cells. It is a regulatory molecule that prevents the overactivation of the immune system and the development of autoimmune diseases. CD 22 is known as a pan B cell marker and is also helpful for diagnosis of hairy cell leukaemia.