present on the membrane of many circulating B lymphocytes; may play a role in antigen triggered lymphocyte differentiation.
An immunoglobulin which accounts for less than 1% of plasma immunoglobulin. It is found on the membrane of many circulating B LYMPHOCYTES.
An immunoglobulin isotype (subclass). This isotype is expressed on naive B cells along with IgM. Little is known about its physiologic role.