CL binding of IgM-expressing B cells. The percentage of double-positive cells (upper right gate) is expressed as the percentage of IgM-positive B cells. Binding of labeled CL vesicles and anti-IgM: (A) patient 1; (B) patient 3; and (C) healthy subject. Inhibition of labeled CL vesicles binding with nonlabeled CL vesicles: (D) patient 1 and (E) patient 3. Inhibition of labeled CL vesicles binding with nonlabeled PC vesicles: (F) patient 1 and (G) patient 3.