CBA/N mice have an X-linked defect in B-lymphocyte function characterized by a failure to respond to certain thymus-independent antigens. When studied by rapid flow microfluorometry, adult CBA/N splenic B lymphocytes labeled with either fluorescein-conjugated (Fl) anti-Ig or Fl anti-mu had fluorescence profiles which were considerably different from those of B lymphocytes derived from normal mi...