[Common variable immunodeficiency: an immunological study (author's transl)].

A 17-year-old school boy with recurrent sinopulmonary infection and diarrhea was found to have marked hypogammaglobulinemia. He had no family history of similar disorder. Serum IgG was measured 240 mg/dl, whereas all the other classes of immunoglobulins were undetectable with Mancini's technique. The polymorphonuclear leukocyte function and complement system were normal. Although the numbers of T and B lymphocytes were normal, we demonstrated that the patient's B cells were able to produce only IgG in subnormal amount and unable to secrete other classes of immunoglobulins. No hyperactive suppressor T cell function or inadequate helper T cell function was found. Therefore, the basic immmunopathogeneic mechanism was ascribed to intrinsic B cell defect.