Immunoregulatory defects in a family with selective IgA deficiency.

Defects in regulation of the humoral immune system were examined in a family with selective IgA deficiency. Two patients (mother and son) were clinically well and had selective abnormalities of B lymphocytes that can differentiate into IgA plasma cells plus specific T cell suppression of IgA production. One patient (daughter) had several clinical problems and received nine monthly transfusions of normal plasma. Prior to therapy, this patient had abnormal immunoregulation of both B and T lymphocyte population that cooperated in the formation of all cases of immunoglobulin-producing cells. After treatment, her clinical problems were resolved and her cellular abnormalities appeared identical in those in her mother and brother.