Synthesis of an M Component by Circulating B Lymphocytes in Severe Combined Immunodeficiency

Abstract

SEVERE combined immunodeficiency is a hereditary disease characterized by considerable impairment of both cellular and humoral immunity and is assumed to result from a defect in lymphoid stem-cell maturation into thymus-derived (T) and bone-marrow-derived (B) lymphocytes.¹ High numbers of circulating immunoglobulin-bearing (B) cells have been reported in a number of cases of the disorder^{2 , 3} although the functional potential of such cells is not known. We have observed a case with a very high percentage of circulating IgM-bearing cells that lacked a surface receptor for complement component C3. These cells behaved as B cells, transforming with pokeweed mitogen and secreting an . . .