Agammaglobulinemia: The fundamental defect

Addition of phytohemagglutinin and of streptolysin S to in vitro cultures of leukocytes of normal and agammaglobulinemic subjects resulted in mitosis of lymphocytes and their differentiation to plasma cells. In contrast, specific antigens induced mitosis and differentiation of lymphocytes of normal but not of agammaglobulinemic donors. The data suggest that the absence of plasma cells in agammaglobulinemia is not in itself responsible for failure of antibody production, but is rather the morphologic concomitant of the primary defect (failure of antibody production on exposure to antigenic stimulus).