[Terminal B-cell maturation and immunoglobulin synthesis in vitro in primary and secondary immune deficiencies].

Peripheral blood lymphocytes (PBL) from patients with various forms of primary and secondary immunodeficiencies and from 30 healthy control persons were examined for their capacity to show terminal B-cell maturation and immunoglobulin (Ig) synthesis in vitro following pokeweed mitogen (PWM) stimulation. PBL were cultured for 9 days with or without PWM and the percentages of B-cells or plasma cells with strongly positive cytoplasmic Ig (CIg+) were determined by indirect immunofluorescence on methanol fixed cytocentrifuged lymphocyte smears. In addition, newly synthesized IgA, IgG and IgM was measured in the cell free culture supernatant by means of a sensitive microplate ELISA. In 29 out of 30 control cultures the proportion of CIg+-cells increased markedly following 9-day stimulation with PWM. CIg+-cells and newly synthesized Ig were significantly correlated. In a group of 18 patients with common variable immunodeficiency (CVID) maturation to CIg+-cells was greatly impaired and the in vitro production of IgA and IgG was reduced. Two infants with severe combined immunodeficiency (SCID) failed to produce Ig prior to and following haplo-identical bone marrow transplantation despite the presence of immature B-cells. A heterogeneous group of secondary immunodeficiencies showed different forms of an impaired terminal B-cell maturation and a reduced capacity to synthesize Ig in vitro. The described PWM culture techniques in combination with the evaluation of CIg+-cells and the measurement of newly synthesized Ig in the culture supernatant proved to be a reliable in vitro correlate for terminal B-cell maturation and represent an important tool for the classification of humoral immunodeficiencies.