Induction of IgG production in a human monoclonal B lymphoblastoid cell line by a B cell-specific monoclonal antibody

IgG production was induced in a human B blastoid cell line, CESS, by stimulation with a human B cell-specific monoclonal antibody (IIIA₄). The number of IgG-producing cells reached its maximal level within 48 hr after incubation with IIIA₄. IgG-producing cells induced by an optimal concentration of antibody was about one-half as many as those induced with TRF, but higher concentrations of the antibody were rather inhibitory. Simultaneous addition of an optimal concentration of the antibody with TRF partially inhibited TRF-induced IgG production in CESS cells, but higher concentrations of the antibody did not block TRF-induced IgG production. TRF activity was completely absorbed with IIIA₄-coated CESS cells as well as nontreated CESS cells. These results suggested that the membrane antigen recognized by IIIA₄ was not the acceptor molecule for TRF. IIIA₄ did not show any inhibitory effect on PWM-induced proliferation of normal B cells, but completely inhibited PWM-induced Ig production of normal B cells.