Induction of human immunoglobulin secretion: III. Inhibition of induction of IgG and IgA production in spleen but not peripheral blood cells by mitogenic antibody to IgM and IgD

Abstract

Human peripheral blood and spleen mononuclear cells (MNC) were induced (SI = 5–30) to proliferate in vitro after stimulation by F(ab′) 2 fragments of goat anti-IgM antibody. Lower levels of DNA synthesis (SI = 2–14) were also observed following stimulation with anti-IgD antibody, whereas no DNA synthesis was detected in cultures containing F(ab′) 2 fragments of normal goat IgG antibody. Both intact and F(ab′) 2 fragments of anti-IgM antibody had stimulatory capacity for MNC, but intact antibody was less active. Anti-immunoglobulin (Ig) antibodies alone did not induce Ig secretion in either peripheral blood or spleen cells. In spleen cultures anti-IgM completely inhibited IgM, IgG, and IgA production induced by Staphylococcus aureus bacteria strain Cowan I, pokeweed mitogen (PWM), or low concentrations of Cowan I plus PWM. Anti-IgD partially inhibited mitogen-generated Ig secretion by spleen cells. However, quite a different result was obtained with peripheral blood MNC in which anti-IgM antibody selectively abrogated the induction of IgM production by the mitogens. No inhibition was observed for induction of IgG and IgA production. Anti-IgD antibody did not show any significant suppressive effect on mitogen-induced production of the three classes of Ig using blood cells. These results suggest a difference in maturation stage of B-cell subsets in peripheral blood compared to spleen.