Antigen‐antibody complexes suppress antibody production by mouse plasmacytoma cells in vitro

Preformed complexes of 2,4‐dinitrophenylated keyhole limpet hemocyanin (DNP‐KLH) and anti‐DNP or anti‐KLH antibodies selectively, suppressed the production of anti‐DNP IgA by the plasmacytoma cell line, MOPC 315, in vitro. Complexes made with DNP8.5KLH (8.5 moles DNP/105 daltons carrier) inhibited the secretion of IgA but not its synthesis, whereas complexes prepared with the more highly substituted DNP20KLH inhibited synthesis as well. Moreover, complexes of DNP‐KLH and anti‐DNP F(ab′)2 fragments were as suppressive as those made with IgG antibodies, suggesting that the mode of presentation of antigenic determinants and not surface Fc receptors may play a major role in this phenomenon.