Antibody response to a protein antigen (ovalbumin) in dissociated spleen cell cultures from primed mice. Evidence for a suppressive effect of antigen.

A system is described with which an antibody response to soluble chicken ovalbumin can be obtained in dissociated spleen cell cultures from primed mice. This was assayed by determining specific anti-ovalbumin plaque-forming cells (PFC). Only IgG-producing cells (indirect PFC) were seen. The mice received alum-precipitated ovalbumin i.p. and cultures were set up either late in the primary splenic response (23–27 days after injection) or near the peak of the response (10–14 days). With both groups secondary responses were seen in the presence of antigen on the fourth day of culture. In the second group PFC were present in the cultures at a high level initially. The number of PFC decreased over the first 2 days, the rate of decrease being greater in the presence of antigen. When mice were primed with alum-precipitated ovalbumin together with as adjuvant, responses could not now be obtained in culture. With mice taken late in the primary response (23–27 days), a considerable number of PFC were present in the cultures initially. The number decreased throughout the 4-day period and the decline was accelerated by antigen. With mice taken near the peak of the response (10–14 days) no PFC were seen in culture, even on the first day, in the presence or absence of antigen. The first phenomenon, suppression by antigen, is considered to be of general significance since it may also be seen in cultures from mice receiving no as described. It is suggested that the second phenomenon is due to adverse culture conditions resulting from the white cell mobilization initiated by ; after 23–27 days conditions have recovered to a point where suppression but not the secondary response can occur. The suppressive effect of antigen could be related to antigenic competition or tolerance.