Comparable T-dependence of 19S and 7S secondary responses to sheep erythrocytes in vitro

Abstract

Cooperation in the secondary plaque-forming cell (PFC) response in vitro was demonstrated between spleen cells from LAF 1 mice taken 56–125 days and taken 2 days after intravenous injection of sheep erythrocytes. The day-2 cells functioned as immune T cells as shown by sensitivity to anti- ϑ . Conditions of immunization determined whether the presence of anti- μ throughout the culture period interfered with the direct PFC response alone or with both the direct (19S) and indirect (7S + 19S) PFC responses. The presence of anti- γ only inhibited the 7S responses. In either case, addition of graded numbers (10 4 –10 6 ) of day-2 cells to the long-term immune spleen cells reconstituted the 19S and 7S antibody responses in parallel. It is concluded that both secondary responses are equally thymus dependent.