Abstract: | Mouse spleen cells from immunized and naive animals were cultured for 3 days with SRBC and antisera to H-2K, H-2D, Ia, or aggregated IgG. Direct and indirect antibody responses were impaired by each of these agents only when the responding cells had been obtained from unimmunized mice. It was found that as lymphoid cells reacted to the antigen and progressed toward a fully matured antibody response, they first became resistant to inhibition by anti-H-2K and H-2D sera and somewhat later they lost their vulnerability to agents that reacted with Ia antigens. |