Modulation in vivo of Lyt 2 antigen expression on T cells by anti-Lyt 2 antibody: effects on Con A-induced unresponsiveness.

After a series of intraperitoneal injections of rat monoclonal anti-Lyt 2 antibody supernatant, BDF1 mice showed a loss of cells bearing Lyt 2 surface antigens but no reduction in the numbers of T cells in the spleen. With overnight culture in vitro, splenic T cells from anti-Lyt 2-treated mice regenerated surface Lyt 2, with the proportion of Lyt 2+ cells returning to control levels. Anti-rat IgG antibody was found in the serum of mice that had received the anti-Lyt 2 treatments. Modulation of the surface Lyt 2 antigens was demonstrable in vitro but only in the presence of mouse anti-rat IgG antibody. Functionally, this series of in vivo anti-Lyt 2 antibody treatments substantially reversed Con A-induced suppression of the anti-sheep red blood cell antibody response.