MODE OF ACTION OF ANTI-LYMPHOCYTE GLOBULIN .2. CHANGES IN LYMPHOID CELL POPULATION IN RATS TREATED WITH ANTI-LYMPHOCYTE GLOBULIN

Abstract

Lymphopeinia in rats made tolerant to normal rabbit immunoglobulin G(IgG) was induced by the administration of rabbit anti-rat immunoglobulin G(IgG). The rats were injected with tritiated thymidine ([3H] thymidine) and the labelling pattern in lymphoid tissues studied. The thymus weight decrease with continued lymphopenia could be explained by the release of small lymphocytes into the circulation. Lymphopoiesis in the thymus and spleen was not inhibited by anti-lymphocyte globulin. Plasmacytosis was noted in the lymph nodes. These findings indicate that anti-lymphocyte globulin acts mainly on peripheral lymphocytes and suppresses the immune function mediated by these cells.