Effect of activated lymphocytes on the regulation of hematopoiesis: suppression of in vitro granulopoiesis by OKT8+Ia+T cells induced by alloantigen stimulation.
We studied the effects of alloantigen-stimulated lymphocytes in the regulation of hematopoiesis. Alloantigen-stimulated lymphocytes were harvested on days 2 to 3, days 6 to 7, or days 9 to 10 of MLC and were tested for their effects on granulocyte/macrophage progenitor cells (CFU-C). Dose-dependent suppression of CFU-C was observed when alloantigen-stimulated lymphocytes from days 6 to 7 and days 9 to 10 MLC were added to the cultures of autologous or allogeneic bone marrow cells for CFU-C assays. Suppressive activity was detected in the T cell fraction but not in the non-T cell fraction. For further characterization of these CFU-C/suppressor cells, alloantigen-stimulated lymphocytes were treated with radiation (2000 rad) or with monoclonal antibodies against T cell subsets and complement (C) before culture. Suppressive activity was completely abolished by treatment with OKT8 or OKIa1 antibodies and C whereas suppression was retained after radiation treatment. These observations suggest that CFU-C/suppressor cells can be induced by alloantigen stimulation in MLC and that they are radioresistant OKT8+ and Ia+ T cells.
D000911:Antibodies, Monoclonal / Q000276:immunology; D001854:Bone Marrow Cells; D003114:Colony-Forming Units Assay; D006098:Granulocytes / Q000166:cytology*; D006410:Hematopoiesis; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D006801:Humans; D007519:Isoantigens / Q000276:immunology; D008213:Lymphocyte Activation; D007959:Lymphocyte Culture Test, Mixed; D008264:Macrophages / Q000166:cytology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000949:Histocompatibility Antigens Class II; D007519:Isoantigens