title: Antibody-dependent cellular cytotoxicity effector cells lack Ia antigens.
abstract: Surface immunoglobulin (sIg)-positive and sIg-negative subpopulations of macrophage-depleted murine splenic lymphocytes were obtained by Sephadex anti-Fab immunoabsorbent fractionation. These lymphocyte subpopulations were analyzed for the presence of Thy 1 and Ia alloantigens and also for Fc receptors by fluorescence microscopy. Concurrently, these lymphocyte subpopulations were studied for effector cell activity in antibody-dependent cellular cytotoxicity (ADCC). Effector cells mediating ADCC were contained in the sIg-negative lymphocyte subpopulation and sIg-positive lymphocytes did not mediate cytotoxicity. The majority of sIg-positive lymphocytes were found to bear Ia antigens and Fc receptors, and these cell surface structures were associated in that treatment of these cells with anti-Ia sera inhibited binding of complexed immunoglobulin to Fc receptors. In contrast, most sIg-negative, Thy 1-negative lymphocytes lacked Ia Antigens, and the Fc receptors detected on such cells were not blocked by anti-Ia sera. In addition, a small subpopulation of sIg-negative, Ia antigen-positive, Fc receptor-positive lymphocytes was found. Elimination of this subpopulation of Ia antigen-positive cells from sIg-negative lymphocytes, by treatment with anti-Ia serum and complement, did not diminish ADCC effector cell activity in the resultant cell population when compared with untreated sIg-negative lymphocytes. Thus, in murine spleen, nonphagocytic mononuclear cells that lack both sIg and Ia antigens were shown to mediate ADCC.
mesh_terms: D000818:Animals; D000918:Antibody Specificity; D002462:Cell Membrane / Q000276:immunology; D002469:Cell Separation; D003601:Cytotoxicity Tests, Immunologic; D005455:Fluorescent Antibody Technique; D006649:Histocompatibility Antigens; D007111:Immunity, Cellular; D007141:Immunoglobulin Fc Fragments; D008214:Lymphocytes / Q000276:immunology; D051379:Mice; D008805:Mice, Inbred A; D008810:Mice, Inbred C57BL; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism; D013154:Spleen / Q000276:immunology
chemical_list: D006649:Histocompatibility Antigens; D007141:Immunoglobulin Fc Fragments; D011947:Receptors, Antigen, B-Cell