Complement-dependent killing of human hematopoietic progenitor cells with noncomplement-fixing monoclonal antibodies in an antiglobulin assay.
A complement (C)-dependent antiglobulin assay was utilized to determine the reactivity of non-C-fixing monoclonal antibodies (MoAb) with human granulocyte-macrophage progenitor cells (CFU-GM). The variables of the assay were analyzed with non-C-fixing MoAb against Ia antigens, including CR11-462, which recognizes the same (or spatially close) determinant identified by the C-fixing anti-Ia MoAb Q5/13. The sensitivity of the antiglobulin assay was influenced by dilutions of anti-mouse Ig xenoantiserum and of rabbit C. Five non-C-fixing MoAb to Ia antigens, seven non-C-fixing MoAb to HLA-A,B antigens, and one non-C-fixing MoAb to beta 2-microglobulin induced marked inhibition of human CFU-GM in the antiglobulin assay. The activity of non-C-fixing MoAb in the antiglobulin assay was comparable to that of C-fixing anti-Ia and anti-HLA-A,B MoAb in the standard cytotoxicity assay. In addition, the cytotoxic effect of dilute C-fixing anti-Ia MoAb was enhanced when the antiglobulin technique was employed. The results of this study indicate that the antiglobulin assay is a rapid and simple technique for the characterization of antigens on human hematopoietic progenitors. Our data also indicate that Ia antigens are expressed on most CFU-GM and that the conflicting results in the literature (that is, those suggesting that Ia antigens are expressed on a smaller proportion of CFU-GM) may reflect differences in the cytolytic activity of the MoAb and rabbit C used.
D000328:Adult; D000911:Antibodies, Monoclonal / Q000502:physiology*; D001854:Bone Marrow Cells; D003165:Complement System Proteins / Q000378:metabolism*; D003298:Coombs Test; D003602:Cytotoxicity, Immunologic; D004306:Dose-Response Relationship, Immunologic; D006680:HLA Antigens / Q000276:immunology; D006412:Hematopoietic Stem Cells / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D006801:Humans
D000911:Antibodies, Monoclonal; D006680:HLA Antigens; D000949:Histocompatibility Antigens Class II; D003165:Complement System Proteins