Inhibition of immune phagocytosis by human sera with HLA A, B, C and DR but not with DQ or EM type reactivity.
613 sera from pregnant women were investigated for inhibition of immune phagocytosis (IPI) by monocytes exposed to anti-D (Rh)-sensitized human red blood cells. IPI was detected in 42 (26%) of 165 and in 78 (17%) of 448 sera assessed against monocytes from 15 or 5 panel donors, respectively. All IPI-positive sera reacted in an allotypic pattern. Eight IPI-positive sera tested with autologous monocytes were found to be nonreactive. Upon comparative analysis of 448 sera, a significant correlation was found between the specific patterns of IPI and lymphocytotoxicity by HLA antibodies. In addition, 13 sera (4%) were positive for IPI, but not for lymphocytotoxicity. Twenty IPI-positive sera were tested by indirect immunofluorescence against platelets and T lymphocytes and revealed IgG antibodies in 16 and 11 sera, respectively. IPI activity could be removed from 8 out of 10 positive sera by platelet pool absorption. While virtually all sera exhibiting HLA, A, B or C-like activity (cytotoxicity with all cells) or HLA DR-like activity (exclusive cytotoxicity with B lymphocytes and monocytes) were IPI-positive, IPI was infrequently observed with sera containing HLA DQ-like activity (cytotoxicity with B lymphocytes only). IPI was also rarely seen with sera cytotoxic only to monocytes and not at all with sera containing antibodies against endothelial/monocyte antigens. We conclude that IPI is caused by cytotoxic as well as noncytotoxic HLA A, B, C, DR-specific antibodies. This effect may bear significance for the maternal immune response against fetal antigens and may be useful for pretransplant histocompatibility testing.
D000328:Adult; D000954:Antigens, Surface / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D004727:Endothelium / Q000276:immunology; D000939:Epitopes; D005260:Female; D006680:HLA Antigens / Q000276:immunology*; D015234:HLA-A Antigens; D015235:HLA-B Antigens; D015236:HLA-C Antigens; D006683:HLA-DQ Antigens / Q000276:immunology; D006684:HLA-DR Antigens / Q000276:immunology; D006801:Humans; D008297:Male; D009000:Monocytes / Q000276:immunology; D010587:Phagocytosis; D011247:Pregnancy
D000954:Antigens, Surface; D000939:Epitopes; D006680:HLA Antigens; D015234:HLA-A Antigens; D015235:HLA-B Antigens; D015236:HLA-C Antigens; D006683:HLA-DQ Antigens; D006684:HLA-DR Antigens