Association between HLA and red cell antigens. IV. Further studies of haemagglutinins in cytotoxic HLA antisera.

Cytotoxic HLA antisera of various specificities were examined on the AutoAnalyzer against red blood cells (RBC) from a great number of HLA-typed donors. HLA-associated haemagglutinins of different specificities were demonstrated. In cytotoxic anti-HLA-A9 and anti-HLA-A10, as well as in anti-HLA-B12, anti-HLA-Bw15 and anti-HLA-B17 sera, haemagglutinins of apparently corresponding specificities were found. This indicates that several HAL antigens may be present on RBC, but they are demonstrable only on RBC from a limited number of donors who possess the corresponding antigens on their white cells. Some antigens, like HLA-A28 and HLA-B7, are relatively strong RBC antigens, whereas others, like HLA-B12 or HLA-Bw15 seem to be much weaker. In cytotoxic anti-HLA-A1 and anti-HLA-B13 sera, no corresponding haemagglutinins were demonstrated. However, haemagglutinins of anti-HLA-B7 specificity were shown to be present in two cytotoxic anti HLA-A1 and three anti-HLA-B13 sera. No cytotoxic anti-HLA-B7 was found in these sera. Cross-reacting antibodies also seem to be frequent amoung HLA associated haemagglutinins.