Dilutions and specificity analysis of pretransplant sera

Six serial dilutions of 51 sera from pretransplant patients were reacted against T and B lymphocytes at 5 degrees C and 37 degrees C. By the use of defined panels of T and B lymphocytes it could be shown that 10% of the 51 positive sera contained T-warm antibodies against HLA-A, -B, and -C specificities. There were 28% of the sera that had antibodies against non-HLA antigens reactive to B lymphocytes in the cold. Other sera contained mixtures of HLA and non-HLA antibodies. By dilution analysis of the sera, the mixtures could be detected and the HLA specificities identified. This ability to distinguish between HLA and non-HLA antibodies should be important in classifying pretransplant patients into high- and low-risk patients. Prior evidence that we have presented suggests that the non-HLA antibodies may be enhancing antibodies.