Role of MLC serum inhibitory factors in high MLC-reactive kidney transplant recipients pretreated with donor-specific blood transfusion (DST).

In order to clarify the beneficial effect of donor-specific blood transfusions (DST) on kidney allograft survival, sera from 16 patients treated with DST were studied using the mixed lymphocyte culture (MLC) serum inhibition test. The results demonstrate that MLC inhibitory factors could be induced in the serum of the recipients after the completion of DST, and that these factors are directed against cells of the recipient but not against cell from the donor. Regarding the correlation with rejection episodes and clinical outcome, a significant improvement in renal transplant survival and reduction in rejection episodes was observed when MLC inhibitory factors were present in post-DST sera. These data suggest that such factors may contain antibodies directed against recognition sites on T lymphocytes, e.g., anti-idiotypic antibodies, and be associated with prolonged graft survival of living-related, high MLC-reactive one-haplotype-mismatched kidney.