Cellular presensitization to alloantigens in haemodialyzed patients

The state of cellular alloimmunity in haemodialyzed patients has been assessed by a microcytotoxicity assay and compared with that in healthy donors. Some of the patients were also studied during the weeks following a first kidney transplant rejection. For comparison, lymphocytes of multiparous women have been studied. Skin fibroblasts from a panel of normal donors were used as targets, and effector cells were cryopreserved peripheral blood lymphocytes. Lymphocyte-mediated cytotoxicity (LMC) demonstrated restricted reactivity against target cells, an indication of specificity. It detected presensitization more often than a standard test for cytotoxic antibodies. This difference is not attributable to differences in sensitivity of the two tests, since some patients were at least once LMC negative and cytotoxic antibody positive, and the antigens detected by both tests were different in patients who had positive LMC and cytotoxic antibodies simultaneously. In some experiments, LMC target determinants were not HLA serologically detectable antigens. Furthermore, lymphocytes obtained after transplant rejection were cytotoxic for targets which did not share the donors' serological mismatches. These results suggest that antigens other than HLA-A and B may be the determinants recognized in the microcytotoxicity assay.