Platelet mixed agglutination for detecting HL A and non HL A antibodies

Platelets adhered to glass by weak formaldehyde fixation have been shown to give strong reactions in mixed agglutination assays; therefore the usefulness of platelet MA as an immunologic monitor of graft rejection was investigated. Antisera were collected from renal transplant patients, multiparous women, and normal controls. Antisera from 2 patients known to be reactive to a large percentage of random individuals were used as positive controls. Five families were studied in which the mother had multiple pregnancies but no cytotoxic antibodies to paternal lymphocytes. In 2 of the 5 families, antibody was detected by platelet MA at titers of 1/90 and 1/270. In another study, a maternal transplant (HL A 2,12; 2,12) was rejected by her son (HL A 2,12; 3,7). After removal of the graft, no antibody was detected by cytotoxicity. In fact, of 6 additional tests detecting allogeneic immunity, only cell mediated cytolysis of maternal kidney cells and platelet MA (titer 1/30) were positive. Six recipients of living, related donor kidney grafts were followed up serially in an effort to detect antibody formation, while the graft was still functioning. Antibody was detected during the period of screening in one patient just prior to and during a rejection crisis. Following steroid therapy, this reactivity subsided and no other crises have occurred. Another patient, who had previously rejected a cadaver transplant, was found to have high titers (1/270) of antibody to his father's platelets. Because other tests were negative, the father was used as the donor of the second transplant. Antibody persisted for the first 3 wk post transplantation. Graft function was so poor during this time that exploration was performed to exclude technical problems. None were found, and the graft is currently functioning well at 8 mth. In the other 4 patients, no antibody was found and no clinical rejections occurred during the period of monitoring. Two other patients received kidneys from the same cadaver donor, and pretransplant serum was positive at dilutions of 1/270 in each case. Both patients lacked cytotoxic antibody to donor lymphocytes. One of the grafts failed completely and was removed at 3 wk, while the other functioned after anuria of 3 wk duration.