CHARACTERIZATION OF DONOR-DIRECTED ANTIBODY CLASS IN THE POSTTRANSPLANT PERIOD USING FLOW-CYTOMETRY IN RENAL-TRANSPLANTATION

Over the past few years there has been increasing awareness of the imp ortance of humoral mechanisms in the rejection of renal transplants. I n this study we have monitored the development of antibodies directed against donor T and B lymphocytes using the sensitive flow cytometric technique. Forty-two cadaveric renal transplants were studied both bef ore and for a maximum of 14 days after transplantation. Donor cells we re separated from spleen on the day of transplantation and stored in l iquid nitrogen until required. The dual colour flow cytometric assay w as used to detect IgG or IgM directed againts donor T or B lymphocytes . Using AB sera as controls, results were expressed as relative median fluorescence (RMF) and then correlated with the clinical performance of the grafts. Significant associations were found between the inciden ce of donor-directed antibodies and the development of clinical reject ion. The magnitude of the rise in antibody levels was also related to graft performance. In patients showing severe graft rejection, high le vels of antibodies of the IgG class developed before the clinical diag nosis of rejection was made. The routine use of this test allows the p rediction of impending severe rejection to be made and may have import ant implications for immunosuppressive therapy.