The correlation between humoral antibodies and rejection after renal transplantation

Sera from 36 renal transplant patients were selected at random and screened for cytotoxic antibodies to a panel of 50 normal lymphocytes and 3 lymphoblasts. 11 of these patients had received more than one kidney transplant. None of the primary renal transplants demonstrated cytotoxic antibodies to the panel of normal cells. However, 4 of the retransplant patients were found to possess cytoxins. These 4 sera were cytotoxic to the normal cell panel (10%, 20%, 50% and 70% of panel lysed) as well as to certain lymphoblasts. 30% of the sera negative to the normal cell panel demonstrated cytoxins to the lymphoblasts; 15% positive to only the B-lymphoblasts, 5% positive to only the T-lymphoblasts and 10% showed cytotoxic antibodies to both T and B-lymphoblasts and 10% showed cytotoxic antibodies to both T and B-lymphoblasts. No correlation between cytotoxicity and inhibition of MLR was obvious. Of the 14 sera showing cytotoxicity to lymphoblasts, 9 exhibited MLR inhibition. However, inhibition of MLR was not found to be restricted to B-cell cytotoxic sera. These sera were tested by radioimmunoassay. A good correlation was found between acute rejection and percent increase in direct binding of patients sera to radiolabelled B-lymphoblast membranes. Of the 36 sera tested the six sera obtained from patients in acute rejection bound the iodinated lysate to a significantly greater amount than the controls. As yet, no characterization of the antigen specificities has been found.