Transplantation tolerance mediated by suppressor T cells and suppressive antibody in a recipient of a renal transplant

This is a report of a patient who underwent cadaveric renal transplantation in spite of the presence of three HLA-A, B and two DR antigen mismatches between the recipient and donor. The recipient received more than 20 units of blood before transplantation. The crossmatch between the recipient's serum and the T and B cells of the donor was negative. The patient exhibited hepatic dysfunction from the early posttransplant period, which eventually led to discontinuation of azathioprine or Bredinin at one year posttransplantation. Thereafter, only betamethasone was administered once every 3 days. The patients has maintained good renal function for more than one year following withdrawal of the immunosuppressants. It appeared that transplantation tolerance was established in this patient. Therefore, we examined the mechanisms sustaining the tolerance. Both nylon-wool-adherent, alloantigen-specific suppressor T cells and nonadherent, nonspecific suppressor T cells were observed in the lymphocytes of the patient after transplantation. It was also shown that suppressive antibody was present in the serum directed toward the clone of autologous lymphocytes that reacted with the mixed lymphocyte reaction (MLR) antigen of the donor. In the inhibition test against various types of MLR antigens using this suppressive antibody, it was found that the reaction against the donor cells was suppressed when the responding cells shared the same class I antigen with the recipient. When the stimulating cells had the class II antigen of the donor, the reaction of the specific responding cells was also inhibited. These inhibiting effects were only seen when the responding cells were pretreated with the antibody, but not when stimulating cells were pretreated.