Transplantation tolerance in heart transplant recipients as demonstrated by unresponsiveness in cell-mediated lympholysis.

ABSTRACT

Transplantation tolerance or adaptation to an allograft is associated with unresponsiveness to donor-specific transplantation antigens measured in in vitro cell-mediated lympholysis (CML). We here demonstrate in a longitudinal follow-up that CML nonreactivity develops in seven of ten patients following heart transplantation. The first manifestation of this nonreactivity manifested between 3 and 27 months after transplantation. CML nonreactivity correlated with time after transplantation and the percentage of activated lymphocytes in peripheral blood. CML nonreactivity was also associated with good graft function, i.e., in condition of nonresponsiveness patients did not manifest acute rejection. The only exception was seen in one patient in whom the immunosuppressive therapy was strongly reduced. A more detailed evaluation of this patient indicated that the underlying mechanism for CML nonreactivity is clonal anergy or active suppression of the alloreactive cells.