Anti-idiotypic antibodies in a patient with a well-functioning renal graft without azathioprine. II. Anti-idiotypic antibodies directed to a clonotype of a certain cytotoxic T lymphocyte.

A recipient who received a renal graft from a living related donor showed good renal function for as long as 15 years after the withdrawal of azathioprine. The patient's creatinine clearance was maintained at 60 ml/min in spite of the administration of only 10 mg of predonisolon per day. Anti-idiotypic antibodies in the patient's serum were found by testing for specific inhibition of the mixed lymphocyte reaction (MLR) and cytotoxic T lymphocyte (CTL) response. The treatment of responder or effector cells with the IgG fraction from the patient's serum resulted in the specific inhibition of the MLR and CTL killing reaction against target cells of the graft donor. These findings indicate that the patient's serum contains anti-idiotypic antibodies against antigen recognition structures of a certain CTL as well as a certain MLR to donor alloantigens.