Prophylactic use of a monoclonal antibody (33B3.1) directed against interleukin 2 receptor following human renal transplantation.

33B3.1, a rat IgG2a monoclonal antibody (MAb) directed against interleukin 2 receptor, has been given in association with prednisone and azathioprine to prevent rejection in 30 recipients of a primary cadaveric kidney transplant. The MAb 33B3.1 had been administered intravenously (IV) at 10 mg per day for 2 weeks. Clinical and biological tolerance were excellent. Only one patient had a rejection episode (reversible) during the MAb treatment period. These results were significantly better than those recorded from a historical group of patients that received only prednisone and azathioprine, and were similar to those from patients who received antithymocyte globulin instead of 33B3.1. There was no life threatening infectious episode and all patients are alive. Ninety-seven percent of the patients have a functional graft (follow-up, 30 to 210 days). Enzyme-linked immunosorbent assay (ELISA) of 33B3.1 indicate that circulating trough blood level peaked at day 6 (30 nm). The majority of patients (85%) developed either IgG or IgM antibodies with a maximal response at day 24 for both isotypes. We conclude that this new treatment that targets a functional receptor present on activated lymphocytes only, is well tolerated and highly efficient in preventing early rejection after human renal transplantation.