Clinical and immunological studies of cadaveric renal transplant recipients given total-lymphoid irradiation and maintained on low-dose prednisone.

Twenty-five recipients of cadaveric renal transplants were given total lymphoid irradiation (TLI), perioperative antithymocyte globulin, and low-dose prednisone as the sole maintenance immunosuppressive drug. Nine patients were diabetic, and follow-up was between 19 and 37 months. One-year graft and patient survival was 76% and 87%, respectively, Serious complications included four deaths from cardiovascular disorders, and two deaths from viral infections. Studies of peripheral blood T cell subsets showed a prolonged reduction in the absolute number of helper (Leu-3+) cells, and a rapid recovery of cytotoxic/suppressor (Leu-2+) cells. Analysis of the latter subset, using the monoclonal antibody 9.3, showed that the ratio of suppressor/cytotoxic cells was approximately 10:1. The normal ratio is 1:1. The mean mixed leukocyte reaction remained below 30% of the pre-TLI value for 6 months, and approached 80% at two years. Similar kinetics were observed in the proliferative response to mitogens. The results show that maintenance immunosuppressive drug therapy can be reduced after TLI as compared with conventional drug regimens that use prednisone in combination with cyclosporine and/or azathioprine.