Total lymphoid irradiation for pretransplant immunosuppression: nine year follow-up.

Total lymphoid irradiation (16 to 30 Gray units) was given to 12 patients (8 who had rejected previous grafts). We found a fall in T and B cell counts with a reversal of CD4/CD8, and a decrease in mitogeneic and allogeneic responses with recovery to pretransplant levels in 24 to 36 months. The total lymphoid irradiation patients (on low dose prednisone and cyclosporine) had nine year graft and patient survival rates of 50% and 81.5%, respectively, versus 56% and 69.8% for 65 patients on conventional immunosuppression. Complications included viral (7) and fungal (1) infections, immunological thrombocytopenia (3), hypothyroidism and radiation pneumonitis and pericarditis (1 each), and there were no non-skin malignancies. There was only one episode of acute rejection in the group with total lymphoid irradiation as compared to 18 in the other group. We believe that total lymphoid irradiation provides effective immunosuppression and has the potential for reducing and possibly eliminating other immunosuppressants.