Endolymphatic Irradiation with¹⁹⁸ Au and³² P as Immunosuppression in Renal Transplantation: The Effect on Hematologic and Immunobiologic Parameters

Twenty patients with end stage renal disease awaiting kidney transplantation were treated with radioisotopes in an investigation of the immunosuppressive effect of endolymphatic irradiation. Twelve patients received¹⁹⁸ Au and eight were treated with³² P. The isotopes were injected into lymph vessels in the foot and localized in the pelvic lymph nodes with only an extremely small release to the blood and urine. The doses given were 2-7.5 mCi¹⁹⁸ Au or 0.4-1.5 mCi³² P. The accumulated dose in the lymph nodes was calculated to be approx 35,000 rad for¹⁹⁸ Au and approx 150,000 rad for³² P. The blood activity was 0.1-0.2 rad. The dose to a kidney graft was calculated to be approx 20 rad, and the dose to a lymphocyte in the first 6 hr after injection approx 1500 rad. The results obtained were lymphocytopenia and a depressed immune response measured with blast transformation tests after stimulation with mitogens, antigens, and allogene cells in mixed lymphocyte culture. No effect was observed on bone marrow, immunoglobulins, complements, liver enzymes, spleen size, or liver size. A small transient fall in erythrocyte count was seen but otherwise no side effects were demonstrated. Thus, the treatment given, with maximum permissible doses, had an effect on the immune response, but as this effect only lasts for a few weeks the treatment has little practical applicability in kidney transplantation.