Pretransplant hyperthermia promotes permanent survival of murine thyroid allografts

Hyperthermic treatment of skin has been shown to abolish stimulation of allogeneic lymphocytes in a mixed skin-lymphocyte reaction. These experiments test the hypothesis that hyperthermic pretreatment of endocrine tissue can promote its permanent survival in allogeneic recipients. Murine thyroid tissues were treated at 37, 43, or 45 degrees C for 0.5-4.0 hr and transplanted to the left renal capsule of recipient mice. Graft survival was determined after 100 days by the ratio of counts between the left and right kidneys 24 hr after administration of 0.5 microCi 125I. Balb/c recipients of C57BL/6 thyroids treated at 43 degrees C for 2 or 4 hr had viable grafts in 4/7 (P = 0.032) and 4/5 (P = 0.015) cases, respectively, compared to controls (0/10). C57BL/6 recipients of Balb/c thyroid treated at 43 degrees C for 4 hr had viable grafts in 6/10 cases (P = 0.009) compared to control (0/10). Treatment at 45 degrees C was lethal, evidenced by failure of all isografts. Pretransplant treatment at 43 degrees C promotes permanent thyroid allograft survival without immunosuppression.