MONITORING OF CARDIAC ANTI-REJECTION THERAPY WITH LYMPHOCYTES-IN-111

Abstract

To determine whether lymphocytes labeled with 111In permit noninvasive assessment of antirejection therapy, 40 allogeneic heterotopic cardiac transplants were performed in rats. Antirejection therapy with azathioprine (30 mg/kg) and sodium salicylate (200 mg/kg) prolonged contractile function of the graft from 7.5 .+-. 1.5 (SD) days in controls to 19.4 .+-. 3.7 days in treated animals. Autologous lymphocytes labeled with 111In were injected i.v. in 7 untreated and 8 treated rats 6-7 days after transplantation. Scintigraphy and organ counting were performed 24 h after administration of labeled cells. At sacrifice all grafts in untreated rats exhibited contractile failure, whereas grafts in all treated rats were beating well. Transplants in untreated recipients exhibited marked accumulation of 111In lymphocytes detectable scintigraphically, with ratios of 7.7 .+-. 1.9 for the activity in the transplant over that in the native heart (HT-HO), as obtained by well counting. Accumulation was not scintigraphically detectable in transplants of treated rats, with HT/HO ratios of 2.6 .+-. 1.8 (P < 0.005). Imaging with 111In-labeled lymphocytes will permit noninvasive assessment of antirejection therapy.