Detection of lung rejection with indium-111-labeled lymphocytes in heterotopic rat heart-lung transplantation.

Abstract

To determine if acute lung rejection after heart-lung transplantation can be detected noninvasively with indium-111-labeled (111In) lymphocytes, we studied 33 allogeneic and 18 isogeneic heterotopic heart-lung transplants in rats. Twenty-four hours after injection of isogeneic splenic 111In-lymphocytes (75 +/- 2 microCi/100 million cells), animals were scanned at 2 to 8 days after transplant (Tx). Also, percent indium uptake of the graft was determined and compared with pathologic lung changes. Between the vascular and destructive phases of lung rejection, 111In-lymphocyte uptake of lung allografts was significantly greater than isografts (p less than 0.001). Lung allografts in the alveolar phase (4-6 days after Tx) showed the most intense uptake (2.7 +/- 0.1%) of injected 111In-lymphocytes. All scintigrams of allografts from the late vascular to the early destructive phase (3-7 days after Tx) showed visualization of the lung graft (27/27 true positive, sensitivity = 100%). In contrast, lung isografts of the same period showed no pathological sign of rejection and were only rarely visualized (12/14 true negative, specificity = 86%). Lung rejection may be accurately assessed noninvasively by gamma scintigraphy with 111In-lymphocytes. This technique may prove useful in the detection of acute lung rejection in human heart-lung transplant recipients. Modification of the labeling dose chosen may further improve scan accuracy.