131I-fibrinogen in the detection of pulmonary allograft rejection.

The uptake of 131I-fibrinogen in canine pulmonary allografts was compared to that in lung autografts or lungs with papain-induced unilateral hemorrhagic pneumonia. In addition to serial lung scans and the postmortem measurement of tissue radioactivity, all dogs had serial chest roentgenograms and histologic study of their lungs. All four animals in the allografted group had increased radioactive uptake on the side of the allograft lung at the same time as or slightly before radiographic abnormalities were evident. However, increases in lung radioactivity also occurred in animals with pneumonia or autografts at the time infiltrates were present. Thus the presence of increased lung scan activity, which occurs in rejecting lung allografts after the injection of 131I-fibrinogen, is not a specific index of pulmonary rejection.