Rejection of combined heart-lung transplants in rats. Function and pathology.

Clinical experience with combined heart-lung transplantation has made it clear that several aspects of the rejection of combined organ transplants need further investigation. In this study, the rejection process of combined heart-lung allografts was examined for determining whether it affects the lung and heart synchronously and whether it differs from rejection when these organs are transplanted alone. The lungs of the combined allografts were functionally rejected prior to the heart (6 and 11 days, respectively). Accordingly, the pathologic changes were most severe in the lungs. The rejection pathology of these combinedly transplanted organs was similar to that described for lungs and hearts transplanted separately, except that the airways were found to be more extensively involved than had been appreciated in previous studies. It is concluded that after combined transplantation the lung is more prone to rejection than the heart. On the basis of the present observations, the definition of sequential rejection phases in the lung was slightly altered.