Pulmonary function tests of nonidentical lung grafts in selectively bred dogs treated with lethal total-body irradiation, autologous bone marrow, and methotrexate post-transplant on days 1, 3, and 6 with no further immunosuppression are described. Each recipient received 125 ml of irradiated blood from the lung donor 9 days post-transplant to augment platelets. Pulmonary function studies were performed 70, 111, 231, 323, 343, 359, and 407 days post-transplant; lung biopsies were performed 315, 352, 469, 436, 579, 591, and 618 days post-transplant in animals currently surviving for 336, 377, 497, 589, 609, 625, and 673 days. Results show a decrease in lung volume in all but one animal. In five animals relatively normal pulmonary function was observed. There was a decrease in ventilation and perfusion proportional to the decrease in lung volume, indicative of normal pulmonary and ventilatory resistance in the transplanted lung. There was a disproportional decrease in ventilation and perfusion in one animal with normal volume of the transplant and in another one with reduced volume of the transplant. Morphological changes suggesting chronic rejection were slight in five grafts, moderate in one, and marked in one. The degree of histological change did not appear sufficient to seriously impair pulmonary function.
It is possible to attain long-term survival with reasonable lung function in mismatched lung transplants in selectively bred animals treated with the described regimen, which may have eventual application in man.