The ultrastructure of early rejection phenomena in lung homografts in dogs.

The ultrastructure of early rejection phenomena was studied in homografts of lung in 5 dogs. There was considerable variation in the time interval from transplantation to indication of early damage. The evolution of changes, once begun, followed a regular pattern. The features which characterised these changes were margination of leucocytes, sticking of lymphocytes to endothelial cells, progressive disintegration of neutrophil leucocytes, swelling and exfoliation of endothelial cells from the basement membrane of pulmonary capillaries and platelet aggregation. The end result was obstruction of some pulmonary capillaries by debris from damaged neutrophils, exfoliated endothelial cells, ballooned out endothelial cells, platelet aggregates, and fibrin.