Collagenolytic activity in hyperacute lung allograft rejection.

Six mongrel dogs were presensitized by full thickness skin grafts followed by orthotopic lung homotransplantation. Tissue explants of the hyperacutely rejected lung grafts were placed on the surface of a gel of native collagen. Collagenase activity was found in each specimen. Lungs of 10 untreated dogs served as controls. The collagenolytic system of the transplanted lungs was inhibited by EDTA only. No inhibitory effect was obtained by the inhibitor of bacterial collagenase, cysteine, and normal serum containing protease inhibitors. By means of inhibition studies it was tried to determine the origin of the collagenolytic activity. It is suggested that the enzyme effect is derived from the lysosomes of polymorphonuclear leukocytes. Collagenase of granulocytic origin seems to participate as mediator in the immunological reaction of hyperacute lung graft rejection.