Page 1126 - Veterinary Immunology, 10th Edition

VetBooks.ir Cardiac Allografts

Acute rejection of canine heart allografts is associated with massive
lymphocytic infiltration and myocyte damage leading to rapid graft

destruction. If, however, the rejection process is slowed for some
reason, the pathological process in the chronically rejected organ
changes. In these cases, lymphocytes and antibodies directed
against vascular smooth muscle cells stimulate vascular rejection. T
cells and macrophages release a chemokine cascade that activates

vascular smooth muscle and endothelial cells. The resulting smooth
muscle cell growth and inflammation lead to obliteration of the
blood vessel lumen and eventually cardiac failure. This graft

arteriosclerosis (or graft vascular disease) results from the growth-
stimulating effects of both T cell–derived cytokines and antibodies.
A similar lesion is seen in renal allografts undergoing chronic
rejection.

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