Cytoimmunologic monitoring using DNA analysis in canine liver transplantation

In this experiment, we evaluated the significance of flow cytometric DNA content measurement of circulating blood mononuclear cells in early detection of canine hepatic allograft rejection. In nonimmunosuppressed controls, the SG2M% of blood mononuclear cells significantly increased on days 5-6 after liver transplantation compared with the pretransplant values (P < 0.01). At the time of SG2M% elevation, microscopic examination of the graft revealed acute mild rejection. These changes in SG2M% and histological findings were observed one or two days earlier than biochemical changes indicative of liver injury. On the other hand, nonrejected cases under sufficient immunosuppression with cyclosporine or FK506 maintained low levels of SG2M% in comparison with the pretransplant values (P < 0.05). The rejecting cases under insufficient immunosuppression showed significantly elevated SG2M% (P < 0.05), and successful steroid pulse therapy provided to the recipients immediate normalization of SG2M% with histological restoration. Moreover, other complications such as pulmonary infection, peritonitis, and marasmus--rather than the rejection reaction--did not influence on SG2M%. These results led us to believe that flow cytometric DNA content measurement of blood mononuclear cells provides relevant and early information with respect to ongoing canine hepatic allograft rejection. The diagnostic value for differentiation between hepatic allograft rejection and infection of the transplant by hepatitic viruses needs further evaluation.