THE OPPORTUNITIES OF NON-INVASIVE LIVER GRAFT REJECTION DIAGNOSTICS BY USING TERMINALLY DIFFERENTIATED EFFECTOR CD8+ T-LYMPHOCYTES

Abstract

Background. Immune-mediated graft dysfunction with the prevalence of 40% is one of the main problems of modern transplantology. Although percutaneous liver graft biopsy is associated with the development of different complications occurring in 2,2% of cases and can also lead to fatal outcome. Objective – to develop a noninvasive method of graft dysfunction diagnostics in the late post-transplant period using terminally differentiated effector CD8+ T-lymphocytes. Material and methods. There was carried out a single center observational retrospective case-control pilot study, including 45 recipients after orthotopic liver transplantation. According to the postoperative clinical course the patients were stratifed into 2 groups depending on the presence of graft rejection episodes. All patients got immunosuppressive therapy after liver transplantation. Immunophenotypes of the recipients were determined by flow cytometry method. Percutaneous liver graft biopsy was performed in all patients, the results of histological examination were evaluated according to the international Banff schema for grading liver allograft rejection. Results. The results of liver biopsies showed that 14 (31%) out of 45 patients had morphological signs of rejection. The patients with rejection had a reliably higher level of CD8+ Temra cells absolute number (0,23 (0,14;0,38) x 109/l) in comparison to those without rejection (0,09) (0,034;0,16) x 109/l (p=0,034)). The results of ROC-analysis have shown that the most optimal cut-off threshold of CD8+ T-lymphocytes level in immune-mediated graft dysfunction diagnostics in the late post-transplant period is 0,1882x109/l; sensitivity and specifcity in this case being 73,33 (95%; 44,9-92,0) and 96,55 (95%; 82,2-99,4) respectively. Conclusions. The increase of terminally differentiated effector CD8+ T-lymphocytes absolute number has diagnostic importance in patients with immune-mediated graft dysfunction in the late post-transplant period. High sensitivity and specifcity of cut-off threshold of CD8+ Temra lymphocytes absolute number in patients after liver transplantation as well as reliable difference between cell number in patients with normal postoperative period and in patients with immune-mediated graft dysfunction allow considering T-lymphocyte subpopulation as a rejection predictor in the late post-transplant period. The correlation between CD8+ T-lymphocyte absolute number and the results of histological examination makes the former an alternative and, what is more, safe noninvasive method in early diagnostics of liver graft rejection.