A new enzyme-linked immunosorbent assay to measure anti-endothelial antibodies after cardiac transplantation demonstrates greater inhibition of antibody formation by tacrolimus compared with cyclosporine

Background. Chronic rejection or transplant-associated coronary artery disease (TxCAD) is the most serious complication after human cardiac transplantation. Previous studies, using Western blotting, have shown formation of antibodies against endothelial antigens of 56 and 58 kDa, which are associated with early TxCAD, These antigens were later identified as being vimentin and its breakdown products. The aims of the present study were to devise a robust assay for detection of anti-vimentin antibodies and to compare antibody formation in patients taking different immunosuppressive drugs. Methods. 106 sequential serum samples from 19 patients taking tacrolimus and 68 sera from 12 patients taking cyclosporine were examined by enzyme-linked immunosorbent assay (ELISA) for anti-vimentin antibodies and Western blotting for reactivity against bands at 56/58 kDa, Serum samples were taken before transplantation and at 1, 3 6, 9, and 12 months. Results. The vimentin ELISA produced significantly higher numbers of positive episodes per patient (3.92+/-1.08) compared with use of Western blotting (2.54+/-0.52). Serum from patients taking tacrolimus contained significantly less antibodies measured by ELISA (15.8%) or Western blotting (6.5%) than sera from patients taking cyclosporine (46.8% for ELISA; P=0.001 and 21% by Western blotting, P=0.01), Intravascular ultrasound performed on six patients at 12 months showed a correlation between anti-vimentin antibody formation and detection of early coronary disease. Conclusions. The results demonstrate first, that differences in antibody profiles produced by different immunosuppressive drugs, and second, that detection of anti-vimentin antibodies may be a noninvasive method of detecting disease activity in transplanted vessels.