Coronary artery immunogenicity: a comparison between explanted recipient or donor hearts and transplanted hearts

Transplant associated accelerated coronary sclerosis (TX-ACS) is the most serious complication following heart transplantation. In order to elucidate the involvement of possible immune mechanisms, we have used immunocytochemistry to characterize the antigens present on the endothelium and the cells present within coronary arteries taken at time of surgery from patients who required retransplantation (n = 4) or at post mortem (n = 10) from transplant patients who died. Coronary arteries from unused donor hearts (n = 4) or heart transplant recipients whose original disease did not involve the coronaries (n = 8) were used as controls. Endothelium from all control coronary arteries strongly expressed MHC class I, DR antigen, PECAM, ICAM-1 and E-selectin. Expression of VCAM-1, DP and particularly DQ antigen was more patchy. There was no significant difference in the expression of MHC or adhesion molecules between control arteries and those from transplant patients. More cells were present in the intima and media of coronary arteries taken from transplanted hearts, particularly those with intimitis/TX-ACS, than were found in control coronaries. T cells were present in the intima of most coronaries, but the media of only the transplanted coronaries. Cells expressing prolyl 4-hydroxylase were more evident on coronaries from transplanted hearts. In conclusion, coronary arteries from hearts used for transplants appear to be highly immunogenic. This suggests the endothelium would need little, if any, stimuli to initiate as well as be a target for an immune response after transplantation.