Immunologic monitoring of the beneficial effect of one HLA-DR-shared blood transfusion in heart transplant patients

Abstract

Background: Pre-transplant blood transfusion (BT) results in better graft survival in organ transplant recipients, especially when BT donor and allograft recipient share an HLA-DR antigen. Although the immunologic mechanisms involved are still poorly understood, we wanted to know whether down regulation of donor-reactive T cells play a role. Methods In a retrospective study, we analyzed the clinical effects of BT for 45 heart transplant (HTx) patients who had each received 1 BT that shared an HLA-DR-antigen with the recipient, and 55 who had a DR-mismatched BT before heart transplantation. From 30 patients, 15 with DR-shared BT and 15 with DR-mismatched BT, peripheral blood lymphocytes (PBL) were available. From each patient, we analyzed PBL samples taken at the day of transplantation (pre-transplant), and 1 to 2 months, 5 to 7 months, 9 to 14 months, 2 years, and 6 to 7 years after transplantation. Cytotoxic T-lymphocyte precursors (CTLp) and helper T-lymphocyte precursors (HTLp) were measured in a combined limiting dilution assay. Results Analysis of survival during the first 10 years revealed a significantly ( p = 0.016) better survival rate in the group of patients who had received HLA-DR–shared BT compared with the group who had received HLA-DR–mismatched BT. Patients of the DR-shared group experienced significantly ( p = 0.042) less acute rejections compared with the patients who received DR-mismatched BT. We found no differences in the development of graft vascular disease. Frequencies of CTLp specific for the organ donor did not change with time after transplantation in the individual patients, nor did we detect any differences between the two BT groups. We found the same for organ donor–specific HTLp frequencies. Conclusions These data suggest again that transfusion effect depends on HLA-DR compatibility between the heart transplant recipient and the pre-transplant BT donor. The mechanism that caused better survival rate was not down regulation of the donor-reactive T-cell frequency.