Alloimmune responses and atherosclerotic disease after kidney transplantation.

BACKGROUND: Chronic exposure to exogenous antigens causes accumulation of proinflammatory CD57(+)CD28(-) hyperactivated CD8(+) T cells that may promote atherosclerosis. We hypothesized that persistent alloimmune responses may induce immune activation and contribute to posttransplant atherosclerosis.

METHODS: This hypothesis was tested in a single-center cohort of 577 kidney transplant patients. Propensity score analysis was performed to address potential confounding variables by indication. Immune exhaustion was studied in subcohort of 103 patients.

RESULTS: Five hundred seventy-seven consecutive renal transplant recipients were included. Seventy-seven atherosclerotic events (AE) (12.3%) occurred during a mean follow-up of 7 years. The cumulative incidence of AE increased with the number of human leukocyte antigen (HLA) mismatches (18%, 10%, and 5% in patients with 5-6, 3-4, and 0-2 mismatches, respectively; P=0.012). Human leukocyte antigen mismatch number (hazards ratio, 1.35; 95% confidence interval, 1.10-1.66, for each supplementary mismatch; P=0.005) was an independent risk factor for AE. In the propensity score match analysis, having received a well-matched kidney conferred a reduced risk of AE (hazards ratio, 0.22; 95% confidence interval, 0.05-0.95; P=0.044). We observed a significant correlation between HLA mismatch numbers and circulating CD57(+)CD28(-) CD8(+) T cells (R=0.31; P=0.017). These CD8(+) T cells were more frequent in patients with more HLA mismatches (P<0.0001).

CONCLUSION: Overall, our results suggest that chronic allogeneic stimulation participates to accelerated atherosclerosis observed after transplantation.