Pretransplant angiotensin II type 1-receptor antibodies are a risk factor for earlier detection of de novo HLA donor-specific antibodies.

BACKGROUND: Angiotensin II type 1 receptor antibodies (AT1Rabs) have been associated with significantly reduced graft survival. Earlier graft loss has been observed in patients who had pretransplant AT1Rabs and posttransplant donor-specific antibodies (DSA).

METHODS: The main goal of this retrospective cohort study was to examine the association between AT1Rabs and the time period to detection of de novo human leukocyte antigen (HLA-DSA) posttransplantation in living donor kidney transplant recipients (KTR). The analysis included 141 KTRs. Pretransplant frozen serum samples were tested for AT1Rabs by ELISA and HLA-DSA by SAB (Luminex) at both the pre- and post-KT time points.

RESULTS: The median AT1Rab level was 9.13 U (interquartile range 5.22-14.33). After a mean follow-up period of 3.55 years, 48 patients were found to harbour de novo HLA-DSAs. The presence of AT1Rabs [hazard ratio (HR) 1.009, 95% confidence interval (CI) 1.002-1.01, P = 0.010], male-to-male transplantation (HR 2.57, 95% CI 1.42-4.67, P = 0.002) and antecedent borderline changes or acute cellular rejection (ACR) (HR 2.47, 95% CI 1.29-4.75, P = 0.006) were significantly associated with de novo DSA detection. A dose-dependent association between AT1Rab levels (<10 U, 10.1-16.9 U, 17-29.9 U and >30 U) and de novo DSA detection was observed (log-rank P = 0.0031). After multivariate analysis of AT1Rab levels (continuous variable), AT1Rabs >30 U, male-to-male transplantation, donor age, higher class I percentage of Panel Reactive Antibody and antecedent borderline changes or ACR remained as independent significant risk factors for the detection of de novo DSAs.

CONCLUSIONS: The findings suggest that higher levels of pretransplant circulating antibodies against AT1R (>30 U) in kidney graft recipients constitute an independent risk factor for earlier de novo HLA-DSA detection during the posttransplant period.