Association of donor-specific anti-MHC class I-related chain A (MICA) antibodies with renal allograft outcome

Abstract

Background. Association of anti-MHC class I-related chain A (MICA) with kidney allograft rejection was suggested. However, associations of donor-MICA specific antibodies (dsMICA) and strength of dsMICA with allograft outcome were not elucidated yet. Methods. From November 2009 to June 2016, 125 remaining sera from renal transplantation recipients with no HLA antibody and biopsy-proven acute rejection (AR) (n = 13), AR + Interstitial Fibrosis and Tubular Atrophy (IFTA) (n = 13), IFTA only (n = 12), IFTA + borderline change (n = 15), borderline change only (n = 18) and normal biopsy (n = 54) were screened for MICA antibody. MICA antibody identification was performed with LABScreen MICA (One Lambda, USA) on sera with positive MICA screening. Patients with positive MICA screening with available residual donor DNA for MICA genotyping (n = 12) were also analyzed for dsMICA. Results. Among 125 sera, 19 were positive for MICA antibody (15.2%). dsMICA was positive on 5 out of 12 sera analyzed (41.7%). Neither MICA antibodies nor dsMICA was associated with acute rejection (AR). However, IFTA was significantly associated with MICA positivity (OR = 3.84

95% CI = 1.34 – 9.98, P = 0.009). The MFI value of dsMICA was significantly higher in patients with IFTA II or III (n = 3, median ± SE, 21919.0 ± 2581.0) compared to patients without IFTA II or III (n = 9, median ± SE, 500.0 ± 155.8) (P = 0.009). Conclusion. MICA was associated with IFTA in patients without HLA antibody. The association of strength of dsMICA with IFTA severity was suspected. MICA or dsMICA was not associated with acute rejection in patients without HLA antibody. The MICA antibody is useful as a predictor of chronic renal damage and as a useful indicator for future treatment strategy.