Peritubular Capillaritis in Early Renal Allograft Dysfunction Is an Indicator of Acute Rejection

BackgroundKidneys showing acute rejection (AR) processes often are accompanied by various levels of peritubular capillaritis (Ptc), especially cases of acute humoral rejection (AHR). However, it is not known whether the presence of Ptc alone is sufficient evidence of allograft rejection. This study was performed to determine the diagnostic value of Ptc as a marker for AR among cases of early renal allograft dysfunction.MethodsFifty-three AR showed C4d deposition in the peritubular capillaries (PTCs; C4d+AR group), 50 AR were without C4d deposition (C4d−AR group), 30 had Ptc alone (Ptc group), 28 had acute tubular necrosis (ATN group), and 78 were surveillance biopsies (control group).ResultsAnalyzing the immunophenotype of infiltrating T lymphocytes and serum antibodies, discovered that 85.9% of control biopsies presented with a regulatory phenotype. Among the Ptc cohort, 93.3% of biopsies showed the cytotoxic phenotype with no significant different between C4d+AR and C4d−AR (96.2% vs 92.0%). We also observed the prevalence of panel-reactive antibody (PRA) and major-histocompatibility-complex class I chain-related gene A (MICA) antibodies to be increased among Ptc (30.0% and 43.3%, respectively), albeit not significantly different from C4d+AR (49.1% and 39.6%, respectively). The prevalences were low in other groups.ConclusionsThese results implied that Ptc in biopsy specimens from patients with early renal allograft dysfunction was an indicator of AR, especially AHR.