Eosinophils in acute renal allograft rejection

Abstract

Tissue eosinophils have been previously implicated in allograft rejection and graft loss. The aim of this study was to evaluate the role of eosinophils in acute renal allograft rejection. Data from 71 patients with 114 renal biopsies with acute allograft rejection were compared with those from 26 controls. The median tissue eosinophil density (0.4−1.1 eosinophils per μm 2 × 10 6) and the median peripheral blood eosinophilia (1.5–3.0%) in all grades of acute interstitial rejection and in acute vascular rejection were higher than in controls (0.0 eosinophils per μm 2×10 6, p<0.0023, and 0.9%, p<0.035). In all grades of rejection, 36–54% of biopsies had tissue eosinophil density ⩾ 1 1 eosinophil per μm 2 × 10 6, and 20–36% of patients had peripheral blood eosinophilia ≥4%, compared with 0% and 4%, respectively, in controls ( p<0.000 and p = 0.0245). The sensitivity, specificity and overall accuracy of predicting acute rejection with tissue eosinophil density ≥1 eosinophil per μm 2 × 10 6 is 41%, 100% and 52%, and for peripheral blood eosinophilia ≥4% is 23%, 96% and 40%, respectively. The median tissue eosinophil density in acute rejection with graft loss was 1.9 eosinophils per μm 2 × 10 6 compared to 0.2 eosinophils per μm 2 × 10 6 in acute rejection without graft loss ( p = 0.014), and 67% of acute rejection with graft loss had tissue eosinophil density ≥1 eosinophil per μm 2 × 10 6 compared with 28% of acute rejection without graft loss ( p = 0.028). It is concluded that peripheral blood eosinophilia and increased tissue eosinophil density occur in up to 50% of patients with acute renal allograft rejection, and these may be regarded as diagnostic and prognostic markers of acute rejection.