Immune Complex-positive Glomerulonephritis in Antineutrophil Cytoplasmic Antibody-positive Patients

Abstract

Antineutrophil cytoplasmic antibody (ANCA)-positive glomerulonephritis (GN) has traditionally been considered pauci-immune (PI); however, various reports have demonstrated the presence of immune reactants in a subset of these cases. The study was done to evaluate the prevalence of immune deposits in ANCApositive GN by direct immunofluorescence (DIF). Renal biopsies of 35 patients with ANCA-positive GN were retrospectively analyzed for light microscopic and DIF findings to look for the presence of immune reactants and to correlate these with the corresponding histologic features. Twenty-seven cases (77.2%) showed PI-GN while 8 (22.8%) cases showed. 2+ positivity for one or more immune reactants in the mesangium and/or capillary loops and were categorized as ANCA-positive immune complex GN. Of these, seven were positive for perinuclear (P-ANCA) and one for cytoplasmic (C-ANCA). Immunoglobulin M (IgM) was the most frequent immunoglobulin. On light microscopy, these cases exhibited significantly increased mesangial cellularity (p = 0.033) and more number of normal glomeruli as compared with PI cases (p = 0.015).