[1655] M2 Macrophages in Early Lesions of Crescentic Glomerulonephritis

Lei Zhao, Anthony Chang, Shane Meehan. University of Chicago, Chicago, IL

Background: T cells, macrophages and neutrophils are implicated in the pathogenesis of crescentic glomerulonephritis (CGN). However, the initial events leading to the perforation of glomerular capillary walls are poorly characterized. The goal of this study was to examine early lesions and characterize the effector cells at the site of initial injury.
Design: We identified 23 kidney biopsies with early disease, including pauci-immune CGN (n=10), anti-GBM CGN (n=5) and immune complex mediated CGN (n=8). Early lesions were defined as segmental fibrinoid necrosis without crescents, and early cellular crescents occupying less than 50% of Bowman's capsule circumference. All biopsies were examined using standard light, electron and immunofluorescence microscopy. Additionally, immunohistochemical staining of paraffin sections for macrophages (CD68, MRP8/14, CD163), T cells (CD3), B cells (CD20) and NK cells (CD56) was performed in each case.
Results: Light microscopy demonstrated frequent mononuclear cells and rare neutrophils at foci of glomerular capillary wall injury. Electron microscopy confirmed mononuclear cells as the predominant cell type at areas of glomerular basement membrane attenuation and rupture. Numerous CD68+ macrophages and rare CD3+ T cells (1-2/per glomerulus) were evident at these foci by immunohistochemistry. CD20+and CD56+ cells were not detected. The overwhelming majority of macrophages were M2 type (CD163+) with few M1 (MRP8/14+) macrophages. The findings were similar in each category of CGN.
Conclusions: The frequent localization of M2 macrophages in early lesions of CGN is an intriguing observation that has not been previously described. This finding suggests an important role of M2 macrophages in the evolution of capillary injury in CGN.
Category: Kidney (does not include tumors)

Tuesday, March 5, 2013 11:15 AM

Proffered Papers: Section H, Tuesday Morning

 

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