ANTIGLOMERULAR BASEMENT-MEMBRANE GLOMERULONEPHRITIS IN THE MOUSE - THE ROLE OF MACROPHAGES

An immunohistochemical study was undertaken on fixed, paraffin-embedde d mouse kidney in order to elucidate the role and significance of infi ltrating macrophages in a mouse model of anti-glomerular basement memb rane glomerulonephritis (anti-GEM GN). Tissue was available representi ng the full gamut of histological features seen in this model. The mou se macrophage-specific antigen F4/80 was detected in tissue sections o f glomerulonephritic kidney and the pattern and extent of staining was compared with normal mouse kidney. In glomerulonephritic kidney, an i ncrease in the number of F4/80-positive cells was evident in close pro ximity to and surrounding Bowman's capsule of those glomeruli which we re severely damaged, with extensive fibrin deposition and well develop ed cellular crescents. F4/80-positive cells did not feature in the glo merular tuft or in the region of the parietal epithelium of Bowman's c apsule even when extensive cellular crescents were present. Breaks in Bowman's capsule were not demonstrated. We conclude that F4/80-positiv e macrophages are not a major constitutive cell type of developing cre scents in this mouse model of anti-GEM GN but, by virtue of their peri -glomerular localization, may be involved in the destructive process, perhaps producing signalling molecules which contribute to the inflamm atory reaction.