PMC5519472_01
Light micrograph of a part of the glomerulus, showing spikes (arrow head) of the basement membrane in the segmental capillary loops (A). Immunofluorescent findings show segmental positive granular IgG (B), IgG1 (C), kappa light chain (D) and lambda light chain (E) staining along the glomerular capillary walls and negative M-type phospholipase A2 receptor staining (F). Indirect immunohistochemistry for IgG shows granular staining along the segmental glomerular capillary walls with a variety of distribution (G-I). A: periodic acid-methenamin silver. Original magnification 600x, B-I: Original magnification 200x. G-I; Polyclonal anti-human IgG (DAKO Japan, Japan) was used.
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The remaining 20 glomeruli showed mild mesangial expansion, no mesangial hypercellularity and no exudative lesions (Fig. 1A). Segmental thickening, spike formation (Fig. 1A) and vacuolization along the very limited GCWs were found in each glomerulus. An immunofluorescence study showed negative staining for IgA, IgM, C1q and C3 but granular staining for IgG (Fig. 1B) and kappa and lambda light chains along segmental GCWs (Fig. 1D and E), suggesting the deposition of polyclonal IgG antibody. IgG subclass consisted of IgG1 (Fig. 1C), but IgG2, IgG3 or IgG4 and glomerular M-type phospholipase A2 receptor (PLA2R) was negative (Fig. 1F). Immunohistochemistry for IgG showed segmental granular IgG staining along GCWs in not than half of the glomerular tuft (Fig. 1G-I), which was found in all of the glomeruli examined.
Electron-microscopic findings. Normal capillary loop (right lower part) and capillary loops with subepithelial electron dense deposits (EDDs) can be seen (A). The area of the square in Fig. 2A shows not only subepithelial EDDs but also intramembranous EDDs (arrows) and mesangial EDDs (arrow heads). A; Bar=5 mum, B; Bar=2 mum.
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Electron microscopy revealed glomerular capillary loops without electron dense deposits (EDD) and with subepithelial EDDs (histological stage I to III according to Ehrenreich and Churg) and a small amount of intramembranous EDDs (Fig. 2). The amount and size of subepithelial EDDs were largely different among capillary loops (Fig. 2A). EDDs (Fig. 2A). Endothelial cells were unremarkable and did not contain tubuloreticular inclusions. EDDs were also contained in some mesangial areas (Fig. 2).