Fig. 1

Diagnostic studies. a Periodic acid-Schiff (PAS) staining at a low magnification (×200). Crescentic glomerular lesions of b PAS, c Periodic acid-methenamine-silver, and d Masson’s trichrome staining (× 400). Scale bar: 100 μm (a) and 50 μm (b-d). e Electron microscopy image. Scale bar: 2 μm. f Immunofluorescence studies using frozen sections. Linear capillary loop staining for IgG, and C3 (1+) was positive on glomerular capillaries. g IgG1 and IgG4 were positive. Staining for IgG1 (3+) was dominant, and the staining intensity for IgG4 (1+) was rather weak. Staining for IgG2 and IgG3 was negative. Immunofluorescence staining was positive for both kappa and lambda. h Immunofluorescence studies using FITC-labeled anti-human IgG (F2020; Dako, Glostrup, Denmark) to determine the presence of IgG binding to the GBM by applying the patient serum to frozen normal kidney tissue after pretreatment in 10 M urea solution for 10 minutes. Anti-GBM antibodies were detected in the Serum (+) specimens in which patient serum was reacted in normal kidney tissue. In contrast, no IgG findings was detected in Serum (−) specimens in which patient serum was excluded in same immunostaining procedures