[Crescent formation in children with Henoch-Schönlein purpura nephritis: a pathological and immunohistochemical study].

There is a strong association between epithelial crescent formation and the outcome of patients with Henoch-Schönlein purpura nephritis (HSPN), but little is known about the mechanisms of crescent formation in this disease. In this study, we examined whether or not glomerular endocapillary proliferation, fibrinoid necrosis and infiltrating inflammatory cells are involved in the process of crescent formation. Renal biopsy specimens were obtained from 19 patients (11 males and 8 females, 7.8 +/- 3.8 years old). The biopsies were performed within the initial 3 months after the onset of urinary abnormalities in all patients. Twelve patients had crescents (% glomeruli with crescents; 27.5 +/- 20.4%), and the other 7 did not. Renal tissues biopsied from 10 patients with asymptomatic hematuria served as controls for quantitative studies of glomerular leukocyte infiltration. Prominent endocapillary proliferation as well as fibrinoid necrosis were encountered in patients with crescents in contrast to patients without crescents. A positive correlation between crescents and endocapillary proliferation or fibrinoid necrosis was also observed. Significant increases in the number of glomerular CD68+ macrophages, CD45RO+ T cells and NP57+ neutrophils were observed in HSPN patients compared with the controls. When patients with or without crescents were compared, patients with crescents had a greater number of inflammatory cells. Although all kinds of inflammatory cells appeared in the endocapillary proliferative lesion, only CD68+ macrophages and NP57+ neutrophils were present in the fibrinoid necrotizing lesion. In conclusion, the present study demonstrated that necrotizing lesions with capillary rupture may be essential in the process of crescent formation seen in HSPN. Although the mechanism by which capillary wall breaks occur is still unknown, this study indicates that infiltrating macrophages as well as neutrophils may be involved in capillary rupture leading to epithelial crescent formation.