[Vitronectin in children with renal disease--1. Immunofluorescence study of vitronectin and C5b-9 in childhood IgA nephropathy].

Renal biopsy specimens from 54 children (33 boys, 21 girls) with IgA nephropathy were investigated by immunofluorescence microscopy to determine the localization of vitronectin and C5b-9. vitronectin and C5b-9 deposits were found within the glomeruli of all cases and the intensity of vitronectin and C5b-9 deposits was as follows: vitronectin: (3+) 17 cases, (2+) 21 cases, (1+) 16 cases and C5b-9: (3+) 28 cases, (2+) 18 cases, (1+) 8 cases. In 19 cases and C5b-9 deposits were shown to be more predominant than vitronectin (Group C) and the same or less intense in 35 cases (Group V). In 33 cases, vitronectin deposits were demonstrated in the mesangial area only (M type), while in 21 cases deposits were presented both the mesangial area and the capillary wall (MC type). Linear staining of vitronectin was noted in Bowman's basement membrane and in the tubular basement membrane. Granular staining of vitronectin was observed in Bowman's basement membrane (29 cases) and tubular basement membrane (46 cases). M type C5b-9 deposits were demonstrated in 34 cases and MC type in 20 cases. C5b-9 deposits were observed in Bowman's basement membrane (19 cases) and in tubular basement membrane (37 cases). Intensely stained vitronectin was found in the sclerotic glomeruli and segmental sclerotic portion of the tissues. In serial biopsy, the intensity of both vitronectin and C5b-9 deposits became less intense. It was found that many patients of Group C had heavy proteinuria (P < 0.05) and that nephrotic patients were more frequent in Group C than in Group V (p < 0.05). In the light microscopic examination, most cases with intense C5b-9 deposits had mesangial proliferation (p < 0.10) and an increase in mesangial matrix (p < 0.10). Mesangial sclerosis index was correlated with the intensity of vitronectin deposits (p < 0.05). These findings suggest that vitronectin and the terminal complement system may play a critical role as a mediator of immunological tissue injury, especially mesangial sclerotic lesion in childhood IgA nephropathy.