Urinary podocytes in childhood IgA nephropathy

SUMMARY: We have previously demonstrated the presence of detached podocytes in the urine in various glomerular diseases. In this study, we investigated the pathological significance of detachment of urinary podocytes (u-podocytes) in childhood IgA nephropathy. We investigated 28 children with IgA nephropathy. U-podocytes were detected in the urinary sediment by immunofluorescence. Renal pathological changes and urinalysis, including the u-podocyte test, were analysed. The expression of glomerular basement membrane (GBM) components, integrins and cytoskeleton components on urinary podocytes was investigated using dual immunofluorescence in 12 patients. The u-podocyte score paralleled the acute glomerular changes in renal biopsy samples. The infiltration of glomerular macrophages and polymorphonuclear leucocytes, and the number of urinary leucocytes, correlated highly with the u-podocyte score. Some of the u-podocytes expressed integrins and also components of the GBM. Detachment of podocytes reflects the presence of acute glomerular lesions. Infiltration of glomerular leucocytes is considered to be the cause of the detachment, partly because of the destruction of the GBM.