[Significance of detecting urinary podocytes in patients with active glomerulonephritis]

To establish a reliable method for detecting urinary podocytes, as a non-traumatic marker to evaluate glomerular injury in patients with glomerulonephritis.

Sixty patients with renal diseases in our renal wards were diagnosed based on the pathological findings in their kidney biopsy tissues, which was examined by light microscopy, immunofluorescence and electron microscopy. Sediments of morning urinary samples were collected and centrifuged onto glass slides before kidney biopsy. Thirty healthy volunteers were enrolled as controls. The podocytes were identified by immunofluorescence staining by using monoclonal antibody against human podocalyxin (PCX) presenting on the surface of podocytes. The patients were divided into active inflammation group and chronic injury group according to their glomerular lesions.

(1)The anti-human PCX antibody we used could specifically recognize the antigen expressed on podocytes in urine sediments examined by indirect immunofluorescence staining. (2) The PCX-positive staining cells in the urine were observed in various glomerulonephritis, and were absent in the healthy controls. (3) The rate of appearance of urinary podocytes was significantly higher in active inflammation group compared with that in chronic injury group (72% vs 22.7%, P<0.05). (4) The glomerular injury index in the patients with PCX-positive staining cells in the urine was markedly increased than that in the patients with PCX-negative staining cells (154+/-60 vs 82+/-46, P<0.05).

The urinary podocytes could be detected in urine sediments from patients with glomerulonephritis by using anti-human PCX antibody, and this method may find further application in the markers to predict the activity of glomerular lesions.