FB21, a monoclonal antibody that reacts with a sialic-acid-dependent carbohydrate epitope, is a marker for glomerular endothelial cell injury.

BACKGROUND

FB21 is reactive with glomerular endothelial cells and distal tubules of the human kidney and is bound to a sialic-acid-dependent cell-surface antigen. We evaluated FB21 staining in fetal kidneys and kidneys of children and adults with normal kidneys and glomerulonephritis and investigated whether FB21 can be used as a marker for endothelial cell injury.

METHODS

This study was performed on 6 children, 10 adults, and 12 fetuses with normal kidneys and 113 patients diagnosed with primary and secondary glomerulonephritis. We evaluated renal staining for FB21 in children with normal kidneys and glomerulonephritis and measured serum E-selectin concentrations in patients with hemolytic uremic syndrome (HUS) and Henoch-Schönlein purpura nephritis (HSPN).

RESULTS

(1) FB21 was reactive with endothelial cells of normal kidneys and detected on the surface of endothelial cells by immunoelectron microscopy. (2) FB21 was reactive with endothelial cells in kidneys of fetuses older than 32 weeks. (3) Endothelial cell FB21 staining scores in the first renal biopsy specimens of patients with HUS and HSPN were lower than those in normal kidneys of children and correlated negatively with serum E-selectin concentrations. (4) Endothelial cell FB21 staining of crescentic and sclerotic glomerular lesions in patients with immunoglobulin A nephropathy, membranoproliferative glomerulonephritis, and focal glomerulosclerosis was weaker than that in normal kidneys.

CONCLUSIONS

These results suggest that FB21 can be used as a marker for glomerular endothelial cell injury in various types of glomerulonephritis.