Heparan sulfate (HS) proteoglycans by playing key roles in the leukocyte-endothelial interactions are thought to mediate inflammatory cell influx in proliferative glomerulonephritis. Here, we evaluated the specific features within glomerular endothelial HS that promote leukocyte adhesion. Mouse and human glomerular endothelial cells activated by tumor necrosis factor (TNF)-alpha or interleukin (IL)-1beta increased expression of inflammatory N- and 6-O-sulfated HS domains. In addition, altered expression of HS-modifying enzymes occurred, a feature also found in mouse kidneys with anti-glomerular basement membrane disease or lupus nephritis. Inhibition of the nuclear factor (NF)-kappaB pathway repressed cytokine-induced alterations in HS and gene expression of modifying enzymes. Firm adhesion of leukocytes to activated mouse glomerular endothelial cells decreased after removal of endothelial HS or addition of sulfated heparinoids. Specific antibodies that block N- and 6-O-sulfated HS domains on activated mouse endothelial cells reduced the number of rolling and firmly adhering leukocytes under dynamic flow conditions, while they increased the average leukocyte-rolling velocity. Our study shows that N- and 6-O-sulfated domains in HS on activated glomerular endothelium are crucial for leukocyte trafficking and are possible therapeutic targets.