Critical role of mac-1 sialyl lewis x moieties in regulating neutrophil degranulation and transmigration.
Leukocyte cell surface sialyl Lewis x (sLe(x)) and related epitopes play an important role in cell rolling and adhesion during diapedesis via interaction with E-selectin. Here, we present evidence that Mac-1 (CD11b/CD18, CR-3) is a major neutrophil glycoprotein decorated with sLe(x) and ligation of these carbohydrate moieties by anti-sLe(x) antibody significantly impairs neutrophil functions. First, Western blot analysis shows that both CD11b and CD18 subunit of purified Mac-1 are decorated with sLe(x) moieties. A significant co-localization of CD11b and sLe(x) moieties is observed at neutrophil secondary granules. With stimulation of formyl-Met-Leu-Phe (fMLP), neutrophil surface labeling with anti-sLe(x) antibody follows an identical up-regulation pattern of Mac-1. Second, protein-binding assays indicate that sLe(x) moieties on Mac-1 are critical for binding interaction of Mac-1 to E-selectin. Removal of sLe(x) moieties completely abolishes Mac-1-E-selectin binding. Finally, ligation of Mac-1 sLe(x) by anti-sLe(x) antibody induces a significant degranulation of neutrophil secondary granules at the absence of chemoattractant stimulation. This "dysregulated" degranulation induced by anti-sLe(x) antibody strongly inhibits neutrophil transmigration in response to fMLP. In summary, Mac-1 sLe(x) moieties play a critical role in regulating beta(2) integrin functions during neutrophil transmigration and degranulation.
Zen
Ke
K
Jiangsu CDC-Nanjing University Joint Institute of Virology, Nanjing University, Nanjing, Jiangsu 210093, China.
Cui
Lun-Biao
LB
Zhang
Chen-Yu
CY
Liu
Yuan
Y
D015153:Blotting, Western; D002448:Cell Adhesion; D002465:Cell Movement; D002634:Chemotaxis, Leukocyte; D019040:E-Selectin / Q000378:metabolism; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006031:Glycosylation; D019073:HT29 Cells; D006801:Humans; D016177:Macrophage-1 Antigen / Q000502:physiology*; D009504:Neutrophils / Q000187:drug effects / Q000502:physiology*; D009844:Oligosaccharides / Q000737:chemistry* / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D000080506:Sialyl Lewis X Antigen; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
D019040:E-Selectin; D016177:Macrophage-1 Antigen; D009844:Oligosaccharides; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D000080506:Sialyl Lewis X Antigen; D048051:p38 Mitogen-Activated Protein Kinases