title: Effects of IL-8, Gro-alpha, and LTB(4) on the adhesive kinetics of LFA-1 and Mac-1 on human neutrophils.
abstract: Firm adhesion of rolling neutrophils on inflamed endothelium is dependent on beta(2) (CD18)-integrins and activating stimuli. LFA-1 (CD11a/CD18) appears to be more important than Mac-1 (CD11b/CD18) in neutrophil emigration at inflammatory sites, but little is known of the relative binding characteristics of these two integrins under conditions thought to regulate firm adhesion. The present study examined the effect of chemoattractants on the kinetics of LFA-1 and Mac-1 adhesion in human neutrophils. We found that subnanomolar concentrations of interleukin-8, Gro-alpha, and leukotriene B(4) (LTB(4)) induced rapid and optimal rates of LFA-1-dependent adhesion of neutrophils to intercellular adhesion molecule (ICAM)-1-coated beads. These optimal rates of LFA-1 adhesion were transient and decayed within 1 min after chemoattractant stimulation. Mac-1 adhesion was equally rapid initially but continued to rise for >/=6 min after stimulation. A fourfold higher density of ICAM-1 on beads markedly increased the rate of binding to LFA-1 but did not change the early and narrow time window for the optimal rate of adhesion. Using well-characterized monoclonal antibodies, we showed that activation of LFA-1 and Mac-1 by Gro-alpha was completely blocked by anti-CXC chemokine receptor R2, but activation of these integrins by interleukin-8 was most effectively blocked by anti-CXC chemokine receptor R1. The topographical distribution of beads also reflected significant differences between LFA-1 and Mac-1. Beads bound to Mac-1 translocated to the cell uropod within 4 min, but beads bound to LFA-1 remained bound to the lamellipodial regions at the same time. These kinetic and topographical differences may indicate distinct functional contributions of LFA-1 and Mac-1 on neutrophils.
authors.affiliation: Institute of Biosciences and Bioengineering, Rice University, Houston 77005, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Seo
authors.forename: L V
authors.initials: LV
authors.lastname: McIntire
authors.forename: C W
authors.initials: CW
authors.lastname: Smith
mesh_terms: D000328:Adult; D002448:Cell Adhesion / Q000187:drug effects; D054360:Chemokine CXCL1; D019743:Chemokines, CXC; D002630:Chemotactic Factors / Q000494:pharmacology*; D005434:Flow Cytometry; D006133:Growth Substances / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins; D016209:Interleukin-8 / Q000494:pharmacology*; D007975:Leukotriene B4 / Q000494:pharmacology*; D016169:Lymphocyte Function-Associated Antigen-1 / Q000494:pharmacology*; D016177:Macrophage-1 Antigen / Q000494:pharmacology*; D009504:Neutrophils / Q000187:drug effects*
chemical_list: C475829:CXCL1 protein, human; D054360:Chemokine CXCL1; D019743:Chemokines, CXC; D002630:Chemotactic Factors; D006133:Growth Substances; D036341:Intercellular Signaling Peptides and Proteins; D016209:Interleukin-8; D016169:Lymphocyte Function-Associated Antigen-1; D016177:Macrophage-1 Antigen; D018799:Intercellular Adhesion Molecule-1; D007975:Leukotriene B4