Activation of human neutrophil Mac-1 by anion substitution.
Substituting the medium chloride with glucuronate or glutamate causes a rapid, 10 to 30-fold, increase in the binding of the monoclonal antibody, CBRM1/5, which recognizes the high-affinity conformation of the Mac-1 integrin. This change is reflected in functional adhesion assays that show increased adhesion to ICAM-1 coated beads. Blocking antibodies indicate that the increased adhesion is almost entirely due to Mac-1. The inhibitor NPPB (100 microM) reduces Cl(-) efflux into low Cl(-) medium by 75%, and blocks increased CBRM1/5 binding after stimulation with fMLP or TNF-alpha, but has no effect on the anion substitution induced increase in CBRM1/5 binding or adhesion to immobilized ICAM-1. Thus, changes in external anion composition, not internal chloride or increases in Cl(-) efflux, are responsible for Mac-1 activation. This effect is substantial. The percentage of Mac-1 in the high affinity state approaches 100% in glutamate and 50% in glucuronate, a far greater response than what is observed after stimulation with fMLP.
Lomakina
Elena
E
Department of Pharmacology and Physiology, School of Medicine, University of Rochester, Rochester, NY 14642, USA.
Knauf
Philip A
PA
Schultz
Joanne B
JB
Law
Foon-Yee
FY
McGraw
Matthew D
MD
Waugh
Richard E
RE
D000911:Antibodies, Monoclonal / Q000378:metabolism; D002448:Cell Adhesion / Q000187:drug effects; D002712:Chlorides / Q000378:metabolism / Q000494:pharmacology*; D045604:Extracellular Fluid / Q000737:chemistry; D005965:Glucuronates / Q000494:pharmacology; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D016177:Macrophage-1 Antigen / Q000378:metabolism*; D008863:Microspheres; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000166:cytology* / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D011487:Protein Conformation / Q000187:drug effects; D017434:Protein Structure, Tertiary; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D000911:Antibodies, Monoclonal; D002712:Chlorides; D005965:Glucuronates; D016177:Macrophage-1 Antigen; D014409:Tumor Necrosis Factor-alpha; D018799:Intercellular Adhesion Molecule-1; D009240:N-Formylmethionine Leucyl-Phenylalanine