Particles binding beta(2)-integrins mediate intracellular production of oxidative metabolites in human neutrophils independently of phagocytosis.
Complement-opsonised particles are readily ingested by human neutrophils through a complement receptor-mediated process leading to phagolysosome fusion and production of oxidative metabolites. To investigate the complement receptor 3 (CR3)-associated signal system involved, cells were challenged with protein A-positive, heat-killed Staphylococcus aureus to which antibodies with specificity for the subunits of the beta(2)-integrins, i.e. anti-CD11b (the alpha subunit of CR3) and anti-CD18 (the beta subunit of CR3), were bound through their Fc moiety. Despite not being ingested by the neutrophils, the surface associated anti-CD18- and anti-CD11b-coated particles were able to activate the neutrophil NADPH-oxidase. Also anti-CD11a- (the alpha subunit of LFA-1) and to a lesser extent anti-CD11c- (the alpha subunit of CR4) coated particles were able to trigger the NADPH-oxidase. The NADPH-oxidase was activated without extracellular release of reactive oxygen species. The activity was inhibited by cytochalasin B, suggesting a necessary role for the cytoskeleton in the signalling pathway that activates the oxidase. We show that particle-mediated cross-linking of beta(2)-integrins on the neutrophil surface initiates a signalling cascade, involving cytoskeletal rearrangements, leading to an activation of the NADPH-oxidase without phagosome formation or extracellular release of reactive oxygen species.
Serrander
L
L
Department of Medical Microbiology, University Hospital of Linköping, S-58185, Linköping, Sweden.
Larsson
J
J
Lundqvist
H
H
Lindmark
M
M
Fällman
M
M
Dahlgren
C
C
Stendahl
O
O
D000906:Antibodies / Q000276:immunology; D000918:Antibody Specificity; D001666:Binding Sites, Antibody; D018845:CD11 Antigens / Q000276:immunology; D018821:CD18 Antigens / Q000276:immunology / Q000378:metabolism*; D003571:Cytochalasin B / Q000494:pharmacology; D004789:Enzyme Activation; D018922:HL-60 Cells; D006801:Humans; D016177:Macrophage-1 Antigen / Q000276:immunology*; D019255:NADPH Oxidases / Q000032:analysis / Q000378:metabolism; D009504:Neutrophils / Q000378:metabolism*; D010084:Oxidation-Reduction; D010587:Phagocytosis; D015398:Signal Transduction / Q000276:immunology; D013205:Staphylococcal Protein A / Q000276:immunology*
D000906:Antibodies; D018845:CD11 Antigens; D018821:CD18 Antigens; D016177:Macrophage-1 Antigen; D013205:Staphylococcal Protein A; D003571:Cytochalasin B; D019255:NADPH Oxidases