C5a-stimulated human neutrophils use a subset of beta2 integrins to support the adhesion-dependent phase of superoxide production.
Isolated human polymorphonuclear neutrophils (PMN) responded to human C5a with an immediate, transient release of superoxide lasting from 0.5 to 5 min. This was followed by a second release of superoxide, which began at 10 min after addition of C5a, was sustained for more than 30 min, and required ICAM-1 immobilized in the wells. F(ab')2 monoclonal antibody (mAb) preparations were used to dissect the role of individual beta2 integrins and to avoid the confounding effects of ligating Fc receptors. Anti-CD18 mAb treatment of the PMN had no effect on the immediate first phase but completely inhibited the second, adhesion-dependent phase of superoxide production. Anti-CR3 mAb only inhibited the adhesion phase of superoxide production partially, implying that other beta2 integrins were involved. A mixture of anti-CD11a, anti-CD11b, and anti-CD11c was not able to block superoxide production completely, suggesting a role for alphad/beta2. Surprisingly, blocking anti-LFA-1 mAb had no effect on superoxide production. Consistent with this observation, immobilized, purified ICAM-2, a specific counter-receptor for LFA-1, did not support the adhesion-dependent phase of-superoxide production. Thus, PMN treated with C5a used signals via CR3, P150/95, and alphad/beta2, but not LFA-1, to support superoxide production. LFA-1 has been shown by others to mediate most of the adhesion necessary for transendothelial migration in vivo. The inability of LFA-1 ligation to stimulate superoxide production may be an important means of preventing blood-vessel damage when PMN migrate across the endothelium.
Tyagi
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S
Department of Medicine, and Charles A. Dana Research Institute and Harvard-Thorndike Laboratory, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02115, USA.
Klickstein
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LB
Nicholson-Weller
A
A
D000911:Antibodies, Monoclonal / Q000494:pharmacology; D015703:Antigens, CD / Q000378:metabolism; D018821:CD18 Antigens / Q000378:metabolism / Q000502:physiology*; D002448:Cell Adhesion / Q000502:physiology; D015815:Cell Adhesion Molecules / Q000378:metabolism; D015936:Complement C5a / Q000494:pharmacology*; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D016169:Lymphocyte Function-Associated Antigen-1 / Q000502:physiology; D009504:Neutrophils / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D013268:Stimulation, Chemical; D013481:Superoxides / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D018821:CD18 Antigens; D015815:Cell Adhesion Molecules; C065289:ICAM2 protein, human; D016169:Lymphocyte Function-Associated Antigen-1; D013481:Superoxides; D018799:Intercellular Adhesion Molecule-1; D015936:Complement C5a