Changed expression of leukocyte adhesion molecules and increased production of reactive oxygen species caused by Streptococcus pyogenes in human whole blood.
To elucidate the innate immune responses to group A streptococci (GAS) important in the pathophysiology of sepsis, flow cytometric techniques were applied to study the effects of live and heat-inactivated GAS, including their particulate and soluble components, on the expression of leukocyte adhesion molecules CD11b (Mac-1) and CD62L (L-selectin), and leukocyte production of reactive oxygen species (ROS) in human whole blood. GAS caused marked time- and concentration-dependent increases in CD11b and ROS, while CD62L was downregulated. Live and heat-inactivated GAS induced similar changes in leukocyte adhesion molecules, whereas ROS production induced by heat-inactivated GAS (and its particulate fraction) was 4 (2.5)-fold higher than with live GAS. Leukocyte nitric oxide production (24 h) was not enhanced. Although GAS proved a more potent inducer of ROS production, leukocyte responses to GAS were similar to those reported for lipolysaccharides, indicating that Gram-positive and Gram-negative bacteria activate common pathways in the inflammatory response. High ROS production may contribute to tissue damage caused by GAS.
Saetre
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Research Forum, Ullevaal University Hospital, Oslo, Norway. torunn.satre@ioks.uio.no
Höiby
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EA
Kähler
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Lyberg
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D001120:Arginine / Q000494:pharmacology; D016470:Bacteremia / Q000097:blood*; D015815:Cell Adhesion Molecules / Q000097:blood*; D002455:Cell Division; D005434:Flow Cytometry; D006358:Hot Temperature; D006801:Humans; D007249:Inflammation; D019041:L-Selectin / Q000097:blood; D007962:Leukocytes / Q000378:metabolism*; D016177:Macrophage-1 Antigen / Q000097:blood; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000096:biosynthesis / Q000097:blood; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012995:Solubility; D013290:Streptococcal Infections / Q000097:blood / Q000276:immunology*; D013297:Streptococcus pyogenes / Q000166:cytology / Q000378:metabolism*
D015815:Cell Adhesion Molecules; D016177:Macrophage-1 Antigen; D017382:Reactive Oxygen Species; D019041:L-Selectin; D009569:Nitric Oxide; D001120:Arginine; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester