Role of calcium during lipopolysaccharide stimulation of neutrophils.
This study investigated the role of intracellular calcium concentration ([Ca]i) as a possible intermediate in the lipopolysaccharide (LPS) second messenger pathway for the activation of neutrophils (polymorphonuclear leukocytes [PMNs]). Isolated PMNs were loaded with the calcium-sensitive fluorescent dye fura-2. The PMNs were stimulated with either LPS or the positive control formyl-Met-Leu-Phe (fMLP). As expected, PMN exposure to fMLP increased [Ca]i. However, LPS stimulation did not induce any detectable changes. Depletion of intracellular Ca stores with thapsigargin, or extracellular Ca with EGTA, significantly inhibited the upregulation of the CD11b/CD18 integrin in response to fMLP but not LPS. We conclude that [Ca]i is not an early intermediate in the second-messenger pathway for the activation of PMNs by LPS.
Rodeberg
D A
DA
Shriners Burns Institute, Cincinnati, Ohio 45229-3095, USA.
Babcock
G F
GF
D018821:CD18 Antigens / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002614:Chelating Agents / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D005456:Fluorescent Dyes; D016257:Fura-2; D006801:Humans; D066298:In Vitro Techniques; D008070:Lipopolysaccharides / Q000494:pharmacology*; D016177:Macrophage-1 Antigen / Q000378:metabolism; D008954:Models, Biological; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism*; D015290:Second Messenger Systems; D013050:Spectrometry, Fluorescence; D013729:Terpenes / Q000494:pharmacology; D019284:Thapsigargin
D018821:CD18 Antigens; D002614:Chelating Agents; D005456:Fluorescent Dyes; D008070:Lipopolysaccharides; D016177:Macrophage-1 Antigen; D013729:Terpenes; D004533:Egtazic Acid; D009240:N-Formylmethionine Leucyl-Phenylalanine; D019284:Thapsigargin; D002118:Calcium; D016257:Fura-2