Bacterial lipopolysaccharides prime macrophages for enhanced release of arachidonic acid metabolites.
Preincubation of resident peritoneal macrophages with 10-100 ng/ml LPS for 60 min resulted in the cells becoming primed for enhanced (three-to eightfold higher) arachidonic acid (20:4) secretion in response to a variety of triggers. The half-maximal concentration of LPS required for priming was 10 ng/ml irrespective of whether the trigger was particulate (examples: zymosan or immune complexes) or soluble (such as PMA or A23187). Similarly, the time required for half-maximal priming of macrophages was 20 min irrespective of which trigger was used. The primed state persisted for at least 30 h. LPS-priming of macrophages also affected the kinetics of 20:4 metabolite secretion. The lag phase characteristically observed when 20:4 secretion is triggered was reduced in LPS-primed cells. Furthermore, LPS-primed cells secreted 20:4 metabolites when challenged with latex beads, while unprimed cells did not. These data suggest that stimuli such as zymosan, which elicit 20:4 secretion in macrophages, promote two signals, a priming signal and a triggering signal. LPS is capable of establishing the priming signal but not the triggering signal, while latex promotes the triggering signal but is unable to prime the cells for 20:4 release. LPS did not effect the profile of 20:4 metabolites secreted in response to any of the triggers, nor did it effect the profile of products synthesized from exogenously added 20:4, suggesting that it did not regulate the 20:4 cascade at the level of either the cyclooxygenase or lipoxygenase pathways. Macrophages respond to LPS without the intervention of T lymphocytes, since the macrophages from nude mice could be primed for enhanced 20:4 secretion.
D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism*; D004306:Dose-Response Relationship, Immunologic; D005260:Female; D007840:Latex; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008262:Macrophage Activation; D008264:Macrophages / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D008813:Mice, Inbred ICR; D008863:Microspheres; D011951:Receptors, Complement / Q000502:physiology; D017463:Receptors, Complement 3b; D013601:T-Lymphocytes / Q000276:immunology; D013997:Time Factors
D001095:Arachidonic Acids; D007840:Latex; D008070:Lipopolysaccharides; D011951:Receptors, Complement; D017463:Receptors, Complement 3b; D016718:Arachidonic Acid