In vivo effect of lipopolysaccharide on alveolar and peritoneal macrophages of rats: superoxide anion generation and 5-lipoxygenase metabolism of arachidonic acid.

Influences of the intravenous administration of Escherichia coli lipopolysaccharide, 3 mg/kg, on the production of superoxide anion (O2-) and 5-lipoxygenase metabolites of arachidonic acid (AA) were evaluated in alveolar macrophages (AM) and peritoneal macrophages (PM) on days 1 and 3 after injection. The dose selected was that found to induce a significant leakage of [125I]bovine serum albumin in the pulmonary vasculature. AM obtained 1 day after LPS injection generated smaller amounts of O2- on stimulation with C5a but generated similar amounts with wheat germ lectin (WGA) or AA compared with control AM. This result suggested a prior complement activation. On day 3, on the contrary, their production of O2- significantly exceeded that by control AM with either of the three stimuli. PM collected on day 1 after LPS injection generated a significantly greater amount of O2- on stimulation with either WGA or AA than did control PM. The amount of O2-, however, decreased from day 1 to day 3. AM collected 1 day after the injection of LPS generated significantly more leukotriene B4 (LTB4) and 5-HETE on stimulation with A23187 alone and in combination with AA than did the cells from untreated rats. Such activities returned to the control levels in the AM collected on day 3. In contrast, the PM collected on day 1 produced amounts of LTB4 and 5-HETE similar to those of the control PM, but the cells on day 3 produced significantly more LTB4.(ABSTRACT TRUNCATED AT 250 WORDS)