Arachidonic acid metabolism in bovine alveolar macrophages: effect of calcium ionophore on lipoxygenase products

The production of lipoxygenase metabolites of arachidonic acid was studied in bovine alveolar macrophages (BAM). Unstimulated macrophages produced small amounts of LTB4 (0.2 +/- 0.2 ng/10(6) BAM) but monohydroxyeicosatetraenoic acids (5-, 12-, and 15-HETE) usually were not detectable. Both exogenous arachidonic acid and the calcium ionophore A23187 induced production of LTB4, 5-, 12-, and 15-HETE, of which 60-80% was 5-HETE. Combined challenge of BAM with both exogenous arachidonic acid and A23187 was more effective in the production of these metabolites than with either stimulus alone. The generation of the peptidoleukotrienes LTC4, LTD4, and LTE4 by BAM could not be detected under these in vitro conditions. Our results demonstrate that bovine alveolar macrophages produce similar lipoxygenase metabolites of arachidonic acid in response to A23187, as do human alveolar macrophages stimulated with the same agonist.