Release of platelet‐activating factor (PAF‐acether) and leukotrienes C and D from inflammatory macrophages

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Abstract
Macrophages (Mϕ) isolated from the peritoneal cavity of C57BL/6 mice were either untreated or treated with various eliciting agents (thioglycollate, sodium caseinate) or with an activating agent bacillus Calmette Guérin (BCG). The various populations were assessed for their ability to release platelet‐activating factor (PAF‐acether), an ether phospholipid mediator, and slow‐reacting substance (SRS), a lipoxygenase arachidonic acid derivative. PAF‐acether was recovered in higher amounts from BCG Mϕ, than from resident Mϕ, whereas elicited Mϕ, exhibited a marked decreased ability to release this mediator. Such variations were only quantitative as evidenced by the similar enzyme sensitivity and high pressure liquid chromatography (HPLC) retention times of the various PAF‐acether‐containing supernatants. Resident, BCG‐and sodium caseinate‐induced Mϕ released similar amounts of SRS, whereas thioglycollate Mϕ, exhibited once again a marked decreased ability to release this mediator. Comparing retention times on HPLC of resident and BCG Mϕ, SRS with those of synthetic leukotrienes C and D, molecular variations were noted. Even though both Mϕ, populations released higher amounts of leukotrienes C than D, the DIC ratio was higher in BCG Mϕ, than in resident Mϕ,. These results show that different environmental factors can influence the release of PAF‐acether and leukotrienes from Mϕ.