Brief Definitive Report Compartmentalized Regulation of Macrophage Arachidonic Acid Metabolism

Mouse peri toneal macrophages given a phagocytic stimulus release large amounts o f cyclooxygenase and lipoxygenase metabolites o f arachidonic acid (20:4) (1,2). After macrophage activation th rough intraperi toneal administration of inf lammatory agents, stimulated 20:4 metabolism by peritoneal macrophages is quantitatively and qualitatively al tered (3, 4). T o determine whether downregulat ion o f 20:4 metabolism occurs in macrophage populations outside a local inf lammatory site, we have developed a method for injection o f particulates into adjacent anatomic compar tments containing comparable populations of mononuclear phagocytes. For this purpose we have used the resident macrophage populations that exist in the pleural and peri toneal cavities. Our results indicate that the downregulat ion o f 20:4 metabolism can occur as a localized process involving a contained macrophage population.