Arachidonic acid remodeling in human inflammatory cells migrating to the lung in vivo

Recent evidence suggests that arachidonic acid (AA), the precursor of eicosanoids, is stored in various glycerolipid pools with different biochemical specificities. Upon cell activation, AA is rapidly remodeled within these glycerolipid pools. We have explored the changes in AA content and distribution in human neutrophils as they are activated in vivo in the lungs of patients with adult respiratory distress syndrome (ARDS). Neutrophils from bronchoalveolar lavage fluid of ARDS patients contained an amount of total cellular AA four times larger than that of blood (resting) neutrophils and accumulated a larger proportion of AA into a pool associated with triglycerides (TG). These biochemical changes were associated with an increased number of cytoplasmic lipid bodies and with the acquisition of the hypodense phenotype. These data indicate that the accumulation of AA into TG is a marker of cell activation and suggest a central role of the TG pool in AA metabolism in inflammatory cells activated in vivo.