Cytoplasmic lipid bodies of human eosinophils. Subcellular isolation and analysis of arachidonate incorporation

Abstract

Lipid bodies are non-membrane-bound cytoplasmic inclusions that are prominent in leukocytes engaged in inflammatory responses. As demonstrated by electron microscopic autoradiography, lipid bodies can serve as intracellular sites of 3H-arachidonic acid localization in eosinophils and other cells. To evaluate the role of lipid bodies as stores of esterified arachidonate, subcellular fractionation of lipid-body-rich human eosinophils was used to isolate lipid bodies free of other organelles. In lipid bodies isolated from 3H-arachidonate-labeled eosinophils, 3H-arachidonate was esterified almost totally in glycerolipids, predominantly in classes of phospholipids, including phosphatidyl-inositol and phosphatidylcholine. Lipid bodies, especially in leukocytes participating in inflammation, could represent intracellular sources of esterified arachidonate available for eicosanoid formation.