Localization of Cyclo-Oxygenase and Prostaglandin E2 in the Secretory Granule of the Mast Cell.

摘要

The application of anti-cyclo-oxygenase and anti-prostaglandin E2 immunoglobulins to A23187-stimulated rat connective tissue mast cells has permitted the localization of cyclo-oxygenase activity(prostaglandin H2 synthetase) and the site of prostaglandin E2(PGE2) formation in the secretory granules. Because binding was carried out after stimulation but before dehydration and embedding, we have limited the loss of these antigens due to normal degradation and to aqueous and solvent washes. As this method permits labeling of exposed cell surfaces, only granules that have been exteriorized can be labeled. Contrary to what might have been expected, no labeling was associated with plasma membranes or with any portion of damaged cells. Antibodies to PGE2 were bound evenly over the surface of the granule matrix, whereas antibodies to cyclo-oxygenase appeared to be bound to strands of proteo-heparin projecting from the surface of the granule matrix. Whereas granule matrix had become unraveled and dispersed, labeled appeared to adhere throughout the ribbon-like proteo-heparin strands. These results support our previous conclusion that the secretory granule is the site of the arachidonic acid cascade during exocytosis. Keywords: Cyclo-oxygenase; Prostaglandin E2; Secretory granules; Mast cell; Exocytosis; Lipid mediators; Inflammation; Arachidonic acid; Eicosanoids; Immunocytochemistry; Reprints. (KT)