The Mast Cell Granule: A Phospholipid Source for Prostaglandin Synthesis
Phospholipid, the source of fatty-acid-derived mediators of the inflammatory response, such as prostaglandins, leukotrienes, thromboxanes, and other eicosanoids, has been localized in the mast cell secretory granule. This matrix-bound granule phospholipid accounts for about 50% of the total content of the mast cell phospholipid. Evidence for the presence of this phospholipid can be observed ultrastructurally in the form of micelles and vesicles when the granule is subjected to water infiltration. It is suggested that the spontaneous sequestration of phospholipid and other hydrophobic elements in response to water influx results in the formation of micelles of various sizes. The coalescence of micelles results in the formation of large spherical micellar aggregates and bilayer vesicles. Since granule matrix is extruded in conjunction with histamine release in radiation injury, this large quantity of matrix-bound phospholipid becomes an available source for eicosanoid synthesis.
KeywordsMast Cell Histamine Release Radiation Injury Micellar Structure Mast Cell Granule
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