Multifunction of mast cells in inflammation tissue

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This research project was intended to investigate the multifunction of mast cells in conjunction with or without other cells in inflammation tissues.1 Control of mast cell function in release and synthesis of histamine. (1) Histamine releasing activity; active tridecamer of compound 48/80, a Ca^<2+>-dependent histamine releaser, was synthesized. The binding of tridecamer induced a rapid accumulation of the arachidonic acid into PA, PI and PC, with concomitant decrease of arachidonic acid from PE prior to the detectable histamine release. (2) Histamine synthesizing activity; histidine decarboxylase in mast cells has first been purified to electrophoretic homogeneity, which has two identical subunits having Mr=31 kDa on SDS-PAGE. The de novo synthesis of the enzyme in mastocytoma cells was stimulated by glucocorticoid in conjunction with activated protein kinase C. (3) Prostaglandin (PG) activity; PGD_2 binding to mast cell membrane is possibly controlled through phosphorylation-dephosphorylation of the receptor itself.2. Interaction of mast cell to other cells. (1) Mast cells to endothelial cells; PGD_2/ PGJ_2 from mast cells induced a de novo synthesis of a new 31 kDa protein in endothelial celts. (2) PGD_2 from mast cells enhanced reaction of neutrophil adhesion to endothelial cells, which activity is more potent than that of LTB_4. (3) Predifferentiated mast cells are capable of adhering to activated endothelial cells by TPA treatment, which stimulates unidentified protein synthesis by the action of protein kinase C.