The Inhibitory Mechanism of Rebamipide on the Mediator Release in the Guinea Pig Lung Mast Cells Activated with Specific Antigen-Antibody Reactions

Abstract

This study aim was to assess the effects of rebamipide on the mechanism of histamine release and biosynthesis and release of leukotrienes caused by mast cell activation. We purified mast cells from guinea pig lung tissues by the use of enzyme digestion, the rough and the discontinuous density percoll gradient method. Mast cells were sensitized with IgG1 (anti-OVA) antibody and challenged with ovalbumin. Mast cells were also stimulated with A23187 and the intracellular Ca2+ level was measured. Histamine and leukotrienes were measured by automated fluorometric analyzer and radioimmunoassay, respectively. The intracellular Ca2+ level was analyzed using a confocal laser scanning microscope. Protein kinase C (PKC) activity was determined by protein phosphorylated with [=γ-32P]ATP. The phospholipase D activity was assessed by the labeled phosphatidylalcohol. Mass 1,2-diacylglycerol (DAG) was measured by the [3H]DAG produced when prelabeled with [3H]myristic acid. PLA2 activity was determined by measuring the arachidonic acid released from the labeled phospholipids. Rebamipide decreased the releases of histamine and leukotrienes, and completely blocked Ca2+ influx during mast cell activation by antigen-antibody reactions. It also decreased the release of histamine and leukotrienes during mast cell activation by A23187. The PKC and PLD activities were also decreased by rebamipide in a dose-dependent manner. Rebamipide inhibited the mass DAG production and PLA2 activity during mast cell activation. The data suggest that rebamipide inhibits intracellular signals and blocks Ca2+ influx in mast cells activated by specific antigen-antibody reactions, which in turn inhibits histamine release and leukotriene generation.