The Effect of Ketotifen on Eosinophils as Measured at LTC₄ Release and by Chemotaxis

Effect of Ketotifen on the Production of Reactive Oxygen Species from Human Eosinophils Primed by Eotaxin

“…Thus, ketotifen might inhibit the effect of cell-bound histamine. Second, ketotifen also has an antiallergic action independent of its histamine-blocking activity [8,9,12]. Our previous studies showed that pertussis toxin-sensitive G proteins, phosphatidylinositol-3-kinases, tyrosine kinase, and the Rho/ROCK pathway in eosinophils were involved in eotaxin-primed ROS production [6,22].…”

“…This is the first report of an effect of ketotifen on human eosinophils primed by chemokine. Several studies on human eosinophils showed that chemotaxis [9], degranulation [10], IL-5-induced eosinophil survival [11], and release of leukotriene C 4 (LTC 4 ) [9,12] are suppressed by ketotifen. However, most of these effects except for LTC 4 release evoked by IgG have been demonstrated with high concentrations such as 10 -5 mol/l or higher [9][10][11][12].…”

“…Several studies on human eosinophils showed that chemotaxis [9], degranulation [10], IL-5-induced eosinophil survival [11], and release of leukotriene C 4 (LTC 4 ) [9,12] are suppressed by ketotifen. However, most of these effects except for LTC 4 release evoked by IgG have been demonstrated with high concentrations such as 10 -5 mol/l or higher [9][10][11][12]. In this study, at concentrations of 10 -10 -10 -6 mol/l, which are physiological concentrations, ketotifen significantly reduced the production of ROS from eosinophils primed by eotaxin, Yamada et al Effect of ketotifen with eotaxinprimed eosinophils on ROS production.…”

“…The inhibitory effect of ketotifen in allergic inflammation occurs via stabilizing of mast cells [7]. In addition, one group reported an inhibitory effect of ketotifen on eosinophil activation in vivo: ketotifen reduced the number of EG2-positive cells in bronchial biopsies in patients with asthma [8], and several studies have demonstrated that ketotifen suppresses eosinophil functions in vitro [9][10][11][12]. However, there has been no study that showed a direct effect of ketotifen on eosinophils primed by chemokines.…”

Development and Sequels of Intestinal Inflammation in Nematode-Infected Rats: Role of Mast Cells and Capsaicin-Sensitive Afferents

“…For example, it may reduce the functions of mobility and phagocytosis of polymorphonuclear cells [43], it may reduce the chemotaxis of neutrophils [44] or it may inhibit their metabolic responses [45]. It also inhibits leukotriene C 4 release and PAF-induced chemotaxis of eosinophils [46]. Thus, the effect of ketotifen on inflammation may consist of a direct action on inflammatory cells or more likely on mast cells by reducing the release of inflammatory and chemotactic factors.…”