Effect of ketotifen on the reactivity of eosinophils with the incubation of anti-IgG.

Blood eosinophils obtained from 25 patients with bronchial asthma were reacted with anti-IgG or with normal rabbit serum as the control. Morphological changes were examined by light microscopy, scanning electron microscopy and transmission electron microscopy. Reactive eosinophils in morphology with anti-IgG (27.8 per cent) were significantly higher (p less than 0.001) than those with the control (1.2 per cent). We also examined the effects of ketotifen and tranilast, both of which have eosinophil chemotactic inhibitory functions, on the morphological changes. Ketotifen altered the morphological reactivation of eosinophils and the generation of leukotrienes induced by anti-IgG, and this inhibition occurred in a concentration-dependent manner. Tranilast had no effect on the morphology of eosinophils and the generation of leukotrienes. These results suggest that eosinophil IgG receptors may have a role in the pathogenesis of asthma and that ketotifen may prevent their reactivity and, thus, could be of potential use in the treatment of asthma.