EOSINOPHIL CATIONIC PROTEIN INDUCES INSULIN-LIKE GROWTH-FACTOR-I RECEPTOR EXPRESSION ON BRONCHIAL EPITHELIAL-CELLS

Although the biologic activity of eosinophil-specific granule proteins , e.g. eosinophil cationic protein (ECP) has been attributed to cytoto xic properties, it has also been shown to be attributable to non-cytot oxic activation of various inflammatory cells. In addition, airway epi thelial cells have been reported to express insulin-like growth factor I (IGF-I) receptor and proliferate in response to IGF-I. The present study examined the regulation of expression of IGF-I receptor on bronc hial epithelial cells by eosinophil granule proteins was examined. ECP significantly induced IGF-1 receptor expression on bronchial epitheli al cells compared with unstimulated cells. These findings suggest that eosinophils participate in the repair process of injured bronchial ep ithelial cells in the inflamed focus through augmentation of IGF-I rec eptor expression by suboptimal degranulation of eosinophil granule pro teins, e.g. ECP.