IL-8 IS EXPRESSED BY HUMAN PERIPHERAL-BLOOD EOSINOPHILS - EVIDENCE FOR INCREASED SECRETION IN ASTHMA

Eosinophils possess the capacity to synthesize various cytokines. We d emonstrate that IL-8 mRNA and protein are constitutively expressed by freshly isolated resting human eosinophils. Most of the patients with bronchial asthma or atopic dermatitis show evidence for up-regulated I L-8 protein expression in eosinophils but not in neutrophils, suggesti ng that an eosinophil-specific cytokine may act in these patients. To investigate whether the intracellular IL-8 can be released, eosinophil s were stimulated by different cytokines and platelet-activating facto r. Priming with granulocyte-macrophage CSF and a subsequent 25-min sti mulation with RANTES or platelet-activating factor resulted in release of IL-8 from highly purified human eosinophils in vitro. As the eosin ophil is the predominant cell in asthmatic inflammation, we determined IL-8 concentrations in bronchoalveolar lavage fluids from normal indi viduals and asthmatic patients. Bronchoalveolar lavage fluids from pat ients with bronchial asthma consistently demonstrated high IL-8 concen tration compared with the controls. This suggests that IL-8 is release d in vivo by inflammatory bronchial cells in asthma.