HUMAN PERIPHERAL-BLOOD EOSINOPHILS EXPRESS AND RELEASE INTERLEUKIN-8

Eosinophils can synthesize various cytokines. We demonstrate that inte rleukin-8 (IL-8) mRNA and protein are constitutively expressed by fres hly isolated resting human eosinophils. Most of the patients with bron chial asthma or atopic dermatitis show evidence for up-regulated IL-8 protein expression in eosinophils but not in neutrophils, suggesting t hat an eosinophil-specific cytokine may act in these patients. To inve stigate whether the intracellular IL-8 can be released, eosinophils we re stimulated by different cytokines and platelet-activating factor (P AF). Priming with granulocyte/macrophage-colory-stimulating factor and a subsequent 25-min stimulation with RANTES or PAF resulted in releas e of IL-8 from highly purified human eosinophils in vitro.