A novel human CC chemokine, eotaxin-3, which is expressed in IL-4-stimulated vascular endothelial cells, exhibits potent activity toward eosinophils

IL-4 has been shown to be involved in the accumulation of leukocytes, espec ially eosinophils, at sites of inflammation by acting on vascular endotheli al cells. To identify novel molecules involved in the IL-4-dependent eosino phil extravasation, cDNA prepared from HUVEC stimulated with IL-4 was subje cted to differential display analysis, which revealed a novel CC chemokine designated as eotaxin-3. The human eotaxin-3 gene has been localized to chr omosome 7q11.2, unlike most other CC chemokine genes. The predicted mature protein of 71 aa showed 27-42% identity to other human CC chemokines, The r ecombinant protein induced a transient increase in the cytosolic Ca2+ conce ntration and in vitro chemotaxis on eosinophils. Furthermore, in cynomolgus monkeys, the accumulation of eosinophils was observed at the sites where t he protein was injected. Eotaxin-3 inhibited the binding of I-125-eotaxin, but not I-125-macrophage inflammatory protein-la, to eosinophils and acted on cell lines transfected with CCR-3, suggesting that eotaxin-3 recognized CCR-3. IL-13 as well as IL-4 up-regulated eotaxin-3 mRNA in HUVEC, whereas neither TNF-alpha, IL-1 beta, IFN-gamma, nor TNF-alpha plus IFN-gamma did. The expression profile of eotaxin-3 is different from those of eotaxin, RAN TES, and monocyte chemoattractant protein-4, which are potent eosinophil-se lective chemoattractants and are induced by either TNF-alpha or TNF-alpha p lus IFN-gamma. These results suggest that eotaxin-3 may contribute to the e osinophil accumulation in atopic diseases.