Eotaxin (CCL11) and Eotaxin-2 (CCL24) Induce Recruitment of Eosinophils, Basophils, Neutrophils, and Macrophages As Well As Features of Early- and Late-Phase Allergic Reactions Following Cutaneous Injection in Human Atopic and Nonatopic Volunteers

Eotaxin and eotaxin-2, acting through CCR3, are potent eosinophil chemoattractants both in vitro and in animal models. In this study we examined the capacity of eotaxin and eotaxin-2 to recruit eosinophils and other inflammatory cells in vivo in human atopic and nonatopic skin. Skin biopsies taken after intradermal injection of eotaxin and eotaxin-2 were examined by immunohistochemistry. Allergen- and diluent-challenged sites were used as positive and negative controls. Eotaxin and eotaxin-2 produced a dose- and time-dependent local eosinophilia of comparable intensity in both atopic and nonatopic individuals. This was associated with an acute wheal and flare response at the site of injection and development of a cutaneous late phase reaction in a proportion of subjects. There was an accompanying decrease in mast cell numbers. Both chemokines also induced the accumulation of basophils and an unexpected early infiltration of neutrophils. Macrophages were prominent at the 24-h point. Although there was surface CCR3 expression on neutrophils in whole blood, we were unable to demonstrate any functional neutrophil responses to eotaxin in vitro. Thus, intradermal injection of eotaxin and eotaxin-2 in humans induced infiltration of eosinophils and other inflammatory cells as well as changes consistent with CC chemokine-induced mast cell degranulation.