The Role of the Eosinophil-selective Chemokine, Eotaxin, in Allergic and Non-allergic Airways Inflammation

Blood eosinophilia and tissue infiltration by eosinophils are frequently observed in allergic inflam-mation and parasitic infections. This selective accumulation of eosinophils suggested the existence of endogenous eosinophil-selective chemoattractants. We have recently discovered a novel eosinophil-selective chemoattractant which we called eotaxin in an animal model of allergic airways disease. Eotaxin is generated in both allergic and non-allergic bronchopulmonary inflammation. The early increase in eotaxin paralled eosinophil infiltration in the lung tissue in both models. An antibody to IL-5 sup-pressed lung eosinophilia, correlating with an inhibition of eosinophil release from bone marrow, with-out affecting eotaxin generation. This suggests that endogenous IL-5 is important for eosinophil migra-tion but does not appear to be a stimulus for eotaxin production. Constitutive levels of eotaxin observed in guinea-pig lung may be responsible for the basal lung eosinophilia observed in this species. Allergen-induced eotaxin was present mainly in the epithelium and alveolar macrophages, as de-tected by immunostaining. In contrast there was no upregulation of eotaxin by the epithelial cells fol-lowing the injection of Sephadex beads and the alveolar macrophage and mononuclear cells surround-ing the granuloma were the predominant positive staining cells. Eotaxin and related chemokines acting through the CCR3 receptor may play a major role in eosino-phil recruitment in allergic inflammation and parasitic diseases and thus offer an attractive target for therapeutic intervention. Key words: eotaxin- eosinophil- airways- inflammatio