Eosinophils from Allergic Individuals, but not Normal Individuals, Show Chemotactic Responsiveness to NAF/IL-8

Abstract

Eosinophils from peripheral blood of normal individuals do not show chemotactic responsiveness to NAF/IL-8. In contrast eosinophils from allergic asthmatics or atopic dermatitis patients do show a significant chemotactic response. In vitro experiments have indicated that eosinophils from normal individuals become responsive toward NAF/IL-8 after pretreatment with pM concentrations of the cytokines IL-3, IL-5, and GM-CSF. The magnitude of this response is almost similar to the one observed in allergic individuals. This suggests that eosinophils from allergic individuals have been primed in vivo and that the above mentioned cytokines could be responsible. NAF/IL-8 becomes chemotactic at a concentration of 0.1 nM and is optimally chemotactic at 10 nM. The number of cells mobilised amounts to about half of that mobilised by optimal PAF concentrations. Moreover, when mild allergic asthmatic individuals were challenged with allergen a significant increase of the NAF/IL-8-induced chemotactic response of eosinophils occurred 3 hours after challenge. This suggests that NAF/IL-8 may contribute to eosinophil mobilisation in allergic inflammatory reactions and more particular in the late phase allergic reaction. This idea is further substantiated by the fact that NAF/IL-8 also is capable of mobilising eosinophils across endothelial cell monolayers.