Chemokines and IL-5: major players of eosinophil recruitment in asthma

It has long been recognized that eosincphils play a major role in the pathogenesis of bronchial asthma. These cells are considered to cause tissue damage leading to disruption of the bronchial epithelium, enhanced bronchial responsiveness. and airway obstruction. Recruitment of eosinophils at the allergic inflammatory site involves a scries of events including rolling, adhesion to endothclial cells, transendothelial migration and subsequent chemotactic movement. The first three steps of eosinophil reeruitment are mediated by a different set of adhesion molecules involved in various specific time-points while the last step is predominantly regulated by the local production of chemoattractants. In this regard a number chernotactic factors including phospholipids (e.g. PAF) and leucotrienes (e.g. LTB4) have been associated with allergic disease [1]. However, these chemoattracTants are rapidly metabolized or taken up by the surrounding cells and their involvement in asthma is not well understood. There is now plenty of evidence to suggest that chemokines and IL-5 play a prominent role in eosinophil recruitnient.