IL5 and asthma: In this context, it is important to note that airway eosinophils, while clearly markers of airway inflammation/exacerbation risk, may not always be directly involved in the pathogenesis of asthma, as evidenced by studies reporting persistent asthmatic responses in patients despite near ablation of blood and tissue eosinophils by anti-IL-5 therapy [26]; this could also be related to the incomplete effect of anti-IL-5 on eosinophil differentiation [27], or to confounding corticosteroid effects, or to a combination of these factors.