IL21 and asthma: The substantial reduction of dexamethasone induced apoptosis of fibroblasts and endothelial cells upon stimulation with IL-21, IL-22 and IL-23 cytokines indicate that these Th-17 cytokines may exert an anti-apoptotic effect on airway structural cells; such an effect could be related to the observed limited anti-inflammatory effect of corticosteroid, or steroid hypo-responsiveness, in some severe asthma patients with predominant Th-17 cytokine profile.