Asthma is a chronic inflammatory airway disease characterized by the involvement of many cells (including eosinophils, mast cells, T cells, neutrophils and airway epithelial cells) and their cellular components.1 While airway eosinophilic inflammation is considered as a characteristic of asthma, our previous reports2,3 and other recent studies4,5 have demonstrated that neutrophils may play important roles in airway inflammation, or even in airway remodeling, particularly in severe asthma. The mechanisms underlying the neutrophil accumulation in asthmatic airway remain to be elucidated. Interleukin-8 (IL-8) is a potent chemotactic factor for neutrophils, and was demonstrated to be increased in asthmatic airways.6,7 More recent studies have shown that T-cell derived IL-17 can accumulate neutrophils via a IL-8 dependent pathway.8,9 Whether IL-17/IL-8 mechanism is involved in airway inflammation in severe asthma is not clear.