IL18 and asthma: Increased concentrations of sputum supernatant interleukin (IL)-8 (CXCL8) [17], endobronchial interferon (IFN)-γ [18] and reduced sputum supernatant IL-18 [19] have been observed in smokers with asthma, leading us to hypothesize that cigarette smoking induced alterations in the airway cytokine environment in asthma could be contributing to the reduced acute airway responses to corticosteroids observed in this group.