Elevated exhaled nitric oxide (ENO) in non-asthmatic atopic adults

Nitric oxide in exhaled air has been proposed as a potential marker of inflammation in the lower airways. Several recent studies have demonstrated that the concentration of exhaled levels of lower airway nitric oxide (ENO) are elevated in asthma, a lung disorder characterized by chronic airway inflammation 13, 42. There also appears to be a weak relationship between atopy or the predisposition to develop IgE antibodies when exposed to foreign substances, and elevated lower airway ENO.;We measured ENO levels in asymptomatic non-asthmatic atopic individuals and found that levels were significantly elevated when compared to non-atopic healthy individuals. For those atopic individuals sensitized to seasonally variable pollens, we measured ENO levels in and out of the respective pollen seasons. We found there was no significant difference in the ENO levels between out-of-season and during season in the absence of allergic exacerbation and symptoms. Lower airway inflammation may be present in atopic individuals without clinical symptoms of asthma. Therefore, ENO measurement may be able to identify sub-clinical inflammation and predict the risk for developing asthma in the future.