Ozone effects on the immediate-phase response to allergen in the nasal airways of allergic asthmatic subjects

Epidemiologic and clinical trials have suggested that exposure to ozone inc reases airway hyperresponsiveness and inflammatory response to inhaled nasa l allergen challenge in allergic asthmatic subjects. Previous studies have demonstrated an increased late-phase response to nasal allergen challenge; however, the early-phase response is unknown,We sought to characterize the early-phase response by measuring mast-cell inflammatory mediators and cell ular influx at time points immediately following ozone exposure and subsequ ent allergen challenge, A cohort of mild, asymptomatic dust mite-sensitive asthmatic subjects was identified. Each subject underwent two separate expo sures to both 0.4 ppm ozone and clean air in a randomized manner, Nasal rav age was performed before and after each exposure, Nasal allergen was then a dministered to a defined clinical end point, followed by nasal lavage, Diff erential cell counts and mast-cell products were identified in each lavage specimen, The mast-cell mediators tryptase and prostaglandin D-2 were analy zed, as was a marker of epithelial cell permeability, albumin, Although all ergen produced an increase in early-onset mediator release (mast cell-deriv ed), no enhancement was noted after exposure to ozone, Neutrophil and eosin ophil inflammatory mediators were not increased after ozone exposure or enh anced after allergen exposure, although ozone did enhance eosinophilic infl ux after exposure to allergen, Ozone exposure does not promote early-phase- response mediator release or enhance the response to allergen challenge in the nasal airways of extrinsic asthmatic subjects, Ozone, however, may prom ote an inflammatory cell influx, which helps induce a more significant late -phase response in this population.