Bronchial hyperresponsiveness in seasonal allergic rhinitis patients is associated with increased IL-18 during natural pollen exposure

Abstract

BackgroundThe mechanism of bronchial hyperresponsiveness (BHR) is not certain in seasonal allergic rhinitis (SAR) patients. ObjectiveWe aimed to investigate the effects of natural pollen exposure on IL-18 and its relationship with BHR. MethodsThirty-two SAR patients with grass pollen sensitivity, 14 nonallergic rhinitis (NAR) patients and 17 normal-controls were included. Sixteen SAR patients had BHR during pollen season and off-season. Serum IL-18 levels were measured in SAR patients during pollen season between May–August and off-season between November–February. IL-18 levels were measured in NAR patients and normal controls once. ResultsDuring pollen season, SAR patients with BHR had significantly increased levels of IL-18 than those without BHR (279.2±161.1 versus 145.3±101.0pg/ml, p=0.012). Serum IL-18 levels were not different between SAR patients with and without BHR during off-season (233.8±139.7 versus 183.2±162.9pg/ml, p=0.16). Serum IL-18 levels in SAR patients during pollen season (212.3±148.8pg/ml) and off-season (208.5±151.5pg/ml) were not different than those NAR patients (224.8±180.1pg/ml, p=0.98 and p=1.0, respectively) and normal controls (174.8±76.0pg/ml, p=0.60 and p=0.76, respectively). ConclusionThe results suggested us that BHR in SAR patients is associated with increased IL-18 during natural pollen exposure.