[Nonspecific bronchial hyperreactivity in patients with seasonal bronchial asthma observed through two consecutive...

Seasonal bronchial asthma causally connected with the exposure to pollen allergens is a chronic, eosinophilic mucosal inflammation of airway. This inflammation is the basis for the development of nonspecific bronchial hyperreactivity which is the most typical but mutable feature of asthma. Bronchial hyperreactivity often determines asthma intensity and the need of asthma treatment. The nonspecific bronchial hyperreactivity over two consecutive years was evaluated in 11 patients (2 women and 9 men) with seasonal bronchial asthma, sensitized to grass, remaining under the conditions of natural allergen exposure and out of this period. Bronchial reactivity to histamine was measured by Cockcroft's at all method. So called histamine threshold (PC20H) in mg/ml was assessed. The values of ventilatory parameters (FVC, FEV1) and asthma symptom scores were also measured. It was showed that nonspecific bronchial hyperreactivity significantly increased in subjects with seasonal bronchial asthma during natural pollen exposure. PC20H in two studies performed during this period decreased 3 and 6 times when compared to preseasonal values. The majority part of patients (80%) has the increased bronchial reactivity to histamine also beyond the of grass season when clinical symptoms of asthma and rhinitis are not observed. This postseasonal hyperreactivity could be the effect of the chronic inflammation process persisted from the period of natural allergen exposure. Continuous subthreshold, which means asymptomatic exposure to perennial allergens to which most of patients are sensitized, could be another reason of this hyperreastivity. The possibility of exposure to the activity of seasonal allergens the whole year in persons with asthma can not omitted, as the presence of pollens in the sample of the house dust in patient's flat is observed during the yield of pollen season. Nonspecific bronchial hyperreactivity in individual patients is fluctuated, which probably is not dependent on the intensity of natural allergen exposure.