Differences in nonspecific bronchial responsiveness between patients with asthma and patients with rhinitis are not explained by type and degree of inhalant allergy.

Patients with allergic asthma have higher levels of nonspecific bronchial responsiveness than patients with allergic rhinitis. The aim of the study was to investigate whether this is caused by differences in the degree of allergy to inhalant allergens between asthmatics and rhinitics. Therefore, bronchial responsiveness to histamine was measured in 25 allergic patients with isolated upper airways symptoms. Nonspecific bronchial responsiveness in this group was compared with nonspecific bronchial responsiveness in a group of 136 patients with allergic asthma, with allergy and % predicted FEV1 as confounding variables. In addition, a matched pair analysis was performed. Twenty-five patients with nonallergic rhinitis served as controls to evaluate the influence of an IgE-independent inflammatory reaction in the upper respiratory tract on the level of bronchial responsiveness. Furthermore, we investigated the level of nonspecific responsiveness in 18 healthy controls. In the patients with allergic asthma, a correlation was found between nonspecific bronchial responsiveness and IgE against indoor allergens (n = 136, r = 0.34, p < 0.001) and % predicted FEV1 (n = 136, r = 0.37), p < 0.001). Patients with allergic asthma and patients with allergic rhinitis differed with respect to the level of bronchial responsiveness (p < 0.001), and the amount of specific IgE antibodies against indoor allergens (p = 0.01). The difference in level of bronchial responsiveness remained (p < 0.001) after correction with % predicted FEV1 and specific IgE against indoor allergens as confounding variables. Similarly, after matching of patients with allergic rhinitis (n = 25) with patients with allergic asthma (n = 25) regarding the specific IgE, total IgE and age of the patients, the difference in level of bronchial responsiveness remained (p < 0.001). Patients with nonallergic rhinitis had higher levels of nonspecific bronchial responsiveness than healthy controls and did not differ from patients with allergic rhinitis. In conclusion, the results confirm that IgE against common indoor allergens plays an important role in the mechanism underlying nonspecific bronchial hyperresponsiveness. However, differences in bronchial responsiveness between patients with asthma and patients with rhinitis are not merely explained by differences in the IgE antibody concentrations.