The importance of serum IgE for level and longitudinal change in airways hyperresponsiveness in COPD

Background Airways hyperresponsiveness (AHR) is an important feature of pat ients with chronic obstructive pulmonary disease (COPD). Little is known ab out factors that modulate AHR in COPD. Objective To study these factors, we performed a long-term, double-blind, p arallel intervention study in 58 male, non-allergic patients with COPD. Methods During a period of 2 years, patients were treated with inhaled bude sonide (1600 mu g/day), inhaled budesonide (1600 mu g/day) plus oral predni solone (5 mg/day), or placebo. PC20 histamine was measured at 4-monthly int ervals. The influence of treatment, smoking, age, level of lung function, i nitial serum IgE level and peripheral blood eosinophils on level and longit udinal change of PC20 histamine was analysed. Results During follow-up, PC20 decreased in our group, and this decrease wa s not influenced by treatment. PC20 tended to decrease faster in current sm okers than in ex-smokers. PC20 was significantly associated with pre-challe nge FEV1 at each time point. Level nor decline of PC20 were significantly r elated to age. A higher initial serum IgE level was independently associate d with a lower PC20 Moreover, a higher initial serum IgE level was associat ed with a slower annual decline of PC20, regardless of treatment, pre-chall enge FEV1, and other modulating factors. No significant associations were f ound between initial blood eosinophils and level or decline of PC20. Conclusion We conclude that AHR increases over time in non-allergic patient s with COPD. Treatment with an inhaled corticosteroid alone or in combinati on with oral prednisolone does not change this increase. Our study suggests an important role for IgE in the course of the disease, since a higher ini tial serum IgE level predicts a more favourable course with regard to annua l decline of PC20 histamine.