Spirometric parameters and levels of interferon gamma and IL-5 in induced sputum from patients with allergic rhinitis or asthma.

Background: This study was designed to analyze spirometric parameters and cytokine (interferon [IFN] gamma and IL-5) levels in induced sputum from patients with asthma or allergic rhinitis (AR) and nonatopic subjects.

Methods: Thirty-three subjects aged 18-60 years were enrolled in the present study. Eight patients had asthma without AR symptoms, 16 had AR without asthma symptoms or history, and both groups had positive skin-prick test (SPT) to aeroallergens. The nine remaining subjects were healthy nonatopic subjects with negative SPT to aeroallergens. Spirometry was performed by evaluating the forced vital capacity (FVC), forced expiratory volume in the 1st second (FEV(1)), and forced expiratory flow between 25 and 75% (FEF(25-75)) of FVC before and after bronchodilator use. Induced sputum samples were also collected for measuring cytokine (IFN-gamma and IL-5) levels by enzyme-linked immunosorbent assay.

Results: Significant pre- and postbronchodilator change was observed only for FEV(1) with higher variation values in asthmatic subjects compared with patients with AR (p < 0.05) and nonatopic subjects (p < 0.01). There was no significant difference in pre- and postbronchodilator spirometric parameters among the three groups, although asthmatic patients showed lower prebronchodilator FEF(25-75) values (p = 0.065). IL-5 levels were higher in induced sputum from patients with asthma and AR compared with nonatopic subjects (p = 0.020 and p = 0.032, respectively), but IFN-gamma levels showed no significant difference between the groups.

Conclusion: Spirometric measurements were not able to show any occurrence of bronchial constriction in patients with AR, but predominant IL-5 levels in induced sputum from these patients reinforce the role of Th2-type immune response in lower respiratory airways that could contribute to the concept of "one airway, one disease."