T cell activation state in the induced sputum of asthmatics treated with budesonide

Bronchial hyperresponsiveness and airway infiltration with eosinophils and T lymphocytes are key features of asthma. In particular, CD4+ T cells are currently believed to play a pivotal role as initiators and coordinators of the asthmatic inflammatory response and, therefore, they represent a crucial target of corticosteroid treatment. The aim of the present investigation is thus to evaluate, in patients with mild asthma, the effects of inhaled corticosteroid therapy on the following parameters: (i) functional state of CD4+ T cells; (ii) airway eosinophilia; (iii) bronchial hyperresponsiveness to methacholine. The study was completed by twenty asthmatic, atopic subjects, subdivided into two groups of ten and treated for 12 weeks with either inhaled budesonide (200 microg twice daily) or terbutaline alone (500 microg twice daily), respectively. Expression of CD4+ T cell activation markers was measured in induced sputum at baseline and after 1, 4, 8 and 12 weeks of treatment by flow cytometry, which showed a down-regulation of HLA-DR and CD25 surface proteins in the budesonide group, compared with the control group; these differences resulted as being statistically significant through weeks 4-12. Budesonide also induced a quick, sharp reduction in the percentage of eosinophils detectable in induced sputum, as well as a more gradual progressive improvement in airway hyperresponsiveness to methacholine. Therefore, in addition to assessing various indices of bronchial inflammation, flow cytometry can be reliably applied to induced sputum in order to monitor, even in mildly symptomatic patients, the effects of anti-asthma treatments on T cell activation.