Sputum in severe exacerbations of asthma : Kinetics of inflammatory indices after prednisone treatment

We have investigated the time-course of symptoms, forced expiratory volume in one second (FEV1), and the airway inflammatory changes in sputum selected from saliva and blood of 10 patients with severe exacerbation of asthma betwen presentation and after 1, 2, 3, 7, and 21 days of treatment. The sputum was induced by a modified standard protocol, and we examined its safety. The severe exacerbation of asthma was defined by the presence of nocturnal symptoms disturbing sleep and/or the need for inhaled short acting beta2-agonist > or = 8 puffs/d and an FEV1 after bronchodilator < 60% of predicted. The treatment consisted of additional prednisone 30 mg daily for 5 d followed by reduction to zero by day 10. Abnormal findings [median (interquartile range)] in spontaneous and induced sputum included low viability of cells [52.0 (34.0)%]; eosinophilia [20.0 (16.4)%]; many free eosinophil granules; and increased levels of fluid-phase ECP [1960 (9204) microg/L], fibrinogen [6045 (10720) microg/L], and IL-5 [160 (212) pg/ml]. Peripheral blood eosinophils [10.4 (7.6)%] and ECP levels [34.0 (35.0) microg/L] were increased. After treatment, symptoms, FEV1, blood eosinophilia, and serum ECP improved in the first 24 h. Sputum eosinophils and ECP did not improve until 48 h and fibrinogen not until 7 d. The improvement in sputum eosinophils and ECP levels was correlated with improvement of FEV1 and in fluid-phase IL-5. Thirty sputum inductions were performed safely in the majority with inhaled isotonic or 3% saline (23.3% or 63.3%, respectively) over a short duration (mean 8.4 min). The patients who had a fall in FEV1 of > or = 10% (10 occasions) after induction differed from those with a fall of < 10% only in the amount of inhaled beta2-agonist used by the patients in the preceding 24 h [8.0 (5.0) versus 4.0 (3.0) puffs/d, p = 0.01]. The results suggest that spontaneous or induced sputum can be used safely to follow the kinetics of effects of antiinflammatory treatment in a severe exacerbation of asthma. The clinical and blood indices improve before those in sputum, raising the possibility that examination of sputum is a better guide in these patients to follow the effects of treatment.