Effect of methacholine challenge on cellular composition of sputum induction

Background-Induced sputum and methacholine inhalation challenge are routine ly used for the assessment of airway inflammation and airway hyperresponsiv eness, respectively. This study investigates whether a methacholine challen ge performed one hour before sputum induction alters the cellular and bioch emical constituents of sputum. Methods-Sixteen stable asthmatic patients with lung function within the nor mal range underwent two sputum inductions within one week. One hour before one of the sputum inductions a methacholine challenge was performed. Results-There were no significant differences in total cell count, macropha ges, neutrophils, eosinophils, lymphocytes, epithelial cells, ECP, and albu min between the two challenges. The repeatability of cell counts was good f or all cells, ECP and albumin, but poor for total cells. Conclusions-In patients with stable asthma a methacholine challenge carried out one hour before sputum induction does not significantly alter the cell ular and biochemical constituents of sputum.