GST alpha immunoreactivity in sputum cells and supernatants. A. Western analysis for GST alpha in induced sputum supernatants revealed an increased immunoreactivity in patients with chronic bronchitis and in Stage II-III COPD compared to healthy non-smokers (p < 0.001). The means of the measured intensities are shown as columns with error bars representing SEM. B. Representative sputum cytospins from a smoker (a), patient with chronic bronchitis (b) and patient with Stage II COPD (c). Macrophages in the induced sputum exhibited positive GST alpha reactivity.