Figure 1.

Number of alveolar macrophages. The number of alveolar macrophages was assessed in healthy non-smokers (NS), smokers without COPD (S), stage I–II COPD and stage IV COPD (for patient characteristics see Table 1). The means of the numbers of alveolar macrophages per square millimeter are marked with horizontal lines. * Significantly increased when compared to non-smokers (p = 0.020).