Fig. 3. The percentage of Listeria monocytogenes killed by alveolar macrophage from smoking (n = 30, circles) and nonsmoking (n = 30, squares) patients after 30 and 120 min incubation. Data are expressed as the mean ± SD. *Statistically significant difference (P < 0.05) from elapsed time zero in each group; #statistically significant difference (P < 0.01) from the nonsmoking group.