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Tobacco smoking inhibits alveolar macrophage function, but cessation of smoking markedly reduces the risk of postoperative pulmonary complications. The authors therefore evaluated the effect of nonsmoking duration on both antimicrobial and inflammatory functions of alveolar macrophages during anesthesia and surgery.The authors studied 15 patients who had never smoked, 15 current smokers, and 41 former smokers, all of whom underwent general anesthesia. Former smokers were further allocated to one of three groups depending on their smoke-free periods: 2 months (n = 13), 3–5 months (n = 13), and 6–12 months (n = 15). Alveolar immune cells were collected by bronchoalveolar lavage immediately after induction of anesthesia, at 2 and 4 h after induction of anesthesia, and at the end of surgery. Opsonized and nonopsonized phagocytosis were measured. Microbicidal activity was determined as the ability of the macrophages to kill Listeria monocytogenes directly. Finally, we determined the expression of proinflammatory cytokines, including interleukin 1ß, interleukin 8, interferon γ, and tumor necrosis factor α, and of antiinflammatory cytokines (interleukin 4 and 10) by semiquantitative polymerase chain reaction.Nonopsonized and opsonized phagocytosis and microbicidal activity of alveolar macrophages (antimicrobial functions) decreased 20–50%, and the expression of genes for all proinflammatory and antiinflammatory cytokines increased 3–30-fold over time in all groups. Starting 4 h after induction of anesthesia, the decreases in antimicrobial functions were 1.5–3 times greater in current and former smokers (2 months’ abstinence) than in patients who had never smoked. Starting 4 h after anesthesia, the increase in expression of all cytokines, except interleukin 8, was twofold to fivefold less in current and former smokers (2–6 months’ abstinence) than in patients who had never smoked.Our data suggest that former smokers may have a limited ability to mount effective pulmonary immune defenses for long as 6 months after stopping cigarette use.