BackgroundSmoking changes numerous alveolar macrophage functions and is one of the most important risk factors for postoperative pulmonary complications. The current study tested the hypothesis that smoking impairs antimicrobial and proinflammatory responses in alveolar macrophages during anesthesia and surgery.MethodThe authors studied 30 smoking and 30 nonsmoking patients during propofol–fentanyl general anesthesia. Alveolar immune cells were harvested by bronchoalveolar lavage immediately and 2, 4, and 6 h after induction of anesthesia and at the end of surgery. The types of alveolar immune cell and macrophage aggregation were determined. The authors measured opsonized and unopsonized phagocytosis. Microbicidal activity was determined as the ability of the macrophages to killListeriamonocytogenes directly. Finally, RNA was extracted from harvested cells and cDNA was synthesized by reverse transcription. The expression of interleukin 1&bgr;, 6, and 8, interferon &ggr;, and tumor necrosis factor &agr; were measured by semiquantitative polymerase chain reaction using &bgr;-actin as an internal standard.ResultsThe fraction of aggregated macrophages increased significantly over time in both groups, whereas phagocytosis of opsonized and nonopsonized particles and microbicidal activity of alveolar macrophages decreased significantly. The changes, though, were nearly twice as great as in patients who smoked. Gene expression of all proinflammatory cytokines in alveolar immune cells except interleukin 6 increased 2- to 20-fold over time in both groups. The expression of interleukin 1&bgr;, interferon &ggr;, and tumor necrosis factor &agr;, however, increased only half as much in smokers as in nonsmokers.ConclusionSmoking was associated with macrophage aggregation but markedly reduced phagocytic and microbicidal activity—possibly because expression of proinflammatory cytokines was reduced in these patients. Our data thus suggest that smokers may have a limited ability to mount an effective pulmonary immune defense after anesthesia and surgery.