Chronic alcohol consumption facilitates the airway macrophage infiltration. Definition of abbreviations: Alc, alcohol; PGN, peptidoglycan. A: C57BL/6 mice (3 mice/each time-point) were treated with alcohol (Alc) via gavage-feeding at a dose of 3 g/kg. Mice were sacrificed at the indicated time points. The curve indicates the serum levels of alcohol. B-C: Mice (6 mice per group) were treated with saline, or 40% alcohol, or PGN, or alcohol/PGN via gavage-feeding at the indicated doses daily for 3 weeks. On the last day, mice were challenged with PGN via nasal drops. Six hours after PGN challenge, mice were sacrificed; BAL was performed. The total cell number was counted under a light microscope (B); the frequency of Mφ was analyzed by flow cytometry (C). Data are presented as mean ± SD. * p < 0.05, compared with saline group. # p < 0.05, compared with the group treated with alcohol alone.