Immunohistochemical study of tumor necrosis factor-alpha, matrix metalloproteinase-12, and tissue inhibitor of metalloproteinase-2 on alveolar macrophages of BALB/c mice exposed to short-term cigarette smoke. 
Alveolar cells were evaluated in BALB/c mice exposed to smoke from 9 cigarettes per day.  The mice were sacrificed at 1, 5, and 10 days and examined by lung morphometry and immunohistochemical staining of alveolar macrophages for tumor necrosis factor (TNF)-alpha, matrix metalloproteinase (MMP)-12, and tissue inhibitor of metalloproteinase (TIMP)-2.  Cigarette smoke (CS)-exposed mice showed a progressive increase in numbers of alveolar macrophages (AMs) up to 10 days.  MMP-12 was increased in AMs compared to the control group.  The number of AMs with TNF-alpha and TIMP-2 labeling was higher at 5 days but decreased at 10 days.  Short-term CS exposure induced pulmonary inflammation with major participation of MMP-12-positive AMs.