In a mouse model of SBP, at 3 h PBI, HAL exposure resulted in a decrease in the number of alveolar macrophages and an increase in the number of neutrophils (PMNs) in the pulmonary airspaces in flu-infected mice. CD-1 mice were inoculated intranasally with 40 plaque-forming units A/PR/8/34 influenza virus (SBP) or mock infected (mock). Mock-HAL and SBP-HAL mice (white bars) were exposed to 2% HAL for 2 h just before infection (day 0) and again for 2 h on day 4 PVI. Mock-cont and SBP-cont mice (black bars) received ketamine sedation. On day 6 PVI, mice were inoculated with 2.5 × 106 CFU EF3030, and 3 h later (3 h PBI), mice were killed, BAL was performed, and lungs were harvested. The cells recovered from the pulmonary airspaces by BAL were analyzed: (A) total number of leukocytes, (B) total number of macrophages, and (C) total number of PMNs. (D) The harvested lungs were homogenized, and MPO activity was determined as a measure of PMN infiltration into the lung parenchyma. Sample sizes are displayed above groups. *P < 0.05, **P < 0.01 SBP-HAL compared with SBP-cont. Data are expressed as mean ± SEM. BAL = bronchoalveolar lavage; CFU = colony-forming units; cont = control; EF3030 = Streptococcus pneumoniae; HAL = halothane; MPO = myeloperoxidase; PBI = postbacterial infection; PMN = polymorphonuclear cell; PVI = postviral infection; SBP = secondary bacterial pneumonia.
