Effect of intratracheal CpG-ODN challenge on the lung permeability. The permeability index was calculated as the BAL fluid-to-plasma ratio of the concentration of human serum albumin injected intravenously 1 hour before sacrifice. CpG-ODN significantly increased the permeability index, which reached the peak 24 h after the instillation. Values are the mean ± SEM; n = 5-6 for each group and vehicle. *p < 0.05 compared with the PBS group. †p < 0.05 compared with the control ODN group.