Pretreatment with CpG ODN inhibits lung fibrosis. Mice were injected i.p. with 200 μg of control or CpG ODN 5 days before 0.03 U of BLM or PBS (no BLM) was delivery intra-tracheally. Lungs were removed 14 days later. A) The amount of collagen was determined analytically using the Sircol collagen assay. Data show the percent change in the amount of collagen in experimental groups vs mice that did not receive BLM. This was calculated by combining results from 3 independent experiments involving 10-15 mice/group. B) Representative histologic sections from these lungs. C) Lung tissue was fixed and stained with Masson’s Trichrome. The severity of lung fibrosis were graded as (0) none, (1) minimal, (2) mild, (3) moderate and (4) severe. Data shows the mean + SE of the combined results from 2 independent experiments involving 6-7 mice/group. *; p < 0.05, **; p < 0.005.