Objective To explore the expression of interleukin-17A(IL-17A) during pulmonary fibrosis. Methods Forty male C57BL/6 mice were randomized as normal control group(N group) and bleomycin-induced pulmonary fibrosis model group(BLM group) with 20 in each.Mice were administered with bleomycin intratracheally at a dose of 5 mg/kg in BLM group and intratracheally administered with 0.9% saline of the same dose in N group.Then they were sacrificed on days 3,7,14 and 28.IL-17A in lung tissues was measured by semi-qua...