Objective:To detect the expression of IL-4 in bleomycin-induced pulmonary fibrosis in rats and to study the effect of IL-4 in pulmonary fibrosis pathogenesis.Methods:Female wistar rats (170～190g weight) were treated with bleomycin(5 mg/kg weight) by intratracheal perfusion on day 0 to induce pulmonary fibrosis

while the controlled animals were only injected with normal saline (NS).The rats were killed on day 7 and 14

and lung tissue and blood serum were collected.The right lung was stained with hematoxylin-eosin.Reverse transcription polymerase chain reaction (RT-PCR) was used to detect the expression of IL-4mRNA in the left lung and ELISA was used to detect the levels of IL-4 in blood serum.Results:Alveolus inflammation was observed on day 7 and fibrosis focus was found on day 14.Compared with controlled group

the expression levels of IL-4mRNA in lung tissue and the levels of IL-4 in blood serum were elevated significantly in model groups(P<0.05).Conclusion:IL-4 may play an important role in pathogenesis of pulmonary fibrosis

and possibly

the down-regulation of IL-4 level or antagonist of IL-4 could be taken as a new direction for studying the treatment of pulmonary fibrosis.