The results of the present study demonstrated that the levels of serum ST2 were significantly elevated on acute exacerbation of IPF; therefore, proinflammatory cytokines such as IL-1?? and TNF-?? may enhance the expression of ST2 on acute exacerbation of IPF. The elevated levels of soluble ST2 protein may be related to the inflammatory process of the accelerated phase of IPF, and reflect the sever