Among T lymphocytes, CD4+CD25+FoxP3+ regulatory T cells (Tregs) play pivotal roles in maintaining immune system homeostasis, and significantly impaired Treg activity has been reported among IPF patients [9] although contradictory results have been reported regarding the role of Tregs in lung fibrosis [10, 11]. Here, FOXP3 is linked to idiopathic pulmonary fibrosis.