These encompassed three Tregs subpopulations and their specific surface antigens (CD45RA+ CD28- CD8+ T cell absolute counts, CD45RA+ CD28- CD8+ T cell %T cell, and CD25 on CD4 Tregs) that positively regulate IPF, corroborating findings from previous studies. This evidence concerns the gene CD4 and idiopathic pulmonary fibrosis.