Furthermore, current evidence suggests that upregulation of PD1/PDL1 in IPF may prompt the differentiation of CD4+T cells into Tregs and lead to depletion of macrophages, thereby enabling myofibroblasts to evade immune clearance and resist macrophage-induced phagocytosis (94, 95). Here, PDCD1 is linked to idiopathic pulmonary fibrosis.