STAT1 and Patent ductus arteriosus: Therefore, it is possible that the IFN‐γ‐STAT1 axis induced by CD4+ or CD8+ T cells, or macrophage‐producing IL‐6‐STAT3 axis, might serve as the primary mechanism of PD‐L1 expression by PDA cells and Tregs infiltration into the TME 29, 30.