CD68 and Patent ductus arteriosus: There were significant positive correlations between membranous PD‐L1 expression on PDA cells and the number of infiltrating CD68+ (membranous PD‐L1 negative: mean n = 392 ± 28 vs. membranous PD‐L1 positive: mean n = 563 ± 63, P = 0.018; Fig. S6A) and FoxP3+ cells (membranous PD‐L1 negative: mean n = 48 ± 11 vs. membranous PD‐L1 positive: mean n = 121 ± 24, P = 0.011; Fig. S6B).