CD8A and atrial fibrillation: The positive rate of PD-L1 in mDCs cells in AF was prominently lower than the rate in control (P < 0.05), and no statistical significance was examined in the positive rate of PD-L2 on mDCs cells and the PD-L1 and PD-L2 levels in cells of CD4+ and CD8+ T (P > 0.05).