CD4 and myelodysplastic syndrome: Total T cells, including both CD4+ and CD8+ T cells, were significantly reduced in primary MDS BM-MNC (Fig. 2a, c, and Supplementary Figure 3a; P < 0.001, P < 0.01, and P < 0.01, respectively), and the PD-1 expression was increased in these cells versus CD4+ and CD8+ T cells from normal BM-MNC (Fig. 2b, d; P < 0.001 and P < 0.005, respectively).