PDCD1LG2 and myelodysplastic syndrome: By profiling the expression levels of PD-1, PD-L1, and PD-L2 in MNCs from MDS and normal individuals, a significantly elevated expression of PD-1 was seen in MDS samples compared with normal samples (58.77 ± 3.820 vs. 31.95 ± 3.692, P = 0.007) (Figure 1D).