CD274 and myeloid leukemia: As NK cells have been shown to upregulate surface PD-L1 expression following exposure to myeloid leukemia cells (19), we hypothesized that the aforementioned differential effect may be due to the presence of PD-L1 expression on NK cells exposed to cervical cancer cells but absent or de minimus PD-L1 antigen expression on NK cells exposed to normal cervical cells.