NT5E and B-cell chronic lymphocytic leukemia: Secondly, since CLL cells can express high levels of PD-L1, and PD-L1 blockade can restore antitumor immunity in Eμ-TCL1 mice [5,21], we also compared PD-L1 expression levels on leukemic cells in male versus female CD73-deficient Eμ-TCL1tg/wt mice.