CD274 and B-cell chronic lymphocytic leukemia: In this neoplastic context, CD4+ and CD8+ TLs circulating or infiltrating the tumor exhibit exhaustion profile since they also express PD-1 (101), either slightly (1/4 cases) (91, 96) or significantly increased (104), and are in close contact with CD23+ CLL cells expressing PD-L1 within the lymph nodes.