CD200 and B-cell chronic lymphocytic leukemia: There was an apparent increase in the percentage of T cells (both CD4 + and CD8+) and CD19 + B cells expressing immune inhibitory molecules (e.g., PD-1, CTLA-4, CD200R) and immunomodulatory ligands (e.g., PD-L1, CD86, CD200) in patients with CLL compared to HV.