CD200 and B-cell chronic lymphocytic leukemia: Both CD200 and CD200R have been thoroughly studied in hematologic malignancies; CD200 is an independent negative prognostic factor for patients with chronic lymphocytic leukemia (CLL), acute myeloid leukemia (AML), multiple myeloma (MM) and myelodysplastic syndromes (MDS) [13,14,15,16].