CD200 and glioblastoma: High levels of CD200 have been found to be expressed on various types of human cancer cells, including hairy cell leukemia (55), acute myeloid leukemia (56), malignant melanoma (22), CLL (21), multiple myeloma (21), testicular cancer (21), renal carcinoma (21), colon carcinoma (21), and GBM (57).