Semiquantitative scoring of CNS infiltration in NSG xenografts. CNS infiltration was determined as described in “Materials and methods.” Hematoxylin/eosin stainings are depicted as examples for the scoring method: (A) ++ scoring (patient Mer^high 3), 1 positive sample; (B) + scoring (patient Mer^low 9), 1 intermediate sample; and (C) − scoring (patient Mer^low 8), 1 negative sample. Magnification: top panels, ×40; bottom panels, ×200. B, bone; BM, bone marrow; C, cerebrum/cerebellum; DM, dura mater; *, leukemic infiltration.