Primary BP CML cells respond to IL-1 and can be killed by ADCC in vitro. (A) IL1RAP cell surface expression on MNCs from 3 BP CML BM samples, 2 of lymphoid and 1 of myeloid phenotype, and including 1 with T315I mutation (black, isotype control; red, IL1RAP). (B) Cell surface expression of IL1RAP on CD34⁺CD38⁻ and CD34⁺CD38⁺ cells from 2 additional BP CML patients after 4 hours incubation with or without 5 μM IM (gray, isotype control [no IM]; red, without IM; blue, with IM). (C) BP CML MNCs were seeded in serum-free medium supplemented with indicated cytokines. The dotted line represents the seeded cell number. Total cell numbers following 7 days culture are presented (n = 4). (D) NF-κB and AKT phosphorylation in BP CML MNCs after 15-minute stimulation with IL-1B (blue, without IL-1B; red, with IL-1B). (E-F) BP CML BM MNCs were analyzed in an ADCC assay using IL1RAP antibodies or a hIgG1 control antibody and with human NK effector cells. Presented is the percentage of target cells killed by ADCC for CML-BP1 and CML-BP2 (E) and CML-BP3 cells (F).