Elevated MHC-II expression is associated with an increase in CD34⁺CML cell immunogenicity. (A) Activated and CTV labeled T cells (MNCs from healthy donors) were cocultured with bulk CD34⁺ CML cells for 72 hours (± treatment as indicated. Block, 10 μg/mL anti-pan HLA-class II blocking Ab). Proliferation of the responder cells was measured as a reduction in the MFI of CTV-labeled CD4⁺CD69⁺ T cells (n = 6 ± SEM; n = 3 for MHC-II blocking assays). (B) The autocrine or paracrine growth factor/cytokine signaling pathways that regulate MHC-II expression. Statistical significance was calculated between UT CML sample and all other samples and, if significant, is indicated by asterisks above the bars.