HLA-E and neoplasm: Although there is great heterogeneity in the frequency of EpCAM+ cells expressing HLA-DR and HLA-E (ranging from 2.1% to 95.9% and 0.5% to 95.6%, respectively), a higher proportion of tumor cells expressed these ligands compared to myeloid cells (median frequency of 29.5% vs. 16.1%, p = 0.0326 and 16.3% vs. 5.2%, p = 0.0009, respectively).