Fig. 1: HLA-E is expressed in MM cells and induced by IFN-γ.

A HLA-E log₂ mRNA expression values in bone marrow plasma cells from healthy individuals (NPCs, n = 22), individuals with monoclonal gammopathy of undetermined significance (MGUS, n = 44), or individuals with smoldering multiple myeloma (SMM, n= 12). 2000904_at probe: ANOVA p value = 0.0004; NPCs vs MGUS p = 0.0036, **; NPCs vs SMM p = 0.0005, ***. 200905_x_at probe: ANOVA p value = 0.0005; NPCs vs MGUS p = 0.0003, ***; NPCs vs SMM p = 0.0179, *. Solid blue lines indicate the median values; black dotted lines represent the 25^th and 75^th percentile. Data are derived from GSE5900 dataset. B HLA-E log₂ mRNA expression values in bone marrow plasma cells from healthy individuals (NPCs, n = 12) or patients with MM (MM, n = 65); 2000904_a probe: p < 0.0001, ****; 200905_x_at probe: p < 0.0001, ****. Solid blue lines indicate the median values; black dotted lines represent the 25^th and 75^th percentile. Data are derived from GSE4452 dataset. C Representative immunohistochemistry staining for HLA-E (20×) in one newly diagnosed patient with MM. Red arrows show MM cells positive for HLA-E. D HLA-E mRNA fold change in a panel of MM cell lines (U266, RPMI-8226, OPM-2, and H929) treated with solvent or IFN-γ 1 ng/mL for 24 h. n = 3, t test, two-tailed; U266 p = 0.0096, **; RPMI-8226 p = 0.0016, **; OPM-2 p = 0.0141, *; H929 p = 0.0031, **. Treated cells are normalized to each control. E HLA-E mean fluorescence intensity (MFI) fold change in a panel of MM cell lines (U266, RPMI-8226, OPM-2, and H929) treated with solvent or IFN-γ 1 ng/mL for 24 h. n = 2, t test, two-tailed; U266 p = 0.0014, **; RPMI-8226 p = 0.0455, *; OPM-2 p = 0.0311, *; H929 p < 0.0001, ****. Treated cells are normalized to each control. F Western blot analysis for HLA-E and GAPDH in a panel of MM cell lines (U266, RPMI-8226, OPM-2, and H929) treated with solvent, IFN-γ 1 ng/mL, or IFN-γ 50 ng/mL for 24 h.