EBV transformation of B cells downregulates CD1d expression. Tonsillar mononuclear cells were incubated with or without EBV B95-8 supernatant for 8 days and analyzed for CD1d and MHC class 1 and class 2 expression. (A) Representative CD1d and isotype control staining of naive B cells and EBV-transformed B cells (LCL). MFI values indicate the level of CD1d expression above the isotype control (n = 10). ***P < .001. (B) MHC class 1 (HLA-A, HLA-B, and HLA-C) and MHC class 2 (HLA-DR, HLA-DP, and HLA-DQ) expression on naive B cells (dotted lines) and LCL (solid lines). Isotype control staining is shown as shaded regions. MFI values of MHC class 1 and MHC class 2 show net staining above the isotype controls for naive B cells (○) and LCL (■) (n = 10). ***P < .001.