Quantitative analysis of the expression of MHCII molecules after IFNα-treatment of human tumor cell lines. (A) Cytofluorometric analysis of SK MEL-23, Me10538, M14, and U87 cells after 48 h with either no IFNα or 250U/ml of IFNα. Solid histograms represent isotype control mAb background fluorescence for each specific mAb investigated; open histograms represent specific fluorescence from cells stained with antibodies specific for MHCI (HLA-A,B,C), HLA-DRA, or HLA-DQ (as indicated next to the relative analysis). The x-axis of each histogram represents specific fluorescence on a five-decade logarithmic scale, and the y-axis represents the number of events. Mean fluorescence intensity (MFI) values are indicated next to the relative analysis. Data presented are from one representative experiment in a series of at least three. (B), (C), and (D) Quantification by RT-PCR in Me10538, M14, and U87 of HLA-DRA- (B) and HLADQA1-specific (C) mRNA after treatment for 24 and 48 h with either no IFNα or 250U/ml of IFNα, and of CIITA-specific mRNA (D) after treatment for 16, 24 and 48 h with either no IFNα or 250U/ml of IFNα. The results are expressed in copy number as the mean ± SEM of three independent experiments. In the absence of IFNα, the copy number of all transcripts did not vary significantly over the time tested.