Figure 3

ER stress impairs MHC I surface expression. (A) Decreased MHC I surface expression induced by palmitate treatment. EL4 cells were either non-treated (dotted line) or treated with 0.25 mM of palmitate (orange) for 18 hours. EL4/HEL-Cyto-SIINFEKL (top) and EL4/HEL-ER-SIINFEKL (bottom) cells were stained with antibodies against H2K^b, H2D^b or the corresponding isotypic control and analyzed by flow cytometry. Representative histograms of one of three independent experiments are depicted. Bars represent % of MFI intensity in treated EL4/HEL-Cyto-SIINFEKL (blue) and EL4/HEL-ER-SIINFEKL (red) cells relative to untreated cells (dotted line). Differences between untreated and treated cells are all significant (P < 0.05). (B) Decreased MHC I surface expression induced by glucose deprivation. EL4 cells were incubated in medium lacking glucose (green) or containing low glucose (1 mg/ml) (purple) or high glucose (4.5 mg/ml) (dotted line) for 18 hours and analyzed as in A. Bars represent % of MFI intensity in glucose-deprived EL4/HEL-Cyto-SIINFEKL (blue) and EL4/HEL-ER-SIINFEKL (red) cells relative to untreated cells (dotted line). Bars represent the mean and SD from three independent experiments performed in triplicate. Differences between control and glucose-deprived cells are all significant (P < 0.05).