Peptide stability and cell-surface turnover of MHC class I molecules. (A) After 2.5 hours of ³⁵S-labeling, lysates from 10 × 10⁶ cells were divided in 4 equal fractions and incubated at 0°C, 25°C, 37°C, and 42°C during 3 hours before W6/32 immunoprecipitation. The bars in the graph represent the intensity of each single band determined by phosphoimaging (a.u., arbitrary units). Representative data are from one experiment repeated 4 times in a total of 4 WT and 7 C282Y homozygous subjects with similar results. (B) PBMCs were cultured overnight at 25°C and 37°C before W6/32 surface staining. Results are presented as percentage of MFI increase of the cells cultured at 25°C. ^*Statistically significant difference between the C282Y and the WT cells (P < .05). Data compare 6 C282Y homozygous with 4 WT subjects. (C) W6/32 surface staining was performed before and after culturing WT and C282Y homozygous PBMCs for 5 hours in the presence of 20 μg/mL BFA. Results are presented as percentage of MFI reduction after the BFA treatment. ^*Statistically significant difference between the C282Y and the WT cells (P < .01). Data compare 8 C282Y homozygous with 6 WT subjects.