C282Y mutant cells display higher levels of surface-expressed free MHC class I HCs. HFE WT or C282Y homozygous PBMCs were surface stained with HC10 and analyzed by flow cytometry. Total lymphocytes (A) and monocytes (B) were gated and analyzed separately. Anti-CD4 (C) and anti-CD8 (D) surface staining of WT and C282Y homozygous PBMCs was carried out to demonstrate the specificity of the result. The dotted line in the 4 histograms represents the C282Y homozygous staining; the thin solid line, the WT staining; and the bold solid line, the negative control obtained by incubation with an isotype-matched nonspecific Ab. These are representative data from one experiment repeated 5 times with similar results.