TAP1-dependencies of HLA-B expression.

(A) Cells from one infection from Fig 1A were subsequently infected with a TAP1-encoding retrovirus. The MFI ratios in the presence and absence of TAP1 (+TAP1/-TAP1) were calculated for each HLA-B–expressing cell line (n = 4 analyses from one infection). (B) Correlation between surface HLA-B expression in SK19 cells (calculated from Fig 1A) and their +TAP1/-TAP1 MFI ratios (calculated from Fig 2A). (C) Cells from the infections shown in Fig 1D were subsequently infected with a TAP1-encoding retrovirus. The MFI ratios in the presence and absence of TAP1 (+TAP1/-TAP1) were calculated for each HA-HLA-B–expressing cell line (n = 4 analyses from one infection). (D) Parental and TAP1-knockdown Hela cells (Hela-TAP1-KD) were assessed by immunoblotting with the anti-TAP1 antibody 148.3 (inset panel; 5, 10 or 20 μg of cell lysate was loaded in each lane) and infected with retroviruses encoding HLA-B allotypes or a control retrovirus (vector). TAP1 expression levels were measured by flow cytometry after intracellular staining with 148.3 antibody. (E) HLA-B expression levels at the surface of Hela or Hela-TAP1-KD cells were measured after W6/32 staining. The MFI ratios (Hela-TAP1-KD/Hela) were calculated for each HLA-B–expressing cell line (n = 6–7 measurements from three separate infections of Hela or Hela-TAP1-KD cells with retroviruses encoding indicated HLA-B). Significant differences are indicated (with an asterisk) on the graph (P<0.05). Statistical significance is based on an ordinary one-way ANOVA analysis with Fisher’s LSD test.