Intracellular distribution of HLA-E in THP1-derived macrophages. (A) THP1-derived macrophages were collected for flow cytometry analysis. Representative graphs of total expression (red) and surface expression (blue) of HLA-E or HLA-Ia are shown. MFI of the unstained sample (gray) was used as the negative control. MFIs shown here are representative of observations made in six independent experiments. (B) Lysates of THP1-derived macrophages were treated with Endo H, followed by detection with immunoblotting. Figures shown here are representative of three independent experiments. (C–G) Representative micrographs of THP1-derived macrophages. Cells were fixed, permeabilized, and co-stained with rabbit antibodies against different marker proteins (ER [calnexin; C], early endosome [EEA1; D], late endosome [Rab7; E], lysosome [LAMP1; F], recycling endosome [Rab11; G]), and mouse antibodies against different HLA-Imolecules (HLA-E [MEM-E/02], HLA-Ia [W6/32]). Cells were then stained with anti-rabbit Alexa568 and anti-mouse Alexa488 secondary antibodies. Scale bars = 10 μm. Micrographs shown here are representative of two independent experiments. (H) Quantification of colocalization of HLA-E or HLA-Ia with different marker proteins from Fig. S1, C–G. The PCC values of each cell and the mean values are shown with 30–40 cells per sample. Statistical analysis was performed using unpaired two-tailed Student’s t test with Welch’s correction. Asterisks show the statistical significance between indicated groups: ns, not significant; ****, P < 0.0001. Source data are available for this figure: SourceData FS1.