Figure 3. Surface MHC class I expression on infected hepatocytes at the early stages of parasite development.

HC-04 cells (A, C, D) or primary freshly isolated human hepatocytes (B) were infected with P. berghei ANKA GFP and surface MHC class I was assessed by flow cytometry in uninfected or GFP+ and GFP- cell populations at 24 and 48 hrs post-infection. The dot plots (A and B) show the proportion of infected (GFP+) cells at 24 hrs post-infection. (A) One representative experiment performed at 24 hrs post-infection. Filled histograms - staining with the isotype control antibody; unfilled - staining with the MHC class I-specific antibody. The numbers are mean fluorescence intensities (MFIs) of MHC class I staining. (B) MHC class I expression on the surface of GFP+, GFP- and uninfected primary human hepatocytes. Filled histograms, staining with the isotype control antibody; solid lines, staining with the MHC class I-specific antibody. (C) Parasite replication does not affect de novo formation and transport of MHC class I complexes to the cell surface. HC-04 cells were subjected to treatment with a low pH buffer at 24 hrs post-infection to dissociate surface MHC class I molecules (time zero) and surface MHC class I expression was determined after the indicated periods of time post treatment. Overlay of contour plots for GFP+ and GFP- cells stained with the isotype control or MHC class I-specific antibody at each time point. Numbers indicate MFI in each population. One of three reproducible experiments. (D) MHC class I expression in GFP+ (filled histogram) and GFP- (unfilled histogram) populations 48 hrs post-infection with P. berghei. The arrow within the plot marks the small population of MHC class I negative cells. The bar-graphs show the means ± SD of MFI values obtained in 6 (for 48 hrs) and 9 (for 24 hrs) separate experiments. White and black bars represent staining with the isotype control or MHC class I-specific antibody, respectively. NS, not significant; p** = 0.03.