Figure 7

HLA class I silenced EC on SIC are protected against CD8+ T cell cytotoxicity. NC, shNS or shβ2m ECs were incubated with CD8+ T cells; *p < 0.05; **p < 0.01; ***p < 0.001. (a) Representative histograms of the frequency of CD107a expression show higher CD8+ T-cell degranulation after exposure to HLA expressing ECs in comparison to HLA class I-silenced ECs. (b) The graph displays mean values and standard deviations of CD107a expression frequencies (n = 5). (c) Similarly, in CD8+ T-cell cytotoxic assays, HLA class I- expressing EC cell lysis rates were significantly higher in comparison to HLA class I-silenced cells. The graph shows mean values and standard deviations of optical densities values indicating LDH activity released by ECs (n = 5). (d,e) SEM analysis of the T-cell cytotoxic assay on SIC indicated the adherence of primed CD8+ T-cells only to non-silenced endothelial cells. For better visualization, the CD8+ T-cells on the NC ECs were highlighted in purple, (f and g) SEM analysis of shβ2m ECs on SIC revealed the absence of CD8+ T-cells on the cell surfaces.