Fig. 1
From: Senescent cells evade immune clearance via HLA-E-mediated NK and CD8+ T cell inhibition
Senescent human fibroblasts express atypical MHC molecules. a Primary human fibroblasts were derived from the human skin and induced to senesce by ionising radiation (IR, 10 Gy X-ray). MHC expression by senescent fibroblasts (white bars) analysed at day 14 after IR using flow cytometry (n = 6 different donors for MHC-I, HLA-E and MICA/B, n = 4 for MHC-II, HLA-G and ULBP). Mean fluorescence intensity (MFI) values are shown as fold change compared with non-irradiated controls, set as one (black bars). b Time course of HLA-E and MICA/B expression at the indicated intervals after irradiation (n = 5). c Representative FACS plots of the total MHC-I, HLA-E and MICA/B expression in senescent fibroblasts induced by ionising radiation (DNA-damage induced senescence), H-RAS activation (oncogene-induced senescence) or continuous passaging (replicative senescence). MHC expression was compared between senescent (black lines), non-senescent (filled histograms) and isotype controls (dashed lines). Human umbilical vein endothelial cells (HUVECs) were irradiated (10 Gy), and MHC expression analysed by flow cytometry as previously described. d Flow-cytometry analysis of co-expression of HLA-E and Ki67 and p16INK4a on irradiated fibroblasts (day 14 after irradiation) and non-irradiated controls. Numbers indicate percentages of cells per quadrant. The data are representative of at least three independent experiments from distinct samples. Statistical significance calculated with Mann–Whitney U test (a) and repeated measures ANOVA with Bonferroni correction (b). The data presented as means ± standard error of the mean (SEM). *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001
