Figure 1

Thy-1 expression promotes fibroblast susceptibility to apoptosis. (a) RFL-6 Thy-1(−) and Thy-1(+) fibroblasts were treated with the indicated concentrations of rhFasL for 16 h, and then cells were collected and stained with Annexin V and PI and apoptosis quantified by flow cytometry. Results are representative of three independent experiments. Upper panels: dot plots of FACS analysis with FITC-Annexin V and PI. The lower-left quadrants of the dot plot panels represent live cells (Annexin V−/PI−); the lower-right quadrants of the panels quadrants represent early apoptotic cells (Annexin V+/PI−); the upper-right quadrants of the panels quadrants represent later apoptotic cells (Annexin V+/PI+). Lower panel shows a quantitative representation of the flow cytograms. Each bar represents the mean±s.e.m. of early + late apoptosis for at least three experiments. * Denotes P<0.0001 compared with controls. (b) Effect of Thy-1 on apoptosis in Thy-1(−) and Thy-1(+) fibroblasts. Cell treatments are the same as above. After treatment, cells were stained with FITC-dUTP, terminal nucleotidyl transferase-mediated nick end labeling assay. The growing cells were treated with rhFasL for 16 h and the extent of apoptosis was assessed by APO-Direct assay kit. The analyses were done using Cell Quest software; bar represents the mean±s.e.m. of at least three experiments. *P<0.0001 compared with controls.