Collagen I inhibits AICD by modulating Fas-L expression.
(A) Collagen I inhibits transcriptional activity of the Fas-L promoter in activated Jurkat cells. Jurkat cells were transiently transfected with luciferase reporter construct containing the 1.2 kb Fas-L promoter together with a pCMVβ-Gal plasmid encoding β-galactosidase. 48 hours after transfection, the cells were stimulated with or without PMA/ionomycin in the presence or absence of 50 μg/mL of poly-l-lysine and collagen I. The relative luciferase activity (RLU) was determined 18 hours after stimulation. *P < .05 between PMA/ionomycin-stimulated control and collagen-treated samples. (B) Collagen inhibits Fas-L expression on the cell surface as determined by a cytotoxicity assay. Jurkat cells were stimulated with 50 μg/mL of anti-CD3 for 6 hours to allow for Fas-L expression. As indicated, 50 μg/mL of collagen I or poly-l-lysine was added. The cells were harvested, washed twice with PBS, and incubated with51Cr-labeled Hut-78 cells for 12 hours. The percentage of cytotoxicity was determined as described in “Materials and methods.” The results are mean of 2 experiments performed in triplicates. *P < .05 between anti-CD3-stimulated control and collagen-treated samples.
