Release of preformed Fas ligand in soluble form is the major factor for activation-induced death of Jurkat T cells.
Interaction of Fas/APO-1 (CD95) and its ligand (FasL) plays an important role in the activation-induced cell death (AICD) of T lymphocytes. In the present work, the contribution of soluble FasL to AICD of the human T-cell line Jurkat has been studied. Jurkat cells prestimulated with phytohaemagglutinin (PHA) induced the death of non-activated Jurkat cells, and also of L1210Fas, but not that of Fas-negative L1210 cells. Culture supernatants from prestimulated Jurkat cells were highly toxic to their non-activated counterparts. Time-course analysis revealed that PHA-stimulated Jurkat cells quickly release (less than 15 min) to the medium a toxic molecule following a biphasic pattern, with maximal cytotoxic activities at 1 hr and 7 hr after stimulation. The cytotoxic effect of those supernatants was prevented by the addition of a blocking anti-Fas monoclonal antibody, suggesting that PHA-stimulated Jurkat cells exert Fas-based cytotoxicity mainly through the release of soluble FasL. The constitutive intracellular expression of FasL in non-activated Jurkat cells and its release as a consequence of PHA activation were detected by immunostaining and immunoblotting using an anti-FasL antibody. These data indicate that, at least in Jurkat cells, AICD is mainly mediated by the rapid release of performed FasL in soluble form upon stimulation.
Martínez-Lorenzo
M J
MJ
Department of Biochemistry and Molecular and Cellular Biology, Faculty of Sciences, University of Zaragoza, Spain.
Alava
M A
MA
Anel
A
A
Piñeiro
A
A
Naval
J
J
D017209:Apoptosis / Q000276:immunology*; D015153:Blotting, Western; D003601:Cytotoxicity Tests, Immunologic; D005455:Fluorescent Antibody Technique; D006801:Humans; D019169:Jurkat Cells; D008024:Ligands; D008213:Lymphocyte Activation; D013601:T-Lymphocytes / Q000276:immunology*; D019014:fas Receptor / Q000276:immunology*
D008024:Ligands; D019014:fas Receptor