Fas ligand (CD95L) protects neurons against perforin-mediated T lymphocyte cytotoxicity.
Previous work showed that neurons of the CNS are protected against perforin-mediated T cell cytotoxicity, but are susceptible to Fas-mediated apoptosis. In this study, we report that Fas ligand (FasL) expression by neurons is involved in protection against perforin-mediated T cell cytotoxicity. Gene transcripts for FasL were identified in single murine hippocampal neurons by RT-PCR combined with patch clamp electrophysiology, and constitutive expression of FasL protein was confirmed in neurons by immunohistochemistry. Neurons derived from wild-type C57BL/6 (BL6) mice and mutant BL6.gld mice lacking functional FasL were confronted with allogeneic CTLs and continuously monitored in real time for changes in levels of intracellular calcium ([Ca(2+)](i)), an indicator of cytotoxic damage. Perforin-mediated plasma membrane lysis, characterized by rapid, massive [Ca(2+)](i) influx into the target cells within 0.5 h, was not detected in wild-type neurons. In striking contrast, FasL-deficient neurons showed rapid increase in [Ca(2+)](i) within 0.5 h, reflecting perforin-dependent cell lysis. FasL seems to protect neurons by blocking degranulation of CTLs, since CD3-induced release of cytotoxic granules was reduced by coapplication of Fas-specific Abs or rFasL.
Medana
I
I
Department of Neuroimmunology, Max-Planck Institute of Neurobiology, Am Klopferspitz 18 A, 82152 Martinsried, Germany.
Li
Z
Z
Flügel
A
A
Tschopp
J
J
Wekerle
H
H
Neumann
H
H
D000818:Animals; D017209:Apoptosis / Q000235:genetics / Q000276:immunology; D017252:CD3 Complex / Q000494:pharmacology; D002478:Cells, Cultured; D003594:Cytoplasmic Granules / Q000276:immunology / Q000378:metabolism; D003602:Cytotoxicity, Immunologic / Q000235:genetics; D053222:Fas Ligand Protein; D008024:Ligands; D008213:Lymphocyte Activation / Q000235:genetics / Q000276:immunology; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000502:physiology* / Q000633:toxicity*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008817:Mice, Mutant Strains; D009474:Neurons / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D019014:fas Receptor / Q000378:metabolism*
D017252:CD3 Complex; D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D008024:Ligands; D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D019014:fas Receptor; D054353:Perforin