Tolerance induction by veto CTLs in the TCR transgenic 2C mouse model. II. Deletion of effector cells by Fas-Fas ligand apoptosis.
The direct assay of veto CTLs in the 2C mouse model enables monitoring, by FACS, the fate of the TCR transgenic effector CD8(+) T cells, the transgene of which can be stained with clonotypic Ab 1B2. After the addition of veto cells, CD8(+)1B2(+) effector cells increasingly express annexin V, and maximal apoptosis is attained 72 h after initiation of MLR. This veto activity can be partially blocked by anti-CD8 Abs directed against the allele expressed by the veto CTLs, but not by the effector cells. When effector CD8(+) T cells were from 2C mice, which lack Fas expression ((2CX lpr)F(2)), deletion of effector cells was not exhibited by veto cells. The protein levels of the apoptosis inhibitors FLIP and Bcl2 in purified CD8(+)1B2(+) effector cells at different time points after MLR showed an initial up-regulation of these inhibitors, with marked reduction of FLIP, but not of Bcl2, by 48 h after initiation of culture. Taken together, these results are in accordance with a Fas-FasL-based mechanism in which prolonged binding between the effector cell and the veto cell might be required to allow FLIP to be down-regulated. Such prolonged interaction might be afforded through the interaction of CD8 molecules on the veto cell with the alpha3 domain of H2 class 1 on the effector cell.
Reich-Zeliger
Shlomit
S
Department of Immunology, Weizmann Institute of Science, Rehovot, Israel.
Gan
Judith
J
Bachar-Lustig
Esther
E
Reisner
Yair
Y
D000818:Animals; D017304:Annexin A5 / Q000096:biosynthesis; D017209:Apoptosis / Q000235:genetics / Q000276:immunology*; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D016827:CD8 Antigens / Q000502:physiology; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology* / Q000276:immunology* / Q000378:metabolism; D002478:Cells, Cultured; D017637:Clonal Deletion / Q000235:genetics*; D053222:Fas Ligand Protein; D005260:Female; D047908:Intracellular Signaling Peptides and Proteins / Q000502:physiology; D008024:Ligands; D007959:Lymphocyte Culture Test, Mixed; D008562:Membrane Glycoproteins / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008822:Mice, Transgenic; D023421:Models, Animal; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology* / Q000378:metabolism; D019014:fas Receptor / Q000378:metabolism / Q000502:physiology*
D017304:Annexin A5; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D016827:CD8 Antigens; C506387:Cflar protein, mouse; D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D008024:Ligands; D008562:Membrane Glycoproteins; D019014:fas Receptor