Participation of target Fas protein in apoptosis pathway induced by CD4+ Th1 and CD8+ cytotoxic T cells.
The results presented here provide evidence that the presence of Fas protein in target cells is essential to permit cytotoxicity (resulting in apoptosis) mediated by cloned CD4+ Th1 cells. Using mitogen-activated B cells as targets, antigen-dependent lysis by CD4+ Th1 effectors was observed with MRL/MpJ+ but not with MRL/MpJ-lpr targets. The congenic MRL/MpJ-lpr strain is defective in Fas expression. Target cells from various lymphoid tissues of C3H.MRL-lpr mice were also resistant to the lectin-dependent cytotoxicity of Th1 effectors, whereas C3H/HeJ targets were sensitive. Moreover, a rapid DNA fragmentation prior to 51Cr release was induced only in C3H/HeJ targets. Thus, cytotoxicity induced by Th1 effectors correlates with target Fas expression. In contrast to Th1 effectors, CD8+ cytotoxic T lymphocytes (CTLs) killed C3H.MRL-lpr targets. When cytotoxicity was assayed in the presence of EGTA and MgCl2, which chelates extracellular Ca2+ [(Ca2+)ext], only C3H.MRL-lpr targets became resistant to CD8+ CTLs. This (Ca2+)ext-independent cytotoxicity of both Th1 and CD8+ effectors could be inhibited with unlabeled C3H/HeJ thymocytes or with a transfectoma carrying a murine Fas-human mu gene construct. In comparison, C3H.MRL-lpr thymocytes and the nontransfected parental cell line were poor inhibitors. Our study demonstrates that CD4+ Th1 cells and CD8+ CTLs differ in their (Ca2+)ext-dependent cytotoxicity but share a (Ca2+)ext-independent cytotoxicity that requires participation of Fas molecules for cytotoxic signal transduction leading to target apoptosis.
Ju
S T
ST
Arthritis Center, Boston University School of Medicine, MA 02118.
Cui
H
H
Panka
D J
DJ
Ettinger
R
R
Marshak-Rothstein
A
A
D000818:Animals; D000954:Antigens, Surface / Q000096:biosynthesis / Q000378:metabolism*; D017209:Apoptosis / Q000276:immunology / Q000502:physiology*; D001402:B-Lymphocytes / Q000276:immunology*; D001483:Base Sequence; D015704:CD4 Antigens / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D016827:CD8 Antigens / Q000276:immunology; D002999:Clone Cells; D003602:Cytotoxicity, Immunologic; D017931:DNA Primers; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008815:Mice, Inbred Strains; D008969:Molecular Sequence Data; D016376:Oligonucleotides, Antisense; D009928:Organ Specificity; D016133:Polymerase Chain Reaction; D013045:Species Specificity; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D014162:Transfection; D019014:fas Receptor
D000954:Antigens, Surface; D015704:CD4 Antigens; D016827:CD8 Antigens; D017931:DNA Primers; D016376:Oligonucleotides, Antisense; D019014:fas Receptor