The molecular mechanism of FasL-mediated cytotoxicity by CD4+ Th1 clones

Cell Immunol. 1995 Jul;163(2):237-44. doi: 10.1006/cimm.1995.1122.


Murine CD4+ Th1 clones require de novo synthesis of proteins to express a cytotoxicity that is mediated by de novo synthesized Fas ligand (FasL). The cytotoxic process of the CD4+ Th1 effectors can be separated into four stages, namely conjugate formation, activation, lethal hit, and effector-independent target cell death. The present study describes the cytotoxic process in terms of FasL induction and Fas/FasL molecular interactions for death signal transduction. Fas-Ig fusion proteins, cycloheximide, actinomycin D, and EGTA+MgCl2 were used to analyze each stage of the cytotoxic process in terms of FasL/Fas participation. The results demonstrate that the activation-induced de novo mRNA and protein synthesis were for FasL, which provided the predominant cytotoxic activity of CD4+ Th1 effectors. Once activated, Th1 effectors express cytotoxic activity in the presence of EGTA+MgCl2, an experimental [Ca2+]ext-independent condition characteristic of FasL-mediated cytotoxicity. The ability of Fas-Ig to inhibit target lysis declined rapidly after conjugate formation, indicating that FasL-mediated lethal hit is critically dependent on conjugate formation and, once delivered, the effector-independent target lysis proceeds. After the lethal hit stage, transduction of Fas-mediated death signal was independent of de novo synthesis of macro-molecules in targets because treatments that inhibited more than 98% of the macromolecule synthesis had little effect on target lysis. Our study provides the first molecular view in terms of FasL/Fas of the cytotoxic process of CD+ Th1 cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, Surface / physiology
  • Base Sequence
  • CD4 Antigens / analysis*
  • Calcimycin / pharmacology
  • Clone Cells
  • Cycloheximide / pharmacology
  • Cytotoxicity, Immunologic / drug effects
  • Cytotoxicity, Immunologic / immunology*
  • Egtazic Acid / pharmacology
  • Fas Ligand Protein
  • Immunoglobulins / physiology
  • Lymphocyte Activation / immunology
  • Magnesium Chloride / pharmacology
  • Membrane Glycoproteins / biosynthesis
  • Membrane Glycoproteins / physiology*
  • Mice
  • Molecular Sequence Data
  • Recombinant Fusion Proteins / physiology
  • Tetradecanoylphorbol Acetate / pharmacology
  • Th1 Cells / immunology*
  • Th1 Cells / physiology*
  • fas Receptor


  • Antigens, Surface
  • CD4 Antigens
  • Fas Ligand Protein
  • Fasl protein, mouse
  • Immunoglobulins
  • Membrane Glycoproteins
  • Recombinant Fusion Proteins
  • fas Receptor
  • Magnesium Chloride
  • Calcimycin
  • Egtazic Acid
  • Cycloheximide
  • Tetradecanoylphorbol Acetate