Role of CD3gamma and CD3delta cytoplasmic domains in cytolytic T lymphocyte functions and TCR/CD3 down-modulation.
TCR engagement leads to down-modulation of TCR/CD3 complexes from the T cell surface. The importance of this effect in T cell physiology is unknown. Here, we characterized a CTL clone deficient in TCR/CD3 surface expression that had lost both CD3delta and CD3gamma mRNA, allowing us to address the role of these chains in the assembly, signaling, and dynamics of the TCR/CD3 complex. Expression of either CD3delta or CD3gamma alone failed to reconstitute surface expression of the TCR/CD3 complex, but reconstitution with a cytoplasmically truncated CD3delta (delta t) and a native (gamma) or cytoplasmically truncated (gamma t) human CD3gamma led to reexpression of TCR/CD3 complexes in both cases. This indicated that CD3delta and CD3gamma assume specific functions in TCR/CD3 assembly independently of their cytoplasmic domains. The delta t gamma t variant specifically killed target cells, expressed the IFN-gamma gene in response to Ag, and produced TNF-alpha in response to anti-CD3 mAb, but it was affected in CD3 ligand-induced TCR/CD3 down-modulation. Both PMA- and CD3 ligand-induced TCR/CD3 down-modulation were defective in the delta t gamma t variant, whereas the delta t gamma variants were unaffected, and previously described delta gamma t variants were affected only in PMA-induced down-modulation. Specific protein kinase C (PKC) inhibitors indicated that PMA- but not CD3 ligand-induced down-modulation was dependent on PKC activity. Thus, amino acid sequences present in either the CD3delta or CD3gamma cytoplasmic domain control ligand-induced TCR/CD3 down-modulation, and neither these sequences nor this property are required for cytolysis and IFN-gamma gene expression in response to Ag.
Luton
F
F
Center of Immunology, INSERM-CNRS of Marseille-Luminy, France.
Buferne
M
M
Legendre
V
V
Chauvet
E
E
Boyer
C
C
Schmitt-Verhulst
A M
AM
D000818:Animals; D017252:CD3 Complex / Q000502:physiology*; D002460:Cell Line; D002469:Cell Separation; D003593:Cytoplasm / Q000502:physiology; D003602:Cytotoxicity, Immunologic; D015536:Down-Regulation; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D018613:Microscopy, Confocal; D011493:Protein Kinase C / Q000502:physiology; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology* / Q000648:ultrastructure; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors
D017252:CD3 Complex; D011948:Receptors, Antigen, T-Cell; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate