Class I- and class II-reactive TCRs coexpressed on CD4+ T cells both trigger CD4/CD8-shared and CD4-unique functions.
CD4+ and CD8+ T cells emerge from thymic selection expressing a TCR restricted by MHC class II (TCRII) and MHC class I (TCRI), and upon Ag stimulation develop respectively into Th and CTL effector cells. The influence of thymic differentiation and antigenic stimulation on the determination of T cell functions was studied, with CD4+ T cells expressing a transgenic TCRI that reacts with the class I alloantigen H-2K(b) in a CD8-independent fashion. Such T cells additionally express a TCR, probably TCRII, in which the transgenic TCR beta-chain is associated with endogenously rearranged TCR alpha-chains. Upon in vitro stimulation with H-2K(b)-expressing cells, both CD8+ and CD4+ transgenic TCR+ T cells developed into CTL capable of killing Ag-expressing target cells through a perforin-dependent mechanism, and secreted IL-2 and IFN-gamma. Fas ligand-dependent killing could also be induced in both CD8+ and CD4+ in vitro stimulated T cells. The capacity to secrete IL-4 was restricted to the CD4+ T cells, however, suggesting that both CD8/CD4-shared and CD4-unique programs can be elicited by stimulation of CD4 T cells through a TCRI. Acquisition of CTL function was also induced upon class II alloantigen stimulation through the endogenously rearranged TCRII, which represents a polyclonal set of TCRs. IL-2, IFN-gamma, and after restimulation, IL-4, were also produced. Thus: 1) events associated with intrathymic selection influence the gene program activated in response to the same TCRI/APC interaction; and 2) CD4+ T cells expressing a TCRI and a TCRII can activate the same gene program after engagement of either one of these TCRs.
Asnagli
H
H
Center for Immunology, INSERM-CNRS of Marseille-Luminy, France.
Schmitt-Verhulst
A M
AM
Guimezanes
A
A
D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002118:Calcium / Q000378:metabolism; D003602:Cytotoxicity, Immunologic; D006183:H-2 Antigens / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D007111:Immunity, Cellular; D007371:Interferon-gamma / Q000096:biosynthesis; D007376:Interleukin-2 / Q000096:biosynthesis; D015847:Interleukin-4 / Q000096:biosynthesis; D008213:Lymphocyte Activation; D008562:Membrane Glycoproteins / Q000502:physiology; D051379:Mice; D008822:Mice, Transgenic; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D011948:Receptors, Antigen, T-Cell / Q000502:physiology*; D013154:Spleen / Q000166:cytology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology; D019014:fas Receptor / Q000502:physiology
D006183:H-2 Antigens; D000949:Histocompatibility Antigens Class II; D007376:Interleukin-2; D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D011948:Receptors, Antigen, T-Cell; D019014:fas Receptor; D054353:Perforin; D015847:Interleukin-4; D007371:Interferon-gamma; D002118:Calcium