title: The duration of TCR/pMHC interactions regulates CTL effector function and tumor-killing capacity.
abstract: Effector CTL contribute to tumoral immunity by killing tumor cells through secretion of cytotoxic granules and cytokines. Activation of CTL requires specific recognition of cognate peptide-MHC-I (pMHC) complexes on the tumor cell surface by the CTL TCR. It has been suggested that the half-life (t(1/2)) of the TCR/pMHC interaction modulates the activation of naïve CD8(+) T cells; however, it remains unknown whether CTL effector function can also be regulated by the TCR/pMHC t(1/2). Here, we have studied CTL activity in response to tumor cells loaded with pMHC that bind the TCR with different t(1/2). We observed that the TCR/pMHC t(1/2) can differentially regulate CTL effector function during the interaction with tumor cells and defines the nature of anti-tumoral CTL responses in vivo. Although prolonged TCR/pMHC t(1/2) promoted only partial expression of cytotoxic molecules, short t(1/2) induced partial polarization of lytic machinery toward target cells. In contrast, intermediate TCR/pMHC t(1/2) induced strong expression of cytotoxic molecules, efficient polarization of lytic machinery and subsequent release of toxic granules by CTL that killed tumor cells. Consistently, efficient in vivo CTL-mediated tumor clearance was only observed for tumors expressing intermediate t(1/2) pMHC ligands. These data suggest that there is an optimal TCR/pMHC t(1/2) for efficient CTL activity.
authors.affiliation: Millennium Nucleus on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Erick
authors.initials: E
authors.lastname: Riquelme
authors.forename: Leandro J
authors.initials: LJ
authors.lastname: Carreño
authors.forename: Pablo A
authors.initials: PA
authors.lastname: González
authors.forename: Alexis M
authors.initials: AM
authors.lastname: Kalergis
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D045744:Cell Line, Tumor; D018920:Coculture Techniques; D003602:Cytotoxicity, Immunologic / Q000276:immunology; D005434:Flow Cytometry; D015395:Histocompatibility Antigens Class I / Q000378:metabolism*; D016219:Immunotherapy, Adoptive; D007371:Interferon-gamma / Q000378:metabolism; D008213:Lymphocyte Activation / Q000276:immunology; D051907:Lysosomal Membrane Proteins / Q000276:immunology / Q000378:metabolism; D008546:Melanoma, Experimental / Q000276:immunology* / Q000473:pathology / Q000628:therapy; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D011485:Protein Binding; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000378:metabolism*; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D013997:Time Factors; D047368:Tumor Burden / Q000276:immunology; D052118:Lysosomal-Associated Membrane Protein 1
chemical_list: D015395:Histocompatibility Antigens Class I; D007371:Interferon-gamma; D051907:Lysosomal Membrane Proteins; D011948:Receptors, Antigen, T-Cell; C052255:Lamp1 protein, mouse; D052118:Lysosomal-Associated Membrane Protein 1