title: Interplay between T cell receptor binding kinetics and the level of cognate peptide presented by major histocompatibility complexes governs CD8+ T cell responsiveness.
abstract: Through a rational design approach, we generated a panel of HLA-A*0201/NY-ESO-1(157-165)-specific T cell receptors (TCR) with increasing affinities of up to 150-fold from the wild-type TCR. Using these TCR variants which extend just beyond the natural affinity range, along with an extreme supraphysiologic one having 1400-fold enhanced affinity, and a low-binding one, we sought to determine the effect of TCR binding properties along with cognate peptide concentration on CD8(+) T cell responsiveness. Major histocompatibility complexes (MHC) expressed on the surface of various antigen presenting cells were peptide-pulsed and used to stimulate human CD8(+) T cells expressing the different TCR via lentiviral transduction. At intermediate peptide concentration we measured maximum cytokine/chemokine secretion, cytotoxicity, and Ca(2+) flux for CD8(+) T cells expressing TCR within a dissociation constant (K(D)) range of ∼1-5 μM. Under these same conditions there was a gradual attenuation in activity for supraphysiologic affinity TCR with K(D) < ∼1 μM, irrespective of CD8 co-engagement and of half-life (t(1/2) = ln 2/k(off)) values. With increased peptide concentration, however, the activity levels of CD8(+) T cells expressing supraphysiologic affinity TCR were gradually restored. Together our data support the productive hit rate model of T cell activation arguing that it is not the absolute number of TCR/pMHC complexes formed at equilibrium, but rather their productive turnover, that controls levels of biological activity. Our findings have important implications for various immunotherapies under development such as adoptive cell transfer of TCR-engineered CD8(+) T cells, as well as for peptide vaccination strategies.
authors.affiliation: Division of Experimental Oncology, Multidisciplinary Oncology Center (CePO), Lausanne, Switzerland.
authors.forename: Melita
authors.initials: M
authors.lastname: Irving
authors.forename: Vincent
authors.initials: V
authors.lastname: Zoete
authors.forename: Michael
authors.initials: M
authors.lastname: Hebeisen
authors.forename: Daphné
authors.initials: D
authors.lastname: Schmid
authors.forename: Petra
authors.initials: P
authors.lastname: Baumgartner
authors.forename: Philippe
authors.initials: P
authors.lastname: Guillaume
authors.forename: Pedro
authors.initials: P
authors.lastname: Romero
authors.forename: Daniel
authors.initials: D
authors.lastname: Speiser
authors.forename: Immanuel
authors.initials: I
authors.lastname: Luescher
authors.forename: Nathalie
authors.initials: N
authors.lastname: Rufer
authors.forename: Olivier
authors.initials: O
authors.lastname: Michielin
mesh_terms: D056704:Adaptive Immunity / Q000276:immunology*; D017209:Apoptosis / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D018925:Chemokines / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D016233:Immunotherapy, Active / Q000379:methods; D008213:Lymphocyte Activation / Q000276:immunology; D008285:Major Histocompatibility Complex / Q000276:immunology*; D018448:Models, Immunological; D009369:Neoplasms / Q000276:immunology; D010446:Peptide Fragments / Q000276:immunology / Q000378:metabolism; D011485:Protein Binding / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*
chemical_list: D018925:Chemokines; D016207:Cytokines; D010446:Peptide Fragments; D011948:Receptors, Antigen, T-Cell; D002118:Calcium