title: T cell activation by antibody-like immunoreceptors: increase in affinity of the single-chain fragment domain above threshold does not increase T cell activation against antigen-positive target cells but decreases selectivity.
abstract: Chimeric TCRs with an Ab-derived binding domain confer predefined specificity and MHC-independent target binding to T cells for use in adoptive immunotherapy. We investigated the impact of receptor binding affinity on the activation of grafted T cells. A series of anti-ErbB2 single-chain fragment binding domains with a K(d) ranging from 3.2 x 10(-7) to 1.5 x 10(-11) M was linked to CD3zeta-derived immunoreceptors and expressed in human PBL. Solid phase bound ErbB2 protein triggered activation of receptor-grafted T cells in a dose-dependent manner. The activation threshold inversely correlated with the affinity of the receptor binding domain. The maximum level of cellular activation, however, was the same and independent of the binding affinity. Upon binding to ErbB2(+) cells, T cells grafted with immunoreceptors carrying a single-chain fragment of K(d) < 10(-8) M were activated in a similar fashion against cells with different amounts of ErbB2 on the surface. T cells with a low affinity receptor (K(d) > 10(-8) M), however, were activated exclusively by cells with high amounts of ErbB2. In conclusion, recombinant immunoreceptors of higher affinity do not necessarily induce a more potent activation of T cells than low affinity immunoreceptors, but the higher affinity immunoreceptors exhibit less discrimination between target cells with high or low Ag expression levels.
authors.affiliation: Klinik I für Innere Medizin, Tumorgenetik, Kliniken der Universität zu Köln, and Center for Molecular Medicine Cologne, Köln, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Chmielewski
authors.forename: Andreas
authors.initials: A
authors.lastname: Hombach
authors.forename: Claudia
authors.initials: C
authors.lastname: Heuser
authors.forename: Gregory P
authors.initials: GP
authors.lastname: Adams
authors.forename: Hinrich
authors.initials: H
authors.lastname: Abken
mesh_terms: D000915:Antibody Affinity / Q000235:genetics; D000941:Antigens / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology*; D002460:Cell Line; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D015536:Down-Regulation / Q000235:genetics / Q000276:immunology; D005822:Genetic Vectors; D006801:Humans; D007128:Immunoglobulin Fragments / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D007371:Interferon-gamma / Q000378:metabolism; D008213:Lymphocyte Activation / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D011971:Receptors, Immunologic / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000138:chemical synthesis / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism*; D015854:Up-Regulation / Q000235:genetics / Q000276:immunology
chemical_list: D000941:Antigens; D007128:Immunoglobulin Fragments; D007371:Interferon-gamma; D018719:Erb-b2 Receptor Tyrosine Kinases; D011971:Receptors, Immunologic; D011993:Recombinant Fusion Proteins