title: Modulation of Naive CD8 T Cell Response Features by Ligand Density, Affinity, and Continued Signaling via Internalized TCRs.
abstract: T cell response magnitudes increase with increasing antigenic dosage. However, it is unclear whether ligand density only modulates the proportions of responding ligand-specific T cells or also alters responses at the single cell level. Using brief (3 h) exposure of TCR-transgenic mouse CD8 T cells in vitro to varying densities of cognate peptide-MHC ligand followed by ligand-free culture in IL-2, we found that ligand density determined the frequencies of responding cells but not the expression levels of the early activation marker molecule, CD69. Cells with low glucose uptake capacity and low protein synthesis rates were less ligand-sensitive, implicating metabolic competence in the response heterogeneity of CD8 T cell populations. Although most responding cells proliferated, ligand density was associated with time of entry into proliferation and with the extent of cell surface TCR downmodulation. TCR internalization was associated, regardless of the ligand density, with rapidity of c-myc induction, loss of the cell cycle inhibitor p27kip1, metabolic reprogramming, and cell cycle entry. A low affinity peptide ligand behaved, regardless of ligand density, like a low density, high affinity ligand in all these parameters. Inhibition of signaling after ligand exposure selectively delayed proliferation in cells with internalized TCRs. Finally, internalized TCRs continued to signal and genetic modification of TCR internalization and trafficking altered the duration of signaling in a T cell hybridoma. Together, our findings indicate that heterogeneity among responding CD8 T cell populations in their ability to respond to TCR-mediated stimulation and internalize TCRs mediates detection of ligand density or affinity, contributing to graded response magnitudes.
authors.affiliation: National Institute of Immunology, New Delhi 110067, India; and.
authors.forename: Renu
authors.initials: R
authors.lastname: Balyan
authors.affiliation: National Institute of Immunology, New Delhi 110067, India; and.
authors.forename: Rupali
authors.initials: R
authors.lastname: Gund
authors.affiliation: National Institute of Immunology, New Delhi 110067, India; and.
authors.forename: Chitra
authors.initials: C
authors.lastname: Ebenezer
authors.affiliation: National Institute of Immunology, New Delhi 110067, India; and.
authors.forename: Jasneet Kaur
authors.initials: JK
authors.lastname: Khalsa
authors.affiliation: National Institute of Immunology, New Delhi 110067, India; and.
authors.forename: Divya Anna
authors.initials: DA
authors.lastname: Verghese
authors.affiliation: National Institute of Immunology, New Delhi 110067, India; and.
authors.forename: Thyagarajan
authors.identifier: 0000-0002-3692-9925
authors.initials: T
authors.lastname: Krishnamurthy
authors.affiliation: National Institute of Immunology, New Delhi 110067, India; and.
authors.forename: Anna
authors.initials: A
authors.lastname: George
authors.affiliation: National Institute of Immunology, New Delhi 110067, India; and.
authors.forename: Vineeta
authors.initials: V
authors.lastname: Bal
authors.affiliation: National Institute of Immunology, New Delhi 110067, India; and satyajit@nii.res.in.
authors.forename: Satyajit
authors.identifier: 0000-0002-7343-1173
authors.initials: S
authors.lastname: Rath
authors.affiliation: National Institute of Immunology, New Delhi 110067, India; and.|Memorial Sloan Kettering Cancer Center, New York, NY 10065.
authors.forename: Ashutosh
authors.identifier: 0000-0003-3379-5236
authors.initials: A
authors.lastname: Chaudhry
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000276:immunology; D000945:Antigens, Differentiation, T-Lymphocyte / Q000235:genetics / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D002460:Cell Line; D003713:Dendritic Cells / Q000276:immunology; D005947:Glucose / Q000378:metabolism; D007376:Interleukin-2 / Q000494:pharmacology; D037181:Lectins, C-Type / Q000235:genetics / Q000276:immunology; D008024:Ligands; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D010455:Peptides / Q000378:metabolism / Q000494:pharmacology; D011948:Receptors, Antigen, T-Cell / Q000276:immunology / Q000378:metabolism*; D015398:Signal Transduction; D000099192:CD69 Antigens
chemical_list: D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D005947:Glucose; D007376:Interleukin-2; D037181:Lectins, C-Type; D008024:Ligands; D010455:Peptides; D011948:Receptors, Antigen, T-Cell; D000099192:CD69 Antigens