Antigen-dependent integration of opposing proximal TCR-signaling cascades determines the functional fate of T lymphocytes.
T cell anergy is a key tolerance mechanism to mitigate unwanted T cell activation against self by rendering lymphocytes functionally inactive following Ag encounter. Ag plays an important role in anergy induction where high supraoptimal doses lead to the unresponsive phenotype. How T cells "measure" Ag dose and how this determines functional output to a given antigenic dose remain unclear. Using multiparametric phospho-flow and mass cytometry, we measured the intracellular phosphorylation-dependent signaling events at a single-cell resolution and studied the phosphorylation levels of key proximal human TCR activation- and inhibition-signaling molecules. We show that the intracellular balance and signal integration between these opposing signaling cascades serve as the molecular switch gauging Ag dose. An Ag density of 100 peptide-MHC complexes/cell was found to be the transition point between dominant activation and inhibition cascades, whereas higher Ag doses induced an anergic functional state. Finally, the neutralization of key inhibitory molecules reversed T cell unresponsiveness and enabled maximal T cell functions, even in the presence of very high Ag doses. This mechanism permits T cells to make integrated "measurements" of Ag dose that determine subsequent functional outcomes.
Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel;
Ron
R
Wolchinsky
Moran
M
Hod-Marco
Kfir
K
Oved
Shai S
SS
Shen-Orr
Sean C
SC
Bendall
Garry P
GP
Nolan
Yoram
Y
Reiter
D000941:Antigens / Q000276:immunology* / Q000494:pharmacology; D002461:Cell Line, Transformed; D017635:Clonal Anergy / Q000187:drug effects / Q000502:physiology*; D004306:Dose-Response Relationship, Immunologic; D006680:HLA Antigens / Q000276:immunology; D006801:Humans; D008213:Lymphocyte Activation / Q000187:drug effects / Q000502:physiology*; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology*; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*
D000941:Antigens; D006680:HLA Antigens; D011948:Receptors, Antigen, T-Cell