Determination of interaction kinetics between the T cell receptor and peptide-loaded MHC class II via single-molecule diffusion measurements

Biophys J. 2012 Jul 18;103(2):L17-9. doi: 10.1016/j.bpj.2012.06.019. Epub 2012 Jul 17.

Abstract

The binding of peptide-loaded major histocompatibility complex (pMHC) to the T cell receptor (TCR) represents the central step in T cell antigen recognition. It proceeds in the cell contact area between a T cell and an antigen-presenting cell termed the immunological synapse. An important and unresolved issue is how T cells discriminate between potentially harmful and harmless antigens. One limitation has been the difficulty to measure interaction parameters directly, that is, as they occur in the immunological synapse. Here we present a single-molecule approach to determine pMHC-TCR interaction kinetics in situ based on diffusion analysis of dye-labeled pMHC. We find synaptic off-rates >10-fold accelerated when compared to the dissociation of purified proteins measured in vitro.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biophysics / methods*
  • Diffusion
  • Histocompatibility Antigens Class II / immunology*
  • Humans
  • Kinetics
  • Models, Immunological
  • Peptides / immunology*
  • Protein Binding / immunology
  • Receptors, Antigen, T-Cell / immunology*
  • Time Factors

Substances

  • Histocompatibility Antigens Class II
  • Peptides
  • Receptors, Antigen, T-Cell