T cell receptor and coreceptor CD8 alphaalpha bind peptide-MHC independently and with distinct kinetics

Immunity. 1999 Feb;10(2):219-25. doi: 10.1016/s1074-7613(00)80022-9.


The T cell surface glycoprotein CD8 enhances T cell antigen recognition by binding to MHC class I molecules. We show that human CD8 alphaalpha binds to the MHC class I molecule HLA-A2 with an extremely low affinity (Kd approximately 0.2 mM at 37 degrees C) and with kinetics that are between 2 and 3 orders of magnitude faster than reported for T cell receptor/peptide-MHC interactions. Furthermore, CD8 alphaalpha had no detectable effect on a T cell receptor (TCR) binding to the same peptide-MHC class I complex. These binding properties provide an explanation as to why the CD8/MHC class I interaction is unable to initiate cell-cell adhesion and how it can enhance TCR recognition without interfering with its specificity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biosensing Techniques
  • CD8 Antigens / metabolism*
  • Cell Adhesion
  • Dimerization
  • HLA-A2 Antigen / metabolism*
  • Humans
  • Kinetics
  • Mice
  • Protein Conformation
  • Receptors, Antigen, T-Cell / metabolism*


  • CD8 Antigens
  • HLA-A2 Antigen
  • Receptors, Antigen, T-Cell