Critical role for CD8 in binding of MHC tetramers to TCR: CD8 antibodies block specific binding of human tumor-specific MHC-peptide tetramers to TCR

J Immunol. 2001 Jul 1;167(1):270-6. doi: 10.4049/jimmunol.167.1.270.

Abstract

There are conflicting opinions about the role that the T cell coreceptors CD4 and CD8 play in TCR binding and activation. Recent evidence from transgenic mouse models suggests that CD8 plays a critical role in TCR binding and activation by peptide-MHC complex multimers (tetramers). Here we show with a human CTL clone specific for a tumor-associated MHC-peptide complex that the binding of tetramers to the TCR on these cells is completely blocked by anti-human CD8 Abs. Moreover, the staining of CTLs with specific MHC-peptide tetramers simultaneously with anti-CD8 Abs was completely blocked with three different anti-CD8 Abs. This blockage was mediated by anti-CD8 Abs but not anti-CD3 Abs and was dose dependent. The blocking effect of the anti-CD8 Abs was attributable to directly inhibiting tetramer binding and was not attributable to Ab-mediated TCR-CD8 internalization and down-regulation. Our results have important implications in TCR binding to MHC-peptide tetramers. MHC-peptide tetramers are widely used today in combination with anti-CD8 Abs for the phenotypic analysis of T cell populations and in the study of T cell responses under various pathological conditions such as infectious diseases and cancer. Our results indicate that also in the human system CD8 plays a critical role in the interaction of MHC-peptide multimers with TCR.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Blocking / metabolism
  • Antibodies, Blocking / pharmacology*
  • Antigens, Neoplasm / metabolism*
  • Binding Sites, Antibody / immunology*
  • Binding, Competitive / immunology
  • CD8 Antigens / immunology*
  • CD8 Antigens / physiology
  • Cell Line
  • Clone Cells
  • Down-Regulation / immunology
  • HLA-A2 Antigen / metabolism*
  • Half-Life
  • Humans
  • Oligopeptides / immunology
  • Oligopeptides / metabolism*
  • Protein Binding / immunology
  • Receptors, Antigen, T-Cell / antagonists & inhibitors*
  • Receptors, Antigen, T-Cell / biosynthesis
  • Receptors, Antigen, T-Cell / metabolism
  • Staining and Labeling
  • Stereoisomerism
  • T-Lymphocytes, Cytotoxic / immunology
  • T-Lymphocytes, Cytotoxic / metabolism
  • Tumor Cells, Cultured
  • beta 2-Microglobulin / antagonists & inhibitors
  • beta 2-Microglobulin / metabolism*

Substances

  • Antibodies, Blocking
  • Antigens, Neoplasm
  • CD8 Antigens
  • HLA-A2 Antigen
  • Oligopeptides
  • Receptors, Antigen, T-Cell
  • beta 2-Microglobulin