Low and high affinity cellular receptors for interleukin 2. Implications for the level of Tac antigen

J Exp Med. 1984 Oct 1;160(4):1126-46. doi: 10.1084/jem.160.4.1126.

Abstract

Interleukin 2 promotes proliferation of T cells by virtue of its interaction with a high-affinity cell surface receptor. This receptor is a 55,000 mol wt glycoprotein that is also recognized by the murine monoclonal antibody, anti-Tac. Quantitative binding studies with radiolabeled IL-2 and anti-Tac, however, initially indicated far more antibody binding sites per cell than IL-2 binding sites. Extension of the IL-2 binding analysis to concentrations several thousand-fold higher than that necessary for the T cell proliferative response demonstrated the existence of a class (or classes) of low-affinity IL-2 binding sites. Inclusion of the low-affinity IL-2 binding greatly reduced the quantitative discrepancy in the ligand binding assays. That the low-affinity binding, as well as the high-affinity interaction, was associated with the Tac molecule was indicated by the finding that the antibody could substantially or totally block the entire spectrum of IL-2 binding and by the finding that IL-2 could in turn block all radiolabeled anti-Tac binding. The low-affinity sites were found on activated T cells, several human and murine T cell lines and two examples of Tac-positive B cells. The physiological role of the low-affinity IL-2 binding sites and the molecular changes in the Tac protein that give rise to the affinity differences remain open to investigation.

MeSH terms

  • Animals
  • Antibodies, Monoclonal / immunology
  • Antibodies, Monoclonal / physiology
  • Antigens, Surface / immunology*
  • Binding Sites, Antibody
  • Binding, Competitive
  • Cell Line
  • Humans
  • Interleukin-2 / metabolism*
  • Interleukin-2 / physiology
  • Kinetics
  • Lymphocyte Activation
  • Mice
  • Receptors, Antigen, T-Cell / analysis*
  • Receptors, Immunologic / analysis*
  • Receptors, Interleukin-2
  • T-Lymphocytes, Cytotoxic / immunology
  • Tumor Necrosis Factor Receptor Superfamily, Member 7

Substances

  • Antibodies, Monoclonal
  • Antigens, Surface
  • Interleukin-2
  • Receptors, Antigen, T-Cell
  • Receptors, Immunologic
  • Receptors, Interleukin-2
  • Tumor Necrosis Factor Receptor Superfamily, Member 7