Characterization of the soluble murine IL-2R and estimation of its affinity for IL-2

J Immunol. 1988 Jul 15;141(2):539-46.


IL-2 induces cells of the cytotoxic T cell line C30.1 to express large numbers of membrane IL-2R (mIL-2R). At the height of activation, these cells also release a soluble form of IL-2R (sIL-2R). Using either crude supernatant or a semi-purified preparation of sIL-2R obtained by affinity chromatography, studies were performed to characterize murine sIL-2R. Its m.w. was determined by both gel filtration and SDS-PAGE. The affinity of sIL-2R for a panel of mAb known to recognize different epitopes of mIL-2R (p55 subunit) was assessed by saturation and competition experiments. The relationship between the various epitopes was studied by cross-inhibition experiments. The data suggest that sIL-2R and mIL-2R (p55 subunit) are structurally similar. The ability of sIL-2R to bind IL-2 was assessed by measuring the dissociation and the inhibition constant of the molecule for IL-2. Both values coincide and indicate that the affinity of sIL-2R for IL-2 is at least 10-fold lower than the that of low affinity mIL-2R. The biologic implications of these findings are discussed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Monoclonal
  • Binding Sites, Antibody
  • Binding, Competitive
  • Cell Line
  • Cell-Free System
  • Chromatography, Gel
  • Electrophoresis, Polyacrylamide Gel
  • Interleukin-2 / metabolism*
  • Kinetics
  • Mice
  • Molecular Weight
  • Receptors, Immunologic / analysis*
  • Receptors, Immunologic / immunology
  • Receptors, Immunologic / metabolism
  • Receptors, Interleukin-2
  • Sodium Dodecyl Sulfate
  • Solubility


  • Antibodies, Monoclonal
  • Interleukin-2
  • Receptors, Immunologic
  • Receptors, Interleukin-2
  • Sodium Dodecyl Sulfate