Characterization of the two heavy chains of the T3 complex on the surface of human T lymphocytes

J Biol Chem. 1984 Oct 10;259(19):12039-48.


The T3 complex has been defined by a group of monoclonal antibodies which react with all human peripheral blood T lymphocytes and a subpopulation of thymocytes. This membrane structure includes glycoproteins of 44 (alpha), 37 (beta), 25 (gamma), and 20 kDa (delta) as well as a nonglycosylated polypeptide of 20 kDa (epsilon). The characterization of the alpha and beta chains has been of particular interest because they may constitute the T cell receptor for antigen. Here we show that the T3 complex prepared by immunoprecipitation from T lymphocytes of a leukemic patient (Sezary syndrome) displays an unusually strong association of the alpha and beta chains with the 20/25-kDa T3 proteins. The alpha and beta chains (48 and 44 kDa) were co-precipitated by anti-20-kDa T3 monoclonal antibodies as a disulfide-linked 90-kDa heterodimer. A minor 220-kDa multimer composed of proteins similar to the alpha and beta chains was also present in these immunoprecipitates. This multimer could be independently precipitated with a new monoclonal antibody WT-31, which detects the larger polypeptide chains of the T3 complex on all human T lymphocytes. After removal of N-linked oligosaccharides, both the alpha and beta chain were found to have 33-kDa peptide backbones with distinct isoelectric points. Using a monoclonal reagent T40/25, a 90-kDa heterodimer, consisting of 40- and 49-kDa chains with peptide backbones of 34 kDa was found to be T3-associated on the T leukemic cell line HPB-ALL. When the alpha and beta chains from the Sezary patient were compared with the corresponding chains from HPB-ALL by peptide mapping, large differences were observed. Taken together, the data presented here provide strong evidence that the T cell receptor for antigen is part of the T3 complex on the surface of human T lymphocytes.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acetylglucosaminidase / metabolism
  • Antibodies, Monoclonal
  • Antigens / blood*
  • CD3 Complex
  • Electrophoresis, Polyacrylamide Gel
  • Humans
  • Leukemia, Lymphoid / blood
  • Macromolecular Substances
  • Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase
  • Mesylates / pharmacology
  • Molecular Weight
  • Peptide Fragments / analysis
  • Sezary Syndrome / blood
  • T-Lymphocytes / analysis*
  • Trypsin / metabolism


  • Antibodies, Monoclonal
  • Antigens
  • CD3 Complex
  • Macromolecular Substances
  • Mesylates
  • Peptide Fragments
  • Acetylglucosaminidase
  • Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase
  • Trypsin
  • trifluoromethanesulfonic acid