Characterization of the Interleukin 2 Receptor β Chain Using Three Distinct Monoclonal Antibodies

• Published in: Proceedings of the National Academy of Sciences - PNAS 1989-03, Vol.86 (6), p.1982-1986
• Main Authors: Tsudo, Mitsuru, Kitamura, Fujiko, Miyasaka, Masayuki
• Format: Article
• Language: English
• Subjects: Animals; Antibodies; Antibodies, Monoclonal - immunology; Binding sites; Biological and medical sciences; Blood; Cell Line; Cell lines; Cell receptors; Cell structures and functions; Crosslinking; Electrophoresis, Polyacrylamide Gel; Epitopes - immunology; Flow Cytometry; Fundamental and applied biological sciences. Psychology; Gels; Humans; Immunoprecipitation; Immunosorbent Techniques; Interleukin-2 - metabolism; Interleukin-2 - pharmacology; Killer Cells, Natural; Lymphocyte Activation; Lymphocytes; Macromolecular Substances; Mice; Mice, Inbred BALB C; Molecular and cellular biology; Molecular Weight; Receptors; Receptors, Interleukin-2 - analysis; Receptors, Interleukin-2 - immunology; Signal Transduction; T lymphocytes
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.86.6.1982

The human high-affinity receptor for interleukin 2 (IL-2) has been proposed as being a membrane complex composed of at least two distinct polypeptide chains: p55 (α chain), recognized by the anti-Tac monoclonal antibody (mAb), and p75 (β chain), both of which are capable of binding IL-2. Whereas the α chain itself has been shown to be nonfunctional, the β chain appears to be pivotal in the IL-2 signal transduction, although the β chain is otherwise poorly characterized. Three β chain-specific mAbs, designated Mik-β 1, -β 2, and -β 3, were developed. Mik-β 1 and -β 2 completely inhibited the IL-2 binding to the β chain, whereas Mik-β 3 immunoprecipitated the β chain crosslinked with 125I-labeled IL-2. The β chain immunoprecipitated by these mAbs was revealed to have a Mr of 68,000-72,000. High-affinity IL-2 binding was completely abolished by Mik-β 1. Although IL-2-dependent T-cell growth at high IL-2 concentrations was not inhibited by the anti-Tac, it was almost completely inhibited by Mik-β 1 in the presence of the anti-Tac. These results clearly indicate that the β chain is an indispensable component to the high-affinity IL-2 receptor and is responsible for the IL-2 signal transduction. The β chain was found to be constitutively expressed without the α chain on the surface of peripheral blood Leu-19+ natural killer cells.