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Structural analysis of high‐ versus low‐affinity interleukin‐2 receptors by means of selective expression of distinct receptor classes.
Author(s) -
Gullberg M.
Publication year - 1986
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1986.tb04481.x
Subject(s) - receptor , biology , microbiology and biotechnology , population , cell surface receptor , interleukin 2 , immune receptor , receptor expression , biochemistry , demography , sociology
Activated T cells express at least two distinct affinity classes of interleukin‐2 (IL‐2) receptors. The number of low‐affinity receptors per cell is normally 10‐30 times greater than that of the high‐affinity receptors, and the difference in the dissociation constant between the two classes of receptors is in the order of 1,000‐fold. In this report normal human T cells are used in a cellular system in which the number of low‐affinity receptors can be manipulated. It is demonstrated that a cell population could be achieved with such low levels of low‐affinity IL‐2 receptors that almost half of the surface pool of anti‐IL‐2 receptor antibody (anti‐Tac) binding sites represented high‐affinity receptors. By using this cellular system it was possible to show that anti‐Tac recognizes both receptor classes with similar affinity and that IL‐2 inhibits Tac binding to both receptor classes in a competitive fashion. Tac antigens were purified from surface 125I‐labeled cells expressing high levels of high‐affinity IL‐2 receptors, but low levels of the low‐affinity receptor class, and this preparation was compared with another pool of Tac antigens obtained from cells expressing the normal 10‐ to 20‐fold excess of low‐affinity IL‐2 binding sites over high‐affinity IL‐2 receptors. Biochemical characterization by peptide mapping by limited proteolysis and two‐dimensional gel analysis revealed that these distinct preparations of Tac antigens were indistinguishable.(ABSTRACT TRUNCATED AT 250 WORDS)