Pseudo-high affinity interleukin 2 (IL-2) receptor lacks the third component that is essential for functional IL-2 binding and signaling

Nobuyoshi Arima, Masanori Kamio, Kazunori Imada, Toshiyuki Hori, Toshio Hattori, Mitsuru Tsudo, Minoru Okuma, Takashi Uchiyama

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84 Citations (Scopus)


Functional studies of the interleukin 2 receptor (IL2R) of two (ED515-D and Kit225) IL-2- dependent and three (ED515-I, 3T3-αβll, and Hut102) IL-2-independent cell lines were done. All of these cell lines appeared to express high as well as low affinity IL-2R. However, ED515-1 and 3T3-ao11, which expressed the IL-2R β chain, did not bind IL-2 at all when IL-2 binding to their IL-2R α chain was blocked with anti-Tac monoclonal antibody, whereas the intermediate affinity binding in ED515-D, Kit225, and Hut102 cells remained. We tentatively called the high affinity IL-2R of the former cells pseudo-high affinity IL-2R. The dissociation constant of pseudo-high affinity IL-2R was higher than that of ordinary high affinity IL-2R. Internalization of cell-bound 1251-IL2 into ED515-I and 3T3-ao11 cells was less efficient than that into ED515-D cells. The addition of IL-2 neither promoted cell growth nor upregulated IL-2R α chain expression in ED515-1 and 3T3-αβ11 cells. Furthermore, tyrosine phosphorylation of the cellular proteins (p120, p98, p96, p54, and p38) was induced or enhanced in response to the addition of IL-2 in ED515-D and Kit225 cells, but not in the cell lines expressing pseudo-high affinity IL-2R. Finally, 1251-IL2 crosslinking followed by SDS-PAGE analysis showed an 80-kD band corresponding to p65 + IL-2, in addition to bands corresponding to IL-2R α and ,β chain + IL-2 in cells bearing ordinary high affinity IL-2R but not in cells with pseudo-high affinity IL-2R. Taken together, we consider that another protein whose molecular mass is approximately 65 kD is functionally important in IL-2 binding and subsequent signal transduction and may be the third component of IL-2R.

Original languageEnglish
Pages (from-to)1265-1272
Number of pages8
JournalJournal of Experimental Medicine
Issue number5
Publication statusPublished - 1992 Nov 1
Externally publishedYes

ASJC Scopus subject areas

  • Medicine(all)


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