title: Down-regulation of KOLT-2 antigen (CD28) by interleukin 2; role of IL-2R (p70).
abstract: Using KOLT-2 monoclonal antibody (mAb) recognizing a 44,000 molecular weight (MW) T-cell activation antigen (CD28), we observed the co-expression of KOLT-2 (CD28) antigen and Tac (CD25) antigen, associated with a 55,000 MW chain of the interleukin-2 receptor (IL-2R) complex. IL-2R (p55), on several T-cell lines transformed by human T-lymphotropic virus-I (HTLV-I), as well as several subclones of the natural killer (NK)-like cell line YT. When YT cells (YTC3T, YT5.1) and IL-2-dependent HTLV-I+ T-cell line cells (ED, ATL35C) expressing both IL-2R (p55) and IL-2R (p70) chains were cultured with recombinant IL-2 (rIL-2), KOLT-2 antigen was down-regulated in 24 hr. However, KOLT-2 antigen on HPB-ALL (Kurume) cells expressing neither of the IL-2R chains was unaffected by IL-2. IL-2 also failed to down-regulate KOLT-2 antigen on MT-1 cells bearing IL-2R (p55)/Tac without IL-2R (p70). To clarify the role of IL-2R (p70) in the IL-2-induced down-regulation of KOLT-2 antigen, we analysed the effect of IL-2 on a Tac- subclone of YT (YT2C2) that expresses IL-2R (p70). As was the case with Tac+ YT cells, KOLT-2 antigen was down-regulated by IL-2, and this down-regulation was inhibited by anti-IL-2R (p70) mAb but not by anti-Tac mAb. These results show that the signalling through the IL-2/IL-2R system down-regulates KOLT-2 (CD28) antigen by way of the interaction between IL-2 and IL-2R (p70), irrespective of IL-2R (p55)/Tac. Possible involvement of the IL-2/IL-2R system in the CD28-mediated mitogenic mechanism is discussed.
authors.affiliation: Institute for Immunology, Faculty of Medicine, Kyoto University, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Shindo
authors.forename: K
authors.initials: K
authors.lastname: Sugie
authors.forename: K
authors.initials: K
authors.lastname: Nakamura
authors.forename: Y
authors.initials: Y
authors.lastname: Tagaya
authors.forename: M
authors.initials: M
authors.lastname: Maeda
authors.forename: T
authors.initials: T
authors.lastname: Uchiyama
authors.forename: K
authors.initials: K
authors.lastname: Sagawa
authors.forename: M
authors.initials: M
authors.lastname: Yokoyama
authors.forename: H
authors.initials: H
authors.lastname: Wada
authors.forename: S
authors.initials: S
authors.lastname: Hitomi
mesh_terms: D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis*; D018106:CD28 Antigens; D002460:Cell Line; D015490:HTLV-I Infections / Q000276:immunology; D006801:Humans; D007376:Interleukin-2 / Q000276:immunology*; D007694:Killer Cells, Natural / Q000276:immunology; D015375:Receptors, Interleukin-2 / Q000032:analysis / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D018106:CD28 Antigens; D007376:Interleukin-2; D015375:Receptors, Interleukin-2