Agustina Tri Endharti, Muhaimin Rifa'I, Zhe Shi, Yukari Fukuoka, Yoshio Nakahara, Yoshiyuki Kawamoto, Kozue Takeda, Ken-Ichi Isobe, Haruhiko Suzuki
We recently identified CD8+ CD122+ regulatory T cells that directly control CD8+ and CD4+ cells without intervention of APCs. In this study, we investigated the effector mechanism of CD8+ CD122+ regulatory T cells by using an in vitro regulation system. The profile of cytokine expression revealed that IL-10 was predominantly produced by CD8+ CD122+ cells, whereas other cytokines were similarly expressed in CD8+ CD122+ cells and CD8+ CD122- cells. Suppression of both proliferation and IFN-γ production by CDS CD122- cells by CD8+ CD122+ cells was blocked by adding anti-IL-10 Ab to the culture but not by adding anti-TGF-β Ab. When IL-10 was removed from the conditioned medium from CD8+ CD122+ cells, the conditioned medium no longer showed regulatory activity. Finally, CD8+ CD122+ cells from IL-10-deficient mice had no regulatory activity in vitro and reduced regulatory activity in vivo. Our results clearly indicate that IL-10 is produced by CD8+ CD122+ cells and mediates the regulatory activity of these cells. Copyright © 2005 by The American Association of Immunologists, Inc.
Department of Immunology, Nagoya University Graduate School of Medicine, Nagoya, Japan; Faculty of Medicine, Brawijaya University, Malang, East-Java, Indonesia; Japan Society for the Promotion of Science, Tokyo, Japan; Department of Immunology, Nagoya University Graduate School of Medicine, Showa-ku, Nagoya 466-8550, 65 Tsurumai-cho, Japan
