Activation of CD8 super(+) Regulatory T Cells by Human Placental Trophoblasts

• Published in: The Journal of immunology (1950) Vol. 174; no. 12; pp. 7539 - 7547
• Main Authors: Shao, Ling, Jacobs, Adam R, Johnson, Valrie V, Mayer, Lloyd
• Format: Journal Article
• Language: English
• Published: 01.06.2005
• ISSN: 0022-1767

The immunological basis by which a mother tolerates her semi-allogeneic fetus remains poorly understood. Several mechanisms are likely to contribute to this phenomenon including active immune regulation by regulatory T cells. In this article, we report that human placental trophoblasts activate a clonal population of CD8 super(+) T cells with regulatory function. These cells are not MHC class I restricted, but require costimulation through a member of the carcinoembryonic Ag family present on early gestation trophoblasts. These regulatory T cells express the mucosal markers CD101 and CD103 and display selective usage of the TCR gene V beta 9. CD8 super(+) T cells isolated from the peripheral blood of pregnant mothers (16-28 wk) also demonstrate expansions in the same V beta family (V beta 9), signaling a possible role for these cells in preventing fetal rejection in vivo. We have previously characterized a subset of CD8 super(+) regulatory T cells activated by the combination of the nonclassical class I molecule CD1d and a costimulatory molecule of the carcinoembryonic Ag family present on the intestinal epithelium. These data support the concept that distinct regulatory T cell populations exist at different sites and may be regulated locally by unique restriction elements, costimulatory signals, and Ags.