AUTHOR=Pandiyan Pushpa , Zheng Lixin , Lenardo Michael TITLE=The Molecular Mechanisms of Regulatory T Cell Immunosuppression JOURNAL=Frontiers in Immunology VOLUME=2 YEAR=2011 URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2011.00060 DOI=10.3389/fimmu.2011.00060 ISSN=1664-3224 ABSTRACT=
CD4+CD25+Foxp3+ T lymphocytes, known as regulatory T cells or Tregs, have been proposed to be a lineage of professional immune suppressive cells that exclusively counteract the effects of the immunoprotective “helper” and “cytotoxic” lineages of T lymphocytes. Here we discuss new concepts on the mechanisms and functions of Tregs. There are several key points we emphasize: 1. Tregs exert suppressive effects both directly on effector T cells and indirectly through antigen-presenting cells; 2. Regulation can occur through a novel mechanism of cytokine consumption to regulate as opposed to the usual mechanism of cytokine/chemokine production; 3. In cases where CD4+ effector T cells are directly inhibited by Tregs, it is chiefly through a mechanism of lymphokine withdrawal apoptosis leading to polyclonal deletion; and 4. Contrary to the current view, we discuss new evidence that Tregs, similar to other T-cells lineages, can promote protective immune responses in certain infectious contexts (Chen et al.,