CD4+ T Cell Tolerance to Tissue-Restricted Self Antigens Is Mediated by Antigen-Specific Regulatory T Cells Rather

Francois P Legoux1, Jong-Baeck Lim1, Andrew W Cauley1

  • 1Center for Immunology and Inflammatory Diseases, and Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital; and Harvard Medical School, Charlestown, MA 02129, USA.

Immunity
|November 18, 2015
PubMed

Deletion of self-antigen-specific T cells during thymic development provides protection from autoimmunity. However, it is unclear how efficiently this occurs for tissue-restricted self antigens, or how immune tolerance is maintained for self-antigen-specific T cells that routinely escape deletion. Here we show that endogenous CD4+ T cells with specificity for a set of tissue-restricted self antigens were not deleted at all. For pancreatic self antigen, this resulted in an absence of steady-state tolerance, while for the lung and intestine, tolerance was maintained by the enhanced presence of thymically-derived antigen-specific Foxp3+ regulatory T (Treg) cells. Unlike deletional tolerance, Treg cell-mediated tolerance was broken by successive antigen challenges. These findings reveal that for some tissue-restricted self antigens, tolerance relies entirely on nondeletional mechanisms that are less durable than T cell deletion. This might explain why autoimmunity is often tissue-specific, and it offers a rationale for cancer vaccine strategies targeting tissue-restricted tumor antigens.

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