PLOS Biology: A Novel Regulatory T Cell Population in the Gut

Each individual T cell expresses just one of myriad different
versions of the TCR, each of which responds to a particular antigen.
This wide diversity allows the recognition of a large repertoire of
threats, but also carries the risk of inappropriate reactivity against
normal tissues. While T cells that may mount such attacks are usually
weeded out during their development, autoreactive cells do occasionally
appear. In addition, changes to body homeostasis may sometimes provoke T
cell autoimmunity. As a failsafe against these problems, a specialized
type of T cell called the “T regulatory” cell (Treg) reins in
inappropriate immune responses by secreting immunosuppressive cytokines
such as IL-10. Tregs can be distinguished from other types of T cells
primarily by their expression of the transcription factor FoxP3,
together with a characteristic set of cell surface proteins.

ability to restrict immune responses is delicately balanced. For
example, the immune system normally tolerates several species of
commensal gut bacteria, and does not mount immune responses against
them. However, perturbances to the mixture of commensal bacteria
communities can lead—through mechanisms that remain unclear—to bowel
inflammation, and sometimes serious autoimmune diseases such as
inflammatory bowel disease (IBD) or ulcerative colitis. In their paper
published this month in PLOS Biology, Guillaume Sarrabayrouse,
Frédéric Altare, Francine Jotereau, and colleagues describe a new type
of T cell that mediates immune tolerance, which may be important for
preventing bowel inflammation.

Here's the paper

CD4CD8αα Lymphocytes, A Novel Human Regulatory T Cell Subset Induced by Colonic Bacteria and Deficient in Patients with Inflammatory Bowel Disease

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