Transcription Factor T-bet Regulates Intraepithelial Lymphocyte Functional Maturation

Reis BS, Hoytema van Konijnenburg DP, Grivennikov SI, Mucida D.

Immunity. 2014 Aug 21;41(2):244-56. doi: 10.1016/j.immuni.2014.06.017.

Mucida Photo

From Left to Right: Bernardo Reis, Sergei Grivennikov, and Daniel Mucida

IELs police the single-cell layer of intestinal epithelium, a fine boundary that spans as much as 400 square meters and allows nutrients in and wastes out. Nearly all IELs belong to a group of lymphocytes (themselves a type of white blood cell) known as T cells, produced by the thymus, an organ below the breastbone. IELs are made one of two ways. “Natural” IELs require no additional activation after they are produced by the thymus. “Induced” IELs, meanwhile, are produced when two types of mature T cells, CD4 and CD8 cells, acquire new traits and move into the gut epithelium, becoming IELs.During an immune response, CD4 cells send out signals to other immune cells, earning them the name helper T cells. The new research took a closer look at this pathway, which the team had since determined leads to all IELs, natural and induced. They focused on two proteins, T-bet and Runx3, transcription factors that regulate the expression of genes. Both T-bet and Runx3 occur in high levels in IELs, and were already known to play a role in the development and function of T cells. PubMed:25148025