located in capable of mature gamma-delta T cell gamma-delta intraepithelial T cell gamma-delta intraepithelial T lymphocyte Gamma-delta intraepithelial T cells, also known as γδ intraepithelial lymphocytes (IELs), are a unique subset of T cells residing in the epithelial layer of mucosal tissues such as the intestine and skin; more are found in intestinal intraepithelial tissue than in other tissues. They are characterized by their distinct T-cell receptor (TCR) that is composed of one gamma (γ) and one delta (δ) chain, unlike the conventional alpha-beta T cells. Most γδ IELs also express the CD8-alpha-alpha homodimer (Cd8-alpha alpha positive, gamma-delta intraepithelial T cells), although some are lacking both co-receptors CD4 and CD8 (CD4-negative CD8-negative gamma-delta intraepithelial T cells). γδ IELs are though to be ‘natural’ IELs as they acquire their activated phenotype in an ‘alternative’ self-antigen-based maturation process in the thymus. Although the function of γδ IELs is still not fully established, current evidence indicates that they serve as a crucial first line of defense against invading pathogens, thus making them an important class of immune cells at the epithelial barrier interfaces. γδ IELs respond to a variety of antigens, including those not recognized by conventional T cells. They are also thought to be involved in recruiting in immune surveillance by promoting homeostasis of host microbiota and in limiting excessive inflammation. In addition to their primary role in immunity, γδ IELs also have roles in epithelial cell homeostasis and repair. They assist in maintaining the epithelial barrier by controlling the equilibrium of epithelial cell growth and death. They also contribute to the healing of lesions and the replacement of damaged epithelial cells. The regulative control exerted by γδ IELs over epithelial cell turnover indirectly influences immunity, underlining the complexity and versatility of these cells. (This extended description was generated by ChatGPT and reviewed by the CellGuide team, who added references, and by the CL editors, who approved it for inclusion in CL. It may contain information that applies only to some subtypes and species, and so should not be considered definitional.) A mature gamma-delta T cell that is found in the columnar epithelium of the gastrointestinal tract. These cells participate in mucosal immune responses. intraepithelial lymphocyte ZFA:0009339 gamma-delta intraepithelial T-cell IEL gamma-delta intraepithelial T-lymphocyte https://cellxgene.cziscience.com/cellguide/CL_0000801 intestinal intraepithelial lymphocyte mucosal immune response intestinal epithelium