Intraepithelial lymphocytes

Intraepithelial lymphocytes (IF.Ls) reside between intestinal epithelial cells and are the first cells to contact luminal antigen that crosses the mucosa in an M cell-independent manner. This heterogeneous population of mainly T cells comprises a very large number of cells (more than half the number of T cells in peripheral organs) but their function remains poorly understood. The majority of murine IELs (80%) arc CD3+, and over 75% of these also express CDS. In mice and chickens, significant numbers of yS TCR' IELs are found (40-60%) in addition to a(3 TCR+ cells; however, this number varies with mouse strain, age and housing conditions. The y8 TCR4 IELs represent a minor component of human IELs (-15%) under normal conditions, but significantly increase under certain conditions, such as celiac disease.

The physiological role of IELs is poorly understood; however, several functions for these cells have been described and this diversity is consistent with their phenotypic heterogeneity. IELs have been shown to mediate antigen-specific delayed-type hypersensitivity (DTH) responses, to exhibit virus-specific CTL function, to express natural killer (NK)-like activity and to produce a local graft-versus-host reaction (GVHR) when transferred to semiallogeneic hosts. IELs respond poorly to conventional T cell mitogens when compared to splenic T cells; however, there is evidence that human IELs are induced to proliferate via a CD2 pathway rather than through stimulation of the CD3-TCR complex. With regard to regulation of humoral immunity, y8 TCRf IEL T

cells have been shown to abrogate the induction of mucosal tolerance, while a(3 TCR IEL T cells provide help for production of IgA. Interestingly, the targeted disruption of the 8 chain of TCR in mice results in a lack of y8 T cells among IELs and in a mucosal IgA deficiency, suggesting that y8 T cells may upreg-ulate CD4+ T helper cells for mucosal immunity. IELs can be induced to produce a variety of cytokines which are characteristically produced by Tnl- and TH2-type cells and a(3 TCR4 IELs can also provide help for B cell responses.

Why Gluten Free

Why Gluten Free

What Is The Gluten Free Diet And What You Need To Know Before You Try It. You may have heard the term gluten free, and you may even have a general idea as to what it means to eat a gluten free diet. Most people believe this type of diet is a curse for those who simply cannot tolerate the protein known as gluten, as they will never be able to eat any food that contains wheat, rye, barley, malts, or triticale.

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