Intestinal intraepithelial lymphocytes: Maintainers of intestinal immune tolerance and regulators of intestinal immunity

Intestinal immune tolerance is essential for the immune system, as it prevents abnormal immune responses to large quantities of antigens from the intestinal lumen, such as antigens from commensal microorganisms, and avoids self-injury. Intestinal intraepithelial lymphocytes (IELs), a special group of mucosal T lymphocytes, play a significant role in intestinal immune tolerance. To accomplish this, IELs exhibit a high threshold of activation and low reactivity to most antigens from the intestinal lumen. In particular, CD8 alpha alpha+TCR alpha beta(+)IELs, TCR gamma delta(+)IELs, and CD4(+)CD8 alpha alpha(+)IELs show great potential for maintaining intestinal immune tolerance and regulating intestinal immunity. However, if the intestinal microenvironment becomes abnormal or intestinal tolerance is broken, IELs may be activated abnormally and become pathogenic.

Automated summary

Intestinal immune tolerance is crucial for preventing abnormal immune responses to antigens from the gut, with IELs playing a significant role in maintaining this balance. Specific subgroups of IELs have the potential to regulate intestinal immunity and tolerance effectively.