The unique surface molecules on intestinal intraepithelial lymphocytes: from tethering to recognizing

Area of Science:

• Immunology
• Gastroenterology
• Cell Biology

Background:

• Intraepithelial lymphocytes (IELs) are crucial immune cells residing within the intestinal epithelial layer.
• IELs comprise T cell receptor-γδ (TCRγδ) and TCRαβ subtypes, functioning as memory-effector cells.
• The intestinal barrier relies on interactions between IELs and epithelial cells (ECs) for its integrity.

Purpose of the Study:

• To review the mechanisms by which IELs reside within the intestinal epithelium.
• To elucidate the sentinel functions of IELs in maintaining intestinal homeostasis.
• To explore how IELs interact with epithelial cells (ECs) to survey the gut environment.

Main Methods:

• This review synthesizes existing literature on IEL biology and function.
• It examines the molecular interactions between IELs and epithelial cells (ECs), including cell adhesion molecules and tight junction proteins.
• The review discusses the T cell receptor (TCR) recognition of antigens presented by major histocompatibility complex (MHC) and non-classical MHC molecules.

Main Results:

• IELs are strategically positioned among epithelial cells (ECs) to form a critical component of the intestinal barrier.
• Cell adhesion molecules and tight junction proteins mediate the residence and surveillance functions of IELs.
• IELs utilize T cell receptors (TCRs) to detect antigens and monitor for stressed or damaged epithelial cells (ECs).

Conclusions:

• IELs play a vital role as sentinels at the gut epithelial interface.
• Their interactions with epithelial cells (ECs) are essential for maintaining intestinal physiological and immunological balance.
• IELs contribute to intestinal homeostasis by recognizing antigens and responding to cellular damage.