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Intraepithelial lymphocytes: origins, distribution, and function
1Discipline of Pathology, Faculty of Medicine, The University of Newcastle, New South Wales, Australia.
Critical Reviews in Immunology
|June 24, 1998
Summary
Intraepithelial lymphocytes (IEL) are key immune cells at epithelial surfaces, acting as a first line of defense against pathogens. This review explores their development, function, and role in immune surveillance.
Area of Science:
- Immunology
- Cell Biology
- Epithelial Biology
Background:
- Intraepithelial lymphocytes (IEL) are immune cells residing within epithelial tissues, including the gut and skin.
- They are the initial responders to pathogens breaching epithelial barriers.
- IEL populations are primarily composed of T cells (CD3+), with a notable presence of CD8+ cells.
Purpose of the Study:
- To review the morphology, distribution, and phenotype of IEL.
- To discuss the potential for extrathymic development of IEL.
- To explore the diverse functions of this unique lymphoid population.
Main Methods:
- Review of existing literature on IEL.
- Analysis of IEL morphology and distribution.
- Phenotypic characterization of IEL populations (TCR alphabeta+, TCR gammadelta+, CD3+, CD8+).
Main Results:
- IEL exhibit cytotoxic activities (CTL, NK activity) supporting immune surveillance.
- IEL are activated in vivo and secrete cytokines, influencing immune responses.
- Subsets of IEL contribute to B cell help, oral tolerance, and epithelial cell regulation.
Conclusions:
- IEL represent a critical first line of defense at epithelial surfaces.
- Their development and selection processes may differ from thymic pathways.
- IEL play multifaceted roles in maintaining tissue immunity and homeostasis.