Definition and research guide
This page combines a MeSH definition, publication statistics and selected research abstracts. It is a starting point for reading the literature, not a medical textbook or a systematic evidence review.
Content available: 4 complete abstracts (725 words), 10 references. Full article text is not stored or reproduced here; follow the PMID, DOI or PMC links to read the original sources and their access terms.
Definition
T Lymphocytes with limited diversity of receptors (e.g., alpha E integrins) in the epidermis of the skin and the mucosal linings. They recognize common microbes via t-cell receptors and pathogen-associated molecular pattern molecules and function as effector cells for innate immunity. Activation of intraepithelial lymphocytes is a marker for various gastrointestinal diseases (e.g., celiac disease; hairy cell leukemia; and enteropathy-associated t-cell lymphoma).
Definition: NLM Medical Subject Headings (MeSH) scope note (Public domain (U.S. National Library of Medicine); attribution requested). View the MeSH record.
Also known as: Intraepithelial Lymphocyte; Lymphocyte, Intraepithelial; Lymphocytes, Intraepithelial; Gamma Delta T Cells; Gamma Delta T Lymphocytes; Intraepithelial T Lymphocytes; T Lymphocyte, Intraepithelial; T Lymphocytes, Intraepithelial.
Where it fits in the MeSH classification
- Broader topics
- T-Lymphocyte Subsets
Related concepts
- Alpha
- Integrins
- T-Cell Receptors
- Pathogen-Associated Molecular Pattern Molecules
- Innate Immunity
- Celiac Disease
- Hairy Cell Leukemia
- Enteropathy-Associated T-Cell Lymphoma
Research landscape
PubMed indexes 838 records tagged with the MeSH heading “Intraepithelial Lymphocytes” (counts retrieved 2026-10-31). 613 of them (73.2%) were published from 2020 onward, and the busiest period so far is 2020 onward with 613 records.
Reviews account for 150 records (17.9%) and meta-analyses for 2. Randomized controlled trials number 2 (0.2%) as a share of all records on the topic. Randomized trials make up only a small share of this literature, so much of what is known comes from laboratory, observational or descriptive work.
Show the data
| Period | Records |
|---|---|
| through 1999 | 0 |
| 2000-2009 | 0 |
| 2010-2019 | 235 |
| 2020 onward | 613 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 150 | 17.9% |
| Meta-analyses | 2 | 0.2% |
| Randomized controlled trials | 2 | 0.2% |
Method: PubMed query "Intraepithelial Lymphocytes"[MeSH Terms] with publication-type and date filters, retrieved 2026-10-31.
Reading the evidence in anatomy and physiology
Anatomy describes how body structures are built and physiology describes how they normally work, so most findings here are descriptive or mechanistic rather than evidence about treatment. Much of what is known comes from dissection, imaging, tissue studies and experiments in animals, and measurements in healthy volunteers can differ from those in people with disease or at different ages. Normal ranges vary between individuals and populations. Check whether a result was measured in people or in another species, the age and health of the participants, and the method used.
Evidence from open-access studies
These open-access studies come from PubMed’s best-match results for this heading (papers whose main topic it is), ranked here by citation count, with one recent addition. Each abstract is reproduced in full under its recorded open licence so that you can read the authors’ own words. They illustrate the literature; they are not a systematic summary of it. Citation counts measure attention, not reliability or clinical benefit.
| Study / authors | Year | Source label / design | Europe PMC citations | Licence / source |
|---|---|---|---|---|
| Single-cell analyses of Crohn's disease tissues reveal intestinal intraepithelial T cells heterogeneity and altered subset distributions | 2021 | Research article Design not recorded in structured metadata | 218 | cc by PMID 33771991 · DOI · PMC7997960 |
| Vaccine-induced systemic and mucosal T cell immunity to SARS-CoV-2 viral variants | 2022 | Research article Design not recorded in structured metadata | 118 | cc by PMID 35561224 · DOI · PMC9171754 |
| Tumor-associated neutrophils suppress pro-tumoral IL-17+ γδ T cells through induction of oxidative stress | 2018 | Research article Design not recorded in structured metadata | 109 | cc by PMID 29750788 · DOI · PMC5965901 |
| IL-17-producing γδ T cells in the tumor microenvironment promote radioresistance in mice | 2025 | Research article Design not recorded in structured metadata | 8 | cc by PMID 41055972 · DOI · PMC12700543 |
Single-cell analyses of Crohn's disease tissues reveal intestinal intraepithelial T cells heterogeneity and altered subset distributions [1]
Abstract reading summary — source excerpts
- Opening excerpt
- Crohn's disease (CD) is a chronic transmural inflammation of intestinal segments caused by dysregulated interaction between microbiome and gut immune system.
- Closing excerpt
- Our analyses of CD tissues thus suggest a potential link, pending additional validations, between transmural inflammation, reduced IEL γδT cells and altered spatial distribution of IEL and LP T cell subsets.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (153 words)
Crohn's disease (CD) is a chronic transmural inflammation of intestinal segments caused by dysregulated interaction between microbiome and gut immune system. Here, we profile, via multiple single-cell technologies, T cells purified from the intestinal epithelium and lamina propria (LP) from terminal ileum resections of adult severe CD cases. We find that intraepithelial lymphocytes (IEL) contain several unique T cell subsets, including NKp30+γδT cells expressing RORγt and producing IL-26 upon NKp30 engagement. Further analyses comparing tissues from non-inflamed and inflamed regions of patients with CD versus healthy controls show increased activated TH17 but decreased CD8+T, γδT, TFH and Treg cells in inflamed tissues. Similar analyses of LP find increased CD8+, as well as reduced CD4+T cells with an elevated TH17 over Treg/TFH ratio. Our analyses of CD tissues thus suggest a potential link, pending additional validations, between transmural inflammation, reduced IEL γδT cells and altered spatial distribution of IEL and LP T cell subsets.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 33771991 · DOI · PMC7997960
Vaccine-induced systemic and mucosal T cell immunity to SARS-CoV-2 viral variants [2]
Abstract reading summary — source excerpts
- Opening excerpt
- The first-generation COVID-19 vaccines have been effective in mitigating severe illness and hospitalization, but recurring waves of infections are associated with the emergence of SARS-CoV-2 variants that display progressive abilities to evade antibodies, leading to diminished vaccine effectiveness.
- Closing excerpt
- Mechanistic insights from this work have significant implications in the development of T cell–targeted immunomodulation or broadly protective SARS-CoV-2 vaccines.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (253 words)
The first-generation COVID-19 vaccines have been effective in mitigating severe illness and hospitalization, but recurring waves of infections are associated with the emergence of SARS-CoV-2 variants that display progressive abilities to evade antibodies, leading to diminished vaccine effectiveness. The lack of clarity on the extent to which vaccine-elicited mucosal or systemic memory T cells protect against such antibody-evasive SARS-CoV-2 variants remains a critical knowledge gap in our quest for broadly protective vaccines. Using adjuvanted spike protein–based vaccines that elicit potent T cell responses, we assessed whether systemic or lung-resident CD4 and CD8 T cells protected against SARS-CoV-2 variants in the presence or absence of virus-neutralizing antibodies. We found that 1) mucosal or parenteral immunization led to effective viral control and protected against lung pathology with or without neutralizing antibodies, 2) protection afforded by mucosal memory CD8 T cells was largely redundant in the presence of antibodies that effectively neutralized the challenge virus, and 3) “unhelped” mucosal memory CD8 T cells provided no protection against the homologous SARS-CoV-2 without CD4 T cells and neutralizing antibodies. Significantly, however, in the absence of detectable virus-neutralizing antibodies, systemic or lung-resident memory CD4 and “helped” CD8 T cells provided effective protection against the relatively antibody-resistant B1.351 (β) variant, without lung immunopathology. Thus, induction of systemic and mucosal memory T cells directed against conserved epitopes might be an effective strategy to protect against SARS-CoV-2 variants that evade neutralizing antibodies. Mechanistic insights from this work have significant implications in the development of T cell–targeted immunomodulation or broadly protective SARS-CoV-2 vaccines.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 35561224 · DOI · PMC9171754
Tumor-associated neutrophils suppress pro-tumoral IL-17+ γδ T cells through induction of oxidative stress [3]
Abstract reading summary — source excerpts
- Opening excerpt
- Interleukin 17 (IL-17)-producing γδ T cells (γδ17 T cells) have been recently found to promote tumor growth and metastasis formation.
- Closing excerpt
- This work thus identifies an unanticipated, immunosuppressive yet antitumoral, neutrophil/ROS/γδ17 T-cell axis in the tumor microenvironment.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (172 words)
Interleukin 17 (IL-17)-producing γδ T cells (γδ17 T cells) have been recently found to promote tumor growth and metastasis formation. How such γδ17 T-cell responses may be regulated in the tumor microenvironment remains, however, largely unknown. Here, we report that tumor-associated neutrophils can display an overt antitumor role by strongly suppressing γδ17 T cells. Tumor-associated neutrophils inhibited the proliferation of murine CD27- Vγ6+ γδ17 T cells via induction of oxidative stress, thereby preventing them from constituting the major source of pro-tumoral IL-17 in the tumor microenvironment. Mechanistically, we found that low expression of the antioxidant glutathione in CD27- γδ17 T cells renders them particularly susceptible to neutrophil-derived reactive oxygen species (ROS). Consistently, superoxide deficiency, or the administration of a glutathione precursor, rescued CD27- Vγ6+ γδ17 T-cell proliferation in vivo. Moreover, human Vδ1+ γδ T cells, which contain most γδ17 T cells found in cancer patients, also displayed low glutathione levels and were potently inhibited by ROS. This work thus identifies an unanticipated, immunosuppressive yet antitumoral, neutrophil/ROS/γδ17 T-cell axis in the tumor microenvironment.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 29750788 · DOI · PMC5965901
IL-17-producing γδ T cells in the tumor microenvironment promote radioresistance in mice [4]
Abstract reading summary — source excerpts
- Opening excerpt
- The immunosuppressive tumor microenvironment (TME) drives radioresistance, but the role of γδ T cells in regulating radiosensitivity remains incompletely understood.
- Closing excerpt
- Targeting γδ T cells and IL-17A enhanced radiosensitivity and improved the efficacy of radiotherapy combined with anti-PD-1 immunotherapy, providing potential therapeutic strategies to overcome radioresistance.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (147 words)
The immunosuppressive tumor microenvironment (TME) drives radioresistance, but the role of γδ T cells in regulating radiosensitivity remains incompletely understood. In this study, we found that γδ T cell infiltration in the TME substantially increased after radiotherapy and contributed to radioresistance. Depletion of γδ T cells enhanced radiosensitivity. Single-cell RNA-seq revealed that γδ T cells in the postradiotherapy TME were characterized by the expression of Zbtb16, Il23r, and Il17a, and served as the primary source of IL-17A. These γδ T cells promoted radioresistance by recruiting myeloid-derived suppressor cells and suppressing T cell activation. Mechanistically, radiotherapy-induced tumor cell-derived microparticles containing dsDNA activated the cGAS-STING/NF-κB signaling pathway in macrophages, upregulating the expression of the chemokine CCL20, which was critical for γδ T cell recruitment. Targeting γδ T cells and IL-17A enhanced radiosensitivity and improved the efficacy of radiotherapy combined with anti-PD-1 immunotherapy, providing potential therapeutic strategies to overcome radioresistance.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 41055972 · DOI · PMC12700543
Key reviews and meta-analyses
The most cited review-type papers among PubMed’s best-match results for this heading, listed with bibliographic details only. Follow the links for the full text and access terms.
- Research article γδ T cells in tissue physiology and surveillance [5]
- Research article γδ T cells in homeostasis and host defence of epithelial barrier tissues [6]
- Research article Intestinal Intraepithelial Lymphocytes: Sentinels of the Mucosal Barrier [7]
- Research article Gamma Delta T-Cell Based Cancer Immunotherapy: Past-Present-Future [8]
- Research article Diverse developmental pathways of intestinal intraepithelial lymphocytes [9]
- Research article Host-microbiota interactions in inflammatory bowel disease [10]
References
- Jaeger N, Gamini R, Cella M, Schettini JL, Bugatti M, Zhao S, et al.. Single-cell analyses of Crohn's disease tissues reveal intestinal intraepithelial T cells heterogeneity and altered subset distributions. . 2021. PMID 33771991 · DOI · PMC7997960
- Kingstad-Bakke B, Lee W, Chandrasekar SS, Gasper DJ, Salas-Quinchucua C, Cleven T, et al.. Vaccine-induced systemic and mucosal T cell immunity to SARS-CoV-2 viral variants. . 2022. PMID 35561224 · DOI · PMC9171754
- Mensurado S, Rei M, Lança T, Ioannou M, Gonçalves-Sousa N, Kubo H, et al.. Tumor-associated neutrophils suppress pro-tumoral IL-17+ γδ T cells through induction of oxidative stress. . 2018. PMID 29750788 · DOI · PMC5965901
- Deng Y, Liu X, Yang X, Wei W, Wang J, Yang Z, et al.. IL-17-producing γδ T cells in the tumor microenvironment promote radioresistance in mice. . 2025. PMID 41055972 · DOI · PMC12700543
- Ribot JC, Lopes N, Silva-Santos B. γδ T cells in tissue physiology and surveillance. Nat Rev Immunol. 2021. PMID 33057185 · DOI
- Nielsen MM, Witherden DA, Havran WL. γδ T cells in homeostasis and host defence of epithelial barrier tissues. Nat Rev Immunol. 2017. PMID 28920588 · DOI · PMC5771804
- Olivares-Villagómez D, Van Kaer L. Intestinal Intraepithelial Lymphocytes: Sentinels of the Mucosal Barrier. Trends Immunol. 2018. PMID 29221933 · DOI · PMC8056148
- Saura-Esteller J, de Jong M, King LA, Ensing E, Winograd B, de Gruijl TD, et al.. Gamma Delta T-Cell Based Cancer Immunotherapy: Past-Present-Future. Front Immunol. 2022. PMID 35784326 · DOI · PMC9245381
- McDonald BD, Jabri B, Bendelac A. Diverse developmental pathways of intestinal intraepithelial lymphocytes. Nat Rev Immunol. 2018. PMID 29717233 · DOI · PMC6063796
- Neurath MF. Host-microbiota interactions in inflammatory bowel disease. Nat Rev Gastroenterol Hepatol. 2020. PMID 31848474 · DOI
About this article
- Sources
- NLM Medical Subject Headings (definition, synonyms); NCBI PubMed (counts, identifiers); Europe PMC (open-access abstracts and citation counts).
- Verification
- Every reference was resolved against PubMed on 2026-10-31; title, year and DOI matched.
- Review state
- automated source verified; no human expert review has been recorded yet.
- Version
- 1, last updated 2026-10-31.
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Evidence strength
EvidenceHelix's computed view of the study designs behind this topic: how common meta-analyses, randomized trials and reviews are, how recent the literature is, and a plain-language reading. It describes the design mix of the literature. It is not a quality appraisal of any study, and it is not medical advice.