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: 3 complete abstracts (796 words), 9 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
Altered reactivity to an antigen, which can result in pathologic reactions upon subsequent exposure to that particular antigen.
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: Hypersensitivities; Allergy; Allergies; Allergic Reaction; Allergic Reactions; Reaction, Allergic; Reactions, Allergic.
Where it fits in the MeSH classification
- Broader topics
- Immune System Diseases
- Narrower topics
- Asthma-Chronic Obstructive Pulmonary Disease Overlap Syndrome; Environmental Illness; Hypersensitivity, Delayed; Hypersensitivity, Immediate; Immune Complex Diseases; Kounis Syndrome; Latex Hypersensitivity; Wissler's Syndrome
- See also
- Desensitization, Immunologic; Multiple Chemical Sensitivity; Anti-Allergic Agents
Research landscape
PubMed indexes 401,684 records tagged with the MeSH heading “Hypersensitivity” (counts retrieved 2026-10-29). 65,000 of them (16.2%) were published from 2020 onward, and the busiest period so far is through 1999 with 166,039 records.
Reviews account for 62,846 records (15.6%) and meta-analyses for 3,277. Randomized controlled trials number 15,410 (3.8%) as a share of all records on the topic.
Show the data
| Period | Records |
|---|---|
| through 1999 | 166,039 |
| 2000-2009 | 77,846 |
| 2010-2019 | 92,799 |
| 2020 onward | 65,000 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 62,846 | 15.6% |
| Meta-analyses | 3,277 | 0.8% |
| Randomized controlled trials | 15,410 | 3.8% |
Method: PubMed query "Hypersensitivity"[MeSH Terms] with publication-type and date filters, retrieved 2026-10-29.
Reading the evidence in immunology
Immune responses are studied in model organisms, in cells from donors and in patients, and the same pathway can behave differently across these settings. Mouse immune systems differ from human ones in important ways, and blood measurements may not reflect what happens in tissues. Clinical conclusions about immune-mediated disease or immunotherapy come mainly from controlled trials and long-term cohorts. Check the species and tissue studied, whether markers were linked to outcomes patients notice, and the follow-up time.
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 |
|---|---|---|---|---|
| When Disability Recognition Fails: Accommodation Refusals and Socioeconomic Challenges Among Canadians with Multiple Chemical Sensitivity | 2026 | Research article Design not recorded in structured metadata | 2 | cc by PMID 42652391 · DOI · PMC13512570 |
| Nasal Epithelial Immune Signatures Are Associated With Age-Dependent Asthma Trajectories in Early Life | 2026 | Research article Design not recorded in structured metadata | 1 | cc by PMID 42703035 · DOI · PMC13646873 |
| Update on biologic and small molecules treatments in pediatric allergic diseases | 2026 | Review article Design not recorded in structured metadata | 1 | cc by PMID 42789457 · DOI · PMC13614551 |
When Disability Recognition Fails: Accommodation Refusals and Socioeconomic Challenges Among Canadians with Multiple Chemical Sensitivity [1]
Abstract reading summary — source excerpts
- Opening excerpt
- BackgroundMultiple chemical sensitivity (MCS), a recognized disability, is a chronic, multisystem condition in which exposure to common chemical substances provokes adverse health effects and functional impairment.
- Closing excerpt
- Addressing these barriers requires clarified guidance on the duty to accommodate multiple chemical sensitivity, proactive scent-free and lowest-emission policies in workplaces and housing, and improved healthcare provider education to support accommodation documentation.
- 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 (308 words)
BackgroundMultiple chemical sensitivity (MCS), a recognized disability, is a chronic, multisystem condition in which exposure to common chemical substances provokes adverse health effects and functional impairment. Although population-level data and emerging clinical research support the pathophysiological basis of MCS, individuals living with the condition frequently encounter barriers to recognition and accommodation across employment, healthcare, and housing systems. This study examines patterns of accommodation requests, refusals, and associated socioeconomic impacts among adults living with MCS in Canada, with particular attention to how institutional recognition shapes access to supports. To our knowledge, this is the first national Canadian study to examine accommodation request outcomes across both employment and housing among adults with MCS, combining quantitative and qualitative data. A national cross-sectional survey of 119 Canadian adults living with MCS was conducted between January and February 2021. Quantitative data were analyzed descriptively to assess accommodation requests, outcomes, employment status, income, and housing stability. Qualitative responses were analyzed thematically to contextualize participants' experiences of disclosure, and accommodation outcomes. Participants were predominantly female (87%) with post-secondary education (90%). Among participants who reported being unemployed (29%), 94% attributed it primarily to MCS-related limitations. Accommodation denial was common: 85% of respondents reported requesting accommodations, and 78% of those experienced refusals. On housing conditions, 52% reported living in unsafe housing (defined as housing with the presence of mould or symptom-triggering exposures), while 17% reported being homeless (e.g., moving frequently, personal vehicle, tent). Findings should be interpreted in light of the cross-sectional design, self-reported data, and community-based recruitment, which may limit generalizability. The findings suggest that inconsistent institutional recognition of MCS can function as a barrier to accommodation, contributing to health, economic, and social inequities. Addressing these barriers requires clarified guidance on the duty to accommodate multiple chemical sensitivity, proactive scent-free and lowest-emission policies in workplaces and housing, and improved healthcare provider education to support accommodation documentation.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42652391 · DOI · PMC13512570
Nasal Epithelial Immune Signatures Are Associated With Age-Dependent Asthma Trajectories in Early Life [2]
Abstract reading summary — source excerpts
- Opening excerpt
- BackgroundPreschool wheeze is heterogeneous and only a subset of children progresses to persistent asthma.
- Closing excerpt
- gov: NCT02496468; adult arm: NCT02419274.
- 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 (218 words)
BackgroundPreschool wheeze is heterogeneous and only a subset of children progresses to persistent asthma. We hypothesized that early-life wheeze reflects divergent airway epithelial maturation trajectories associated with distinct mucosal immune programs.MethodsNasal epithelial transcriptomes from 265 children and young adults (79 healthy, 81 wheezers, 105 asthmatics; median age 10.4 [1.1-20.3] years) from the All Age Asthma Cohort (ALLIANCE) cohort were analyzed using a hypothesis-driven candidate approach based on predefined cytokine axes. Transcriptional signatures were mapped to epithelial cells by scRNA-sequencing. Asthma-outcome associations were assessed in age- and sensitization-adjusted multivariate models.ResultsThe candidate approach identified three antagonistic epithelial immune programs: an interferon-associated (E1; IDO1, CSF3, CCL20), a type-2-associated (E2; POSTN, CCL26, CST1), and a type-17-associated program (E3; IL36G, KLK7, KRTDAP). These programs were detected across basal, ciliated, and secretory epithelial cells. In early childhood (1-3 years), wheezers predominantly exhibited E1/E3-dominant epithelial profiles (n = 36). Age-group-specific comparisons showed higher E2 and lower E1/E3 expression in wheezers aged 4-6 years (n = 38) than in those aged 1-3 years (n = 36). E2 dominance correlated with IgE, FeNO, and eosinophilia (p ConclusionEarly-life wheeze reflects distinct airway epithelial immune programs characterized by age-associated patterns in epithelial immune activity. Nasal epithelial transcriptional signatures capture molecular trajectories associated with asthma persistence and may enable early risk stratification.Trial registrationAll-Age-Asthma (ALLIANCE) cohort: clinicaltrials.gov: NCT02496468; adult arm: NCT02419274.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42703035 · DOI · PMC13646873
Update on biologic and small molecules treatments in pediatric allergic diseases [3]
Abstract reading summary — source excerpts
- Opening excerpt
- Biologics have revolutionized the treatment of severe allergic diseases in children that cannot be controlled by conventional treatments.
- Closing excerpt
- The aim of this review is to discuss the most recent data in the use of biologics and small molecules in pediatric allergic diseases and to highlight the remaining gaps in knowledge.
- 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 (270 words)
Biologics have revolutionized the treatment of severe allergic diseases in children that cannot be controlled by conventional treatments. These diseases are commonly driven by dysregulation of immune response, often driven by Type 2 pathways. By targeting them, biologics have the potential for treating one or more allergic diseases. Thus, a "treat to target" strategy is now prioritized, allowing treatment of allergic diseases in a personalized approach. The pioneer anti-IgE monoclonal antibody, omalizumab, was initially indicated for the treatment of moderate to severe allergic asthma and is now indicated for chronic spontaneous urticaria (CSU), chronic rhinosinusitis with nasal polyps (CRSwNP), and food allergy (FA), highlighting the ability of biologics to target multiple allergic diseases. Other biologics have been developed in asthma and other allergic diseases, including mepolizumab (anti-IL5), benralizumab (anti-IL5 receptor), dupilumab (anti-IL-4 receptor α), and more recently tezepelumab (anti-TSLP). Clinical trials in children and/or teenagers have demonstrated their efficacy and safety, confirmed by real-life studies, in asthma, atopic dermatitis (AD), CSU, and more recently in eosinophilic esophagitis (EoE) and FA. Beyond biologics, small molecules such as Janus kinase inhibitors target other key pathways and have already been approved in AD, with ongoing clinical trials in other allergic diseases. In the pediatric specific context, these treatments raise questions, particularly regarding the choice of biologics and the goals. In the long term, the sustained efficacy, safety and impact on the natural history of allergic diseases need to be further studied. The aim of this review is to discuss the most recent data in the use of biologics and small molecules in pediatric allergic diseases and to highlight the remaining gaps in knowledge.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42789457 · DOI · PMC13614551
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 Clinical remission attainment, definitions, and correlates among patients with severe asthma treated with biologics: a systematic review and meta-analysis [4]
- Research article Inflammatory and clinical risk factors for asthma attacks (ORACLE2): a patient-level meta-analysis of control groups of 22 randomised trials [5]
- Research article Systemic Immunomodulatory Treatments for Atopic Dermatitis: Living Systematic Review and Network Meta-Analysis Update [6]
- Research article Biologic agents licensed for severe asthma: a systematic review and meta-analysis of randomised controlled trials [7]
- Research article Inhaled Reliever Therapies for Asthma: A Systematic Review and Meta-Analysis [8]
- Research article Burden of Respiratory Syncytial Virus Disease in Adults with Asthma and Chronic Obstructive Pulmonary Disease: A Systematic Literature Review [9]
References
- Diallo NA, Molot J, Bray R, Trifunovski A, Peris R. When Disability Recognition Fails: Accommodation Refusals and Socioeconomic Challenges Among Canadians with Multiple Chemical Sensitivity. . 2026. PMID 42652391 · DOI · PMC13512570
- Jakwerth CA, Illi S, Charles H, Oelsner M, Gabr AA, Zissler UM, et al.. Nasal Epithelial Immune Signatures Are Associated With Age-Dependent Asthma Trajectories in Early Life. . 2026. PMID 42703035 · DOI · PMC13646873
- den Dekker HT, Chauveau AD, Sterling B, Coopman S, Chinthrajah RS, Lejeune S, et al.. Update on biologic and small molecules treatments in pediatric allergic diseases. . 2026. PMID 42789457 · DOI · PMC13614551
- Shackleford A, Heaney LG, Redmond C, McDowell PJ, Busby J. Clinical remission attainment, definitions, and correlates among patients with severe asthma treated with biologics: a systematic review and meta-analysis. Lancet Respir Med. 2025. PMID 39549709 · DOI
- Meulmeester FL, Mailhot-Larouche S, Celis-Preciado C, Lemaire-Paquette S, Ramakrishnan S, Wechsler ME, et al.. Inflammatory and clinical risk factors for asthma attacks (ORACLE2): a patient-level meta-analysis of control groups of 22 randomised trials. Lancet Respir Med. 2025. PMID 40215991 · DOI · PMC12117016
- Drucker AM, Lam M, Prieto-Merino D, Malek R, Ellis AG, Yiu ZZN, et al.. Systemic Immunomodulatory Treatments for Atopic Dermatitis: Living Systematic Review and Network Meta-Analysis Update. JAMA Dermatol. 2024. PMID 39018058 · DOI · PMC11255974
- Kyriakopoulos C, Gogali A, Markozannes G, Kostikas K. Biologic agents licensed for severe asthma: a systematic review and meta-analysis of randomised controlled trials. Eur Respir Rev. 2024. PMID 38657997 · DOI · PMC11040390
- Rayner DG, Ferri DM, Guyatt GH, O'Byrne PM, Brignardello-Petersen R, Foroutan F, et al.. Inhaled Reliever Therapies for Asthma: A Systematic Review and Meta-Analysis. JAMA. 2025. PMID 39465893 · DOI · PMC11519786
- Penders Y, Brusselle G, Falsey AR, Rohde G, Betancur E, Guardado ME, et al.. Burden of Respiratory Syncytial Virus Disease in Adults with Asthma and Chronic Obstructive Pulmonary Disease: A Systematic Literature Review. Curr Allergy Asthma Rep. 2025. PMID 39994162 · DOI · PMC11850418
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 2026-10-29.
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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.