Peripheral Blood T-Helper Cells and Eosinophil Populations in Patients with Atopic and Nonatopic Chronic Rhinosinusitis

Development of a novel self-assessment tool following endoscopic sinus surgery in the management of chronic rhinosinusitis

OBJECTIVE

To propose a novel quality metric tool for retrospectively examining ESS performed on chronic rhinosinusitis (CRS) patients, ultimately to facilitate clinician self-assessment and optimize care provision within this population.

DESIGN

Quality improvement study.

SETTING

Multi-center.

PARTICIPANTS

Observational, prospective research database of adult patients with medically recalcitrant CRS, presenting to seven North-American academic rhinology centers, who underwent ESS between 2011 and 2021. Participant characteristics, comorbidities, and preoperative study measures were collected.

MAIN OUTCOMES AND MEASURES

A simple ratio of preoperative Lund-Mackay (LM) score to the number of sinus regions operated on during the course of ESS was determined for each participant and dichotomized into ratios of >1.0 or <1.0.

RESULTS

828 study participants with medically recalcitrant CRS met final study inclusion, of which 47.8 % were male with an average age of 49.0 years. Approximately 50.9 % of participants had a history of previous ESS. Overall mean ratio between preoperative LM scores and numbers of surgically addressed sinuses for all patients with CRS (n = 828) was 1.61 (range: 0.00-6.00), with a minority of subjects (n = 108; 13.0 %) found to have ratios below 1.00. Mean ratios between patients who underwent primary ESS versus revision ESS were not statistically different (2.00 [±0.83] vs 1.98 [±0.88]; 0.02 %, 95 % CI -0.10, 0.14; P = 0.76), whereas differences in mean ratios between CRSsNP patients (without nasal polyposis) and CRSwNP patients (with nasal polyposis) were statistically significant (1.78 [±0.93] vs 2.26 [±0.67]; 0.48 %, 95 % CI 0.37, 0.59; P ≤ 0.001).

CONCLUSIONS AND RELEVANCE

This quality metric ratio represents a simple operational means for clinicians to integrate qualitative methodology into self-reflection when evaluating the extent of ESS performed on CRS patients. Its use as a clinical tool for retrospective self-reflection enables the surgeon to identify areas for improvement, assess situational specifics, and hone their craft.

Iron metabolism and peripheral eosinophil count do not correlate in the general population

Iron is a primary component of the human body and exerts many functions, mainly concerning red cells and the immune system. In addition, there is evidence that iron-deficiency anemia is associated with allergic diseases. Type 2 inflammation characterizes allergic diseases. Peripheral eosinophils are a reliable biomarker for type 2 inflammation. Therefore, the present study investigated the possible relationship between iron metabolism and peripheral eosinophils in a large population. Eosinophils also play important roles in immune and tissue homeostasis. A growing body of data suggests tissue eosinophils represent a plastic and heterogeneous population of functional sub-phenotypes, shaped by environmental (systemic and local) factors. The retrospective study included 2795 subjects who were afferent to the Clinical Chemistry Analysis Laboratory during the year 2022. Men had higher peripheral eosinophil count than women (p<0.001). Furthermore, stratifications for sex, eosinophil, and hemoglobin cut-offs showed that men had more eosinophil counts than women. However, there was no correlation between iron biomarkers and peripheral eosinophils. The present study did not demonstrate a clear relationship between iron deficiency and peripheral eosinophil count. Even if this large population may include allergic subjects and patients with different diseases, it seems that iron does not directly affect eosinophil count.

Blood eosinophil count in the diagnosis of allergic-like rhinitis with chronic rhinosinusitis

BACKGROUND

Allergic rhinitis (AR) and nonallergic rhinitis (NAR) often are comorbid with chronic rhinosinusitis (CRS). Finding a convenient test that distinguishes these complex conditions is helpful for effective treatment. We aimed to analyse blood parameter differences between AR and NAR patients with/without CRS.

METHODS

Eight hundred thirteen patients, including AR and NAR with different conditions [CRS with nasal polyps (CRSwNP) and CRS without nasal polyps (CRSsNP)] were analysed in this retrospective study. Patients with a nasal deviation alone were included as healthy controls (HC). Receiver operating characteristic analysis was used to assess the value of blood parameters for diagnosing AR or NAR with/without CRS.

RESULTS

Compared to nonallergic-like rhinitis (HC, CRSwNP and CRSsNP), the blood eosinophil count was significantly increased in the allergic-like rhinitis groups, except for NAR-CRSsNP (AR, AR-CRSwNP, AR-CRSsNP, NAR and NAR-CRSwNP). The NAR-CRSsNP group had a higher level of eosinophils than the HC and CRSsNP groups. Among allergic-like rhinitis patients, eosinophils were higher in allergic-like rhinitis patients with CRSwNP (AR-CRSwNP and NAR-CRSwNP) than in allergic-like rhinitis patients without CRSwNP (AR, AR-CRSsNP, NAR and NAR-CRSsNP). However, no difference in blood eosinophils was observed between AR and NAR. There was also no difference among nonallergic-like rhinitis patients. Similar findings were found for the blood eosinophil proportion. Furthermore, the blood eosinophil count was a good predictor of allergic-like rhinitis, especially allergic-like rhinitis with CRSwNP.

CONCLUSION

The blood eosinophil count and proportion may be good diagnostic predictors of allergic-like rhinitis but cannot differentiate between AR and NAR. This indicator may be much better in predicting allergic-like rhinitis with CRSwNP.

International consensus statement on allergy and rhinology: rhinosinusitis 2021

I.

EXECUTIVE SUMMARY

BACKGROUND: The 5 years since the publication of the first International Consensus Statement on Allergy and Rhinology: Rhinosinusitis (ICAR-RS) has witnessed foundational progress in our understanding and treatment of rhinologic disease. These advances are reflected within the more than 40 new topics covered within the ICAR-RS-2021 as well as updates to the original 140 topics. This executive summary consolidates the evidence-based findings of the document.

METHODS

ICAR-RS presents over 180 topics in the forms of evidence-based reviews with recommendations (EBRRs), evidence-based reviews, and literature reviews. The highest grade structured recommendations of the EBRR sections are summarized in this executive summary.

RESULTS

ICAR-RS-2021 covers 22 topics regarding the medical management of RS, which are grade A/B and are presented in the executive summary. Additionally, 4 topics regarding the surgical management of RS are grade A/B and are presented in the executive summary. Finally, a comprehensive evidence-based management algorithm is provided.

CONCLUSION

This ICAR-RS-2021 executive summary provides a compilation of the evidence-based recommendations for medical and surgical treatment of the most common forms of RS.

The role of preoperative blood eosinophil counts in distinguishing chronic rhinosinusitis with nasal polyps phenotypes

BACKGROUND

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a common heterogenous disease in the patients with chronic airway diseases. This study investigated the role of blood eosinophil count (BEC) in the classification of CRSwNP and its recurrence in eosinophilic CRSwNP.

METHODS

Sixty-five patients who underwent nasal endoscopic resection of CRSwNP were recruited and divided into eosinophilic CRSwNP and non-eosinophilic CRSwNP groups based on the levels (10% cutoff) of eosinophil infiltration as indicated by hematoxylin and eosin (H&E) staining.

RESULTS

We recruited 30 patients in the eosinophilic CRSwNP group and 35 patients in the non-eosinophilic CRSwNP group. The outcome of preoperative visual analogue scale (VAS) score, preoperative Lund-Mackay score, and preoperative Lund-Kennedy score between the 2 groups were comparable. The level of BEC in the eosinophilic CRSwNP group was significantly higher than that of non-eosinophilic CRSwNP group (0.79 ± 0.27 × 10⁹ /L vs 0.30 ± 0.22 × 10⁹ /L; p < 0.001). We observed a statistical significance in the number of H&E eosinophils (29.11 ± 2.93 vs 3.17 ± 0.51; p < 0.001) and CRSwNP phenotypes (eosinophilic/non-eosinophilic, 28/3 vs 2/32; p < 0.001) when the cutoff value of BEC was set at 0.39 × 10⁹ /L. The disease-free recurrence (DFR) was found to be statistically significant when the cutoff value of BEC was 0.73 × 10⁹ /L in eosinophilic CRSwNP (p = 0.009).

CONCLUSION

Results indicate that BEC may be capable of distinguishing CRSwNP phenotypes as well as predicting polyp recurrence in eosinophilic CRSwNP. Given the relatively small sample size, further studies will be necessary to confirm a role for BEC as a systemic biomarker in CRSwNP.

Updates on current evidence for biologics in chronic rhinosinusitis

PURPOSE OF REVIEW

The purpose of this review is to present the most important recent developments concerning biologics as a therapeutic option for chronic rhinosinusitis (CRS).

RECENT FINDINGS

mAb anti-IL-4 receptor α (Dupilumab) was recently approved by Food and Drug Administration (FDA) for patients with CRSwNP and four other biologics are under investigation, with promising preliminary results.

SUMMARY

CRS is a disease associated with a significant symptom burden and high-indirect costs. Despite recent advances in combined approaches, persistent symptoms or recurrences are not uncommon. Monoclonal antibodies, used mainly to treat asthma, have recently been shown to have a positive impact on controlling the symptoms of CRS and reducing the need for endoscopic sinus surgery. Dupilumab, mepolizumab, reslizumab, benralizumab and omalizumab are discussed and their mechanism of action, risk and current evidence on efficacy are presented. Preliminary studies show encouraging results with relatively few side effects. Once the high cost of such therapies is addressed, they could prove an important adjuvant therapy for patients with CRS. Large-scale clinical trials designed to evaluate them are called for.

Nasal cytology with emphasis on mast cells can improve the diagnosis and treatment of chronic rhinosinusitis

Objective:

Chronic rhinosinusitis (CRS) involves inflammation of the nasal and para-nasal mucosa. Due to its heterogeneous nature, unknown pathogenesis, and high recurrence rate, effective treatment is difficult. Nasal cytology is presently not a part of the routine diagnosis or treatment decision for CRS.

Data sources:

A literature search was performed for published papers in English between January 1990 and June 2019 using MEDLINE.

Study selection:

Terms used were chronic rhinosinusitis, eosinophils, etiology, immunopathology, inflammation, mast cells, nasal cytology, polyps, and treatment. Both reviews and original articles were collected and studied.

Results:

There is no standard nasal fluid, mucus sampling, or staining techniques for identifying inflammatory cell types. Results were divergent from different countries. Moreover, the main focus of these papers on the cells in nasal washings was eosinophils, with infrequent mentioning of other cell types that may imply different etiology and pathology. The heterogeneous cell profile of CRS and the role of mast cells have been unappreciated due to the lack of specific immunohistochemical technique or study of its unique mediators.

Conclusions:

Nasal cytology could help distinguish the type and the activation state of inflammatory cells. Thus it can help in providing a clearer picture of CRS pathogenesis, identifying different patient groups, and developing effective treatments.

Dynamic Change of T-Helper Cell Cytokines in Nasal Secretions and Serum after Endoscopic Sinus Surgery in Chronic Rhinosinusitis with Nasal Polyps

BACKGROUND/AIMS

This study aimed to determine the dynamic change of postoperative T-helper cell cytokines in nasal secretions and serum in chronic rhinosinusitis with nasal polyps (CRSwNP).

METHODS

Nasal secretions and serum samples of 30 CRSwNP patients and 10 healthy subjects were collected. Among CRSwNP patients, samples of 30 patients were collected 1 day before endoscopic sinus surgery (ESS) and that of 18 patients (12 asthmatic and 6 non-asthmatic) were collected 4, 8, and 12 weeks after ESS. Concentrations of interleukin (IL)-2, IL-4, IL-5, IL-17, and interferon gamma (IFN-γ) were determined by Cytometric Beads Array. The Sino-Nasal Outcomes Test 22 and Lund-Kennedy endoscopic scoring (LKES) system were collected for all patients.

RESULTS

The levels of IL-2 and IL-5 in secretions of CRSwNP were significantly higher than that of healthy control at the baseline. At the 4th and 8th week after ESS, the IL-4 levels in nasal secretions of the asthmatic group were significantly higher than their baseline controls (preoperatively). From the 4th to 12th week after ESS, the IL-2, IFN-γ, IL-4, and IL-17 levels in nasal secretions of the non-asthmatic group were significantly increased as compared to their baseline controls. Postoperative IL-5 levels in serum of the asthmatic group decreased significantly as compared to their baseline controls. There was no significant association between LKES and levels of cytokines in postoperative secretions and serum.

CONCLUSIONS

Our results indicate that postoperative endoscopic findings may not directly reflect the underlying mucosal inflammation, and surgery could not change the systemic immunity status. Despite endoscopic resolution of mucosal abnormalities, it may not avert the need for subsequent postoperative medical intervention to treat the underlying mucosal inflammation.

Endotype-driven care pathways in patients with chronic rhinosinusitis

Chronic rhinosinusitis (CRS) has been differentiated clinically into CRS without nasal polyps and CRS with nasal polyps, with both forms subjected to glucocorticosteroid and antibiotic treatments and, if not successful, to nasal and sinus surgery tailored to endoscopic and computed tomographic scan findings. The elaboration of endotypes based on pathomechanisms involving different immune responses offers new possibilities in terms of prediction of prognosis and risks and sophisticated guidance in personalized pharmacotherapy, surgical approaches, and innovative treatment approaches in the CRS field with various biologics. Surgical approaches can vary from classical functional endoscopic sinus surgery to extended and "reboot" approaches, with the idea to completely remove the dysfunctional and inflamed mucosa and replace it with a newly grown healthy mucosa. Biologics in this field are targeting the type 2 cytokines IL-4, IL-5, and IL-13, as well as IgE. Phase I and II study results are promising, and phase III studies are currently being performed. The development of endotype-driven integrated care pathways appreciating these innovations are now needed for the management of CRS.

Non-Eosinophilic Chronic Rhinosinusitis With Nasal Polyps: Eosinophil, Basophil, and Neutrophil Blood Counts Before and After Surgery

OBJECTIVES

Research selectively investigating non-eosinophilic chronic rhinosinusitis with nasal polyps (CRSwNP) is lacking. The inflammatory patterns seen in non-eosinophilic CRSwNP are still poorly understood. The present study is the first to compare blood eosinophil, basophil, and neutrophil counts before/after surgery in patients with non-eosinophilic CRSwNP stratified by their clinical features.

METHODS

The study concerned 107 consecutive patients with histologically confirmed non-eosinophilic CRSwNP who underwent endoscopic sinus surgery (ESS).

RESULTS

Statistical analysis ruled out any significant change in mean blood eosinophil, basophil, and neutrophil counts after ESS. A significant positive correlation emerged between blood eosinophil and basophil counts in both pre- and post-ESS laboratory tests. In the subcohort of allergic patients, a significant negative correlation was found after ESS between eosinophil and neutrophil levels and between basophil and neutrophil levels.

CONCLUSIONS

In eosinophilic CRSwNP, ESS can clear polyps, remove inflammatory tissue, and reduce the inflammatory cytokines it generates, with a consequent reduction in blood eosinophil levels. The different results in non-eosinophilic CRSwNP support the conviction that the 2 types of CRSwNP are entities with distinct inflammatory response patterns.

Recent advances in understanding chronic rhinosinusitis endotypes

Chronic rhinosinusitis (CRS) is a heterogeneous inflammatory disease with an as-yet-undefined etiology. The management of CRS has historically been phenotypically driven, and the presence or absence of nasal polyps has frequently guided diagnosis, prognosis, and treatment algorithms. Research over the last decade has begun to question the role of this distinction in disease management, and renewed attention has been placed on molecular and cellular endotyping and a more personalized approach to care. Current research exploring immunologic mechanisms, inflammatory endotypes, and molecular biomarkers has the potential to more effectively delineate distinct and clinically relevant subgroups of CRS. The focus of this review will be to discuss and summarize the endotypic characterization of CRS and the potential diagnostic and therapeutic implications of this approach to disease management.

Systemic Predictors of Eosinophilic Chronic Rhinosinusitis

Background Eosinophilic chronic rhinosinusitis (eCRS) is linked with skewed T-helper 2 or immunoglobulin E (IgE)-mediated allergic responses, with differing diagnosis, prognosis, and management to non-eCRS. Objective The association between biomarkers and eCRS was investigated to assess the predictors of eCRS. Methods A cross-sectional study of adult patients with chronic rhinosinusitis (CRS) undergoing endoscopic sinus surgery was conducted. eCRS was defined by histopathological assessment showing >10 eosinophils/high-power field on sinus mucosal biopsy. Blood tests were performed preoperatively and assessed for a full blood count including eosinophils and a white cell count (WCC) as well as biochemical markers of inflammation and atopy including Immunoglobulin E (IgE), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and ImmunoCAP testing for serum-specific IgE. Comparisons between eCRS and non-eCRS patients were performed. Results 345 patients (48.1% female, age 48.72 ± 15.06 years) were recruited, with 206 (59.7%) identified as eCRS, 41% with asthma and 47% CRS with nasal polyps. eCRS patients were more likely to have asthma ( P < .01) and nasal polyps ( P < .01). Blood eosinophils were significantly elevated in eCRS (0.42±0.34 vs 0.17±0.13 × 10⁹/L, P < .01) as were eosinophils as a ratio of WCC (6.21 ± 4.48 vs 2.55 ± 1.84, P < .01). ESR was decreased when compared with non-eCRS (8.1±7.87 vs 10.65±11.91, P = .03). Receiver operating characteristic curve analysis predicted high tissue eosinophilia at blood eosinophil levels above 0.24 × 10⁹/L (sensitivity 70.9%, specificity 78.4%, area under the curve [AUC]: 0.792, P < .01). eCRS was predicted at eosinophil above 4.27% of total WCC (sensitivity 64.1%, specificity 88.5%, AUC 0.797; P < .01; positive predictive value 89.2%, negative predictive value 62.4%, positive likelihood ratio 5.57, and diagnostic odds ratio 13.71). There was no significant association among WCC, CRP, IgE, or ImmunoCAP testing. Conclusion eCRS is associated with elevated blood eosinophils (>0.24 × 10⁹/L), eosinophil ratio (>4.27% of total WCC), and lower ESR when compared with non-eCRS.

Clinical Predictors of Frontal Ostium Restenosis After Draf 3 Procedure for Refractory Chronic Rhinosinusitis

Background The Draf 3 procedure has been demonstrated to be effective in the treatment of refractory frontal sinus disease. A variety of clinical factors may contribute to the change of frontal neo-ostium (FNO) area after this procedure. Imaging plays a vital role in the evaluation and follow-up after surgery and provides useful prognostic information. Objectives (1) To investigate the influence of local anatomic factors on FNO after a Draf 3 procedure by radiological measurements on imaging software and (2) to explore other predictive factors of FNO restenosis. Methods Twenty-four patients with chronic rhinosinusitis who underwent a Draf 3 procedure and were followed up for more than 12 months (2012-2014) were enrolled in this study. Data on patient demographics, medical history, and computed tomography scans were collected. Anatomic dimensions were measured with OsiriX® (Pixmeo, Geneva, Switzerland). Stenotic ostium was defined as a loss of more than 50% of the original intraoperative area. Multivariate linear regression was used to assess independent factors linked to frontal neo-osteogenesis 1 year after the surgery. A receiver operating characteristic curve was built for the cutoff value of preoperative dimension to predict restenosis of FNO area. Results A significant association was demonstrated between the minimum anteroposterior diameter (FOAP_MIN) of the frontal ostium preoperatively and FNO area 1 year postoperatively. Multivariate linear regression showed that FOAP_MIN of the frontal ostium preoperatively and the percentage of serum eosinophils (EOSs) correlated with the contour area of the FNO 1 year postoperatively. FOAP_MIN ≤ 3.592 mm yielded a sensitivity of 95% and a specificity of 75% for the diagnosis of FNO restenosis. Conclusions Both FOAP_MIN and EOS are independent predictors of the contour area of the FNO 1 year postoperatively. Patients with a higher risk of developing frontal ostium restenosis can be identified preoperatively by measurements of the frontal sinus anatomic dimensions.

Blood Eosinophil and Basophil Values Before and After Surgery for Eosinophilic-type Sinonasal Polyps

Background Blood eosinophil and basophil levels have recently been considered for the purpose of endotyping chronic rhinosinusitis with nasal polyps (CRSwNP). Histologically, eosinophilic-type CRSwNPs have been associated with high recurrence rates after treatment. Objective The present study was the first to compare blood eosinophil and basophil counts in eosinophilic-type CRSwNP patients before and after endoscopic sinus surgery. Methods The study concerned 79 consecutive patients with histologically confirmed eosinophilic-type CRSwNP treated with endoscopic sinus surgery. Results A significant drop in mean blood eosinophil counts and percentages occurred from before to after endoscopic sinus surgery in the cohort as a whole. Mean blood eosinophil counts and percentages were also reduced after surgery in the subcohorts of CRSwNP patients with (i) asthma, (ii) aspirin-exacerbated respiratory disease (AERD), and (iii) no allergy. Although blood eosinophil and basophil counts correlated directly before and after surgery, a statistical reduction in blood basophil counts and percentages after surgery emerged only in the subcohort of nonallergic CRSwNP patients. Conclusion Endoscopic sinus surgery can clear polyps, remove inflammatory tissue, and reduce inflammatory cytokine levels. Consistently with the biological mechanism described, endoscopic sinus surgery could coincide with a reduction in blood eosinophils in eosinophilic-type CRSwNP.

Diagnostic Accuracy of Symptoms, Endoscopy, and Imaging Signs of Chronic Rhinosinusitis Without Nasal Polyps Compared to Allergic Rhinitis

Objectives The diagnosis of chronic rhinosinusitis without nasal polyps (CRSsNP) and distinguishing it from allergic rhinitis is difficult. Yet, early detection of CRSsNP is important to prevent progressive and severe chronic rhinosinusitis. Our aim was to compare diagnostic accuracy of symptoms, endoscopy, and imaging signs of CRSsNP and allergic rhinitis -only phenotypes. Setting Prospective controlled follow-up study. Participants Forty-two nonsmoking patients visiting tertiary care due to CRSsNP and 19 nonsmoking volunteer controls with allergic rhinitis filled a symptoms questionnaire and underwent nasal endoscopy off-seasonally. All CRSsNP patients underwent computed tomography scans of paranasal sinuses. All the allergic rhinitis control subjects and 14 of the CRSsNP patients underwent sinus magnetic resonance imaging. Results Radiologic Lund-Mackay score, duration of symptoms, visual analogue scale scores of symptoms, and Sinonasal Outcome Test 22 were significantly higher in the CRSsNP group compared to allergic rhinitis control group. These factors also correlated in part with each other. Endoscopic score did not correlate with other factors, nor did it differ between CRSsNP and allergic rhinitis groups. The highest area under curve value was demonstrated for visual analogue scale score of facial pain/pressure (0.93) and score ≥4/10 showed 60% sensitivity and 95% specificity for detecting CRSsNP group ( P < .001). Radiologic sign of obstructed osteomeatal complex showed 100% specificity and 38% sensitivity for detecting CRSsNP group ( P < .001). Conclusions CRSsNP phenotype could be primarily distinguished from allergic rhinitis by higher facial pain/pressure score and secondarily by radiologic sings of obstructed ostiomeatal complex and higher Lund-Mackay score. Endoscopic score has limited value in distinguishing CRSsNP from allergic rhinitis.

Characterization of T-cell subpopulations in patients with chronic rhinosinusitis with nasal polyposis

Background:

There is an ongoing discussion concerning the potential origins of chronic rhinosinusitis with nasal polyposis (CRSwNP).

Objective:

The aim of this study was to quantify subpopulations of T cells in peripheral blood and nasal polyps in CRSwNP to examine their influence on the etiology of this disease.

Methods:

Tissue and blood samples were collected from 11 patients who underwent nasal sinus surgery, and these samples were analyzed by multicolor flow cytometry.

Results:

There was a significantly lower frequency of CD4⁺ T-helper (Th) cells and a significantly higher frequency of CD8⁺ T cells among lymphocytes isolated from nasal polyps compared with peripheral blood mononuclear cells (PBMC). In both T-cell subpopulations, a shift mainly from naive T cells among peripheral blood lymphocytes toward an effector memory and terminally differentiated subtype predominance in nasal polyps was observed. Among CD4⁺ T cells, the frequencies of cluster of differentiation (CD) 45RA- Forkhead-Box-Protein P3high (FoxP3^high) cytotoxic T-lymphocyte-associated Protein 4high (CTLA-4^high) activated regulatory T (T_reg) cells, and CD45RA- Forkhead-Box-Protein P3low (FoxP3^low) memory T cells were significantly increased in nasal polyps compared with PBMC.

Conclusion:

In this study, we presented a detailed characterization of CD4⁺ and CD8⁺ T-cell subpopulations in patients with CRSwNP. CD8⁺ T cells were more prominent in nasal polyps than in CD4⁺ T cells. Both nasal CD8⁺ T cells and CD4⁺ T cells predominantly had an effector memory phenotype. Among CD4⁺ T cells, activated T_reg cells were increased in nasal polyps compared with PBMC. The data point toward a local regulation of T-cell composition within the microenvironment of nasal polyps, which might be further exploited in the future to develop novel immunotherapeutic strategies.