Non-pollen Season Research Articles

Impact of pollen season and viral disease COVID-19 on respiratory function of the adult population in Eastern Slovakia: analysis of spirometric data and results of a questionnaire survey

Introduction Asthma is a chronic heterogeneous disease with characteristic symptoms, but with proper treatment the patient can lead a full life. In patients with allergic asthma, symptoms appear after irritation with an allergen, most often in the pollen season. In 2019, the viral disease COVID-19 appeared, which, especially in people with asthma, led not only to an asthma attack, but also to other serious diseases. Methods The main aim was to investigate differences in patients’ health status by comparing spirometric values in and out of pollen season (A), spirometric values before and after COVID-19 viral illness (B) and an anonymous questionnaire (C). Spirometric values were recorded in each patient (control group - patients diagnosed with asthma, research group - patients after overcoming COVID-19 disease) in 3 cycles, namely (in the pollen period, in the non-pollen period and after overcoming COVID-19 disease - at an interval of 2 months after a negative PCR test). Results We observed significant results during the individual spirometry performed (A) during the pollen season and non-pollen season. We observed the same in patients after they received COVID-19 treatment (B). Patients were also asked questions regarding family history, symptoms and their variability, worsening of the condition or correct inhalation technique (C). Conclusion Our research shows that the PEF parameter is most affected by the pollen and non-pollen season in asthmatic patients. Significant differences in PEF parameter were observed between genders, where we observed highly significant statistical significance of PEF parameter in pollen and non-pollen season in females.

The effects of meteorological conditions on allergenic airborne pollen in arid Northwest China

Understanding the variations in temporal allergenic airborne pollen (AAP) distribution and the mechanisms of pollen release and dispersal during pollen season is fundamental for predicting respiratory allergies, as well as assessing the effects of meteorological conditions on vegetation. In this paper, we described the seasonal variations of in situ AAP for dominant taxa in samples obtained from 11 May 2019 to 31 March 2022, with uninterrupted quasi-monthly sampling time intervals (22–48 days). We also discussed how meteorological factors drive pollen variations in an arid region of Northwest China through correlation analysis and the HYSPLIT model. Results showed: (1) The three most prevalent AAP taxa were Artemisia (65.1% by average), Amaranthaceae (13.5% by average), and Poaceae (6.5% by average), with a high cumulative pollen concentration (CPC) value during July–September period. (2) The duration and total CPC in pollen season were shorter and lower in 2020 than that in 2019 and 2021, which were attributed to the lower precipitation and higher temperature from July to September 2020. In contrast, the wind was the dominant factor influencing each sample's CPC in the non-pollen season. (3) Both the predominant potential source area (PSA) and short transport pathways suggested AAP mainly comes from the local and regional areas. (4) There would be a serious risk of allergy to the three AAP types, especially Artemisia. Our results reveal that precipitation and temperature during July–September have an immediate effect on the characteristics of the AAP pollen season in arid regions.

Developing nomograms for identifying allergic rhinitis among chronic rhinitis: A real-world study

BackgroundIt is difficult to discriminate allergic rhinitis (AR) and nonallergic rhinitis (NAR) in clinical practice due to the similar clinical manifestations. The study was to assess both the demographical and clinical features of AR and NAR in the real-world data of outpatients in China. MethodsIt was a cross-sectional real-world study. AR and NAR were defined based on both subjective symptoms and objective specific serum IgE test. General demographic characteristics as well as clinical information were documented. Patients were further classified according the seasons of initial visiting hospital (during pollen seasons or not). A scoring system presented as nomograms for presence of AR was performed. ResultsIn the pollen season group, age distribution, the duration of rhinitis, comorbidity of asthma, food allergies, and score of coughing were found significantly associated with AR. Additionally, in the non-pollen season group, we found that ethnicity, age distributions, duration of rhinitis, comorbidity of asthma, food allergies, and family history of allergy, together with scores of gritty eyes were associated factors of AR. Based on multivariate logistic model, we built two nomograms which included previously identified significant risk factors that could be acquired easily during clinical practice with predictive variables to assess their roles in predicting the risk of AR among outpatients with rhinitis. ConclusionsThe characteristics of patients with different phenotypes of chronic rhinitis are distinctive in different seasons and the developed nomogram in this study might be beneficial for clinical practice.

Dynamic changes in peripheral type II innate lymphoid cell (ILC2) subpopulation and its clinical significance in children with hay fever during the pollen season

Objective To analyze the dynamic changes in the expression and function of peripheral type Ⅱ innate lymphoid cell (ILC2) subpopulation and the activity of signal transducers and activators of transcription (STAT6) in children with hay fever during pollen season. Methods A total of 10 patients with hay fever, 10 patients with house dust mite (HDM)-sensitized asthma and 12 healthy controls (HC) were enrolled in this study. Changes in peripheral ILC2 and the intracellular expression of Th2-related cytokines were detected by flow cytometry during and outside the pollen season. Peripheral Lin- cell population was isolated from each group and cultured with the presence of IL-25 or IL-33 for 7 d. The concentrations of IL-5 and IL-13 in culture supernatants were measured by ELISA. Expression of phospho-STAT6 at protein level was quantified by Western blot. Results Within the pollen season, the percentage of peripheral ILC2 cells was significantly higher in children with hay fever [(23.09±7.86)%] than in children with HDM-sensitized asthma [(6.84±3.85)%, P<0.05] and healthy children[(1.69±0.87)%, P<0.05]. In the non-pollen season, the peripheral ILC2 cells in children with hay fever presented a decreasing trend [(11.30±2.45)%], but was still higher than that in HDM-sensitized asthmatics [(3.76±1.96)%, P<0.05] and HC [(1.32±0.91)%, P<0.05] at the same time point. Moreover, peripheral IL-13+ ILC2 cells in children with hay fever [(6.94±3.16)% vs(4.17±1.98)%, P<0.05] and in HDM-sensitized asthmatics [(1.89±0.70)% vs(1.44±0.55)%, P<0.05] during the pollen season were significantly higher than those in the non-pollen season. After the in vitro stimulation with IL25 or IL-33, the levels of IL-5 and IL-13 in culture supernatants were both increased in children with hay fever and HDM-sensitized asthmatics, and a synergistic action was observed when IL25 and IL-33 were used in combination. Meanwhile, the protein level of phospho-STAT4 in Lin- cells was significantly up-regulated in the hay fever group after stimulation with IL25 and IL-33. Conclusions During the pollen season, the abnormal number and function of ILC2 subpopulation in children with hay fever might be another cause of the occurrence of clinical symptoms in a short period of time or acute exacerbation. Key words: Hay fever; House dust mite; Artemisia; Signal transducer and activator of transcription 6; Type Ⅱ innate lymphocyte cells

Occurrence of pollen season at the end of the first trimester predicts clinical atopic diseases in the offspring: A Finnish population-based study.

To evaluate the association between potential exposure to different pollen concentrations at the 11th fetal week and subsequent clinical atopic diseases. Parents of 1- to 4-year-old children (N=3035) returned a questionnaire regarding physician-diagnosed atopic diseases. The children were born between 2001 and 2005 in the province of South Karelia, Finland. Results of allergy tests were collected from patient records in the area. The prevalence of atopic diseases with sensitisation was higher in children whose 11th fetal week occurred during pollen rather than non-pollen season: atopic eczema 6.3% vs. 4.3% (adjusted odds ratio, aOR 1.58, 95% CI 1.10─2.28), food allergy 5.7% vs. 3.9% (1.63; 1.12─2.38), respiratory allergy or asthma 3.7% vs. 2.2% (2.03; 1.24─3.33) and any atopic diseases 7.4% vs. 5.5% (1.48; 1.07─2.05), respectively. Respectively, the prevalence was higher in the children exposed to high rather than low tree pollen concentrations (>1000 vs. <10 particles/m3) at the 11th fetal week: 12.1% vs. 4.4% (3.35; 1.89─5.95), 12.1% vs. 3.9% (3.77; 2.11─6.72), 4.7% vs. 2.5% (2.95; 1.21─7.20) and 14.0% vs. 5.7% (3.15; 1.86─5.35). Coincidence of potential exposure to high tree pollen concentrations at the 11th fetal week is associated with subsequent clinical atopic diseases with sensitisation.

The Pattern of Sensitization Influences Exhaled and Nasal Nitric Oxide Levels in Young Adults.

Nitric oxide (NO) from upper (nasal NO, nNO) or lower airways (fractional exhaled NO, FeNO) is considered a surrogate marker for Th2-type inflammation, which is influenced by atopy. The aim of this study was to analyze nNO and FeNO in regard to qualitative and quantitative aspects of sensitization. We evaluated 244 non-smoking young adults. All of them were first-year students recruited for a longitudinal study. An inhalation allergy screening tool was used for atopy definition (specific immunoglobulin E (sIgE) to sx1≥0.35 kU/L), and also sIgE response to three inhalant perennial allergens, house dust mite (HDM, d1), cat (e1), and dog (e5), was determined in the non-pollen season. With respect to sx1, 100 subjects could be classified as atopic. Sensitization to one, two, or three perennial allergens could be demonstrated in 46, 10, and 16 students, respectively. The subjects with positive IgE response to sx1, but not sensitized to HDM, cat, and/or dog, had FeNO levels comparable to those of non-atopic subjects (13.5 vs. 13.0ppb, respectively; p=0.485). These levels were significantly lower compared to atopic subjects being sensitized to any perennial allergen (19.0ppb; p=0.0003). After grouping the atopic subjects for perennial sensitization patterns, significantly higher FeNO could be detected in subjects with poly-sensitization (n=26; 26.0ppb) compared to the mono-sensitized ones (n=46; 18.0ppb; p=0.023). Regarding nNO, no differences could be observed. Applying a two-way ANOVA, we could reveal a significant correlation of specific HDM-IgE CAP-class with FeNO (p<0.0001) and nNO levels (p=0.007). Finally, a significant relationship was found between nNO and FeNO for the whole cohort (p<0.0001). In summary, our findings support the argument that atopy and perennial sensitization should be considered for the interpretation of NO.

Application of a stable carbon isotope for identifying Broussonetia papyrifera pollen.

The objective of this study was to investigate whether δ13C values can be used to identify pollen specie in the atmosphere. A Burkard 7-day recording volumetric spore trap was used to collected pollens in the atmosphere in Tainan City, Taiwan, from January 2 to December 28, 2006, and a light microscope was used to identify the pollen species and concentrations. A Burkard cyclone sampler was used to collect particulate matter and an elemental analyzer with an isotope ratio mass spectrometer was used to analyze the δ13C values. Our data showed that the predominate pollen specie in the atmosphere was Broussonetia papyrifera pollen and that the annual average concentration was 27 grains/m3 (pollen season, 36; nonpollen season, 9 grains/m3). The average δ13C value was - 26.19‰ for particulate matter in the atmosphere (pollen season, - 26.00‰; nonpollen season, - 26.28‰). No significant association was observed between δ13C values and Broussonetia papyrifera pollen concentrations. However, the δ13C value in the atmosphere was associated with the levels of Broussonetia papyrifera pollen among the samples with a diameter of particulate matter smaller than 10μm at a level lower than 40μg/m3. In addition, the relative contribution of Broussonetia papyrifera pollen to the carbon in the atmosphere using a two end-member mixing models was found to be associated with the Broussonetia papyrifera pollen concentration. In summary, our study suggested that δ13C values can be applied in the assessment of Broussonetia papyrifera pollen specie under specific conditions in the atmosphere.

Dynamic changes in Th17/Treg balance among children with seasonal allergic rhinitis

Objective To investigate the levels and significance of Th17 cells and regulatory T cells (Treg) in peripheral blood of children with allergic rhinitis during pollen and non-pollen seasons. Methods Thirteen children with hay fever, 10 children with house dust mite(HDM)-allergic asthma and 10 healthy children were recruited into this study. Percentages of Th17 and Treg cells were detected by flow cytometry. Levels of IL-17, IL-10 and TGF-β in cell culture supernatants were measured by ELISA. Results (1) The percentages of Th17 cells in children with allergic rhinitis [(3.4±2.4)%] were significantly higher than those in HDM-allergic asthmatics [(2.1±1.6)%] and those in healthy children [(0.5±0.3)%] during pollen season (both P<0.05). The levels of Treg cells in allergic rhinitis group [(2.1±1.3)%] and in HDM-allergic asthma group [(3.6±1.9)%] were significantly lower than those in healthy control group [(5.5±2.8)%] (both P<0.05). The levels of Th17 cells [(3.0±1.9)% vs (3.4±2.4)%, P<0.05] and ratios of Th17/Treg cells [(1.4±1.0)% vs (1.7±1.5)%, P<0.05] in children with allergic rhinitis were significantly decreased during non-pollen season as compared with those during pollen season, but the levels of Treg cells were up-regulated [(2.4±1.6)% vs (2.1±1.3)%, P<0.05]. (2) Correlation analysis revealed that the ratios of Th17/Treg cells were positively correlated with the concentrations of FeNO (fractional concentration of exhaled NO) (r=0.321, P<0.05) and the counts of circulating eosinophils (r=0.198, P<0.05) in children with allergic rhinitis during pollen season. Conclusion The imbalanced Th17 and Treg cells in children with allergic rhinitis during pollen season might play a vital role in the regulation of allergic airway inflammation. Key words: Allergic rhinitis; Bronchial asthma; Pollen; House dust mite; Th17 cell; Regulatory T cell

“Allergic mood” – Depressive and anxiety symptoms in patients with seasonal allergic rhinitis (SAR) and their association to inflammatory, endocrine, and allergic markers

A growing number of studies show an association between seasonal allergic rhinitis (SAR) with depression and anxiety. The underlying mechanisms of a link between SAR and affect, however, are still unclear. The objective of the present study was to investigate depressive symptoms and anxiety in SAR patients and their association to inflammatory and endocrine parameters. SAR patients (n=41) and non-allergic, healthy controls (n=42) were assessed during (pollen season) and out of symptomatic periods (non-pollen season). Inflammatory cytokine profile (Interleukin [IL]-2, IL-4, IL-6, IL-8, IL-10, IL-17, IFN-γ, TNF-α), Immunoglobulin-E (IgE), hair cortisol concentrations (HCC), as well as sleep quality were measured. The present data show that during acute allergic inflammation SAR patients experienced a significant increase in Beck Depression Inventory (BDI-) II scores when (a) compared to the asymptomatic period and (b) when compared to the non-allergic controls, while no differences in anxiety were observed. Increased BDI-II scores in SAR patients were significantly associated with levels of IL-6 as well as IL-6/IL-10 and IFN-γ/IL-10 ratios and further, to an early age at manifestation of SAR and poor sleep quality. These findings support a close relationship between acute allergic processes and affective states, with inflammatory cytokines, sleep, and age of manifestation as potentially relevant mediators.

Memory and multitasking performance during acute allergic inflammation in seasonal allergic rhinitis.

In previous research, patients with seasonal allergic rhinitis (SAR) showed poorer school and work performance during periods of acute allergic inflammation, supporting the idea of an impact of SAR on cognitive functions. However, the specific cognitive domains particularly vulnerable to inflammatory processes are unclear. In this study, the influence of SAR on memory and multitasking performance, as two potentially vulnerable cognitive domains essential in everyday life functioning, was investigated in patients with SAR. Non-medicated patients with SAR (n = 41) and healthy non-allergic controls (n = 42) performed a dual-task paradigm and a verbal learning and memory test during and out of symptomatic allergy periods (pollen vs. non-pollen season). Disease-related factors (e.g. symptom severity, duration of symptoms, duration of disease) and allergy-related quality of life were evaluated as potential influences of cognitive performance. During the symptomatic allergy period, patients showed (1) poorer performance in word list-based learning (P = 0.028) and (2) a general slowing in processing speed (P < 0.001) and a shift in processing strategy (P < 0.001) in multitasking. Yet, typical parameters indicating specific multitasking costs were not affected. A significant negative association was found between learning performance and duration of disease (r = -0.451, P = 0.004), whereas symptom severity (r = 0.326; P = 0.037) and quality of life (r = 0.379; P = 0.015) were positively associated with multitasking strategy. Our findings suggest that SAR has a differentiated and complex impact on cognitive functions, which should be considered in the management of SAR symptoms. They also call attention to the importance of selecting sensitive measures and carefully interpreting cognitive outcomes.

Allergic rhinitis and voice change

The aim of this study was to investigate voice function in patients with birch pollen allergy. Voice recordings for acoustic analysis were performed during pollen season and non-pollen season, with 30 patients and 30 controls, and all participants answered a questionnaire about voice symptoms. The results show that the patients reported more voice symptoms than controls during both seasons. In the non-pollen season the symptoms were decreased in the patient group but not in the controls. Speaking fundamental frequency was lower in patients compared to controls during both seasons. The results suggest chronic edema of the vocal folds in the patients. Laryngeal examination with stroboscope was not performed but is recommended for future patients diagnosed with an air-borne allergy.

Airborne particulate matter (PM2.5) and the prevalence of allergic conjunctivitis in Japan

ObjectiveExposure to particulate matter less than 2.5μm in diameter (PM2.5) is associated with asthma and respiratory symptoms, but little is known about the influence of PM2.5 on allergic conjunctivitis. The purpose of this study was to examine the association of PM2.5 with outpatient attendance for allergic conjunctivitis. MethodsWe conducted a time-series analysis of the association between outpatient attendance for allergic conjunctivitis and PM2.5 levels from May to July (non-pollen season) and from August to October (the autumnal pollen season) in 2012. Air pollution data (including the levels of PM2.5, oxidants, nitric oxide, nitrogen dioxide, nitrogen oxide, carbon monoxide, methane, non-methane hydrocarbons, and total hydrocarbons) and data on the daily weather conditions (temperature, wind speed, and humidity) were collected at a centrally located monitoring station in Tokyo. We calculated weekly average values for the daily number of outpatient visits, as well as the air pollution and weather data, and used the weekly average values for analysis. ResultsThere was a significant association between the number of outpatient visits for allergic conjunctivitis and the PM2.5 level (r=0.62, p=0.0177) from May to July, while no correlation was found between the number of outpatient visits and any variable assessed from August to November. Multivariate analysis also showed that PM2.5 was a significant predictor of the number of outpatient visits from May to July (odds ratio=9.05, p=0.0463), while there were no significant predictors of the number of outpatient visits from August to October. From May to July, PM2.5 showed a negative correlation with humidity (r=−0.53, p=0.0499). ConclusionsThese findings suggest a possible role of PM2.5 in the development of allergic conjunctivitis during the non-pollen season. This association between PM2.5 and allergic conjunctivitis may have broad public health implications in relation to allergic diseases.

Altered MicroRNA Expression of Nasal Mucosa in Long-Term Asthma and Allergic Rhinitis

Background: Asthma and allergic rhinitis (AR) commonly coexist and can be taken as manifestations of one syndrome. Evidence exists that microRNAs (miRNAs) are important in controlling inflammatory processes and they are considered promising biomarkers. However, little is known about the differences in miRNA expression in patients with chronic allergic airway disease. This study evaluated the inflammatory and miRNA profiles of the nasal mucosa of patients with long-term asthma with and without AR. Methods: We analyzed inflammatory cells, cytokines, and miRNAs in nasal biopsies and measured exhaled and nasal nitric oxide levels during the nonpollen season in 117 middle-aged men who had suffered mainly from allergic asthma for approximately 20 years and also in 33 healthy controls. Results: The differences in the number of nasal eosinophils and cytokine expression levels were modest in nasal biopsies taken from asthmatics. Downregulation of miR-18a, miR-126, let-7e, miR-155, and miR-224 and upregulation of miR-498, miR-187, miR-874, miR-143, and miR-886-3p were observed in asthmatic patients in comparison to controls. The differences in miRNA expression were mainly similar in asthmatics with and without AR. With regard to asthma severity, a trend of increased miRNA expression in persistent asthma was seen, whereas the downregulation of certain miRNAs was most distinct in nonpersistent-asthma patients. Conclusions: Differences in miRNA expression in the nasal mucosa of subjects with long-term asthma and AR can be seen also when no markers of Th2-type inflammation are detected. Asthma severity had only a minor impact on miRNA expression.

Cedar and cypress pollen counts are associated with the prevalence of allergic diseases in Japanese schoolchildren

Patients allergic to pollen have been known to become more symptomatic during pollen season compared with the nonpollen season. However, there are few studies regarding whether higher exposure to pollen might increase the prevalence of allergic diseases. An ecological analysis was conducted to evaluate whether pollen exposure is associated with the prevalence of allergic diseases in schoolchildren. Pollen count data of Japanese cedar (Cryptomeria japonica) and Japanese cypress (Chamaecyparis obtusa), which are the major pollen allergens in Japan, were obtained from each prefecture. The prevalence of allergic diseases in schoolchildren in each prefecture was based on a nationwide cross-sectional survey using the International Study of Asthma and Allergies in Childhood questionnaire. After omitting three prefectures where pollen data were not available, data of 44 prefectures were analysed. The prevalence of allergic rhinoconjunctivitis in children aged 6-7 years was positively associated with both cedar and cypress pollen counts (P = 0.01, both), whereas the prevalence of allergic rhinoconjunctivitis in children aged 13-14 years was positively associated with only cypress pollen counts (P = 0.003). Furthermore, the prevalence of asthma was positively associated with cedar pollen counts in 6- to 7-year-old children (P = 0.003) but not cypress pollen counts in either age group. There are ecological associations between pollen counts and the prevalence of allergic diseases in Japanese schoolchildren. Further studies are needed to determine whether the difference between the effects of cedar and cypress pollens is attributable to pollen counts or allergenicity.

Classification of Allergic Rhinitis: What is Most Suitable in Korea?

Classification of Allergic Rhinitis: What is Most Suitable in Korea?

Nasal symptoms among workers exposed to soft paper dust.

To clarify whether occupational exposure to paper-dust is associated with an increased risk of non-infectious rhinitis. Thirty-seven workers exposed to paper-dust in a soft-paper mill were compared with 36 unexposed controls. The study was performed under normal working conditions during the non-pollen season. Medical and occupational history was taken down in a comprehensive questionnaire and nasal symptoms were scored on a visual analogue scale (VAS). Pulmonary and nasal function was assessed by spirometry, acoustic rhinometry and peak nasal inspiratory flow. Nasal lavage was analysed for interleukin-8 (IL-8) and nasal transit time was monitored with the saccharine test. Concentrations of inhalable dust for each exposed subject during the day of the clinical study were measured with personal sampling devices. There was an increased prevalence of nasal blockage and crust formation among the exposed workers. However, there was no difference with regard to acoustic rhinometry, nasal transit time or nasal peak inspiratory flow. In the whole population, IL-8 in nasal lavage was higher among men than among women, 193 ng/l vs 132 ng/l, P = 0.006. There was also a positive trend (P = 0.01) with increasing nasal IL-8 going from non-smokers (122 ng/l), ex-smokers (126 ng/l) to current smokers (235 ng/l). We have found that occupational exposure to paper-dust is associated with symptoms of nasal blockage and nasal crusting. We find no objective signs of nasal inflammation, even among the subgroup with the highest current exposure.

Exhaled and nasal NO levels in allergic rhinitis: relation to sensitization, pollen season and bronchial hyperresponsiveness.

Exhaled nitric oxide is a potential marker of lower airway inflammation. Allergic rhinitis is associated with asthma and bronchial hyperresponsiveness. To determine whether or not nasal and exhaled NO concentrations are increased in allergic rhinitis and to assess the relation between hyperresponsiveness and exhaled NO, 46 rhinitic and 12 control subjects, all nonasthmatic nonsmokers without upper respiratory tract infection, were randomly selected from a large-scale epidemiological survey in Central Norway. All were investigated with flow-volume spirometry, methacholine provocation test, allergy testing and measurement of nasal and exhaled NO concentration in the nonpollen season. Eighteen rhinitic subjects completed an identical follow-up investigation during the following pollen season. Exhaled NO was significantly elevated in allergic rhinitis in the nonpollen season, especially in perennially sensitized subjects, as compared with controls (p=0.01), and increased further in the pollen season (p=0.04), mainly due to a two-fold increase in those with seasonal sensitization. Nasal NO was not significantly different from controls in the nonpollen season and did not increase significantly in the pollen season. Exhaled NO was increased in hyperresponsive subjects, and decreased significantly after methacholine-induced bronchoconstriction, suggesting that NO production occurs in the peripheral airways. In allergic rhinitis, an increase in exhaled nitric oxide on allergen exposure, particularly in hyperresponsive subjects, may be suggestive of airway inflammation and an increased risk for developing asthma.

Spirometry and ventilation‐perfusion inequality in patients with mild allergic asthma before and during the pollen season

Several studies on asthma have shown a low correlation between gas exchange and spirometry, especially after treatment with bronchodilators. The aim of the present study was therefore to examine both spirometry results and gas exchange during a pollen-free period and at the end of the pollen season in patients with mild and well-controlled allergic asthma. Pulmonary gas exchange was studied using a modified form of the multiple inert gas elimination technique. Lung volumes and forced expiratory flows were measured by common spirometry. During the non-pollen season, spirometry and forced expiratory flows were within the reference values in all but one patient, who had decreased indices for airway flow. Three other patients showed signs of minor gas exchange impairment. During the pollen season, FRC was slightly increased (P < 0.05) and MEF50 was slightly decreased (P < 0.05) for the group. Two patients had an increased index for gas exchange impairment (log SDQ was 0.64 and 0.59) and four patients had borderline log SDQ (0.50 to 0.56). However, the mean log SDQ was not increased in the pollen season. The results show that, both in the pollen season and in the pollen-free season, low degrees of gas exchange impairment could be present in pollen allergic asthmatic patients despite normal spirometry. The low degree of gas exchange impairment in some patients indicates the presence of airway inflammation with oedema and/or secretion. However, high degrees of ventilation-perfusion inequality were not observed in these patients where air flow rates were mainly normal.

Increase in CD4+ and CD45RO+ memory T cells in the nasal mucosa of allergic patients

By means of immunocytochemistry we have investigated subsets of T lymphocytes in frozen sections of nasal mucosa from patients with seasonal allergic rhinitis and healthy control persons. All participants were subjected to time-course provocation during the non-pollen season, and samples were taken during provocation as well as during the natural pollen season. Computerized image analysis was applied for evaluation of the immunostained lymphocytes. CD45RO+ memory T cells outnumbered the remaining leukocyte populations in the mucosa of both allergic patients and controls on all occasions. During the repeat provocation there was no difference in numerical values, with respect to any of the five leukocyte subpopulations studied (CD4, CD8, CD25, CD45RA and CD45RO), between patients and controls. However, during continuous exposure in the pollen season a significant increase in CD4+ cells was observed in allergic patients compared to before provocation (p < 0.05). No changes were observed with respect to CD8+ and CD25+ cells. Similarly, an increase in CD45RO+ memory was found in allergic patients during the pollen season compared to the non-pollen season (p < 0.02). This latter finding was, however, only evident in the patients who did not use nasal corticosteroids. Hence the present investigation has demonstrated an allergen-induced increase in CD4+ and CD45RO+ memory T cells in the mucosa of allergic patients during the pollen season. These events may constitute a cellular basis for local continuous production of certain cytokines, particularly interleukin-4, which is essential for IgE synthesis.

Phenotype switch and activation of T lymphocytes in patients with allergic rhinitis.

The peripheral blood of 17 patients with seasonal allergic rhinitis (birch pollen) and of 10 healthy subjects were analysed before and during a provocation study in the non-pollen season as well as during the pollen season. Analytical flow cytometry comprised a panel of monoclonal antibodies investigating helper/suppressor T cells, activated T cells, and naive/memory T helper cells. Allergic patients showed no increase in the amount of T lymphocytes but an increased proportion of CD4+ helper T cells early during pronounced exposure (provocation) but not during natural antigen exposure (pollen season). Allergic patients showed a significant increase in activated T cells during the non-pollen season compared with healthy subjects, and furthermore, the nasal allergen provocation induced an additional increase in activated T cells among allergics. The T cell activation mainly affected helper T cells (85%) rather than suppressor T cells. Furthermore, allergic patients showed a significant increase in naive T helper cells during the pollen season. The presence of a double-positive subpopulation indicates an activated T helper subpopulation that switches its phenotype from naive (CD45RA) to memory (CD29). The results indicate at least two important differences between patients with allergic rhinitis and healthy controls. In allergic patients T helper cells become activated upon allergen exposure, and circulate in the blood and switch their phenotype. These T cells have a potential homing tendency to the nasal mucosa. These two events do not occur in non-allergic individuals and may thus constitute new insights into the basic mechanisms of allergic rhinitis.