Relationship between Serum Omega-3 Fatty Acid and Asthma Endpoints.

Recent studies have highlighted the potential protective role of omega-3 polyunsaturated fatty acids (n-3 PUFA) in asthma. This study aimed at determining the association between seafood intake, serum PUFA composition and clinical endpoints of asthma in adults. A cross-sectional study of 642 subjects used the European Committee Respiratory Health Survey (ECRHS) questionnaire, skin prick tests, spirometry and methacholine challenge tests following ATS guidelines. Sera was analysed for n-3 and n-6 PUFA composition. Subjects had a mean age of 34 years, were largely female (65%) and 51% were current smokers. While 99% reported fish consumption, rock lobster, mussels, squid and abalone were also consumed less frequently. The prevalence of asthma symptoms was 11%, current asthma (ECRHS definition) was 8% and non-specific bronchial hyperresponsiveness (NSBH) was much higher (26%) In adjusted models the n-3 PUFAs 20:5 (EPA) and 22:5 (DPA) were significantly associated with a decreased risk of having NSBH. Total n-3 PUFA composition was associated with decreased NSBH risk (OR = 0.92), while high n-6 PUFA composition was associated with an increased risk (OR = 1.14).

Population-based study of multiplexed IgE sensitization in relation to asthma, exhaled nitric oxide, and bronchial responsiveness.

BACKGROUND: IgE sensitization is an important risk factor for the development of asthma. OBJECTIVE: The aim of this study was to investigate the IgE antibody profile for a broad spectrum of allergen molecules in asthmatic patients. METHODS: Participants from the European Community Respiratory Health Survey II (n=467) were tested with ImmunoCAP ISAC against 103 allergen molecules. The presence of bronchial hyperresponsiveness was measured with a methacholine challenge test and bronchial inflammation with fraction of exhaled nitric oxide (Feno). RESULTS: A total of 38% of the controls and 72% of the asthmatic patients were sensitized against at least 1 of the allergen components (P<.0001). Asthma was independently related to having IgE antibodies against pollen (odds ratio=2.2) and perennial airway allergens (odds ratio=5.6), increased Feno was independently related to having IgE antibodies against food allergens and perennial allergens, while bronchial responsiveness was independently associated with having IgE antibodies against only perennial allergens. Sensitization to food allergens was related to asthma and increased Feno if IgE antibody against pollen allergens was present. Simultaneous sensitization to perennial, pollen, and food allergens involves the highest risk of asthma (odds ratio=18.3), bronchial inflammation, and responsiveness. CONCLUSIONS: Feno, bronchial responsiveness, and the risk of asthma increase with multiple sensitizations to different allergen groups. We show for the first time that the presence of IgE antibodies against food allergens is independently associated with increased Feno and increases the risk of asthma in subjects with simultaneous sensitization to pollen allergens.

[On general practitioners' care of patients with asthma]. / HausärztlicheVersorgung von Patienten mit Asthma.

UNLABELLED: This review offers readers new aspects for the guideline-compliant care of asthma patients. Here, attention is focused on illustrating the bottlenecks in the administration of good and practicable therapeutic care and listing these as "major challenges for GPs". The interdisciplinary team of authors - consisting of three hospital-based pulmonologists, one pulmonologist in private practice, one internist in general practice, one pharmacist and one health economist discussed aspects of asthma therapy relevant in clinical practice. RESULTS AND CONCLUSIONS: Practicable results for the reader included an asthma pentagram, a graphic depicting the links and interactions between diagnosis, symptom management, communication, application and costs. From this emerged a consensus on four recommendations that can help GPs improve their care of their patients: (1) Whenever possible, have a specialist verifythe diagnosis. (2) Practice inhalation techniques with the patient and check up on their technique at regular intervals. (3) Monitor and fine-tune the therapeutic goals set down together with the patient. (4) Clearly define the (patient's) responsibilities and who is organizing care (communication between GP-specialist-patient-pharmacist-family members).

Maternal use of folic acid supplements during pregnancy, and childhood respiratory health and atopy.

Previous studies have suggested possible adverse side-effects of maternal use of folic acid-containing supplements (FACSs) during pregnancy on wheeze and asthma in early childhood. We investigated the association between maternal use of FACSs and childhood respiratory health and atopy in the first 8 yrs of life. Data on maternal use of FACSs, collected during pregnancy, were available for 3,786 children participating in the Prevention and Incidence of Asthma and Mite Allergy birth cohort study. Questionnaire data on children's respiratory and allergic symptoms were collected annually and allergic sensitisation and bronchial hyperresponsiveness (BHR) were measured at 8 yrs of age. No overall (from 1 to 8 yrs of age) associations were observed between maternal use of FACSs and (frequent) asthma symptoms, wheeze, lower respiratory tract infection, frequent respiratory tract infection and eczema. Maternal folic acid use was associated with wheeze at 1 yr of age (prevalence ratio 1.20, 95% CI 1.04-1.39), but not with wheeze at later ages. Pre-natal exposure to FACSs was not associated with sensitisation and BHR. Apart from a small increased risk of early wheeze, we observed no adverse respiratory or allergic outcomes associated with pre-natal FACSs exposure in our study population.

Occupational endotoxin exposure reduces the risk of atopic sensitization but increases the risk of bronchial hyperresponsiveness.

BACKGROUND: Microbial exposures in both childhood and adult life are protective against atopy, allergic rhinitis and atopic asthma. In adults, this protective effect is paralleled by an increased prevalence of non-atopic asthma. This study was undertaken to investigate associations between occupational endotoxin exposure and atopic sensitization and bronchial hyperresponsiveness to methacholine (BHR) in agricultural workers. In addition, the role of atopy in endotoxin-related respiratory effects was studied. METHODS: Data were available for 427 farmers and agricultural industry workers, for whom airborne endotoxin exposure levels were estimated by 249 personal exposure measurements. Atopy was assessed as specific serum IgE to common inhalant allergens, and respiratory symptoms and personal characteristics by standardized questionnaires. BHR was determined in a subset of 113 subjects. Associations were adjusted for age, sex, smoking and living on a farm during childhood. RESULTS: Endotoxin exposure was positively associated with BHR and wheeze (p < 0.05). In contrast, endotoxin exposure was inversely associated with atopy and IgE to grass pollen (p < 0.001). The proportions of wheeze and BHR that were attributable to atopy were only 16.6 and 32.8%, respectively. CONCLUSIONS: High endotoxin exposure is a risk factor for BHR and wheeze, which were characterized by a predominantly non-atopic phenotype. At the same time, endotoxin exposure is related to a reduced risk of atopy and IgE to grass pollen in adults. It is unlikely that this is entirely a result of healthy worker selection, as significant inverse associations between endotoxin and IgE to grass pollen were found regardless of reported allergic symptoms.

Onions, myths, beliefs, fashion and reality in asthma.

Some myths and unsupported beliefs about asthma are very popular and enjoy general public acceptance and fairly strong support on the Internet. Onions for cough; dairy products avoidance for asthma; and some other popular myths are reviewed, along with some other medical and mixed (popular and medical) myths comparing their popular and scientific support. Classifying medical statements as realities or unsupported beliefs is a hard and serious work nowadays addressed by Evidence Based Medicine methods, which are not devoid of the influence of medical fashion: the medical community is more prone to accept fashionable statements compared to non-fashionable or old-fashioned statements.

Health risks due to coffee dust.

OBJECTIVE: This study assessed current health risks due to occupational exposure to coffee dust. METHODS: We performed a cross-sectional study in a coffee haulage company (n = 24), a coffee silo (n = 19), and a decaffeinating company (n = 17). Cross-shift and cross-week case histories of these employees as well as lung function values were recorded. During the handling of green coffee, measurements of airborne dust were conducted. RESULTS: The employees in these workplaces were mainly affected by erythematous and rhinoconjunctival symptoms. They occurred especially in subjects exposed to a high dust load (> 10 mg of inhalable dust per cubic meter of air; n = 28) [Pearson chi(2) test, p = 0.020 and p = 0.023]. IgE antibodies to green coffee and castor beans were detected in 3 workers and 10 workers, respectively. The majority of them (two employees and six employees, respectively) had shown respiratory symptoms during the past 12 months. The preshift lung function values were below average but were not dependent on the level of the inhalable coffee dust exposure. Employees with a coffee dust load > 10 mg/m(3) of air showed higher unspecific bronchial responsiveness more frequently than those with lower exposures. CONCLUSION: During the transshipment (especially during unloading) of green coffee, a high and clinically relevant exposure to irritative and sensitizing dust occurs. Therefore, efforts to reduce these dust exposures are generally recommended.

[Fifty percent of pollinosis patients sensitive to birch pollen demonstrate bronchoconstriction during bronchial provocation test with the allergen]. / Polowa chorych na pylkowice, uczulonych na pylek brzozy, reaguje skurczem oskrzeli w trakcie oskrzelowego testu prowokacyjnego z alergenem.

UNLABELLED: Birch pollens are known as seasonal asthma precipitants. Our earlier studies evidenced a very high frequency of positive results bronchial allergen challenges in pollinosis patients sensitive to grass pollen. The aim of the study was to evaluate how often the bronchial challenge with birch pollen allergen causes bronchoconstriction. MATERIAL AND METHODS: Studies were performed outside of pollen season on 30 patients sensitive to birch pollen allergen. Before the allergen challenges bronchial provocation tests with methacholine were performed in all subjects. RESULTS: About 13% of examined group had bronchial hyperreactivity (PC20FEV1Mch < 8 mg/ml) and 50% demonstrated bronchoconstriction after birch pollen allergen inhalation. CONCLUSIONS: About 13 percent of patients sensitive to birch pollen demonstrated nonspecific hyperrectivity out of pollen season. Bronchial birch allergen challenge tests are positive in about half of birch sensitive patients with pollinosis.

Glutamine-enriched enteral nutrition in very low-birth-weight infants: effect on the incidence of allergic and infectious diseases in the first year of life.

OBJECTIVE: To determine the effect of glutamine-enriched enteral nutrition in very low-birth-weight infants on the incidence of allergic and infectious diseases during the first year of life. DESIGN: Follow-up study. SETTING: Tertiary care hospital. PARTICIPANTS: All surviving infants who participated in a trial of glutamine-enriched enteral nutrition in very low-birth-weight infants. INTERVENTION: Enteral glutamine supplementation (l-glutamine, 0.3 g/kg per day) from 3 through 30 days of life. MAIN OUTCOME MEASURES: The incidence of allergic and infectious diseases during the first year of life, as assessed by means of validated questionnaires. RESULTS: Seventy-seven of 90 infants (86%) participated in the follow-up study. Baseline patient, maternal, and environmental characteristics did not differ between the glutamine-supplemented (n = 37) and control (n = 40) groups, except for the incidence of serious neonatal infections and child care attendance. After adjustment for confounding factors, the risk for atopic dermatitis was lower in the glutamine-supplemented group (odds ratio [OR], 0.13; 95% confidence interval [CI], 0.02-0.97). However, the incidence of bronchial hyperreactivity (OR, 0.34; 95% CI, 0.10-1.21) and infections of the upper respiratory (OR, 0.99; 95% CI, 0.35-2.79), lower respiratory (OR, 0.39; 95% CI, 0.13-1.24), and gastrointestinal (OR 1.25, 95% CI 0.23-6.86) tracts was not different between the treatment groups. CONCLUSIONS: Glutamine-enriched enteral nutrition in very low-birth-weight infants decreased the incidence of atopic dermatitis during the first year of life but had no effect on the incidence of bronchial hyperreactivity and infectious diseases during the first year of life.

[Effect of natural allergens exposure on serum concentration of soluble form of intercellular adhesion molecule 1 in patients with seasonal airway allergy]. / Wplyw naturalnej ekspozycji na alergeny na stezenie rozpuszczalnej formy czasteczki adhezji miedzykomórkowej 1 w surowicy chorych z sezonowa alergia dróg oddechowych.

UNLABELLED: Chronic inflammation is a feature of bronchial asthma and allergic rhinitis. Intercellular adhesion molecules, especially ICAM-1 and its soluble form sICAM-1 present in systemic liquids play an important role in allergic inflammation. The aim of this study was to assess the effect of natural pollen exposure to plants on serum sICAM-1 concentration in patients with different clinical expression of seasonal allergy and to determine the relation between concentrations of these molecules to clinical symptom score and nonspecific bronchial hyperresponsiveness (BHR). MATERIAL AND METHODS: The study comprised 48 patients with isolated seasonal allergic rhinitis (SAR), 26 patients with seasonal asthma (SA) and 16 healthy volunteers. Serum s/CAM-1 concentration using an immunoenzymatic ELISA method and BHR to methacholine were measured twice, before grass season and during symptomatic period of SAR and SA. Clinical symptoms severity were evaluated by pointing method from patients diary cards. RESULTS: The study revealed no differences in mean concentration of serum sLCAM-1 between patients with SAR and SA but significant increase of serum sICAM-1 level during natural allergen exposure in all patients was observed. CONCLUSION: Serum concentration of sICAM-1 was not correlated to symptom score and BHR in both SAR and SA patients in and out of season.

Limits of longitudinal decline for the interpretation of annual changes in FEV1 in individuals.

OBJECTIVE: Spirometry-based screening programmes often conduct annual assessment of longitudinal changes in forced expiratory volume in 1 second (FEV1) to identify individuals with excessive rates of decline. Both the American Thoracic Society (ATS) and the American College of Occupational and Environmental Medicine (ACOEM) recommend a reference limit value of > or =15% for excessive annual decline. Neither the ATS nor the ACOEM adjust this limit for the precision of the existing spirometry data. The authors propose an improved method of defining the reference limit of longitudinal annual FEV1 decline (LLD) based on the precision of the spirometry data. METHOD: The authors used data from four monitoring programmes and measured their data precision using a pair-wise within-person variation statistic. They then derived programme- and gender-specific absolute and relative LLD values and validated these against the 95th percentiles for observed yearly changes in FEV1. RESULTS: The relative limit for annual decline was more practical than the absolute limit as it adjusted for gender differences in the magnitude of FEV1. The programme-specific relative limit values were in good agreement with 95th percentiles for year-to-year FEV1 changes and ranged from 6.6% to 15.8%. For individuals with COPD and bronchial hyperreactivity the 95th percentiles for year-to-year changes were about 15% and higher. CONCLUSIONS: The relative longitudinal limit for annual FEV1 decline based upon precision of measurements is valid and can be generalised to different gender and population groups. A relative limit of approximately 10% appears appropriate for good quality workplace monitoring programmes, whereas a limit of about 15% appears appropriate for clinical evaluation of individuals with an obstructive airway disease. Computer software based on the method described is available from the corresponding author.

Seasonal asymptomatic lower airway hyperresponsiveness in patients with allergic rhinitis.

BACKGROUND: Allergic rhinitis is considered a risk factor for bronchial asthma. It therefore seems essential to identify patients threatened with this disease in whom no disturbing bronchial symptoms have occurred. The study's aim was to evaluate the incidence of nonspecific bronchial hyperactivity based on exercise results in pollinosis patients. MATERIAL/METHODS: The study group comprised 27 patients with seasonal allergic rhinitis allergic to tree pollens but without asthma symrptom. Exercise provocation tests were performed before, during, and after completion of the pollination period. During the pollination period, specific IgE (sIgE) and nasal eosinophilia were also determined. Twelve patients allergic to Artemisia pollen made up the control group. The results were also evaluated in relation to desensitization therapy. RESULTS: In the study group a pathological result of the provocation test was obtained in 1 patient (3.7%) before the pollination period, in 7 patients (25.9%) during, and in 4 patients (11.8%) after its completion. The subjects with a positive test result had higher levels of nasal eosinophilia, while there was no relation between the result and sIgE levels. Only one case of positive exercise challenge was identified among the desensitized patients. CONCLUSIONS: During the pollination period, nonspecific bronchial hyperreactivity develops in some patients with seasonal allergic rhinitis; it can be sustained for some time after the disappearance of pollens from the atmosphere and can he identified using an exercise challenge. Incidence of bronchial hyperreactivity in desensitized patients was lower than in those subjected to symptomatic treatment.

[Multiple chemical sensitivity (MCS) -- a case series]. / Multiple Chemikalienüberempfindlichkeit (MCS) - eine Fallserie.

BACKGROUND AND OBJECTIVE: The phenomenon of Multiple Chemical Sensitivity which generally cannot be explained organically is frequently associated with psychic impairment. This case series deals with the question if in addition to a standardized interview a routine psychiatric-psychosomatic examination alters the classification if a patient suffers from symptoms compatible with MCS or not. METHODS: Nine consecutive outpatients (m = 3, f = 6, mean age 44 yrs) of the environmental medicine centre were investigated. Somatic diseases were evaluated by standard medical procedures and emotional disturbances were assessed by the Munich Composite International Diagnostic Interview (M-CIDI) and a psychiatric-psychosomatic examination. RESULTS: In all but one patients emotional disturbances (F-codes of the ICD-10) were diagnosed by the M-CIDI and the psychiatric-psychosomatic examination. The diagnoses of the M-CIDI and the psychiatric-psychosomatic examination often did not match. MCS was ruled out in seven patients. CONCLUSIONS: According to the criteria defined by Cullen (5), emotional disturbances must be ruled out before MCS is diagnosed. Therefore, an examination by a specialist in psychiatry or psychosomatics is mandatory because evaluation solely based on the M-CIDI is insufficient. Performing a routine psychiatric-psychosomatic examination, MCS could be ruled out much more often than previously.

[The results of exercise challenge in patients with seasonal allergic rhinitis]. / Ocena wyników próby wysilkowej u chorych z alergicznym sezonowym niezytem nosa.

BACKGROUND: Allergic rhinitis is considered a risk factor for the future development of bronchial asthma. It therefore seems essential to identify patients who are threatened with this disease and in whom no disturbing bronchial symptoms have already occurred. The aim of this study was to evaluate the incidence of nonspecific bronchial hyperactivity based upon exercise results of patients with pollinosis. INVESTIGATED GROUP: The study encompassed 27 patients with seasonal allergic rhinitis allergic to tree pollens, but without symptoms of asthma. Exercise provocation test were performed in patients in the period before, during and after completion of the pollination period. Additionally, during the pollination period sIgE and nasal eosinophilia were determined. The control group was composed of 12 patients allergic to Artemisia pollen. RESULTS: In the study group, a pathological result of provocation test was obtained in 1 patient (3.7%) before the pollination period, in 7 patients (25.9%) during and in 4 patients (14.8%) after completion of the pollination period. Subjects with positive test result had higher levels of nasal eosinophilia, while there was no relation between its result and sIgE levels. Only one case of positive exercise challenge was identified among desensitized patients. CONCLUSIONS: During the pollination period nonspecific bronchial hyperreactivity develops in some patients with seasonal allergic rhinitis; it can be sustained for some time after disappearance of pollens from the atmosphere and can be identified using an exercise challenge. Incidence of bronchial hyperreactivity in desensitized patients was lower than in those subjected to symptomatic treatment.

Food and fatty acid intake and atopic disease in adults.

The aim of the study was to assess the relationship between dietary intake of selected foods and fatty acids with atopic disease prevalence in adults. Data from the European Community Respiratory Health Survey in Erfurt, combined with a 3-day weighed records dietary survey, was used. Complete data was available from 469 males and 333 females aged 20-64 yrs. Multiple logistic regression was applied comparing the highest with the lowest quartile of dietary exposures and linear trends were tested stratified by sex. In males, margarine intake and a high ratio of omega-6 to omega-3 fatty acids were positively associated with hay fever. In females, a high intake of total fat, palmitoleic and oleic acids were positively associated with sensitisation. A high total fat, high monounsaturated fatty acid and high oleic acid consumption were positively associated with hay fever. Whilst an excessive intake of fat or imbalance in fat intake, particular of monounsaturated fatty acids, increased the risk for hay fever and allergic sensitisation in females, mostly no significant associations were found for males. Dietary factors were mostly not related with prevalence rates of bronchial hyperresponsiveness and atopic eczema either in males or in females.

Association between asthma and rhinitis according to atopic sensitization in a population-based study.

BACKGROUND: Although asthma and rhinitis often occur together, the reason for this common comorbidity is still a matter of debate. OBJECTIVE: We sought to assess whether the coexistence of asthma and rhinitis could be explained by common risk factors. METHODS: International cross-sectional study of representative samples of young adults, who completed a detailed questionnaire and underwent lung function tests, bronchoprovocation challenge, IgE measurements, and skin prick tests. RESULTS: In all countries, asthma and bronchial hyperreactivity were more frequent in subjects with rhinitis than in those without (odds ratio [OR], 6.63; 95% CI, 5.44-8.08; and OR, 3.02 95% CI, 2.66-3.43, respectively). Seventy-four percent to 81% of subjects with asthma reported rhinitis, depending on sensitization to specific allergens. Conversely, the risk of asthma increased from 2.0% in subjects without rhinitis to 6.7% in subjects with rhinitis only when exposed to pollen, 11.9% in subjects with rhinitis when exposed to animals, and 18.8% in subjects with rhinitis either when exposed to pollen or to animals. The association between rhinitis and asthma remained significant after adjustment for total IgE, parental history of asthma, and allergen sensitization (OR, 3.41; 95% CI, 2.75-4.2 suggesting that the coexistence of asthma and rhinitis is not solely due to atopic predisposition to these 2 diseases. CONCLUSIONS: Although there were some variations in the association between asthma and rhinitis according to sensitization to individual allergens, the strong association between asthma and rhinitis was not fully explained by shared risk factors, including atopy. Our findings are consistent with the hypothesis that rhinitis might increase the risk of asthma.

Individual allergens as risk factors for asthma and bronchial hyperresponsiveness in Chinese children.

The role of allergen sensitization in the development of asthma in the Chinese is not clear. This study aims to determine the relationship of sensitization to individual allergens, and the development of asthma and bronchial hyperresponsiveness (BHR) in schoolchildren from three Chinese cities: Hong Kong, Beijing and Guangzhou. Community-based random samples of 10-yr-old schoolchildren from three Chinese cities were recruited for study using the International Study of Asthma and Allergies in Childhood (ISAAC) Phase II protocol. Subjects were studied by parental questionnaires (n=10,902), skin-prick tests (n=3,479), and methacholine challenge tests (n=608). The prevalence rates of wheeze in the past 12 months (Hong Kong, 5.8%; Beijing, 3.8%; Guangzhou, 3.4%) and atopy (Hong Kong, 41.2%; Beijing, 23.9%; Guangzhou, 30.8%) were highest in schoolchildren from Hong Kong. Multivariate logistic regression analyses revealed that sensitization to Dermatophagoides pteronyssinus (odds ratio (OR)=4.48; 95% confidence interval (CI): 3.02-6.66), cat (2.59; 1.67-4.03), Dermatophagoides farinae (2.41; 1.65-3.51) and mixed grass pollen (2.85; 1.24-6.50) were significantly associated with current wheeze. Atopy, defined as having > or = 1 positive skin-prick tests, was not an independent risk factor for current wheeze in children from any of the three cities. Furthermore, atopy (OR=2.53; 95% CI: 1.07-5.97), sensitization to cat (3.01; 1.39-6.52) and D. farinae (3.67; 1.93-6.97) were significantly associated with BHR. The authors confirmed that sensitization to house dust mite and cat was significantly associated with current wheeze and bronchial hyperresponsiveness in Chinese schoolchildren. However, the difference in the prevalence rate of atopic sensitization cannot explain the higher prevalence of childhood asthma in Hong Kong, when compared with those children from Beijing and Guangzhou.

Prevalence of sensitization to Cupressus sempervirens: a 4-year retrospective study.

In the last few years Cupressus sempervirens has been identified as the cause of an increasing number of cases of late winter-early spring pollinosis in Mediterranean countries. We conducted a 4-year retrospective study of a large group of subjects with documented allergic respiratory disease in order to determine the prevalence, clinical significance and annual rate of sensitization to C. sempervirens pollen. Anamnestic data and skin prick tests (SPT) with common aeroallergens and C. sempervirens extract were collected from 1397 subjects (712 male and 685 female) resident in Latium, a region in central Italy, with complaints related to upper- or lower-respiratory-tract disorders or conjunctival disease. Two hundred and forty-three subjects (17.4%) showed positive results to C. sempervirens extract: 47 (19.3%) of them were monosensitized. The annual sensitization rate of SPT positivity to C. sempervirens varied from 7.2% in 1995 to 22% in 1998. All the subjects monosensitized to cypress pollen had symptoms from January through April. Our study suggests that sensitivity to C. sempervirens is responsible for respiratory symptoms in an increasing percentage of subjects. Further studies are needed to determine its frequency at the national level.

Sensitivity to the house dust mite and airway hyperresponsiveness in a young adult population.

BACKGROUND: The pathogenic mechanisms of airway hyperresponsiveness (AHR) in asthma are unknown and only a few studies have examined the importance of sensitivity to antigens in AHR in young adults. OBJECTIVE: We investigated the correlation between AHR and sensitivity to specific antigens, atopy, history of childhood asthma and spirometry in a young adult population. METHODS: Based on the results of interviews with 447 students at our university, 308 non-smoker students were classified into six groups. Group 1 comprised subjects with intermittent mild bronchial asthma; group 2, subjects with history of childhood asthma; group 3, subjects with atopic disease, and a RAST score for Dermatophagoides farinae (Def) of > or = 2; group 4, normal subjects with a RAST score for Def of > or = 2; group 5, subjects with cedar pollinosis; and group 6, normal subjects. We measured AHR to methacholine (MCh), spirometry, immunoglobulin E-radioimmunosorbent test (IgE-RIST), IgE-radioallergosorbent test to six common antigens, eosinophil cationic protein (ECP), and eosinophil count in peripheral blood in each subject. RESULTS: Airway hyperresponsiveness to MCh did not correlate with IgE-RIST, eosinophil count, or ECP. The highest AHR to MCh was present in groups 1 and 2 and lowest in groups 5 and 6. Multiple regression analysis showed that sensitivity to Def was the only factor that significantly influenced AHR to MCh. Airway hyperresponsiveness to MCh of groups with a RAST score for Def of 0/1 was lower than groups with a RAST score of 2 to 6. Airway hyperresponsiveness to MCh did not correlate with the degree of positivity to Def antigen among positive sensitized groups (RAST score 2 to 6). CONCLUSIONS: Sensitivity to mite antigen may be important in the pathogenesis of AHR and Def is a major contributing antigen in young adults in Japan. Once asthma occurs, AHR remains positive for a long time even after the disappearance of asthma-related symptoms.

Seasonal variation in bronchial hyperreactivity (BHR) in allergic patients.

As summarized in Table 1, the literature consistently supports the hypothesis that allergic asthmatic patients have seasonal BHR changes that parallel allergen exposure. These seasonal changes appear to be preventable by treatment with corticosteroids (systemic, inhaled, or nasal), disodium cromoglycate, and immunotherapy. Studies have almost exclusively focused on pollens, though similar limited data exist for dust mites. Though the dust mite is a perennial allergen, mite levels are well known to fluctuate with seasonal temperature and humidity trends (44-46), and therefore, seasonal BHR variation in mite-sensitive asthmatic patients is not surprising. Allergenic mold species have not been studied in this regard. In allergic rhinitis patients, the data are less consistent (see Table 2). However, the studies that failed to identify a seasonal BHR difference were either small or had other design limitations. The seasonal changes identified by the larger analyses were similar to those identified for asthmatic patients. Thus, although confirmatory studies would be helpful, it seems likely that in the absence of clinical asthma, allergic rhinitis patients with baseline BHR have allergen-related seasonal changes in BHR. The BHR effects of seasonal changes in air pollution and viral URIs are not known, since they have not yet been directly studied. However, interesting recent reports have identified possible synergistic effects of air pollution exposure on BHR and allergic responses. Similarly, the availability of new viral identification techniques has resulted in the discovery that viral infection may be more prevalent during clinical asthma exacerbation than previously realized. Therefore, air pollution and viral infections may well influence BHR seasonally, and (along with allergens) may contribute to seasonal asthma morbidity and mortality peaks. The mechanism(s) underlying seasonal BHR changes is (are) not known. One plausible possibility with regard to allergen-driven BHR changes involves a type I hypersensitivity late-phase reaction. Characterized by recruitment of eosinophils, lymphocytes, and other cells that are central components of allergic inflammation and are not normally found in the lower airways, this reversible inflammatory process could in turn act, presumably via chemical mediators, on the airway smooth muscle. This may cause bronchoconstriction, but may also increase responsiveness to bronchoconstrictive stimuli independent of bronchoconstriction. This explanation for seasonal BHR changes is supported by findings of blood eosinophil (31,47) and BAL eosinophilic cationic protein (31) level changes that parallel BHR. Prevention of seasonal BHR changes using anti-inflammatory medications (32,33,35) also supports this hypothesis (30) however, and the complex potential interactions between infectious agents and air pollutants on seasonal BHR changes have yet to be studied directly. Therefore, although BHR indeed may predictably vary season to season in allergic individuals, additional investigation is needed to better characterize the reasons for this phenomenon. Further insight in this area may help address the reasons why there are often seasonal epidemics in asthma morbidity and mortality.