Use of a chimeric ELISA to investigate immunoglobulin E antibody responses to Der p 1 and Der p 2 in mite-allergic patients with asthma, wheezing and/or rhinitis

BACKGROUND: Sensitization to indoor allergens, particularly to dust mites, is a strong risk factor for asthma in children and adults. Assessment of sensitization is carried out using in vivo and in vitro tests to detect specific IgE antibodies. OBJECTIVE: To investigate IgE antibody responses to mites in patients with asthma, wheezing and/or rhinitis, using chimeric ELISA to measure specific IgE antibodies to mite allergens Der p 1 and Der p 2. METHODS: Specific IgE antibodies to Der p 1 and Der p 2 were quantified by chimeric ELISA, and compared with IgE to Dermatophagoides pteronyssinus (Dpt) measured using the CAP system (Pharmacia). A panel of sera from 212 patients with asthma, wheezing and/or rhinitis and 11 controls was analysed. RESULTS: There was a significant correlation between IgE to Dpt measured by CAP and IgE to Der p 1 (r = 0.81, P < 0.001), Der p 2 (r = 0.79, P < 0.001) and combined Der p 1 and Der p 2 (r = 0.86, P < 0.001). Seventy per cent of all patients had IgE to Dpt, and of those, 76.5% had IgE to Der p 1, 79.2% had IgE to Der p 2 and 83.1% had IgE to Der p 1 and Der p 2 combined. Considering the cut-off level of 2 IU/mL of IgE to either Der p 1 or Der p 2, the predictive value for a positive IgE to Dpt by CAP was greater than 95%. CONCLUSIONS: The chimeric ELISA allowed accurate quantification of IgE antibodies to Dpt allergens Der p 1 and Der p 2, and it could be useful for studying immune responses to mites in patients with asthma and/or rhinitis.     

The prevalence of IgE sensitization to formaldehyde in asthmatic children

BACKGROUND: Formaldehyde (FA) is well documented as a cause of occupational asthma. Recently, attention has been paid to FA as an allergen and a pollutant that enhances allergic sensitization. We have investigated the prevalence of FA-specific IgE in asthmatic children and the correlation between IgE sensitization to FA and the severity of asthma. METHODS: One hundred and fifty-five children were investigated, 122 of them asthmatic and 33 nonallergic. Specific IgE against FA was measured by CAP RAST. In addition, the patients answered a questionnaire, containing questions on clinical features of their asthma, their living conditions, and symptoms of mucosal irritation. RESULTS: Of all the subjects assessed, FA-specific IgE was detected in only two asthmatics, and their IgE levels of FA were low (0.42 and 0.46 UA/ml). One of the two patients with FA-specific IgE had severe asthma and frequent symptoms of mucosal irritation, but the other had mild asthma and only rare symptoms of mucosal irritation. CONCLUSIONS: The prevalence of IgE sensitization to FA appears very low in Japanese children, whether or not they have asthma. Therefore, it appears likely that FA is not one of the major allergens causing childhood asthma.     

Skin test reactivity to natural and recombinant Blomia and Dermatophagoides spp. allergens among mite allergic patients in the UK

BACKGROUND: Many asthmatics in tropical and subtropical areas have positive skin prick tests to both Dermatophagoides spp. and to the mite Blomia tropicalis. This may be due to recognition by IgE of cross-reactive allergens between the different mite species or because of sensitization to species-specific allergens. A 14-kDa Blomia tropicalis allergen, Blo t 5, has been cloned and shows 40% sequence homology with Der p 5. The aim of this study was to investigate reactivity to B. tropicalis in patients known to be sensitized to D. pteronyssinus and to assess allergenic activity and cross-reactivity of recombinant (r) Group 5 allergens amongst these patients, who live in the UK and who are not exposed to B. tropicalis in their homes. METHODS: Patients (n = 19) with asthma and/or rhinitis were selected based on clinical history and a positive skin prick test to D. pteronyssinus extract and were compared with non-allergic skin test negative controls (n = 10). IgE antibody responses to Blomia tropicalis, Dermatophagoides pteronyssinus, rDer p 5 and rBlo t 5 were compared by quantitative intradermal skin testing using serial 10-fold dilutions of each allergen. End point titre was the highest dilution giving an 8 x 8 mm wheal at 15 min. IgE antibodies to Blomia tropicalis, Dermatophagoides pteronyssinus, rDer p 5 and rBlo t 5 were measured using RAST, CAP and RIA, respectively. RESULTS: All 19 patients had positive skin tests to D. pteronyssinus at concentrations of 0.001 to 1 AU/ml and 10 were skin test positive to rDer p 5 at concentrations of 10-4 to 5 micro g/ml. Positive intradermal tests to Blomia tropicalis were seen in 12/19 patients at concentrations of 0.002 to 2 micro g/ml. However none of the patients had positive skin tests to rBlo t 5. Non-allergic controls were all skin test negative at the highest concentration of each allergen tested. All subjects had quantifiable specific IgE to D. pteronyssinus, but only two had IgE to B. tropicalis. IgE to Der p 5 was found in six patients, but no patients had IgE to Blo t 5. CONCLUSIONS: This study of patients naturally exposed to D. pteronyssinus but not to Blomia tropicalis, provides evidence for IgE mediated cross-reactivity between allergens produced by both mite species. The results suggest that the Group 5 allergens of D. pteronyssinus and B. tropicalis are species-specific.     

Humoral immune response to the insect allergen Chi t I in aquarists and fish-food factory workers

Our examination of 225 subjects who had been exposed to the insect allergen Chi t I involved the degree of allergen exposure, the exposure-associated symptoms, and their relationship to the presence of specific IgE and IgG antibodies as well as sensitization to ubiquitous allergens. It could be shown that specific IgE antibodies found in 34% of these subjects were closely associated with symptoms ( P <0.01), whereas no relationship between IgG antibodies and complaints could be observed. Conjunctivitis (63%) and rhinitis (62%) were predominant, followed by asthma (45%) and urticaria (37%). Antibody levels of patients suffering from asthma were highest. In addition, symptoms were associated with the degree of exposure. While nearly all IgE-sensitized subjects of the medium-, high-, and very high-exposure group were symptomatic, only 57% of the sensitized individuals of the low-exposure group reported complaints. Furthermore, specific IgE antibodies were most frequently present in the groups with medium (46%) and high (54.5%) exposure, whereas IgG antibodies predominated in individuals with very high exposure (69.1%). In the low-exposure group, most subjects (73.6%) had neither IgE nor IgG antibodies.
In addition, within Chi t I sensitized subjects, sensitization to common allergens and elevated total IgE levels were more frequently present than within non- Chi t 1 sensitized individuals, indicating a predisposition to allergy.     

IgE-mediated sensitization to mould allergens among patients with allergic respiratory diseases in a desert environment

BACKGROUND: The importance of fungal allergens in the development of allergic diseases in a desert environment is uncertain. This study evaluated the prevalence of IgE sensitization to moulds among patients with allergic respiratory diseases in Kuwait - a desert country. METHODS: A total of 810 patients (male:female ratio 1.4) with a mean age of 32.3 years (range 2-76 years) with extrinsic asthma or allergic rhinitis were studied. Sera from the patients were tested by the CAP-RAST method for specific IgE to 6 fungi (Penicillium, Cladosporium, Aspergillus, Candida, Alternaria and Helminthosporium). For comparison house dust mite and Bermuda grass were also assessed. RESULTS: The overall positivity to at least one mould was 20.9%. Among 120 matched control subjects, the value was 5. 8%. The value was much higher among patients with asthma alone (45. 8%) or both asthma and rhinitis (28.3%) than those with rhinitis alone (11.8%; p < 0.001). Asthmatic children had the highest sensitization rate (66.0% in the 7- to 12-year age group), which declined sharply with age. Among asthmatics, Candida and Aspergillus had the highest sensitization rates (23.1 and 21.3%, respectively), followed by Helminthosporium (18.8%), Cladosporium (15.9%), Alternaria (14.6%) and Penicillium (13.9%). The values for mite and Bermuda grass were 41.2 and 54.6%, respectively. Among asthmatic children, severe asthma was significantly more frequent among mould-positive (51.6%) than mould-negative patients (17.5%; p < 0. 0001). CONCLUSIONS: Even in this desert environment, sensitization to moulds is quite common among patients with allergic respiratory diseases, with a striking preponderance among children with asthma. Mould allergy could also be an important factor determining asthma severity in this environment.     

Sensitization to aeroallergens among patients with allergic rhinitis in a desert environment.

BACKGROUND: The causative allergens of allergic rhinitis in desert environments are uncertain. OBJECTIVE: To determine the sensitizing aeroallergens in patients with allergic rhinitis in Kuwait, a desert country. METHODS: A total of 706 patients aged 6 to 64 years (mean 34.3 years) with allergic rhinitis were studied. Sera from the patients were screened for specific IgE to 14 inhalant allergens by the CAP-RAST method. RESULTS: Specific IgE to any allergen was detected in 86.3% of patients. The prevalence rates for allergen groups were: pollens (77.3%), house dust (62.3%), and molds (14.7%). The individual allergens with the highest positive rates were pollens of the weed Chenopodium (64.3%); Bermuda grass (55.0%), and Prosopis tree (50.3%). These plants were all imported and cultivated for the purpose of "greening" the desert. German cockroach (48.2%) and house dust mites (32.4% to 39.2%) were the most prevalent indoor sensitizers. With the exception of the molds, sensitization rates were higher for males than females. The youngest age group (6 to 17 years) had significantly higher sensitization rates than the older ones, particularly with respect to the molds (P < .01 to .001). Severe sensitization was more common with Alternaria than the other allergens and in general mold sensitization was more frequently associated with severe symptoms. Polysensitization was very common, with 81.8% of all sensitized patients positive to more than one allergen. CONCLUSIONS: Pollens of the local horticultural plants are the main sensitizing allergens among patients with allergic rhinitis in this desert environment. The practices that "green" the desert seem to also encourage allergen sensitization.     

The relationship between seroatopy and symptoms of either allergic rhinitis or asthma

BACKGROUND: Epidemiologic data on allergic rhinitis and asthma are frequently based on self-reported symptoms. OBJECTIVE: This cross-sectional study examined the relationship between self-reported symptoms and histories of allergic rhinitis or asthma and a marker of allergic sensitization, allergen-specific IgE. METHODS: We surveyed 702 pregnant women in Michigan. Blood samples were analyzed for specific IgE to 9 allergens: dust mites (Dermatophagoides farinae and Dermatophagoides pteronyssinus), cat, dog, cockroach, ragweed, timothy grass, egg, and Alternaria alternata. Seratopy was defined as a specific IgE greater than or equal to 0.35 kU/L to any allergen. RESULTS: Seroatopy was found in 66.7% of those with hay fever symptoms, 68.3% with a physician's diagnosis of asthma, and 72.1% of those with both conditions. These results differed significantly from asymptomatic subjects, where 49.8% of patients without hay fever and 50.4% without asthma were seroatopic. Race and education did not modify the relationships. Symptoms related to specific exposures were modest predictors of positive specific IgE to related allergens (positive predictive values from 26.5% to 50.3%). CONCLUSION: Self-reported symptoms of allergic rhinitis or asthma were significantly associated with allergic sensitization, but the odds ratios were of relatively low magnitude for this historical information to be considered evidence of current allergic sensitization. A 66% to 68% probability existed that those with symptoms of allergic rhinitis or asthma would have a positive specific IgE test. CLINICAL IMPLICATIONS: Self-reported histories of hay fever or asthma alone are only modest predictors of allergic sensitization. When knowledge of allergic sensitization is important, information beyond self-reported symptoms is necessary.     

Detection of recombinant Alt a1 in a two-site, IgM based, sandwich ELISA opens up possibilities of developing alternative assays for the allergen

Alternaria alternata is well known to induce IgE-mediated asthma in humans. Alt a1, a 29 kD glycoprotein doublet composed of 14.5 and 16 kD subunits, is the major allergen of this mould. Detection of Alt a1 relies on a two-site sandwich ELISA using the same IgG subclass immunoglobulin as primary and secondary antibody. In this study, we have compared two IgM monoclonal antibodies against recombinant and native Alt a1 in detecting the allergen in a two-site sandwich ELISA. Although both IgM clones detected the native and the recombinant allergen by SDS-PAGE immunoblotting and by the antibody-capture ELISA, only the IgM against recombinant Alt a1 was able to detect the corresponding, and not the native allergen, in a two-site sandwich ELISA. The IgM against native Alt a1 was unable to detect either allergen by this method. A combination of the two IgM clones and with a commercially available IgG failed to detect both allergens. However, atopic human IgE detected both forms of the allergen with the two IgM clones as primary antibody. This is the first time to demonstrate detection of Alt a1 in a two-site, IgM based, sandwich ELISA opening up possibilities for exploring novel detection methods, based on this approach.     

Occupational asthma and rhinitis related to laboratory rats: serum IgG and IgE antibodies to the rat urinary allergen

Allergic reactions to rat urinary proteins are an important cause of occupational asthma and rhinitis among laboratory workers. We have measured IgG and IgE antibodies to a purified rat urinary allergen in sera from 179 laboratory workers of whom 30 reported symptoms on exposure to rats. There was a very good correlation between IgE antibodies and positive skin tests. In addition, there was a close correlation between reported asthmatic reactions and serum IgE antibody to rat allergen: IgE ab was present in 12/18 of workers with asthmatic reactions but in only 2/135 of workers without symptoms (p less than 0.001). Serum IgG antibodies to rat allergen were present in all sera with IgE antibody but were also present in 30% of asymptomatic individuals. The incidence and quantity of IgG antibody correlated with the degree of exposure to animals (i.e., hours per day) but not with the length of exposure in years. Our results on rat allergy confirm that there is an increased incidence of asthma among individuals who were atopic as judged by positive skin tests to other allergens. However, this relationship did not apply to individuals with rhinitis alone, and excluding atopic individuals from employment would have been a very inefficient method of reducing asthma or rhinitis in this group. Our results confirm that IgE antibody responses to rat urinary allergen are an important cause of occupational disease. The results for IgG antibody suggest that their prevalence represents a marker for the degree of exposure to rat proteins.     

Clinical characteristics of seafood allergy and classification of 10 seafood allergens by cluster analysis]

The aim of this study was to investigate the clinical characteristics of children who showed sensitization to any type of seafood and to classify the 10 seafood allergens based on IgE reactivities by a cluster analysis. In children with bronchial asthma (BA) and/or atopic dermatitis (AD), we defined the 'seafood' group as 23 patients having any type of seafood specific IgE antibody (CAP system). We analyzed the clinical features, the serum total IgE and each allergen specific IgE level. In addition, ten seafood allergens were also classified by a cluster analysis. Three patients revealed immediate hypersensitivity to some seafood. The frequency of patients with AD and the total IgE in the seafood group were high and the patients in this group were tend to be sensitized to multiple allergens. Seafood allergens were classified into 4 groups, 1) salmon, sardine, horse mackerel and mackerel, 2) cod and tuna, 3) octopus and squid, and 4) crab and shrimp, by a cluster analysis. These findings corresponded to the biological classification and the classification by the reported common allergens among various types of seafood. Based on our findings, this classification is therefore considered to be useful when selecting allergens to screen for sensitization to seafood.     

Association between sensitized to food allergens and childhood allergic respiratory diseases in Taiwan

BackgroundSensitization to allergen has long been known to be relate to childhood allergic diseases. Polysensitised children have more severe atopic diseases, whereas allergic rhinitis or asthma children with cosensitized to food and inhalant allergens were under-researched.ObjectiveTo realize the association between sensitization to food allergens and pediatric allergic rhinitis and asthma in Taiwan.MethodsWe included 138 participants with sensitized to allergen as assessed by serum-specific IgE. 87 of 138 participants had allergic rhinitis and 51 participants had asthma. All participants underwent a physical examination and measurement of serum total and specific IgE values. Besides, nasal peak expiratory flow rate (nPEFR) that was performed by the participants with allergic rhinitis and were requested to complete the Pediatric Rhinoconjunctivitis Quality of Life Questionnaires (PRQLQ). Lung function test and asthma control test (ACT)/child asthma control test (C-ACT) were performed by the participants with asthma.Results39 of 87 allergic rhinitis participants with sensitized to food and inhalant allergens (AR food group), 48 of 87 allergic rhinitis participants with sensitized to inhalant allergen alone (AR inhalant group). The AR food group had significantly lower nPEFR values and higher total IgE values (p < 0.05) compared with the AR inhalant group. The AR food group had higher PRQLQ scores than the AR inhalant group. 24 of 51 asthma participants with sensitized to food and inhalant allergens (Asthma food group), 27 of 51 asthma participants with sensitized to inhalant allergen alone (Asthma inhalant group). The Asthma food group had significantly higher total IgE values (p < 0.05) compared with the Asthma inhalant group. The Asthma food group had lower lung function test values and asthma control test (ACT) scores than the other group.ConclusionsChildren with cosensitized to food and inhalant allergens have more severe clinical symptoms and abnormal laboratory findings. Sensitization to food allergen was more related to pediatric allergic rhinitis than asthma. We may need larger, longer and extended studies to confirm these findings.     

Allergenic materials in the house dust of allergy clinic patients.

INTRODUCTION: Environmental agents including animal, fungal, tree, and weed antigens are known to cause allergic rhinitis and asthma. The following study was performed to measure the antigen concentration of several of these in house dust of children seen in an allergy clinic. Comparisons are made between household allergen levels of children seen for asthma and children seen for other reasons. METHODS: Dust samples were solicited from patients in a pediatric allergy specialty clinic and other individuals associated with the clinic. Persons submitting dust were asked to complete a questionnaire describing their house. Samples were extracted, centrifuged, and filtered for sterility. Samples were stored in 50% glycerol at -20 degrees C. Specific antigens for Alternaria, Cladosporium, Aspergillus, Candida, Dermatophagoides farinae, cat, dog, oak, fescue, ragweed, plantain, and cockroach were measured using inhibition assays developed with whole antigen extract. Allergens Der p1, Der f 1, Alt a 1, and Alt a 70 kD were measured using double monoclonal antibody assays. RESULTS: Significant concentrations of whole antigen from cat, dog, oak, Alternaria, and Cladosporium were detected. Between 0.1 and 18 microg of Der f1 and Der p1 per gram of dust were also measured. Alt a 1 and Alt a 70 kD levels varied between 3.0 and 1000 U/g of dust. Significant positive correlations were observed in levels of dust mite and Alternaria allergen for patients with an evaluation of asthma. CONCLUSIONS: We found measurable levels of fungal antigens (Alternaria, Cladosporium), mite antigens, and animal antigens (dog and cat) in the majority of dust samples in this self-selected set of allergy clinic patients. Specific allergens Alt a 1, Alt a 70kD, and Der p 1 were significantly higher in the homes of asthmatic patients when compared with patients seen for reasons other than asthma. These studies support the hypothesis that fungal allergen exposure is an important component in the pathogenesis of the clinical condition known as asthma.     

Effect of environmental allergen sensitization on asthma morbidity in inner-city asthmatic children

Background Asthma causes significant morbidity in children, and studies have demonstrated that environmental allergies contribute to increased asthma morbidity.
Objective We investigated the differences between allergen skin tests and specific IgE (SIgE) and the role of IgG in regards to allergen exposure levels, and asthma morbidity in inner-city children.
Methods Five hundred and six serum samples from the National Cooperative Inner City Asthma Study (NCICAS) were evaluated for SIgE to cockroach ( Blattella germanica ), dust mite ( Dermatophagoides farinae ), and Alternaria as well as specific IgG (SIgG) and IgG₄ to cockroach ( B. germanica) and total IgE levels. Associations between sensitization to these allergens, exposures, and asthma morbidity were determined.
Results Sensitization to environmental allergens and total IgE correlated with increased health care and medication use, but not with symptoms of wheeze. Sensitization with exposure to cockroach was associated with increased asthma morbidity, whereas dust mite sensitization was correlated with asthma morbidity independent of exposure. There was also a strong correlation between SIgE levels and skin test results, but the tests did not always agree. The relationship between SIgE and asthma morbidity is linear with no obvious cutoff value. Increased Bla g 1 in the home was a good predictor for sensitization; however, this relationship was not demonstrated for Der f 1. Cockroach SIgG correlated with increased health care use, however, there was no modifying effect of SIgG or SIgG₄ on the association between cockroach SIgE and asthma morbidity.
Conclusions SIgE levels and skin prick test results to environmental allergens can serve as markers of severe asthma for inner-city children. Asthma morbidity increased in a linear manner with SIgE levels. IgG was not an important predictor or modifier of asthma morbidity.     

Quantitative assessments of IgG and IgE antibodies to inhalant allergens in patients with atopic dermatitis

Using antigen-binding radioimmunoassays, we have measured class specific antibodies against two major inhalant allergens, antigen P₁ from D. Pteronyssinus and Rye I from grass pollen, in sera from 69 patients with atopic dermatitis. The results show that many of the patients have IgE ab to these allergens in keeping with their skin tests. In all cases, the IgE ab was paralleled by IgG ab to the same allergen. In many sera, IgE ab to these inhalant allergens made a significant contribution to the total serum IgE. With two other allergens to which these patients had not been exposed, specific IgE ab was detected in only one serum, whereas the 42 sera tested did not contain IgE ab to diphtheria toxin. Eleven of the adult patients with atopic dermatitis had no history of asthma and had strongly positive skin tests. This group of patients had levels of total IgE and specific ab to antigen P₁ that were very similar to those found in a comparable group of patients who had both atopic dermatitis and asthma. Our recent finding that allergens applied to the skin can induce delayed eczematous lesions provides a mechanism by which allergens could contribute to skin lesions. Our present results support the view that specific sensitivity to common allergens should be taken into account in considering the causes of these patients' skin lesions.     

Diagnosis of Alternaria alternata sensitization with natural and recombinant Alt a 1 allergens

BACKGROUND: Diagnosis of Alternaria alternata sensitization is hampered by the variability and complexity of fungal extracts, and thus simplification of the diagnostic procedures with purified allergens should be pursued. OBJECTIVE: We sought to compare A alternata extract and purified natural Alt a 1 (nAlt a 1) and recombinant Alt a 1 (rAlt a 1) allergens for their diagnostic value. METHODS: Forty-two patients allergic to A alternata , 10 atopic patients with negative skin prick test responses to A alternata extract, and 10 healthy subjects were investigated. Skin prick tests and determination of specific IgE levels were performed with nAlt a 1 and 2 different types of rAlt a 1: rbAlt a 1, expressed in Escherichia coli , and ryAlt a 1, expressed in the yeast Yarrowia lipolytica . RESULTS: Prevalence for Alt a 1, Alt a 2, and Alt a 11 by IgE dot-blot testing was 98%, 0%, and 15%, respectively, and therefore Alt a 1 was used as a marker for A alternata sensitization. Immunoblotting and inhibition analysis showed no IgE-binding differences between nAlt a 1 and rAlt a 1. The whole group of patients with allergy to A alternata had positive skin test reactions to purified allergens at 100 microg/mL, whereas no false-positive reactions were detected. Natural or ryAlt a 1 elicited a similar response in skin tests compared with A alternata extract, although a reduced reactivity was observed with rbAlt a 1. Specific IgE levels to nAlt a 1 or rAlt a 1 showed significant correlation and similar sensitivity and specificity. CONCLUSIONS: Alt a 1, either in its natural or recombinant form, is sufficient for a reliable diagnosis of A alternata sensitization and induces skin prick reactivity comparable with that produced by A alternata extract.     

High prevalence of sensitization to cat allergen among Japanese children with asthma, living without cats

BACKGROUND: Cat allergy is common among children with asthma. Many cat-allergic patients in Japan and elsewhere do not keep cats, but nonetheless become sensitized through environmental exposure to cat allergen. OBJECTIVE: To assess the frequency of cat allergy and cat-specific immunoglobulin E (IgE) and immunoglobulin G (IgG) antibody responses in young Japanese patients with asthma in relation to self-reported cat exposure and Fel d 1 levels in dust samples. METHODS: Cat dander-specific IgE antibody was measured in sera from asthma patients using the CAP system. IgE and IgG antibody to Fel d 1 was measured by antigen binding radioimmunoassay and by chimeric enzyme immunoassay. Fel d 1 levels in dust samples from a subset of patients' homes were measured by monoclonal antibody-based enzyme immunoassay. RESULTS: Cat-specific IgE (CAP class>/=2) was found in sera from 70% of 44 patients who kept cats and 34% of 394 patients who had never kept cats. The prevalence of sensitization increased progressively to age 6 years (40%: positive), and then increased gradually to age 16 years (approximately 60%: positive) in patients who had never kept cats. There was an excellent correlation between cat CAP values and IgE levels to Fel d 1. The absolute amount of IgE antibody to Fel d 1 ranged from 0.01 to 15.6% of total IgE. Most patients who did not keep cats were exposed to Fel d 1 levels ranging from 0.07-8 microg/g dust. CONCLUSIONS: Sensitization to cat allergen is common among young asthmatic patients in Japan, even among patients who do not keep cats. Use of CAP and the chimeric enzyme-linked immunosorbent assay allows accurate diagnosis of cat allergy and quantification of specific IgE antibody levels.     

Comparative prevalence of sensitization to common animal, plant and mould allergens in subjects with asthma, or atopic dermatitis and/or allergic rhinitis living in a tropical environment

BACKGROUND AND OBJECTIVES: Current information suggests that the expression of allergic diseases is determined by the exposure and nature of the allergen. The objectives of the present study were to determine if the nature of allergenic exposition to animal, plant or fungal allergens influenced the clinical manifestations of atopic dermatitis (AD), allergic rhinitis (AR) or asthma (AS) in patients living in a tropical environment. The prevalence and degree of sensitization to these allergens were analysed by age and gender. SUBJECTS AND METHODS: A total of 1496 atopic cases, grouped according to the primary diagnosis of AD or AR or AS, were skin tested using a standardized allergen panel. Participants were categorized by age groups. The atopic index (AI) and mean weal diameter (MWD) as well as the prevalence of positive skin tests were determined for each of the patient groups and compared by age groups. RESULTS: The prevalence of atopy as well as the AI and the MWD peaked at 6-15 years of age and declined thereafter. In all the patients tested, the prevalence of sensitization was, in decreasing order; dust mites 94.3%, cockroach 41.5%, pets 31.5%, plant allergens 31.1% and fungal 19.4%. Eight hundred and ninety-three atopic patients were exclusively sensitized only to animal allergens. Of these, 38.4% had AD, 31.3% had AR and 30.5% with AS. CONCLUSION: These data demonstrate that for patients with AD, AR and AS living in a tropical environment, the prevalence of positive skin reactions to animal allergens is highest followed by plant and fungal allergens. We did not observe any association between the type of allergen and clinical manifestations. The index of atopy was similar for both sexes. The prevalence and degree of sensitization were shown to peak in young adults independent of the allergen in AD and AR patients.     

Longitudinal study on the relationship between cat allergen and endotoxin exposure, sensitization, cat-specific IgG and development of asthma in childhood--report of the German Multicentre Allergy Study (MAS 90)

BACKGROUND: Controversial data have emerged regarding the question whether cat exposure in childhood favours or decreases the risk of sensitization and allergic airway disease. In a prospective birth-cohort study, we assessed the association between longitudinal cat allergen exposure, sensitization (immunoglobulin E, IgE), IgG antibody (ab) levels to cat and the development of asthma in children up to the age of 10 years. METHODS: Of 1314 newborn infants enrolled in five German cities in 1990, follow-up data at age 10 years were available for 750 children. Assessments included yearly measurements of specific serum IgE to cat and at age 6 and 18 months, 3, 4 and 10 years measurement of cat allergen Fel d 1 in house dust samples. Additionally, Fel d 1-specific IgG ab were determined in 378 serum samples of 207 children. Endotoxin exposure in mattress dust was measured in a subgroup of 153 children at age 10 years. From age 4 years on, International Study of Asthma and Allergy in Childhood (ISAAC) questionnaires were completed yearly in order to assess the prevalence of wheeze and asthma. RESULTS: Serum IgG-levels to cat showed a large variation, however, intraindividually values showed rather constant concentration over a longer time period. The IgG levels at school-age correlated with cat allergen exposure during the first 2 years of life. Specific IgE to cat was clearly associated with wheeze ever, current wheeze and bronchial hyperresponsiveness (BHR), this was also observed for children with specific IgE ab to cat (>0.35 kU/l) plus IgG levels above 125 U/ml. A large percentage of very highly exposed children showed high IgG but no IgE responses to cat, however, not all highly exposed children were found to be protected from sensitization. Children with IgG but without IgE ab to cat showed the lowest prevalence of wheeze ever and current wheeze despite high cat allergen exposure, however, this trend did not achieve significance. While homes of cat owners showed higher Fel d 1 concentrations than homes without cats, homes of cat owners were not found to have higher endotoxin levels in carpet dust samples than homes without cats. CONCLUSIONS: We could confirm that high cat allergen exposure in a cohort with lower community prevalence of cats is associated with higher serum IgG and IgE levels to cat in schoolchildren. Sensitization to cat allergen (IgE) is a risk factor for childhood asthma. While exposure to cat allergen during infancy is associated with sensitization (IgE), only in the very highly exposed children the likelihood of sensitization (IgE) is decreased and high IgG levels to cat without IgE were associated with low risk of wheeze. However, cat-specific IgG ab levels did not protect children with IgE-mediated sensitization from wheeze.     

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.     

In vitro and in vivo responses to the recombinant bovine dander allergen Bos d 2 and its fragments

BACKGROUND: About one in every four cases of occupational rhinitis recorded in Finland is animal-induced. Bovine allergens are the most important in this respect and the largest patient group consists of dairy farmers. Allergen immunotherapy, if proven effective, safe and feasible, would be ideal for their treatment. The development of recombinant allergens has offered new potential therapeutic prospects. Fragments of recombinant Bos domesticus (Bos d 2) allergen could be suitable for this purpose because they are recognized by T cells but their IgE-binding capacity is attenuated. OBJECTIVE: The aim of this study was to verify whether the potential of the two fragments of recombinant Bos d 2 (corresponding to amino acids 1-131 and 81-172) to induce immediate allergic reaction in a shock organ (nose) was decreased compared to the complete recombinant allergen, which would be an advantageous property for a preparation intended for allergen immunotherapy. METHODS: The study group consisted of 10 dairy farmers with cow-induced allergic rhinitis. We used the IgE titres against native Bos d 2 measured by indirect IgE ELISA to characterize the level of sensitization and compared the IgE titres in the rhinitis patients with 12 cow-sensitized asthmatic farmers and 12 healthy students. In vitro reactivity against recombinant Bos d 2 and its two fragments was studied by indirect IgE ELISA and in vivo reactivity by nasal provocation tests. RESULTS: The IgE titres against native Bos d 2 of patients with rhinitis tended to be lower than the titres of asthmatics. The healthy students did not exhibit any detectable IgE reactivity to native Bos d 2. In the patients with rhinitis, there was no statistically significant difference between IgE responses against native and recombinant Bos d 2, whereas with both in vitro and in vivo, the reactivity to both fragments of recombinant Bos d 2 was lower than the reactivity to the complete recombinant allergen. CONCLUSIONS: Due to the decreased in vivo capacity to induce immediate allergic reactions, the fragments may be better tolerated in allergen immunotherapy than the complete allergen.