Coincidence of atopy and its profile (monosensitization/polysensitization) between sibling pairs.

BACKGROUND: Results of epidemiologic studies have shown that childhood atopy is probably a hereditary disorder. In the atopic population, some individuals are sensitized to only 1 class of allergens (monosensitized), whereas others are sensitized to more than 1 class of allergens (polysensitized). OBJECTIVE: To investigate whether atopy and its profile (monosensitization/polysensitization) tend to coincide in sibling pairs. METHODS: We evaluated sensitization to 5 classes of aeroallergens (house dust mites, animal danders, pollens, molds, and cockroach) using skin prick testing in 564 children with symptoms suggestive of allergic diseases (index children) and their paired siblings. RESULTS: The frequency of sibling atopy was highest (56.8%) for polysensitized index children (n=222), intermediate (45.4%) for monosensitized index children (n=196), and lowest (30.8%) for nonsensitized index children (n=146). The proportion of polysensitization among atopic siblings was significantly higher for polysensitized (47.6%) than for monosensitized (32.6%) index children. Polysensitized index children were found to more frequently have polysensitized siblings (27.0%) than were monosensitized index children (14.8%), with an odds ratio of 2.13 (95% confidence interval, 1.30-3.49), whereas the likelihood of having a monosensitized sibling was similar for monosensitized and polysensitized index children. CONCLUSION: These data suggest a coincidence of atopy and its profile in terms of monosensitization and polysensitization in sibling pairs, although the relative importance of genetic and environmental influences requires further study.     

Coincidence of atopy profile in terms of monosensitization and polysensitization in children and their parents

BACKGROUND: Results from epidemiologic studies have shown that childhood atopy is probably a hereditary disorder, because the offspring of affected parents have a higher risk of developing atopy. Among the atopic population, some subjects are sensitized to only one class of allergens (monosensitized), while other subjects are sensitized to more than one class of allergens (polysensitized). The aim of this study was to investigate whether atopy profile (monosensitization/polysensitization) in children is linked to the same conditions in their parents. METHODS: We evaluated sensitization to five classes of aeroallergens (house dust mites, animal danders, pollens, molds, and cockroach) by skin prick testing in a group of 494 children with suspicious allergic symptoms and in their parents. RESULTS: The frequency of parental atopy was highest (51.6%) in polysensitized children (n = 189), intermediate (37.1%) in monosensitized children (n = 178), and was lowest (22.4%) in nonsensitized children (n = 127). The proportion of polysensitized subjects among atopic parents was significantly higher for polysensitized children (45.6%) than for monosensitized children (31.1%). Polysensitized children were found to more frequently have one or both parents polysensitized (32.3%, 7.4%) than monosensitized children (18.5%, 2.2%) with odds ratios of 2.09 (95% CI: 1.29-3.40) and 3.48 (1.12-10.78), respectively, whereas the likelihood of having one or two monosensitized parents was not increased for polysensitized children. CONCLUSION: Our data suggest a familial coincidence of atopy profile in terms of monosensitization and polysensitization, although the relative importance of genetic or environmental influence should be studied further.     

The natural history of allergy: the development of new sensitizations in asthmatic children

Allergy is an important risk factor for asthma in children as most of asthmatic children are sensitized. The aim of the study was to investigate the natural course of sensitizations in a group of children (340) at the onset of asthmatic symptoms. We subdivided children in three groups depending on the age at first visit (3-7-11 years) and followed them for 4 years. All children underwent three visits, each including skin prick test, every two years. In the 3-year age group (n = 133), 59% of children were sensitized at first visit, but the percentage increase to 88% at third visit. When looking only at allergic children at first visit (261), we demonstrated that polysensitization became higher than monosensitization since the age of 11. Analysis of sensitization distribution over the time revealed that house dust mites were prominent from the age of 3 years. Parietaria and grass pollens as well as olive pollen significantly increased, particularly during the 4-year follow-up in the 7-year group. Analysis of sensitization score demonstrated that the age range from 3 to 11 is at high risk to polysensitization. In conclusion, this study provides evidence that sensitization is frequent in asthmatic children, polysensitization represents the natural history of allergy and the type of immune response should appear different for each allergen.     

Multiple-allergen and single-allergen immunotherapy strategies in polysensitized patients: looking at the published evidence

In allergen immunotherapy there is debate as to whether polysensitized patients are best treated with many allergens simultaneously (chosen according to the sensitization profile, a predominantly North American approach) or a single allergen (chosen according to the most clinically problematic allergy, a predominantly European approach). In patients seeking treatment for moderate-to-severe respiratory allergies, polysensitization is more prevalent (range, 50% to 80%) than monosensitization in both the United States and Europe. Safe, effective, single-allergen preparations will most likely have been tested in polysensitized patients. In robust, large-scale clinical trials of grass pollen sublingual tablets, polysensitized patients benefited at least as much from allergen immunotherapy as monosensitized patients. A recent review of multiallergen immunotherapy concluded that simultaneous delivery of multiple unrelated allergens can be clinically effective but that there was a need for additional investigation of therapy with more than 2 allergen extracts (particularly in sublingual allergen immunotherapy). More work is also required to determine whether single-allergen and multiallergen immunotherapy protocols elicit distinct immune responses in monosensitized and polysensitized patients. Sublingual and subcutaneous multiallergen immunotherapy in polysensitized patients requires more supporting data to validate its efficacy in practice.     

The most common phenotypes of sensitization to inhalant allergens in childhood

Background Atopic individuals are frequently sensitized to a limited number of certain allergens, although most of them are exposed to multiple inhalant allergens in daily life. Objective We investigated the hypothesis that observed common patterns of sensitization might occur with similar frequency within two independent study populations of school-children. Methods The results were derived from skin-prick tests conducted on two large samples of children (study 1:n= 583; study 2: n= 1099) examined with the same panel of six inhalant allergens. Results In order to ensure that the comparison was uniform, the younger subpopulation of study 1 (n= 147) was compared with the sample of study 2 (n= 374). The highest frequency for monosensitization was found for sensitization to Dermatophagoides pteronyssinus (study 1: 18.4%, study 2: 20.3%), followed by monosensitization to grass pollens (study 1: 12.2%; study 2: 8.8%). Using multiple logistic regression for each specific sensitization, a significantly increased relative risk of sensitization to hazel pollens (study 1 OR 5.9; study 2 OR: 24.3) appeared to be associated with sensitization to birch pollens. The same applied to dog dander (study 1 OR: 7.3; study 2 OR: 2.6), which showed an association with sensitization to cat dander. Conclusion In summary, our data suggest that certain clusters of monosensitization and polysensitization to common inhalant allergens exist among a given population. This may well be a reflection of diversity in disposition to specific sensitization and/or antigen crossreactivity. From a practical point of view the data also might help in counselling parents of allergic children.     

Age at symptom onset and distribution by sex and symptoms in patients sensitized to different allergens

The aim of our study was to analyze the clinical features, particularly the age at symptom onset, of allergic subjects (asthma and/or rhinitis) on the basis of the etiologic elements (sensitization to various allergens). We identified a group of monosensitized patients and a group of polysensitized patients. Within these groups, we identified subgroups of subjects monosensitized to one of the five main allergenic mixes (mites, Gramineae, trees, Parietaria, and Artemisia) and five subgroups of patients sensitized nonexclusively, that is, polysensitized, to the same allergens. The comparison between the two groups and among the various subgroups enabled us to conclude that:

• 1)

  mono- and polysensitized patients present some clinical features so different as to constitute two clearly distinct clinical groups
• 2)

  analysis of the clinical features associated with the sensitization to a specific allergen brings us to significantly different conclusions when we consider subgroups of monosensitized or polysensitized patients
• 3)

  the parameter "age at symptom onset" shows great heterogeneity among both the mono- and the polysensitized subgroups - in particular, the great differences in mean age among the monosensitized subgroups (trees>y4rtemi.s(fl>Pflrie/flria>Gramineae>mites) appear very interesting and are open to various interpretative hypotheses
• 4)

  unlike the polysensitized group, in the monosensitized group and subgroups, mean age is similar between men and women and, only for tree- and parietaria -monosensitive patients, also between asthmatic and rhinitic subjects.

     

Evaluation of recombinant allergens Bet v 1 and Bet v 2 (profilin) by Pharmacia CAP System in patients with pollen-related allergy to birch and apple

Sixty-five patients presenting either rhinoconjunctivitis or asthma and sensitized to pollens of trees of the order Fagales were studied by the Pharmacia CAP system in order to assess specific IgE for the important birch pollen allergens Bet v 1 and Bet v 2. All 65 subjects reacted to at least one of the recombinant birch allergens: 43% to Bet v 1, 30.7% to Bet v 2, and 26% to both. Patients monosensitized to birch did not react to Bet v 2. of patients with a history of oral allergy syndrome after eating apples, 16/28 (57%) reacted to Bet v 1; among 20 polysensitized subjects presenting oral allergy syndrome after consumption of apple, four reacted to Bet v 2 (20%). Among patients with IgE against both recombinant allergens, six (35.30%) presented symptoms of allergy after eating apples. Our results indicate that sensitization to Bet v 1 is specific for birch and apple allergies, whereas sensitization to Bet v 2 is common in polysensitized patients.     

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.     

Skin sensitization to common allergens in Turkish wheezy children less than 3 years of age

Infants and small children with asthma are not commonly skin tested, as allergy is not considered to be a major cause of infantile asthma. The aim of this study was to determine the frequency of skin test positivity to various allergens in wheezy children less than 3 years of age. We evaluated 161 patients with infantile asthma (median age 20 months) and 100 healthy controls (median age 18 months). Infantile asthma was defined as three or more episodes of wheezing in a child less than 3 years of age, whose symptoms improved on treatment with beta-agonist and anti-inflammatory agents. All children were skin tested to house dust mites (HDM), pollens, molds, and cow milk extracts using prick technique. One hundred and eighteen (73.3%) children In the patient group tested positive to HDM, 84 (52.1%) to pollens, 37 (22.9%) to molds, and 16 (10%) to cow milk. Sensitization rates to HDM were significantly higher in the patient group than In the healthy controls. Sensitization rates to pollens were not statistically different between the two groups. There was no association between family history of atopy and frequency of sensitization to allergens in the wheezy and control groups. We concluded that skin sensitization to allergens was common In wheezy infants. The prevalence of sensitization to indoor allergens was higher than to outdoor or food allergens.     

Relationship between Bet v 1 and Bet v 2 specific IgE and food allergy in children with grass pollen respiratory allergy

Grass allergy is the most common pollinosis in Northern Italy. Some patients with grass allergy show polysensitization against other pollens and plant-derived foods. In these patients oral allergic syndrome (OAS) is frequently associated. To evaluate the correlation between food allergy or food sensitization and specific IgE against panallergens such as Bet v 1 and Bet v 2, we studied 56 children (mean age: 8 years 5 months) suffering from respiratory allergy due to grass pollens were enrolled. Specific IgE against the most important food, inhalant allergen and Bet v 1, Bet v 2 were performed by ImmunoCAP technology (UniCAP 1000, Pharmacia Diagnostics, Uppsala, Sweden). We found 14 children (25%) sensitized to Bet v 1 and 13 (23%) to Bet v 2; in 24 cases (42.3%) a sensitization to at least one of the 2 panallergens was observed. Five of the 14 cases (36%) sensitized to Bet v 1 showed food allergy and 8 (57%) food sensitization; 6 (46%) of the 13 children sensitized to Bet v 2 showed food allergy and 7 (54%) food sensitization; only one case of Bet v 1 specific IgE without food allergy or sensitization was seen. Sixteen subjects (29%) showed food allergy (group A); 20 children (35.5%) multiple sensitizations to inhalant and at least one plant-derived food (group B); 20 subjects (35.5%) only inhalant allergens (group C). Sensitization to Bet v 1 (P<0.03) and Bet v 2 (P<0.009) is from a statistical point of view significantly higher in groups A and B than in group C. In the 16 patients with food allergy hazelnut was the major triggering food (50%), followed by peanut (38%), kiwi (31%), apple and walnut (19%). Specific IgE for Bet v 1 is more associated with nuts and legumes, while Bet v 2 is more related to fresh fruit and vegetables. In conclusion grass pollinosis is frequently associated with polysensitization to other pollen and food allergens. Bet v 1 and Bet v 2 specific IgE are significantly higher in these patients than in patients with grass monosensitization, and this sensitization may be considered a possible risk factors to evolve later into food allergy. Among the offending foods, legumes and the nut group are mostly related to Bet v 1, while vegetables and fresh fruits to Bet v 2.     

Injection immunotherapy with different airborne allergens did not prevent de novo sensitization to ragweed and birch pollen north of Milan

BACKGROUND: Previous studies suggest that allergen-specific immunotherapy (SIT) with a single allergen may prevent sensitization to other airborne allergens. OBJECTIVE: To assess the effectiveness of injection SIT in preventing sensitization to birch and ragweed pollen north of Milan, a geographical area that was recently colonized by these two airborne allergens. METHODS: 691 adult patients monosensitized to grass (n = 342), pellitory (n = 76), ragweed (n = 66), birch (n = 112), and house dust mite (n = 95) were studied. 284 (41%) of them received injection SIT as part of routine outpatient care; the remaining 407 (59%) not submitted to SIT, served as controls. All patients underwent follow-up visits after no less than 2 years in order to detect possible new sensitization to birch and/or ragweed. RESULTS: 227 (33%) patients became sensitized to birch and/or ragweed pollen during the follow-up period. Surprisingly, the prevalence of new sensitizations was significantly higher among subjects receiving SIT (132/284; 46%) than among those not receiving SIT (95/407; 23%; p < 0.001). 27 subjects developed new sensitization to birch and/or ragweed pollen while undergoing SIT. These findings were consistent in all subgroups with different airborne allergies. CONCLUSION: In this study, injection SIT did not exert any preventive effect against denovosensitization to the two novel airborne allergens, birch and ragweed pollen, in adult monosensitized patients.     

Recent pollen sensitization and its possible involvement in allergic diseases among children in a pediatric allergy clinic]

We studied the rate of sensitization to several pollen allergens as well as to house dust mites in 226 children visiting our pediatric allergy clinic during the past 3 years (from April 1996 to March 1999). The allergens studied were Sugi (Japanese cedar pollen, Cryptomeria japonica), Kamogaya (Dactylis gromerata), Butakusa (ragweed, Ambrosia artemisiifolia), and Der f (house dust mite, Dermatophagoides farinae). The presence of nasal symptoms (either seasonal and perenial) was checked in 97 children visiting the clinic in March 1999. Overall average sensitization rates were 82.3% for Der f, 53.1% for Sugi, 38.5% for Kamogaya, and 17.1% for Butakusa. Among children aged 12 or more, sensitization rates for Sugi and Kamogaya were much higher (68.8%, 56.3%, respectively). Those who had seasonal nasal symptoms showed significantly higher rates of sensitization to the pollens. However, more than half of patients without nasal symptoms, 62.8% of whom had only atopic dermatitis (AD), also showed sensitization to the pollens. Several possible factors accounting for pollen sensitization in children with only AD and no sasal symptoms, such as existence of occult allergic rhinitis, future onset of allergic rhinitis, or pollen as directly aggravating factor of AD, need to be evaluated by careful follow-up of these cases.     

Statistical analysis of IgE antibodies to the common inhalant allergens in 44,496 sera

A statistical analysis of RAST screening of 44,496 sera, submitted in 1986 and 1987 for routine diagnostic allergic examination, was performed. The sera were tested on a fixed panel of allergens, regardless of the patient's history. The association of a positive RAST with age and month of birth was studied. It was concluded that among the inhalant allergens, house-dust mite was the most frequent sensitizer for all age groups, followed by grass pollen and cat dander. Sensitization to cat dander occurred twice as often as sensitization to dog dander. Among children less than 4 years of age, a different profile of sensitization was found, indoor allergens (mites, animal danders) being more important than outdoor allergens (pollen). Furthermore, we found that children born during December-February had a slightly but significantly greater chance of becoming sensitized to grass pollen compared with children born during September and November (P less than .05). Children born during July-September had a greater chance of becoming sensitized to house dust mite compared with children born during January-March (P less than .05). Finally, it was found that children born during October-December had a greater chance of becoming sensitized to dog dander compared with children born during March-May.     

Comparison of allergic indices in monosensitized and polysensitized patients with childhood asthma

Monosensitization differs both immunologically and clinically from polysensitization, and specific immunotherapy is more effective in patients sensitized only to a single pollen than in multiple-pollen sensitized patients. To further examine the differences between monosensitized and polysensitized allergies, allergic indices were examined in 68 monosensitized and 62 polysensitized patients with childhood asthma. Measurements included symptom scores, eosinophil counts, skin prick tests, serum total and specific IgE levels, and IL-10 levels, and were used to compare allergic indices between the two groups. Patients were followed for 18 months following immunotherapy to examine the effectiveness of the treatment. Symptom scores and total IgE levels were significantly higher in the polysensitized group than those in the monosensitized group (p<0.05). The levels of skin test response decreased significantly in both groups following immunotherapy. In the monosensitized group, symptom scores and specific IgE levels were significantly reduced after immunotherapy (p<0.05). In the polysensitized group, symptom scores were reduced after immunotherapy (p<0.05), but the degree of reduction was less than that of the monosensitized group (p<0.05). Moreover, in the polysensitized group, specific IgE levels after immunotherapy did not differ from that before immunotherapy. Serum IL-10 levels were not significantly increased after immunotherapy in either group. In conclusion, polysensitized patients tend to show higher allergic indices and immunotherapy might be less effective for these patients.     

Sensitization to different pollens and allergic disease in 4-year-old Swedish children

BACKGROUND: Although the relationship between sensitization to different inhalant allergens in adolescents and adults has been intensively studied, information concerning sensitization in children is scarce in particular to pollens. OBJECTIVES: In 4-year-old children to elucidate the pollen immunoglobulin (IgE) antibody profile (birch only, timothy only and combinations of three pollens (birch, timothy or mugwort) and to relate the results to other inhalant and food allergens, as well as the presence of allergic diseases. METHODS: A total of 2551 4-year-old children belonging to a prospective birth cohort, which has been followed longitudinally (BAMSE), were investigated with respect to IgE antibodies to pollen and other inhalant and food allergens, and expression of allergic disease, based on questionnaire data. RESULTS: Eleven percent (n=285) of the children were sensitized to pollen. Birch was the dominating cause of pollen sensitization (birch sensitization only, n=133); followed by timothy grass pollen (n=56) and a combination of two (n=64) or three (n=30) pollens. A remarkably high proportion of the children sensitized only to birch was also sensitized to other inhalant allergens. This was not seen for children sensitized only to timothy. The highest frequencies of IgE reactivity to food were found in the group of children sensitized to the combination of birch, timothy and mugwort pollen. Children sensitized to timothy only, exhibited symptoms of allergic disease significantly less frequently compared with children sensitized to birch only. Sensitization to birch pollen was found to be closely associated with rhinitis and eczema compared with asthma. The highest frequency of asthma and/or rhinitis and/or eczema was reported in children sensitized to at least two pollens. CONCLUSION: Our results demonstrate that birch is the dominating source of pollen sensitization at the age of four in Sweden. This might associate with the pattern of sensitization to other inhalant and food allergens as well as influence on the expression of allergic disease in this particular age group.     

Relationship between aeroallergen and food allergen sensitization in childhood

BACKGROUND: Previous studies measuring the prevalence of allergen sensitization have been relatively small and used small numbers of allergens. To effectively evaluate children with atopic disease, we need an accurate knowledge of which allergens are important. OBJECTIVE: To measure the prevalence of sensitization within a large unselected birth cohort, to examine the associations between sensitization to different allergens and determine whether atopy can be defined by a small panel of allergens. METHODS: The Avon Longitudinal Study of Parents and Children is a population-based birth cohort of 13,638 singletons surviving to 4 weeks of age. The cohort was skin tested at 7 years of age to house dust mite (Dermatophagoides pteronyssinus), grass pollens, cat, peanuts, mixed tree nuts and egg and one of three other panels: animal danders, foods or aeroallergens. Sensitization was defined as a weal diameter of > or =3 mm. The strength of associations between sensitization to different allergens was tested by calculating the odds ratio adjusted for sensitization to D. pteronyssinus and grass pollen and gender. RESULTS: Valid data were obtained from 6412 singletons. Sensitization was most common to aeroallergens: grass pollens (8.5%), D. pteronyssinus (7.8%), cat (4.9%), D. farinae (3.6%), dog (2.7%), horse (1.4%), rabbit (1.4%). Of the foods tested, the most common sensitization was to peanut (1.4%) and mixed tree nuts (1.0%). More than 95% of subjects with sensitization to any of the 29 allergens tested were sensitized to one of grass, D. pteronyssinus or cat allergen. There were strong associations of multiple sensitizations both within and between different allergen classes (pollens, animals, foods, peanut and tree nuts). CONCLUSIONS: Seven-year-old children in the UK are primarily sensitized to aeroallergens, but also to peanuts and tree nuts. There are strong associations between sensitization within allergen groups as well as between allergen groups. Further studies are required to observe whether similar associations are seen with clinical allergy to these allergens.     

House dust mite and cockroach exposure are strong risk factors for positive allergy skin test responses in the Childhood Asthma Management Program

BACKGROUND: Children with asthma have a high prevalence of environmental allergies, especially to indoor allergens. The relationships of exposure to indoor allergens (dust mites, cat, dog, cockroach, and molds) and other host factors to allergy sensitization have not been evaluated simultaneously in a large cohort. OBJECTIVES: We studied 1041 children aged 5 to 12 years with mild-to-moderate asthma to determine risk factors associated with having positive allergy skin test responses to indoor allergens. Also, we described, compared, and contrasted 6 allergens in the home environments of these children from 8 North American cities. METHODS: Data were used from baseline visits of the Childhood Asthma Management Program. Patients' sensitivities to house dust mites (Dermatophagoides farinae and Dermatophagoides pteronyssinus), cats, dogs, cockroaches, and molds were examined for relationships to demographic variables, home dust allergen exposures, number of other positive allergy skin test responses, total serum IgE levels, and smoking in the home. RESULTS: San Diego (78.5%) and Toronto (59.3%) had the topmost percentages of homes with moderate-to-high house dust mite levels. Boston (21.5%), St Louis (16.3%), and Baltimore (13.4%) had the highest percentages of homes with detectable levels of cockroach allergen. For house dust mites, the higher the level of allergen exposure, the more likely patients were to have positive allergy skin test responses, with relative odds of 9.0 (95% confidence interval, 5.4-15.1) for those exposed to high mite levels (>10.0 microg/g dust) relative to those unexposed. Even exposure to low levels of mite allergen (0.020-2.0 microg/g) was found to be a significant risk factor for sensitization. For cockroach allergen, those with detectable home exposure were more likely to have positive skin test responses (relative odds, 2.2; 95% confidence interval, 1.3-3.8) than those with undetectable exposure. In contrast, levels of exposure to cat, dog, and mold allergens were not related to sensitization rates. For cat allergen, this may reflect lower rates of cat ownership among highly sensitized subjects. Furthermore, the number of allergy skin test responses that were positive, excluding the test for the outcome of interest for each model, and total serum IgE levels were strong independent predictors of sensitization. CONCLUSIONS: Levels of exposure determined by house dust analysis are important determinants of sensitization for dust mite and cockroach allergen. This relationship was not demonstrable for cat, dog, or mold allergens, possibly because of confounding factors. For all allergens studied, the degree of atopy, determined by the total number of positive skin test responses or by total serum IgE levels, is an important contributing risk factor for sensitization.     

Sensitization to house dust mites in Reykjavik, Iceland, in the absence of domestic exposure to mites

BACKGROUND: House dust mites are common sources of indoor allergens. In Reykjavik, Iceland, 9% of the young adult population had serum-specific IgE to Dermatophagoides pteronyssinus. Sensitization to mites is usually assumed to be due to exposure to house dust mites in the indoor environment. This investigation was carried out to measure the concentrations of house dust mite allergens and to investigate which species of mites were present in beds in Iceland. METHODS: A total of 197 randomly selected adults were visited at home using the European Community Respiratory Health Survey (ECRHS) II Indoor protocol. Dust samples were collected from mattresses for measurement of house dust mite allergen concentrations and to estimate the number and type of house dust mites. Additional samples from mattresses and floors were collected from the homes of 10 patients with positive skin prick tests (SPT) to D. pteronyssinus. House dust mite allergen concentrations were measured using ELISA and examination of mite species was carried out using microscopy. Climatic parameters were assessed using psychrometer readings in the bedrooms and outdoors. RESULTS: We found two single mite specimens, both D. pteronyssinus, in two dust samples. Mite allergen analyses indicated that two other dust samples had Der f 1 results close to the cut-off of 0.1 microg/g of dust. No samples were positive for Der p 1. In an additional collection of dust from the homes of 10 SPT-positive patients no Dermatophagoides spp. were found. CONCLUSIONS: Reykjavik citizens are exposed to extremely low amounts of house dust mite allergens in their homes. Possible alternative sources for sensitization are discussed, such as bird nests, exposure from travelling abroad, or other mites or invertebrates that cross-react with house dust mite allergens. Our findings suggest that exposures other than to house dust mites indoors are possible sources of mite allergen exposure.     

House dust mite allergen (Der p I) and respiratory symptoms in children: a case-control study

The association between house dust mite allergen in house dust and childhood respiratory symptoms was investigated in a case-control study of 259 children with reported chronic respiratory symptoms and 257 control children without reported respiratory symptoms. The Der p I concentration in floor dust of the living room and bedroom and in mattress dust was determined using an enzyme immunoassay. Venous blood samples were taken from all children for serum IgE determination against house dust mite (Dermatophagoides pteronyssinus) by radioallergosorbent assay (RAST). A questionnaire was administered to the parents of the children to elicit information about the home, about changes made to the home in the past in relation to respiratory symptoms, and about a number of risk factors for childhood respiratory disease. In 83% of the dwellings of cases and 89% of those of controls, Der p I concentrations higher than 2000 ng/g were found, and in 54% of the dwellings of cases and 57% of those of controls, the concentrations exceeded 10 000 ng/g dust. In a crude analysis, cases were generally exposed to lower Der p I concentrations than controls. Restriction of the analysis to cases sensitized to dust mites, and non-sensitized controls, taking the type of floor covering into account, showed not significantly higher Der p I concentrations in bedroom floor dust of cases. However, restriction of the analysis to cases sensitizied to dust mites and cases not sensitized to house dust mites — adjusting for allergen avoidance measures taken in the past — revealed a positive association between the Der p I concentrations in bedroom floor dust and mattress dust and sensitization. This finding indicates that allergen avoidance measures modify current exposure to Der p I. This obscures the relationship between the exposure to mite allergens and sensitization, and hampers the estimation of the association between exposure to house dust mite allergens, sensitization and the development of respiratory symptoms.     

Cross-allergenicity of pollens from the Compositae family: Artemisia vulgaris, Dendranthema grandiflorum, and Taraxacum officinale.

BACKGROUND: Chrysanthemum, dandelion, and mugwort belong to the Compositae (Asteraceae) family. Their cross-allergenicity has not yet been completely evaluated. OBJECTIVE: To investigate the sensitization and cross-allergenicity of these 3 plants. METHODS: We reviewed 6,497 respiratory allergic patients who underwent skin prick tests (SPTs) during the last 10 years (1995-2005) and analyzed the sensitization rates of the 3 pollens. We sorted this population by wheal size and selected the monosensitized or cosensitized patients. Their serum samples were used to evaluate specific IgE (sIgE) and cross-allergenicity of the 3 pollens by CAP, immunoblotting, and inhibition enzyme-linked immunosorbent assay (ELISA). RESULTS: On SPTs, mugwort, chrysanthemum, and dandelion sensitized 13.4%, 10.0%, and 8.5% of the enrolled population, respectively, and 5.2% of the population was cosensitized to all 3 pollens. Some patients were monosensitized to 1 species (1.5% to chrysanthemum, 1.4% to dandelion, and 4.5% to mugwort). In inhibition ELISA that used a pooled serum sample cosensitized to all 3 pollens, mugwort inhibited sIgE bindings to chrysanthemum, dandelion, and mugwort up to 95%, 86%, and 96%, respectively. The 50% inhibitory allergen concentrations for sIgE to each of the 3 species were not different between solid-phase antigen and mugwort. The mugwort sIgE of this pooled serum was suppressed up to 74% and 27% by chrysanthemum and dandelion, respectively. The 50% inhibitory allergen concentrations of chrysanthemum and dandelion for mugwort sIgE were 0.3 and 57.0 microg/mL, respectively, whereas that of mugwort was 0.05 microg/mL. We found a patient who was truly monosensitized to dandelion. CONCLUSION: Chrysanthemum and dandelion were frequently cosensitized with mugwort in the general population with respiratory allergic diseases. These 2 species also showed extensive cross-allergenicity with mugwort. True monosensitization to these 2 species was possible.