Relevance of specific IgE antibody titer to the prevalence, severity, and persistence of asthma among 19-year-olds in northern Sweden

Isotype diversity of antibodies specific for component allergens in the context of allergic diseases: eosinophilic esophagitis (EoE), asthma, and the alpha-gal syndrome (AGS)

From the earliest days of studying the reagins in allergic sera that give rise to the Prausnitz-Kuestner reaction, there was evidence that there were other types of antibodies (Ab) specific for allergens, particularly those induced by immunotherapy. By 1980, not only was IgE recognized and could be measured, but the presence of other isotypes including IgG and IgA in patients with IgE was well established. From that time onwards the development of monoclonal antibodies made it possible to distinguish and measure antibodies of other isotypes such as IgG4, IgG2, and IgG3. Over the past 40 years two things have dominated the field- firstly, the techniques for measuring isotype specific antibodies to allergens have improved steadily. Secondly, several different allergic diseases or phenomena have been identified in which isotype diversity of the antibodies has become a major issue. Prior to 1990 only occasional cases of eosinophilic esophagitis (EoE) had been identified, but since then they have become common. Most of the cases have positive skin tests and/or IgE Ab to cow's milk or wheat, but it became obvious that most cases of EoE are not primarily related to IgE. Today it is clear that IgG4 Ab to these allergens play a significant role in cases of EoE. In 2000 the first reports of children developing tolerance to cat allergen appeared. Today it is clear that this tolerance depends on high levels of IgG4 antibodies and there is increasing evidence that the IgG4 response is primarily against Fel d 1. The most recent novel allergic disease is the alpha-gal syndrome (AGS). This condition is based on IgE antibodies specific for the oligosaccharide galactose alpha,1-3-galactose, which are primarily induced by tick bites. However, in this case it was already well known that all immunocompetent primates have made IgG and IgM antibodies to this oligosaccharide. Furthermore, it is not clear whether the IgG isotypes, particularly IgG1 and IgG3, play a role in the inflammatory response to the oligosaccharide. Overall, it is clear that current and future investigation of allergic diseases requires careful assessment of allergen specific antibodies of diverse isotypes in addition to IgE.

High risk of asthma among early teens is associated with quantitative differences in mite and cat allergen specific IgE and IgG4: a modified Th2 related antibody response revisited

BACKGROUND

Although proteins derived from cats are an important contributor to indoor allergen exposure in relation to asthma, it has been known for at least twenty years that some children who live in a house with a cat can become clinically tolerant to these animals. In 2001, we reported that children exposed to high levels of cat allergens made high levels of IgG4 antibodies to the cat allergen Fel d 1, and we coined the term "a modified Th2 response". However, this phenomenon is still poorly understood.

METHODS

We studied serum antibodies among 616 individuals in the Viva unselected birth cohort recruited at their early teen visit (mean age 13.1 SD 0.8). IgE and IgG4 antibodies were measured by ImmunoCAP to inhaled allergens as well as the best characterised component allergens of cat, Fel d 1, Fel d 2, Fel d 4, and Fel d 7, and the dust mite allergens Der p 1, Der p 2, Der p 10, and Der p 23.

FINDINGS

The results confirm that young teens living in a home with a cat make high levels of IgG4 specific for cat allergens, and that those antibodies, and specifically those to Fel d 1 are negatively associated with asthma. By contrast, the IgG4 responses to Fel d 4 and Fel d 7 are significantly lower and have no significant association with asthma. Perhaps more surprisingly, a similar effect is seen in relation to dust-mite allergens. Although the allergen Der p 1 is a major part of the IgE response to mite allergens, this protein also induced high prevalence and levels of IgG4 antibodies and has a less strong relationship to asthma than IgE to Der p 2 or Der p 23. Indeed, values of specific IgE to Der p 1 >3.5 IU/mL were not significantly related to asthma (OR 1.5 CI 0.8-2.8, p = 0.3, Chi2 test). The prevalence and levels of specific IgG4 to these less abundant allergens are significantly lower for Der p 2 and almost absent for Der p 23.

INTERPRETATION

High exposure to specific allergens in household dust can enhance production of both sIgE and sIgG4 antibodies, while allergens where abundance is significantly lower in dust can induce sIgE with limited or no sIgG4. The result is that the less abundant allergens, i.e., Fel d 4, Fel d 7, Der p 2, and Der p 23, may have a significantly higher relevance to asthma than expected because they induce less sIgG4.

FUNDING

This work was funded by R01-AI20565 (TPM) and support for the IgE and IgG4 assays provided by Phadia/Thermo Fisher Kalamazoo, Michigan. Project Viva is also supported by NIH R01HD034568 and R24ES.

Prevalence and risk factors for allergic sensitization: 3 cross-sectional studies among schoolchildren from 1996 to 2017

Background

The prevalence of allergic sensitization and allergic diseases has increased for decades in Northern Europe, but recent studies are lacking.

Objective

We sought to study the prevalence trends of allergic sensitization, associated risk factors, and the association with asthma and allergic rhinitis (AR) among children in Northern Sweden.

Methods

Three cohorts of children aged 7 to 8 years participated in a skin prick test (SPT) with 10 airborne allergens in 1996, 2006, and 2017, with 2148, 1693, and 1762 participants tested, respectively, representing 87% to 90% of schoolchildren in the catchment communities. Adjusted Poisson regression was used to identify risk factors for allergic sensitization and the association with asthma and AR.

Results

The prevalence of any positive SPT response increased from 21% in 1996 to 30% in 2006 and remained at 30% in 2017 (P < .001). Sensitization to cat was the most common for all the years. The risk factor pattern for a positive SPT response was similar in all examinations, with positive and significant associations with a family history of allergy (risk ratio, 1.4-1.5) and negative and significant associations with having a cat at home (risk ratio, 0.7-0.8). The prevalence of physician-diagnosed asthma increased, but the association with allergic sensitization weakened. The opposite trends were found for AR-decreasing prevalence and strengthened association with allergic sensitization.

Conclusions

The prevalence of allergic sensitization increased from 1996 to 2006 but plateaued in the next decade, whereas the risk factor pattern remained stable. The diverging trends of associations between allergic sensitization and asthma and AR suggest secular trends in the clinical management of allergic diseases.

Sensitization patterns to cat molecular allergens in subjects with allergic sensitization to cat dander

BACKGROUND

The use of molecular allergology has increasingly become common in the diagnosis and management of allergic diseases. However, there is still a lack of data on cat molecular allergens in adults. Therefore, we aimed to uncover the sensitization patterns to cat molecular allergens.

METHODS

Participants were recruited from the West Asthma Sweden Study, a population-based study enriched with asthma subjects aged 16-75 years. Of 1872, 361 individuals were positive for cat dander immunoglobulin E and were further analysed for cat molecular allergens (Fel d 1/2/4/7). Sensitization patterns were classified as monosensitization, polysensitization, and concomitant sensitization, and were related to demographic and clinical measurements.

RESULTS

Among cat-sensitized subjects, 84.2% were sensitized to secretoglobin, while 42.4% were sensitized to lipocalins. Nearly half of the subjects were monosensitized to Fel d 1. Polysensitization was observed in 20.2%, and concomitant sensitization to protein families was seen in 7.2%. Asthma prevalence, cat exposure, and rural living were associated with poly- and concomitant sensitization to protein families. Concomitant sensitization to single allergens was more common in those with asthma than in those without, while concomitant sensitization to both Fel d 1 and Fel d 4 was the most common pattern in individuals with asthma. Sensitization patterns also differed according to cat ownership and the degree of urbanization.

CONCLUSION

Sensitization to molecular allergens was observed in 90.9% of cat-sensitized subjects and showed variations across participants' background characteristics and the presence of asthma. Identification of sensitization patterns to cat allergens might provide better characterization of cat-allergic subjects.

Sensitization to molecular dog allergens in an adult population: Results from the West Sweden Asthma Study

BACKGROUND

As the prevalence of dog allergy rises, component resolved diagnosis might improve the diagnosis, understanding of the clinical outcomes and the effectiveness of immunotherapy. Considering the paucity of data in adults, the current study characterized the patterns of sensitization to dog molecular allergens in an adult population.

METHODS

Data were derived from the West Sweden Asthma Study, a population-based and representative sample of adults from western Sweden. Of the 2006 subjects clinically examined, 313 participants sensitized to whole dog allergen extract were measured for specific immunoglobulin E (sIgE) levels to Can f 1, Can f 2, Can f 3, Can f 4, Can f 5 and Can f 6 using ImmunoCAP™. Polysensitization was defined as sensitization to ≥3 components. Overlapping sensitization was defined as having concomitant sensitization to at least two dog molecular allergen families (lipocalin, albumin or prostatic kallikrein).

RESULTS

Of 313, 218 (70%) subjects tested positive to at least one dog allergen component. Sensitization to Can f 1 (43%) was the most common, followed by Can f 5 (33%) among molecular allergens, while sensitization to lipocalins (56%) was the most common among component families. Polysensitization was found in 22% of all participants and was more common in participants with than in those without asthma. Subjects with asthma were less likely to be monosensitized to Can f 5 than those without asthma. Subjects with asthma had higher IgE levels of Can f 3, Can f 4 and Can f 6 than those without asthma. Overlapping sensitizations also differed between those with asthma and allergic rhinitis and those without.

CONCLUSION

Increased knowledge about the sensitization patterns of dog allergen components can aid in defining their role in asthma and rhinitis. In complex clinical cases of dog allergy, a detailed analysis of dog allergen components can provide additional information on the nature of sensitization.

Allergic sensitization pattern as a marker of bronchial hyperresponsiveness in allergic rhinitis patients living in temperate continental climate zone

BACKGROUND

Bronchial hyperresponsiveness (BHR) is a key feature of asthma, but it may also appear in allergic rhinitis. The type of allergen, as well as regional characteristics, play an important role in the development of BHR. The aim of our study was to analyze allergen sensitization patterns and the factors that affect BHR in allergic rhinitis patients living in temperate continental climate zone.

METHODS

This study retrospectively analyzed allergic rhinitis patients from Eastern Slovakia who underwent skin-prick tests to aeroallergens, spirometry, histamine and methacholine bronchial provocation tests for evaluation of lower airway symptoms. We analyzed the associations between BHR and the pattern of aeroallergen sensitization, lung function parameters, and the total IgE and eosinophil levels.

RESULTS

Out of 365 allergic rhinitis patients (age range 16-64 years), 114 showed BHR. Sensitization to house dust mites (HDMs) and grass were the most common. BHR was significantly associated with sensitization to dogs (odds ratio, OR = 2.15, 95% confidence interval, CI: 1.13-4.11) and Alternaria (OR = 2.15, 95% CI: 1.06-4.35); however, BHR did not show a relationship with HDMs sensitization. The levels of total IgE and eosinophils were higher in the BHR-positive group. Sensitization to more than six allergens significantly increased the probability of BHR (p < 0.01).

CONCLUSION

Dogs and Alternaria, but not HDMs, were the sensitizing agents most closely associated with BHR. High-grade sensitization and increased total IgE and eosinophil levels were characteristic clinical signs in BHR-positive allergic rhinitis patients in the temperate continental climatic zone.

Allergic sensitization to lipocalins reflects asthma morbidity in dog dander sensitized children

Background

Sensitization to dog is an important risk factor for asthma in children, but the clinical relevance of IgE to available dog‐ and furry animal allergen molecules is uncertain.

Methods

Spirometry, methacholine challenge, fraction of exhaled nitric oxide, nasal challenge with dog extract and questionnaires were performed in 59 dog‐sensitized children (age 10–18 years). Serum IgE to dog‐, cat‐, horse extracts and the allergen molecules Can f 1–6, Fel d 1, Fel d 2, Fel d 4 and Equ c 1 were evaluated.

Results

Median numbers of positive IgE results to furry animal allergen molecules among children without asthma was 3, with asthma 5.5 and with troublesome asthma 9 (asthma vs. no asthma; p = 0.039; troublesome asthma vs. no asthma; p = 0.009). The odds ratio for asthma if sensitized to any lipocalin was 7.2 (95% confidence Interval: 1.44–35.9). Children with troublesome asthma had higher IgE levels to the lipocalins Can f 2, Can f 4 and Can f 6 compared to the rest of the study population (44 vs. 4.1 kU_A/L, p = 0.015; 5.8 vs. 0.9 kU_A/L, p = 0.018 and 1.3 vs. 0.7 kU_A/L, p = 0.03 respectively). Furthermore, a positive nasal challenge was more common among children with troublesome asthma (83% vs. 36%, p = 0.036).

Conclusions

Polysensitization to furry animal allergens and lipocalins is associated with asthma in dog‐sensitized children. Children with troublesome asthma have higher IgE levels to several dog lipocalins than other dog sensitized children.

Key message

Polysensitization to furry animal allergens and high IgE levels to the dog lipocalins Can f 2, Can f 4 and Can f 6 is associated with asthma severity in dog dander sensitized children. Molecular allergy diagnostics may thus help the clinicians to evaluate the impact of allergic sensitization on asthma morbidity.

Inhalant Mammal-Derived Lipocalin Allergens and the Innate Immunity

A major part of important mammalian respiratory allergens belongs to the lipocalin family of proteins. By this time, 19 respiratory mammalian lipocalin allergens have been registered in the WHO/IUIS Allergen Nomenclature Database. Originally, lipocalins, small extracellular proteins (molecular mass ca. 20 kDa), were characterized as transport proteins but they are currently known to exert a variety of biological functions. The three-dimensional structure of lipocalins is well-preserved, and lipocalin allergens can exhibit high amino acid identities, in several cases more than 50%. Lipocalins contain an internal ligand-binding site where they can harbor small principally hydrophobic molecules. Another characteristic feature is their capacity to bind to specific cell-surface receptors. In all, the physicochemical properties of lipocalin allergens do not offer any straightforward explanations for their allergenicity. Allergic sensitization begins at epithelial barriers where diverse insults through pattern recognition receptors awaken innate immunity. This front-line response is manifested by epithelial barrier-associated cytokines which together with other components of immunity can initiate the sensitization process. In the following, the crucial factor in allergic sensitization is interleukin (IL)-4 which is needed for stabilizing and promoting the type 2 immune response. The source for IL-4 has been searched widely. Candidates for it may be non-professional antigen-presenting cells, such as basophils or mast cells, as well as CD4+ T cells. The synthesis of IL-4 by CD4+ T cells requires T cell receptor engagement, i.e., the recognition of allergen peptides, which also provides the specificity for sensitization. Lipocalin and innate immunity-associated cell-surface receptors are implicated in facilitating the access of lipocalin allergens into the immune system. However, the significance of this for allergic sensitization is unclear, as the recognition by these receptors has been found to produce conflicting results. As to potential adjuvants associated with mammalian lipocalin allergens, the hydrophobic ligands transported by lipocalins have not been reported to enhance sensitization while it is justified to suppose that lipopolysaccharide plays a role in it. Taken together, type 2 immunity to lipocalin allergens appears to be a harmful immune response resulting from a combination of signals involving both the innate and adaptive immunities.

Cat allergen exposure in a naturalistic exposure chamber: a prospective observational study in cat-allergic subjects

Background

To determine the proportion and reproducibility of cat‐allergic mild asthmatics with early asthmatic response (EAR) during cat allergen exposure in a naturalistic exposure chamber (NEC).

Methods

This was a prospective, observational study in 30 cat‐allergic mild asthmatics who received two 180‐min cat‐allergen (Felis domesticus allergen 1 [Fel d 1]) challenges 27 days apart in an NEC.

Results

An EAR (≥20% reduction from baseline in forced expiratory volume in 1 s [FEV1]) was observed in 67% and 52% of subjects at first and second NEC exposure, respectively, with similar median time to EAR; 44% of subjects had an EAR on days 1 and 28. Late asthmatic response (≥15% reduction in FEV1 within 24 h of NEC exit) was observed in 33% of subjects following either exposure. Average FEV1 and total nasal symptom score during NEC exposure were highly correlated within subjects between NEC exposures (r = 0.91, p < 0.0001; r = 0.73, p < 0.001), but total ocular symptom score was not. Time to EAR, but not average FEV1, was significantly associated with NEC Fel d 1 concentration, which was variable. There were no serious adverse events; 12/30 subjects experienced 20 adverse events (including asthma, 10%; headache, 10%).

Conclusions

The NEC model demonstrates that average FEV1 change is highly reproducible and has a low correlation with cat allergen levels. However, time to EAR and incidence of EAR are less reproducible and are highly correlated with NEC allergen levels. Average FEV1, rather than incidence of EAR or time to EAR, could be considered as an endpoint for interventional trials testing cat‐specific anti‐allergy therapies using an NEC.

The majority of children sensitized before school-age develop allergic disease before adulthood: a longitudinal population-based study

BACKGROUND

Allergic sensitization increases the risk of and asthma and allergic rhinitis, but the impact of age at onset of sensitization is less studied.

OBJECTIVE

To examine the cumulative incidence of asthma and rhinitis up to age 19 years in relation to age at onset of sensitization to airborne allergens.

METHOD

All children in grade one and two (median age 8 years) in two municipalities in Northern Sweden were invited to skin prick tests and a questionnaire about allergic diseases, and 88% participated. At ages 12 and 19 years the protocol was repeated, and n=1510 individuals participated in all three examinations. Specific IgE was collected in a random sample at age 19, n=770. Onset of sensitization was defined; ≤8 years, 8-12 years, 12-19 years, and never sensitized. Adjusted Poisson regression was utilized to calculate risk ratios.

RESULTS

At age 19, those sensitized ≤8 year had the highest risk of asthma (RR 4.68 (95%CI 3.14-6.97)) and rhinitis (RR 22.3 (95%CI 13.3-37.6)), and 84% had developed either asthma or rhinitis. The combination of sensitization ≤8 year and family history of allergic diseases rendered high risks for asthma (RR 10.6 (6.71-16.7)) and rhinitis (RR 36.3 (18.9-69.7). Individuals sensitized ≤8 year showed significantly highest level of sensitization, as judged by number of positive skin tests and titers of specific IgE.

CONCLUSION

The majority of individuals with sensitization ≤8 years developed asthma or rhinitis before young adulthood. The high level of sensitization in early sensitized contribute to the high incidence of allergic airway conditions.

The Composition and Diversity of the Gut Microbiota in Children Is Modifiable by the Household Dogs: Impact of a Canine-Specific Probiotic

The development of the infant gut microbiota is initiated during pregnancy and continued through early life and childhood, guided by the immediate environment of the child. Our aim was to characterize the shared microbiota between dogs and children as well as to determine whether introduction to dogs of a dog-specific probiotic combination modifies the transfer process. We studied 31 children from allergic families with pet dog(s) and 18 control families without a dog. Altogether 37 dogs were randomized for a 4-week period in a double-blind design to receive canine-derived probiotic product containing a mixture of L. fermentum, L. plantarum, and L. rhamnosus, or placebo. Fecal samples from children and dogs were taken before and after the treatment. Distinctive gut microbiota composition was observed in children with dogs compared to those without a dog, characterized by higher abundance of Bacteroides and short-chain fatty acid producing bacteria such as Ruminococcus and Lachnospiraceae. Probiotic intervention in dogs had an impact on the composition of the gut microbiota in both dogs and children, characterized by a reduction in Bacteroides. We provide evidence for a direct effect of home environment and household pets on children microbiota and document that modification of dog microbiota by specific probiotics is reflected in children's microbiota.

α-Gal specific-IgE prevalence and levels in Ecuador and Kenya: Relation to diet, parasites, and IgG4

BACKGROUND

IgE to α-Gal is a cause of mammalian meat allergy and has been linked to tick bites in North America, Australia, and Eurasia. Reports from the developing world indicate that α-Gal sensitization is prevalent but has been little investigated.

OBJECTIVE

We sought evidence for the cause(s) of α-Gal sensitization and lack of reported meat allergy among children in less developed settings in Ecuador and Kenya.

METHODS

IgE to α-Gal and total IgE were assessed in children from Ecuador (n = 599) and Kenya (n = 254) and compared with children with (n = 42) and without known (n = 63) mammalian meat allergy from the southeastern United States. Information on diet, potential risk factors, and helminth infections was available for children from Ecuador. IgG₄ to α-Gal and antibodies to regionally representative parasites were assessed in a subset of children.

RESULTS

In Ecuador (32%) and Kenya (54%), α-Gal specific IgE was prevalent, but levels were lower than in children with meat allergy from the United States. Sensitization was associated with rural living, antibody markers of Ascaris exposure, and total IgE, but not active infections with Ascaris or Trichuris species. In Ecuador, 87.5% reported consuming beef at least once per week, including 83.9% of those who had α-Gal specific IgE. Levels of α-Gal specific IgG₄ were not high in Ecuador, but were greater than in children from the United States.

CONCLUSIONS

These results suggest that in areas of the developing world with endemic parasitism, α-Gal sensitization is (1) common, (2) associated with Ascaris exposure, and (3) distinguished by a low percentage of specific/total IgE compared with individuals with meat allergy in the United States.

Component-resolved diagnostics in pet allergy: Current perspectives and future directions

Furry mammals kept as pets are important allergen sources. The prevalence of sensitization to dander from various animals appears to be increasing worldwide. Several mammalian allergens from diverse species and distinct protein families have been characterized, and some are available for component-resolved diagnostics (CRD). This review presents an overview of mammalian aeroallergens, with a focus on cat, dog, and horse allergens. The potential of CRD in fine-tuning the diagnostic workup following traditional methods based on whole- allergen extracts and allergen immunotherapy is discussed. The review highlights the clinical utility of CRD, particularly as a marker/predictor of increased asthma risk and disease severity. Finally, several perspectives of the future implications of CRD are offered in the context of furry animal allergens.

A dynamic relationship between two regional causes of IgE-mediated anaphylaxis: α-Gal syndrome and imported fire ant

BACKGROUND

A syndrome of mammalian meat allergy relating to IgE specific for galactose-α-1,3-galactose (α-Gal) was first reported 10 years ago in the southeastern United States and has been related to bites of the lone star tick (Amblyomma americanum).

OBJECTIVE

Here we investigated the epidemiology of the "α-Gal syndrome" in the United States and sought additional evidence for the connection to tick bites.

METHODS

A survey of allergists was conducted by using a snowball approach. A second tier of the survey included questions about anaphylaxis to imported fire ants (IFAs). History of tick bites and tick-related febrile illness were assessed as part of a case-control study in Virginia. Antibody assays were conducted on sera from subjects reporting allergic reactions to mammalian meat or IFA.

RESULTS

In North America the α-Gal syndrome is recognized across the Southeast, Midwest, and Atlantic Coast, with many providers in this area managing more than 100 patients each. The distribution of cases generally conformed to the reported range of A americanum, although within this range there was an inverse relationship between α-Gal cases and cases of IFA anaphylaxis that were closely related to the territory of IFA. The connection between tick bites and α-Gal sensitization was further supported by patients' responses to a questionnaire and the results of serologic tests.

CONCLUSIONS

The α-Gal syndrome is commonly acquired in adulthood as a consequence of tick bites and has a regional distribution that largely conforms to the territory of the lone star tick. The epidemiology of the syndrome is expected to be dynamic and shifting north because of climate change and ecologic competition from IFA.

Does Air Filtration Work for Cat Allergen Exposure?

PURPOSE OF REVIEW

The goal of this review is to compress all important information and results of the research in reducing cat allergen exposure using air filtration. Fel d 1 is the major allergen responsible for IgE responses in 90 to 95% of patients with cat allergy.

RECENT FINDINGS

Reduction of cat allergen in indoor air with different air filtration systems and portable devices has been demonstrated in the majority of the studies. Recently, early and late asthmatic responses were significantly reduced using portable HEPA air cleaners in an environmental exposure chamber. This review provides a comprehensive overview of the current state of airborne Fel d 1 air filtration targeting the most efficient devices in cat allergen reduction. Novel emerging HEPA filters are targeting reduction of cat indoor asthma trigger so patient can might benefit from efficient solution.

The allergenic activity and clinical impact of individual IgE-antibody binding molecules from indoor allergen sources

A large number of allergens have been discovered but we know little about their potential to induce inflammation (allergenic activity) and symptoms. Nowadays, the clinical importance of allergens is determined by the frequency and intensity of their IgE antibody binding (allergenicity). This is a rather limited parameter considering the development of experimental allergology in the last 20 years and the criteria that support personalized medicine. Now it is known that some allergens, in addition to their IgE antibody binding properties, can induce inflammation through non IgE mediated pathways, which can increase their allergenic activity. There are several ways to evaluate the allergenic activity, among them the provocation tests, the demonstration of non-IgE mediated pathways of inflammation, case control studies of IgE-binding frequencies, and animal models of respiratory allergy. In this review we have explored the current status of basic and clinical research on allergenic activity of indoor allergens and confirm that, for most of them, this important property has not been investigated. However, during recent years important advances have been made in the field, and we conclude that for at least the following, allergenic activity has been demonstrated: Der p 1, Der p 2, Der p 5 and Blo t 5 from HDMs; Per a 10 from P. americana; Asp f 1, Asp f 2, Asp f 3, Asp f 4 and Asp f 6 from A. fumigatus; Mala s 8 and Mala s 13 from M. sympodialis; Alt a 1 from A. alternata; Pen c 13 from P. chrysogenum; Fel d 1 from cats; Can f 1, Can f 2, Can f 3, Can f 4 and Can f 5 from dogs; Mus m 1 from mice and Bos d 2 from cows. Defining the allergenic activity of other indoor IgE antibody binding molecules is necessary for a precision-medicine-oriented management of allergic diseases.

Asthma and Allergies in the School Environment

The school is a complex microenvironment of indoor allergens, pollutants, and other exposures. The school represents an occupational model for children and exposures in this environment have a significant health effect. Current research establishes an association between school exposure and asthma morbidity in children. This review will focus on common school environmental exposures (cockroach, rodents, cat, dog, classroom pets, dust mite, fungus, and pollution) and their impact on children with allergies and asthma. Understanding and evaluation of school-based environments is needed to help guide school-based interventions. School-based interventions have the potential for substantial benefit to the individual, school, community, and public health. However, there is a paucity data on school-based environmental interventions and health outcomes. The studies performed to date are small and cross-sectional with no control for home exposures. Randomized controlled school-based environmental intervention trials are needed to assess health outcomes and the cost-effectiveness of these interventions. The School Inner-City Asthma Intervention Study (SICAS 2), a NIH/NIAID randomized controlled clinical trial using environmental interventions modeled from successful home-based interventions, is currently underway with health outcome results pending. If efficacious, these interventions could potentially help further guide school-based interventions potentially with policy implications. In the meanwhile, the allergist/immunologist can continue to play a vital role in improving the quality of life in children with allergies and asthma at school through the use of the ADA policy and Section 504 of the Rehabilitation Act as well as encouraging adoption of toolkits to build successful school-based asthma programs and asthma-friendly schools.

Children Monosensitized to Can f 5 Show Different Reactions to Male and Female Dog Allergen Extract Provocation: A Randomized Controlled Trial

BACKGROUND

Dog dander consists of several allergenic molecules including Can f 5, which is a protein expressed in the prostate of male dogs.

OBJECTIVE

To investigate whether children monosensitized to Can f 5 show different reactions to provocation tests with male versus female dog dander in a double-blind randomized clinical trial.

METHODS

Twenty-two children (15-18 years) with a history of dog sensitization were enrolled from the COpenhagen Prospective Studies on Asthma in Childhood₂₀₀₀ mother-child cohort. Skin prick test, specific IgE levels to dog dander (e5), and dog components Can f 1, 2, 3, and 5 were first assessed. We subsequently performed skin prick test and conjunctival allergen provocation test using dog dander collected separately from male and female dogs.

RESULTS

Seven of the 22 children were monosensitized to Can f 5. Eight were sensitized to a mix of the dog components, and 7 were no longer sensitized to dog. Of the children monosensitized to Can f 5, all had a positive skin prick test result to male dog extract and 1 of 7 was also positive to female dog extract (P = .01). Furthermore, 5 of 7 had a positive conjunctival allergen provocation test result to male dog extract and 1 of 7 also reacted to the female dog extract (P = .03). There was no difference between reactions to male and female dog extract provocation in children sensitized to a mix of the dog components.

CONCLUSIONS

Children monosensitized to Can f 5 show different reactions to male and female dog extract provocation using both skin prick test and conjunctival allergen provocation test, suggesting tolerance to female dogs.

Efficacy of air cleaners in asthmatics allergic to cat in ALYATEC® environmental exposure chamber

BACKGROUND

Air cleaners have been promoted for respiratory allergic disease prevention, but there is no clear clinical proof of their efficacy in allergic asthma.

OBJECTIVE

To examine the efficacy of a new air cleaner on early and late asthmatic responses in cat-allergic patients.

METHODS

This randomized, cross-over, double-blind placebo-controlled study enrolled 24 cat-asthmatic patients with GINA 1 asthma. At baseline, participants were exposed to 40 ng/m³ of airborne cat allergen for a maximum of 2 hours in ALYATEC^® environmental exposure chamber (EEC). All participants were subsequently randomized into two groups that were exposed to cat allergen, either with active then placebo air cleaners or with placebo then active air cleaners with a 3-week interval in the EEC. This study was registered under number (NCT03928561).

RESULTS

Fewer patients experienced an EAR with active air cleaners (seven patients; 29.17%) than placebo (21 patients; 87.50%). The response incidence was lower with active than with placebo air cleaners. A Cox model demonstrated a significant treatment effect (hazard ratio, 0.10; P = .002). Active air cleaners also prevented late asthmatic response: four patients (16.67%) had a late asthmatic response with active air cleaners compared to 11 patients (45.83%) with placebo (Prescott test P = .002). Active air cleaners also decreased the maximal severity of bronchial response (FEV1 decrease of 17.24% with active vs 25.62% with placebo air cleaners; P = .001).

CONCLUSIONS

Our present results demonstrated that Intense Pure Air XL^® air cleaners significantly prevented early and late asthmatic responses among cat-allergic asthmatics during cat allergen exposure in the ALYATEC^® EEC.

Home Environmental Interventions for House Dust Mite

It has been 50 years since the dust mite was first appreciated to be a major source of allergen in house dust, and by extension a key trigger of allergic respiratory disease. Since that time a number of protein allergens have been identified and characterized, mainly from mite feces, and standardized mite extracts and IgE assays have been developed. Insights into the lifecycle of dust mites and aspects of mite allergen biology have shed light on the mechanisms that lead to respiratory disease and to the development of interventions that can minimize dust mite allergen exposure. It is now clear that dust mite allergy is a key contributor to asthma in many parts of the world, and that long-term avoidance can be effective for preventing sensitization and minimizing the development and severity of respiratory disease. Here, we discuss the evidence linking dust mites with respiratory disease, outline studies that support the efficacy of home environmental interventions, and highlight practical methods that have been shown to be effective as part of a multifaceted approach to dust mite avoidance.

IgE sensitization in a cohort of adolescents in southern Sweden and its relation to allergic symptoms

Background

There is a strong and consistent association between IgE sensitization and allergy, wheeze, eczema and food hypersensitivity. These conditions are also found in non-sensitized humans, and sensitization is found among individuals without allergy-related diseases. The aim of this study was to analyse the sensitization profile in a representative sample of the population, and to relate patterns of allergens and allergen components to allergic symptoms.

Methods

A population of 195 adolescents took part in this clinical study, which included a self-reported questionnaire and in vitro IgE testing.

Results

Sensitization to airborne allergens was significantly more common than sensitization to food allergens, 43% vs. 14%, respectively. IgE response was significantly higher in airborne allergens among adolescents with rhinitis (p < 0.001) and eczema (p < 0.01). Among 53 children with allergic symptoms according to the questionnaire, 60% were sensitized. Sensitization to food allergens was found among those with rhinitis, but only to PR-10 proteins. None of the participants had IgE to seed storage proteins.

Conclusion

The adolescents in this study, taken from a normal Swedish population, were mainly sensitized to grass pollen and rarely to specific food allergens. The major grass pollen allergen Phl p 1 was the main sensitizer, followed by Cyn d 1 and Phl p 2. Sixty-one percent reporting any allergic symptom were sensitized, and the allergen components associated with wheeze and rhinoconjunctivitis were Fel d 4, Der f 2 and Can f 5.

Characterization of sensitization to furry animal allergen components in an adult population

BACKGROUND

There are paucity of data on sensitization to furry animal allergen components in adults. Furry animals are major sensitizers and contributors to asthma burden in northern Europe and North America.

OBJECTIVE

To characterize sensitization patterns to furry animal allergen components in Swedish adults.

METHODS

Based on the West Sweden Asthma Study, a random population (n = 1103) and an asthma sample (n = 769) were tested for allergen sensitization using Phadiatop^® . Those with IgE ≥ 0.35 kU_A /L were tested for cat (Fel d 1, 2, and 4), dog (Can f 1, 2, 3, and 5), and horse (Equ c 1) allergen component sensitization. We defined allergen component poly-sensitization patterns, identified data-driven sensitization clusters, described component sensitization overlaps, and assessed determinants of sensitization patterns.

RESULTS

The prevalence of allergen component sensitization ranged from 0.8% for Fel d 2 and Can f 3 to 8.9% for Fel d 1. The most common dog component was Can f 5 (3.6%); 2.1% were sensitized to Equ c 1. Those sensitized to Fel d 2 and Fel d 4 were commonly sensitized to Fel d 1. The most common dog component overlap was between Can f 1/Can f 2 and Can f 5. Mono-sensitization was 5.6%, double sensitization 1.5% and poly-sensitization 2.1%. Sensitization was always higher in the asthma than in the random sample. Three sensitization clusters were derived, namely non-sensitized (90% in random vs 66% in asthma sample); Fel d 1-driven sensitized (7% vs 19%); and multi-sensitized (3% vs 15%). Key determinants of sensitization were gender, age, raised on a farm, family history of allergy or asthma, smoking, and occupational exposure to dust or fumes.

CONCLUSIONS & CLINICAL RELEVANCE

Fel d 1 and Can f 5 are the most common cat and dog components sensitization in this adult Swedish population. Mono-sensitization is more common than poly-sensitization. This detailed characterization highlights the current distribution of furry animal allergen components in Swedish adults, and their impact on clinical outcomes of asthma will be further explored.

Dog characteristics and future risk of asthma in children growing up with dogs

There is observational evidence that children exposed to dogs in early life are at lower risk of asthma. It is unknown whether this association is modified by dog characteristics such as sex, breed, number of dogs, and dog size. The aim of this study was to determine whether different dog characteristics modify the risk of asthma among children exposed to dogs during their first year of life. In the main analysis, we used national register data for all children born in Sweden from Jan 1st 2001 to Dec 31st 2004 with a registered dog in the household during their first year of life (n = 23,585). We used logistic regression models to study the association between dog characteristics and the risk of asthma or allergy diagnosis and medication at age six. The prevalence of asthma at age six was 5.4%. Children exposed to female dogs had lower risk of asthma compared to those exposed to male dogs, odds ratio, OR = 0.84 (95% confidence interval, CI 0.74 to 0.95). Children with two dogs or more had lower risk of asthma than those with one dog only, OR = 0.79 (95% CI 0.65 to 0.95). Children whose parents had asthma and allergy had a higher frequency of exposure to dog breeds anecdotally described as “hypoallergenic” compared to those parents without asthma or allergy (11.7% vs 7.6%, p < 0.001). Exposure to these breeds were associated with higher risk of allergy OR = 1.27 (95% CI 1.02 to 1.59) but not asthma. In conclusion, we found evidence of an association between the sex of dog and the number of dogs with a lower risk of childhood asthma in dog-exposed children.

The use of machine learning to understand the relationship between IgE to specific allergens and asthma

Thomas Platts-Mills and Matthew Perzanowski provide their expert Perspective on a translational study from Custovic and colleagues that identifies pairings of IgE that show value in estimating risk of concurrent asthma.

Does allergy explain why some children have severe asthma?

Asthma is a common disease in childhood with a minority of affected children having severe therapy-resistant asthma (STRA). Children with STRA can be differentiated from those with mild-moderate disease by greater allergic sensitization, increased eosinophilic airway inflammation, increased airway remodelling and reduced corticosteroid responsiveness. The aetiology of STRA in children is multifactorial but allergy seems to play a key role. Many children with asthma have coexisting allergic disease, and severe rhinitis seems to be an important driver of STRA in children. Allergies to foods, moulds, pollen and pets have also been associated with severe asthma exacerbations. Identifying allergens that are driving asthma symptoms in children with STRA may provide additional strategies for improving their disease control. Avoidance strategies may be possible. Additional monoclonal antibody therapy with Omalizumab or Mepolizumab may be helpful in children with clinically important polysensitization.

Bedroom Allergen Exposure Beyond House Dust Mites

PURPOSE OF REVIEW

The review provides insight into recent findings on bedroom allergen exposures, primarily focusing on pet, pest, and fungal exposures.

RECENT FINDINGS

Large-scale studies and improved exposure assessment technologies, including measurement of airborne allergens and of multiple allergens simultaneously, have extended our understanding of indoor allergen exposures and their impact on allergic disease. Practical, streamlined methods for exposure reduction have shown promise in some settings, and potential protective effects of early-life exposures have been further elucidated through the investigation of specific bacterial taxa. Advances in molecular allergology have yielded novel data on sensitization profiles and cross-reactivity. The role of indoor allergen exposures in allergic disease is complex and remains incompletely understood. Advancing our knowledge of various co-exposures, including the environmental and host microbiome, that interact with allergens in early life will be crucial for the development of efficacious interventions to reduce the substantial economic and social burden of allergic diseases including asthma.

Evaluation of the manufacturer-dependent differences in specific immunoglobulin E results for indoor allergens

BACKGROUND

Even though allergies are an important health issue, the detected amount of allergen-specific IgE (sIgE) has differed widely between manufacturers in the past, and even as recently as this year. These discrepancies hinder diagnostics and can even impact allergen immunotherapy.

OBJECTIVE

The aim of this study was to evaluate the development and status quo of the quality of in vitro diagnostic testing for house dust mites (HDM) and cat epithelium, 2 important indoor allergen sources.

METHODS

We analyzed data on the allergen sources European HDM, American HDM, and cat epithelium, which were collected by the Society for Promoting Quality Assurance in Medical Laboratories (INSTAND e.V.) during 7 years as part of External Quality Assessment schemes (EQAs). A pseudoanonymized comparison was made of the semiquantitative data and allergen-class results of the 4 main suppliers of in vitro diagnostic sIgE tests. Coefficients of variation (CV) were determined in order to evaluate interlaboratory comparability.

RESULTS

In vitro allergy diagnostic testing for the major allergen sources HDM and cat epithelium still reveals manufacturer-dependent differences. Despite this, a cautious trend was found towards an alignment of the results and interlaboratory comparability, with the exception of 1 supplier.

CONCLUSION

Even though these results are promising, future EQAs have to be closely monitored to ensure this positive trend is not just a snapshot.

Molecular allergy diagnostics refine characterization of children sensitized to dog dander

BACKGROUND

Sensitization to dog dander is an important risk factor for rhinoconjunctivitis and asthma but is not sufficient for diagnosing dog allergy. Molecular allergy diagnostics offer new opportunities for refined characterization.

OBJECTIVES

We sought to study the association between sensitization to all presently known dog allergen components and clinical symptoms of dog allergy in children evaluated by using nasal provocation tests (NPTs).

METHODS

Sixty children (age, 10-18 years) sensitized to dog dander extract underwent NPTs with dog dander extract. Measurement of IgE levels to dog dander and to Can f 1, Can f 2, Can f 3, and Can f 5 was performed with ImmunoCAP, and measurement of IgE levels to Can f 4 and Can f 6 was performed with streptavidin ImmunoCAP. An IgE level of 0.1 kU_A/L or greater was considered positive.

RESULTS

There was an association between sensitization to an increasing number of dog allergen components and a positive nasal challenge result (P = .01). Sensitization to lipocalins (odds ratio [OR], 6.0; 95% CI, 1.04-34.5), in particular Can f 4 (OR, 6.80; 95% CI 1.84-25.2) and Can f 6 (OR, 5.69; 95% CI, 1.59-20.8), was associated with a positive NPT result. Monosensitization to Can f 5 was related to a negative NPT result (OR, 5.78; 95% CI, 1.01-33.0).

CONCLUSION

Sensitization to an increasing number of dog allergen components and to lipocalins is associated with dog allergy. Monosensitization to Can f 5 should not be regarded primarily as a marker for dog allergy.

Specific IgG4 antibodies to cow's milk proteins in pediatric patients with eosinophilic esophagitis

BACKGROUND

Allergen-specific IgG₄ (sIgG₄) antibodies are often associated with tolerance, but sIgG₄ antibodies to causally relevant foods have been reported recently in adults with eosinophilic esophagitis (EoE). Prevalence and levels of food sIgG₄ are not well established in the general pediatric population.

OBJECTIVE

We sought to investigate serum food sIgG₄ with component diagnostics in children with EoE and children from an unselected birth cohort and to explore the effects of sex, age, and milk consumption on sIgG₄ levels.

METHODS

Sera from 71 pediatric patients with EoE and 210 early adolescent children from an unselected birth cohort (Project Viva) were assayed for sIgG₄ and specific IgE (sIgE) to major cow's milk (CM) proteins (α-lactalbumin, β-lactoglobulin, and caseins) and to wheat, soy, egg, and peanut proteins.

RESULTS

In the EoE cohort high-titer sIgG₄ (≥10 μg/mL) to CM proteins was more common than in control sera and achieved odds ratios for EoE ranging from 5.5 to 8.4. sIgE levels to CM proteins were mostly 4 IU/mL or less in patients with EoE, such that sIgG₄/sIgE ratios were often 10,000 or greater. When adjusted for age and milk consumption, high-titer sIgG₄ to CM proteins was strongly associated with EoE, with an odds ratio of greater than 20 to all 3 CM proteins in boys.

CONCLUSIONS

sIgG₄ to CM proteins are common and high titer in children with EoE. Although it is not clear that this response is pathogenic, sIgG₄ levels imply that these antibodies are an important feature of the local immune response that gives rise to EoE.

An update on molecular cat allergens: Fel d 1 and what else? Chapter 1: Fel d 1, the major cat allergen

Background

Cats are the major source of indoor inhalant allergens after house dust mites. The global incidence of cat allergies is rising sharply, posing a major public health problem. Ten cat allergens have been identified. The major allergen responsible for symptoms is Fel d 1, a secretoglobin and not a lipocalin, making the cat a special case among mammals.

Main body

Given its clinical predominance, it is essential to have a good knowledge of this allergenic fraction, including its basic structure, to understand the new exciting diagnostic and therapeutic applications currently in development. The recent arrival of the component-resolved diagnosis, which uses molecular allergens, represents a unique opportunity to improve our understanding of the disease. Recombinant Fel d 1 is now available for in vitro diagnosis by the anti-Fel d 1 specific IgE assay. The first part of the review will seek to describe the recent advances related to Fel d 1 in terms of positive diagnosis and assessment of disease severity. In daily practice, anti-Fel d 1 IgE tend to replace those directed against the overall extract but is this attitude justified? We will look at the most recent arguments to try to answer this question. In parallel, a second revolution is taking place thanks to molecular engineering, which has allowed the development of various forms of recombinant Fel d 1 and which seeks to modify the immunomodulatory properties of the molecule and thus the clinical history of the disease via various modalities of anti-Fel d 1-specific immunotherapy. We will endeavor to give a clear and practical overview of all these trends.

An update on molecular cat allergens: Fel d 1 and what else? Chapter 1: Fel d 1, the major cat allergen

Background

Cats are the major source of indoor inhalant allergens after house dust mites. The global incidence of cat allergies is rising sharply, posing a major public health problem. Ten cat allergens have been identified. The major allergen responsible for symptoms is Fel d 1, a secretoglobin and not a lipocalin, making the cat a special case among mammals.

Main body

Given its clinical predominance, it is essential to have a good knowledge of this allergenic fraction, including its basic structure, to understand the new exciting diagnostic and therapeutic applications currently in development. The recent arrival of the component-resolved diagnosis, which uses molecular allergens, represents a unique opportunity to improve our understanding of the disease. Recombinant Fel d 1 is now available for in vitro diagnosis by the anti-Fel d 1 specific IgE assay. The first part of the review will seek to describe the recent advances related to Fel d 1 in terms of positive diagnosis and assessment of disease severity. In daily practice, anti-Fel d 1 IgE tend to replace those directed against the overall extract but is this attitude justified? We will look at the most recent arguments to try to answer this question. In parallel, a second revolution is taking place thanks to molecular engineering, which has allowed the development of various forms of recombinant Fel d 1 and which seeks to modify the immunomodulatory properties of the molecule and thus the clinical history of the disease via various modalities of anti-Fel d 1-specific immunotherapy. We will endeavor to give a clear and practical overview of all these trends.

Immunotherapy for pet allergies

Allergic diseases compose a serious challenge for modern societies. Their individual, medical and economical burden is large. As humans spend most of their time indoors, exposure to indoor allergens is a significant contributor to the development of allergic sensitization and respiratory allergies, such as allergic rhinoconjunctivitis and asthma. One important source of indoor allergens are pets, in particular cats and dogs. Allergens from these and other mammals spread effectively and they are encountered widely in public places. If patient education, allergen avoidance and pharmacotherapy do not suffice for controlling the symptoms of pet allergy, allergen immunotherapy can be a treatment option. Current information on allergen immunotherapy in pet allergy suggests that it can be effective in reducing allergic symptoms. However, the low number of high-quality randomized controlled trials of allergen immunotherapy in pet allergy warrants for further investigations.

Low Serum IgE Is a Sensitive and Specific Marker for Common Variable Immunodeficiency (CVID)

Although small prior studies have suggested that IgE can be low in common variable immunodeficiency (CVID), the workup for patients with recurrent infections and suspected hypogammaglobulinemia does not include the routine measurement of serum IgE. We sought to test the hypothesis that low/undetectable serum IgE is characteristic of CVID by comparing the frequency of low/undetectable serum IgE in healthy controls and patients with CVID. We measured total serum IgE in a large multi-center cohort of patients with CVID (n = 354) and compared this to large population-based cohorts of children and adults. We further compared IgE levels in patients with CVID to those with other forms of humoral immunodeficiency, and in a subset, measured levels of allergen-specific serum IgE and IgG subclasses. Lastly, we evaluated for the presence of IgE in commercially available immunoglobulin replacement therapy (IgRT) products. An undetectable serum IgE (< 2 IU/ml) occurs in only 3.3% (95% CI, 1.9-5.7%) of the general population. In contrast, an undetectable IgE occurs in 75.6% (95% CI, 65.6-85.7%) of patients with CVID. Conversely, a high IgE (> 180 IU/ml) is very uncommon in CVID (0.3% of patients). IgE is > 2 IU/ml in 91.2% of patients with secondary hypogammaglobulinemia, and thus, an IgE < LLOD is suggestive of a primary humoral immunodeficiency. Allergen-specific IgE is not detectable in 96.5% of patients with CVID. Sufficient quantities of IgE to change the total serum IgE are not contained in IgRT. The IgG1/IgG4 ratio is increased in subjects with low IgE, regardless of whether they are controls or have CVID. These findings support the routine measurement of serum IgE in the workup of patients with hypogammaglobulinemia.

Component-resolved microarray analysis of IgE sensitization profiles to Felis catus major allergen molecules in Russian cat-allergic patients

We aimed to determine the profile of IgE reactivity to three major cat allergens, Fel d 1, Fel d 2 and Fel d 4, in cat-allergic patients in the Moscow region in Russia. sIgE levels to recombinant proteins expressed in Escherichia coli (Fel d 1 and Fel d 4) and to Fel d 2 protein purified from cat serum were measured using a microarray method developed in our laboratory. Sera from 174 anonymous subjects with a positive reaction (≥0.35 IU/mL) to cat dander extract (e1, ImmunoCAP) and 56 negative controls were used for IgE testing. Fel d 1 was recognized by 92.5%, Fel d 2 by 29.9% and Fel d 4 by 39.1% of the tested patient sera. The sensitivity to these three proteins was approximately 98% compared to cat dander extract (correlation coefficient to ImmunoCAP is 0.94 with PPV = 0.99 and NPV = 0.95). These predictive values appeared to be even more statistically significant than the divergence between the ISAC IgE test and the extract-based singleplex ImmunoCAP. The combination of the three investigated proteins (Fel d 1, Fel d 2 and Fel d 4) is suitable for in vitro molecular (serological) diagnosis of cat allergy in this region as a complement to cat dander extract. Moreover, with this method, we found distinction between Fel d 2 and other Feline sIgEs formation.

Atopy and prostate cancer: Is there a link between circulating levels of IgE and PSA in humans?

BACKGROUND

Atopy has been investigated as a potential risk factor for prostate cancer. IgE antibodies may be major players in protective responses against tumours, through engendering antigen presentation and enhancing adaptive immune responses targeted towards a specific allergen, but potentially also against tumour-associated antigens such as prostate-specific antigen (PSA). We therefore cross-sectionally investigated associations between circulating levels of PSA and IgE in the National Health and Nutrition Examination Survey 2005-2006.

METHODS

We focused on all men aged 40+ years with measurements for PSA and IgE, and no previous diagnosis of prostate cancer (n = 1312). We estimated the association between total and specific IgE concentration and levels of PSA with logistic regression models, adjusted for age, ethnicity/race, education, smoking status, body mass index (BMI), physical activity status, and history of asthma.

RESULTS

Both total IgE and the sum of specific IgE were inversely associated with the risk of having PSA levels ≥10 ng/mL, though most findings were not statistically significant. The odds ratios for the second and third tertile of total IgE as compared to the first were 0.21 (95% CI 0.06-0.72) and 0.42 (0.08-2.31). The odds ratio for sum of abnormal specific IgE measurements was 0.77 (0.44-1.34).

CONCLUSION

Despite statistical insignificance, the observed trend warrants further research given the increasing evidence of the role of atopy and IgE antibodies in protective responses against tumours. A lifecourse approach of measuring IgE, specific subtypes, and other markers of the humoral immune system (i.e. IgG) could shed more light on its potential anti-cancer characteristics.

Clustering of conformational IgE epitopes on the major dog allergen Can f 1

Immunoglobulin E (IgE)-associated allergy affects more than 25% of the population. Can f 1 is the major dog allergen associated with respiratory symptoms but the epitopes recognized by allergic patients IgE on Can f 1 are unknown. To characterize IgE epitopes of Can f 1 recognized by dog allergic patients, six overlapping peptides spanning the Can f 1 sequence were synthesized. In direct IgE epitope mapping experiments peptides were analyzed for IgE reactivity by dot blot and Enzyme-linked immunosorbent assay (ELISA) with sera from dog allergic patients. For indirect epitope-mapping, rabbits were immunized with the peptides to generate specific IgG antibodies which were used to inhibit allergic patients’ IgE binding to Can f 1. IgE binding sites were visualized on a model of the Can f 1 three-dimensional structure. We found that Can f 1 does not contain any relevant sequential IgE epitopes. However, IgE inhibition experiments with anti-peptide specific IgGs showed that Can f 1 N- and C-terminal portion assembled a major conformational binding site. In conclusion, our study is the first to identify the major IgE epitope-containing area of the dog allergen Can f 1. This finding is important for the development of allergen-specific treatment strategies.

Environmental determinants of allergy and asthma in early life

Allergic disease prevalence has increased significantly in recent decades. Primary prevention efforts are being guided by study of the exposome (or collective environmental exposures beginning during the prenatal period) to identify modifiable factors that affect allergic disease risk. In this review we explore the evidence supporting a relationship between key components of the external exposome in the prenatal and early-life periods and their effect on atopy development focused on microbial, allergen, and air pollution exposures. The abundance and diversity of microbial exposures during the first months and years of life have been linked with risk of allergic sensitization and disease. Indoor environmental allergen exposure during early life can also affect disease development, depending on the allergen type, dose, and timing of exposure. Recent evidence supports the role of ambient air pollution in allergic disease inception. The lack of clarity in the literature surrounding the relationship between environment and atopy reflects the complex interplay between cumulative environmental factors and genetic susceptibility, such that no one factor dictates disease development in all subjects. Understanding the effect of the summation of environmental exposures throughout a child's development is needed to identify cost-effective interventions that reduce atopy risk in children.

Sensitization and Exposure to Pets: The Effect on Asthma Morbidity in the US Population

BACKGROUND

Although pets are found in more than 50% of US homes, the effect of pet allergen exposure on asthma morbidity in the US population is not well documented.

OBJECTIVE

To determine the effect of dog and cat allergen exposures on asthma morbidity in the US population.

METHODS

The National Health and Nutrition Examination Survey is a representative sample of civilian US population. Data on asthma, dog and cat allergen levels in bedroom dust, as well as specific IgE to dog and cat were analyzed for all participants 6 years or older.

RESULTS

Pets are common in the United States, with more that 50% of households having a dog or a cat or both. The prevalence of allergic sensitization in the National Health and Nutrition Examination Survey population was similar for dog and cat, with both being approximately 12%. Among those who were sensitized, exposure to elevated levels of pet allergens was associated with an increased prevalence of asthma and asthma attacks. Indeed, 44.2% of the asthma attacks were attributable to exposure to high levels of dog allergen in the bedroom among patients with asthma sensitive to dog and 30.3% were attributable to cat allergen exposure among the comparable cat-sensitive and exposed group. Projecting these results to the US population indicates more than 1 million increased asthma attacks each year for the dog-sensitive and exposed group and more than 500,000 increased asthma attacks for the cat-sensitive and exposed population of patients with asthma.

CONCLUSIONS

Exposure to elevated levels of dog and cat allergens among those sensitized individuals with asthma is associated with excess asthma attacks. Reducing pet allergen exposures has the potential for a significant decrease in asthma morbidity.

Exposure to Indoor Allergens in Different Residential Settings and Its Influence on IgE Sensitization in a Geographically Confined Austrian Cohort

BACKGROUND

Exposure to indoor allergens is crucial for IgE sensitization and development of allergic symptoms. Residential settings influence the allergen amount in house dust and hence allergic sensitization. Within this study, we investigated allergen exposure and molecule-based IgE levels in a geographically confined region and evaluated the impact of housing, pets and cleaning.

METHODS

501 adolescents from Salzburg, Austria participated in this cross-sectional study. House dust samples were examined regarding major mite, cat, dog, and mold allergens using a multiplex assay. Serum samples of participants were analyzed for specific IgE to Der p 1, Der p 2, Fel d 1, Can f 1 and Alt a 1 using the multiplex array ImmunoCAP ISAC. Information on allergies, living areas, dwelling form (house, flat, farm), pets, and household cleanliness were obtained by a questionnaire.

RESULTS

In investigated house dust samples, the concentration of cat allergen was highest while the prevalence of mold allergens was very low. Participants showed IgE sensitization to Der p 1 (13.2%), Der p 2 (18.2%), Fel d 1 (14.4%), Can f 1 (2.4%) and Alt a 1 (2.0%). In alpine regions, lower mite allergen concentrations were detected which correlated with reduced IgE levels. A trend for increased sensitization prevalence from rural to alpine to urban regions was noted. Living on farms resulted in lower sensitization prevalence to mite and cat allergens, even though exposure to mites was significantly elevated. The presence of cats was associated with a lower sensitization rate and IgE levels to cat and mite allergens, and less frequent allergic diseases. Cleaning did not impact allergen concentrations, while IgE reactivity to mites and allergic diseases were more pronounced when living in cleaner homes.

CONCLUSION

Allergen exposure to indoor allergens was influenced by setting of homes. Living in a farm environment and having a cat at home showed a protective effect for IgE sensitization and allergies. This cross-sectional study in combination with hereditary and lifestyle factors enables development of risk schemes for a more efficient management and potential prevention of allergic diseases.

Indoor allergen exposure and asthma outcomes

PURPOSE OF REVIEW

The aim of the present review is to discuss updates on research regarding the relationship between indoor allergen exposure and childhood asthma with a focus on clinical effects, locations of exposure, and novel treatments.

RECENT FINDINGS

Recent data continue to demonstrate that early life sensitization to indoor allergens is a predictor of asthma development later in life. Furthermore, avoidance of exposure to these allergens continues to be important especially given that the vast majority of children with asthma are sensitized to at least one indoor allergen. New research suggests that mouse allergen, more so than cockroach allergen, may be the most relevant urban allergen. Recent evidence reminds us that children are exposed to clinically important levels of indoor allergens in locations away from their home, such as schools and daycare centers. Exposure to increased levels of indoor mold in childhood has been associated with asthma development and exacerbation of current asthma; however, emerging evidence suggests that early exposure to higher fungal diversity may actually be protective for asthma development. Novel treatments have been developed that target TH2 pathways thus decreasing asthmatic responses to allergens. These therapies show promise for the treatment of severe allergic asthma refractory to avoidance strategies and standard therapies.

SUMMARY

Understanding the relationship between indoor allergens and asthma outcomes is a constantly evolving study of timing, location, and amount of exposure.