A comparison of skin prick tests, intradermal skin tests, and specific IgE in the diagnosis of mouse allergy

International consensus statement on allergy and rhinology: Allergic rhinitis - 2023

BACKGROUND

In the 5 years that have passed since the publication of the 2018 International Consensus Statement on Allergy and Rhinology: Allergic Rhinitis (ICAR-Allergic Rhinitis 2018), the literature has expanded substantially. The ICAR-Allergic Rhinitis 2023 update presents 144 individual topics on allergic rhinitis (AR), expanded by over 40 topics from the 2018 document. Originally presented topics from 2018 have also been reviewed and updated. The executive summary highlights key evidence-based findings and recommendation from the full document.

METHODS

ICAR-Allergic Rhinitis 2023 employed established evidence-based review with recommendation (EBRR) methodology to individually evaluate each topic. Stepwise iterative peer review and consensus was performed for each topic. The final document was then collated and includes the results of this work.

RESULTS

ICAR-Allergic Rhinitis 2023 includes 10 major content areas and 144 individual topics related to AR. For a substantial proportion of topics included, an aggregate grade of evidence is presented, which is determined by collating the levels of evidence for each available study identified in the literature. For topics in which a diagnostic or therapeutic intervention is considered, a recommendation summary is presented, which considers the aggregate grade of evidence, benefit, harm, and cost.

CONCLUSION

The ICAR-Allergic Rhinitis 2023 update provides a comprehensive evaluation of AR and the currently available evidence. It is this evidence that contributes to our current knowledge base and recommendations for patient evaluation and treatment.

Diversity and complexity of mouse allergens in urine, house dust, and allergen extracts assessed with an immuno-allergomic approach

BACKGROUND

Mouse allergy is an important cause of indoor asthma and allergic rhinoconjunctivitis. The major mouse allergen, Mus m 1, is a complex of homologous pheromone-binding lipocalins called major urinary proteins (MUPs).

METHODS

We analyzed the proteome of MUPs in mouse urine, commercial mouse epithelial extracts, and environmental samples using several approaches. These include as follows: two-dimensional electrophoresis and immunoblotting; liquid chromatography-high-resolution mass spectrometry (LC/HRMS); multiple reaction monitoring (MRM) mass spectrometry; and LC/HRMS analysis of glycans at the N-66 residue of MUP3.

RESULTS

Albumin is predominant in the extracts, while MUPs are predominant in urine. LC/HRMS of 4 mouse allergen extracts revealed surprising heterogeneity. Of 22 known mouse MUPs, only 6 (MUP3, MUP4, MUP5, MUP13, MUP20, and MUP21) could be identified with MRM using unique peptides. Assessment of MUP content in urine, extracts, and dust samples showed good correlation between MRM and other methods working with different detection principles. All 6 identifiable MUPs were found in electrophoretically separated urine bands, but only MUP3 and MUP20 were above LOQ in unseparated mouse urine, and only MUP3, MUP4, and MUP20 were found in mouse epithelial extracts. Glycan heterogeneity was noted among 4 individual inbred mice: of 13 glycan structures detected, 8 were unique to one mouse, and only 2 glycan modifications were present in all 4 mice.

CONCLUSIONS

Using mass spectrometry and MRM, mouse allergen extracts and urine samples are shown to be complex and heterogeneous. The efficacy and safety of commercial mouse allergen extracts will be improved with better controls of allergen content.

High Histamine Control Concentration Leads to False Negative Allergy Skin Testing

BACKGROUND

Allergy skin test reliability depends on the reagents and controls selected. Histamine is used at 1 mg/ml and 6 mg/ml concentration but few studies address the rationale for selecting one versus the other and how this may impact diagnostic accuracy.

OBJECTIVE

To determine the rate of false negative allergen skin tests responses between UniTest PC (using the 1 mg/mL histamine) and Quintip devices (using 6 mg/mL) for 4 common aeroallergens.

METHODS

Subjects aged 18-65 with symptoms of allergy to cat and/or ragweed received skin testing with 4 aeroallergens (dust mite mix, timothy grass, ragweed, cat), histamine and control diluent. Those individuals who tested positive to cat or ragweed with one skin prick test (SPT) device but not the other then proceeded to nasal allergen challenge (NAC). The primary outcomes were the aeroallergen false negative rates and sensitivities of the skin test devices followed by nasal allergen (NAC).

RESULTS

Twenty-five individuals were recruited and underwent a total of 300 SPTs. SPT to allergens (ragweed, dust mite, cat, and timothy grass) resulted in a statistically significant difference in wheal size among the two skin testing devices (p value <0.0001, 0.0001, 0.0006, and 0.0053 respectively). Six NAC procedures were performed to cat/ragweed and 5 of 6 (83% were positive). The overall allergen sensitivity rate for UniTest and Quintip were 97% and 78% respectively with most false negatives due to the use of 6 mg/ml histamine control reagent.

CONCLUSION

Our study shows that 6 mg/ml concentration of histamine control reagent may contribute to a false interpretation of aeroallergen skin prick test results.

Aeroallergen Exposure and Spread in the Modern Era

Since the initial discovery of aeroallergens in the 20th century, our understanding of their properties including sources and factors influencing their spread continues to expand. Both habits of daily living and the presence of environmental factors such as exposure to animals or pollution can influence susceptibility to atopic disease. Because relevant allergens may vary in individuals and communities, it is necessary to understand the physical properties of environmental aeroallergens that are associated with clinical disease to explain symptoms and to implement successful integrated interventions. The objective of this review was to present an overview of aeroallergens and the environmental factors influencing their current distribution. Using historical studies along with recent advancements, we will give an up-to-date description of the physical characteristics and aerodynamics of aeroallergens in addition to location, quantities, and timing of exposure.

Allergic sensitization among Danish infants at 13 months of age

Background

Sensitization means elevated number of specific immunoglobulin E, either measured by skin prick test or in blood samples. Sensitization is associated with, but not synonymous with, allergic disease.

Methods

The Danish Calmette Study was conducted from 2012 to 2015 at three Danish hospitals, with the aim of exploring nonspecific effects of neonatal Bacillus Calmette‐Guérin vaccination. Participants at Kolding Hospital were invited to have a blood sample analyzed for allergic sensitization at 13 months of age. Telephone interviews gave information about allergic symptoms, and the children were examined for signs of atopic dermatitis at 3 and 13 months.

Results

Of the 1241 children included in the Danish Calmette Study in Kolding 1066 (86%) had a blood sample drawn, representing 36% of the invited families. The blood sample cohort had a relatively high percentage of atopic predisposition (66.6%) and most mothers had a medium or long education. We found 90 infants (8.4%) to be sensitized, with sensitization against food items (milk, egg, peanut, and hazelnut) being the most common. Atopic dermatitis was found in 19% of the children, and it was significantly associated with sensitization against egg, peanut, wheat, cat, and dog.

Conclusion

In a partly selected Danish cohort, sensitization was present in 8% at 13 months of age, especially sensitization against food items. Children with atopic dermatitis were significantly more sensitized (16.6%). However, most sensitized children did not have any allergic symptoms at this age.

Time for Allergists to Consider the Role of Mouse Allergy in Non-Inner City Children with Asthma

Mouse allergen is endemic in the inner cities of the United States, with research predominantly in the Northeastern United States. A recent practice parameter notes the effect of mouse exposure in asthma in inner cities. However, studies are emerging that find a role of mouse allergen in non-inner cities as well. Mouse sensitization is associated with mouse allergen exposure and has been linked with adverse asthma outcomes including increased asthma symptoms, poorer lung function, and increased risk of exacerbations. There are commercially available extracts for testing for mouse sensitization although they are not standardized. Pest management studies have had varying results, but with decreased allergen exposure, there is a trend toward improved asthma outcomes. Physicians should be aware of the potential for rodent exposure and sensitization and consider screening for mouse allergy in asthmatic children, especially if they are located in the inner city, have poorly controlled asthma, or have a history of mouse infestation in their location. Evidence is emerging that this allergen should be considered in non-inner-city asthmatics as well. Finally, advocacy efforts are necessary to ensure that removal of this allergen is accomplished, when possible, in the environments of asthmatic children sensitized to mouse.

International Consensus Statement on Allergy and Rhinology: Allergic Rhinitis

BACKGROUND

Critical examination of the quality and validity of available allergic rhinitis (AR) literature is necessary to improve understanding and to appropriately translate this knowledge to clinical care of the AR patient. To evaluate the existing AR literature, international multidisciplinary experts with an interest in AR have produced the International Consensus statement on Allergy and Rhinology: Allergic Rhinitis (ICAR:AR).

METHODS

Using previously described methodology, specific topics were developed relating to AR. Each topic was assigned a literature review, evidence-based review (EBR), or evidence-based review with recommendations (EBRR) format as dictated by available evidence and purpose within the ICAR:AR document. Following iterative reviews of each topic, the ICAR:AR document was synthesized and reviewed by all authors for consensus.

RESULTS

The ICAR:AR document addresses over 100 individual topics related to AR, including diagnosis, pathophysiology, epidemiology, disease burden, risk factors for the development of AR, allergy testing modalities, treatment, and other conditions/comorbidities associated with AR.

CONCLUSION

This critical review of the AR literature has identified several strengths; providers can be confident that treatment decisions are supported by rigorous studies. However, there are also substantial gaps in the AR literature. These knowledge gaps should be viewed as opportunities for improvement, as often the things that we teach and the medicine that we practice are not based on the best quality evidence. This document aims to highlight the strengths and weaknesses of the AR literature to identify areas for future AR research and improved understanding.

Comparative effectiveness of allergy testing method in driving immunotherapy outcomes

BACKGROUND

Skin-prick testing (SPT), in vitro testing (IVT), and intradermal-dilutional testing (IDT) are methods to detect patient sensitivities to specific allergens and direct immunotherapy dosing. We used objective and subjective measures of improvement to compare outcomes based on test method.

METHODS

Patients underwent 1 of 3 protocols: SPT, screening SPT followed by IDT, or IVT. We used institution billing data to do a cost analysis of these tests. The time to maintenance (TTM) therapy was analyzed and patients were stratified into high and low reactors. The Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) was used to quantify symptoms pre-maintenance and post-maintenance.

RESULTS

Of 177 patients (SPT, n = 40; IVT, n = 91; IDT, n = 46), 115 (SPT, n = 35; IVT, n = 39; IDT, n = 41) were high reactors. Out of 90 patients (SPT, n = 17; IVT, n = 37; IDT, n = 36) reaching maintenance, 58 were high reactors (SPT, n = 15; IVT, n = 12; IDT, n = 31). Overall, SPT, IVT, and IDT median TTM were 542, 329, and 578.5 days, respectively. IDT TTM was shorter compared to IVT overall and in high reactors (hazard ratio [HR] = 1.91, p = 0.02; HR = 2.12, p = 0.03), but was not significant compared to SPT high reactors (p = 0.33). The IDT cost was $62.66, translating to an incremental cost-effectiveness ratio of $0.23 per day of shortened TTM. Median RQLQ change for the SPT, IVT, and IDT groups was 6.5, 1, and 1.5, respectively, but was not significant (p = 0.60).

CONCLUSION

IDT reached maintenance immunotherapy quicker than IVT but there was no difference compared to SPT. TTM did not correlate with improvements in patient symptoms between testing methods. This study represents a novel comparison of outcomes based on initial allergy testing method.

Diagnosing environmental allergies: Comparison of skin-prick, intradermal, and serum specific immunoglobulin E testing

Background:

Allergists commonly perform intradermal skin testing (IDST) after negative skin-prick testing (SPT) to comprehensively diagnose environmental allergic sensitization. However, with the availability of modern methods to detect serum-specific immunoglobulin E (ssIgE), it is unclear if ssIgE testing could substitute for IDST.

Objective:

To determine the efficacy of ssIgE testing and IDST when added to SPT in diagnosing environmental allergic sensitizations.

Methods:

SPT, IDST, and ssIgE testing to nine common environmental allergens were analyzed in 75 patients with oculonasal symptoms who presented to our allergy clinics in the Bronx, New York, between January 2014 and May 2015.

Results:

A total of 651 SPT and 499 ssIgE tests were independently performed and revealed 162 (25%) and 127 (25%) sensitizations, respectively. When SPT results were negative, IDST results revealed 108 of 452 additional sensitizations (24%). In contrast, when SPT results were negative, ssIgE test results only revealed 9% additional sensitizations. When both SPT and IDST results were negative, ssIgE testing only detected 3% of additional sensitizations, and ssIgE levels were typically low in these cases (median, 1.25 kU/L; range, 0.357–4.47 kU/L). When both SPT and ssIgE test results were negative, IDST results detected 15% additional sensitizations.

Conclusion:

IDST detected more additional environmental sensitizations compared with ssIgE testing. IDST, therefore, may be useful when the SPT and/or ssIgE testing results were negative, but the exposure history indicated relevant allergic sensitization. Serology added only a little more information if both SPT and IDST results were negative but may be useful in combination with SPT if IDST cannot be performed.

Allergen-specific immunoglobulin E and allergic rhinitis severity

BACKGROUND

Allergic rhinitis (AR) is a common disorder. The diagnosis is based on the concordance between allergy sensitization and history. Serum allergen specific immunoglobulin E (sIgE) assessment allows characterization of the relevant sensitizing allergens. Presently, Allergic Rhinitis and its Impact on Asthma (ARIA) classification subdivides AR based on symptoms severity and duration. However, the relationship between sIgE levels and symptom severity is still a matter of debate.

OBJECTIVE

Therefore, this study aimed at relating sIgE levels with symptom severity assessed by ARIA classification in a group of patients with AR.

METHODS

We enrolled 217 patients with AR (123 women; median age, 39.5 years). The sIgE levels (expressed in kUA/L) to house-dust mite were detected by the fluorescence enzyme immunoassay in peripheral blood samples. The IgE calibrators were traceable to the second international reference preparation 75/502 of human serum IgE from the World Health Organization. Symptom severity was assessed by ARIA classification.

RESULTS

We found a significant difference in sIgE levels in patients with mild intermittent versus mild persistent symptoms (p < 0.05), mild intermittent versus moderate-to-severe persistent symptoms (p < 0.001), moderate-to-severe intermittent versus moderate-to-severe persistent symptoms (p < 0.01), and mild persistent versus moderate-to-severe persistent symptoms (p < 0.05).

CONCLUSION

Analysis of these findings indicated that the sIgE level to house-dust mite might be a reliable biomarker for symptom severity in patients with AR. This outcome might be clinically relevant, particularly in candidates for immunotherapy.

Work-Related Asthma

OBJECTIVE

Summarize developed evidence-based diagnostic and treatment guidelines for work-related asthma (WRA).

METHODS

Comprehensive literature reviews conducted with article critiquing and grading. Guidelines developed by a multidisciplinary expert panel and peer-reviewed.

RESULTS

Evidence supports spirometric testing as an essential early test. Serial peak expiratory flow rates measurement is moderately recommended for employees diagnosed with asthma to establish work-relatedness. Bronchial provocation testing is moderately recommended. IgE and skin prick testing for specific high-molecular weight (HMW) antigens are highly recommended. IgG testing for HMW antigens, IgE testing for low-molecular weight antigens, and nitric oxide testing for diagnosis are not recommended. Removal from exposure is associated with the highest probability of improvement, but may not lead to complete recovery.

CONCLUSION

Quality evidence supports these clinical practice recommendations. The guidelines may be useful to providers who diagnose and/or treat WRA.

Skin testing versus in vitro testing in the evaluation of aeroallergy: The great debate

When one examines reviews regarding diagnostic allergy testing, it generally is noted that the advantage of skin testing is that it uses testing to an end organ, is less expensive, is more sensitive, and provides immediate results, which are easily visualized by the patient. In the case of in vitro testing, it is thought to be more helpful for patients with dermographia or widespread dermatitis, is not affected by H1 or H2 antagonists, and is thought to be safer than skin testing. This may not be entirely correct because studies actually demonstrated phlebotomy to be associated with more morbidity than skin-prick testing. Other concerns regarding both tests include allergen quality, the need from proficiency testing, and the fact that these tests should be used for corroborating a diagnosis as opposed to a screening test for allergy.

Skin testing versus serum-specific IgE testing: which is better for diagnosing aeroallergen sensitization and predicting clinical allergy?

An accurate diagnosis of aeroallergen sensitization is pivotal to clinical practice and research. Given the recent technological advances in analyzing serum allergen-specific IgE, the question of which testing method, skin or serum testing, is superior in diagnosing allergic sensitization must be readdressed, as well as their value in predicting clinical disease. This review article provides a detailed summary of recent studies addressing these questions. Conclusively, most studies show substantial discordance between serum-specific IgE and skin testing results, suggesting that the two testing methods compliment each other and cannot be used interchangeably. On average, using only one testing method may misdiagnose every fourth allergically sensitized patient as non-sensitized. In addition, depending on the allergen tested, skin prick testing and serum-specific IgE testing appear to be the methods of choice in predicting outcomes of experimental allergen challenge, while intradermal testing is less contributory.

Management of rodent exposure and allergy in the pediatric population

Although rodent allergy has long been recognized as an occupational disease, it has only been in the past decade that it has been recognized as a community-based disease that affects children. Most homes in the US have detectable mouse allergen, but the concentrations in inner-city homes are orders of magnitude higher than those found in suburban homes. Home mouse allergen exposure has been linked to sensitization to mouse, and children with asthma who are both sensitized and exposed to high mouse allergen concentrations at home are at greater risk for symptoms, exacerbations and reduced lung function. Rat allergen is found primarily in inner-city homes and has also been linked to asthma morbidity among sensitized children. The objective of this review is to summarize the scientific literature on rodents and their allergens, the effects of exposure to these allergens on allergic respiratory disease, and to make recommendations, based on this evidence base, for the evaluation and management of mouse allergy in the pediatric population.

Sensitization to rodents (mouse/rat) in urban atopic populations without occupational exposure living in Campania district (Southern Italy): a multicenter study

BACKGROUND

Up to now very few data on allergic sensitization to rodent allergens in Western Europe and Italy are available, and there are no information at district level.The aim of this report was to investigate clinical significance and characteristics of allergic sensitization to mouse/rat (M/Rt) allergens in atopic subjects living in Campania district (Southern Italy).

METHODS

Allergists from the whole Campania district were required to report the results of skin prick tests of at least 100 consecutive subjects. In 1,477 consecutive outpatients, we selected all subjects with an immediate skin reaction to M/Rt dander. Clinical history including a careful evaluation of the modality of exposure and the results of skin-prick tests (SPTs) were recorded.

RESULTS

Fifty seven patients were sensitized to M/Rt dander (5.78%). Two patients were mono-sensitized. Fourteen patients reported indoor conditions suggesting presence of rodents allergens at home. All patients exhibited low-moderate degree of SPT positivity to M/Rt. High frequency of concomitant allergic sensitization to dust mites was found.

CONCLUSIONS

Our results suggest that the role of allergic sensitization to rodents is not negligible in atopic subjects without occupational exposure living in Campania district area; these values are higher in comparison to those previously found in Naples area. Highly atopic individuals should be tested by SPTs/evaluation of serum specific IgE to rodents in the case they should begin an occupational exposure to M/Rt or keep these animals as pets.

Prevention of laboratory animal allergy in the United States: a national survey

OBJECTIVE

Respiratory allergy to laboratory animals is a common and preventable occupational health problem. This study documents current laboratory animal allergy (LAA) prevention programs in the United States.

METHODS

An online survey was e-mailed to designated institutional officials at laboratory animal facilities identified by the National Institutes of Health Office of Laboratory Animal Welfare.

RESULTS

A total of 198 organizations responded and more than 80% required the use of uniforms and gloves to control exposure. Respirators were required by 25% of organizations. Medical surveillance was mandated by 58% of organizations (70% for organizations with at least 100 employees working with animals). Work restriction practices varied. Only 25% of organizations reported knowing the prevalence (range: 0% to 75%) and 29% reported knowing the incidence of LAA (range: 0% to 18%).

CONCLUSIONS

There is broad variation in policy and practice to prevent LAA. An evidence-based consensus would ensure greater protection of workers.

Overview of serological-specific IgE antibody testing in children

Allergic diseases are among the most common chronic conditions in the pediatric population. Allergy diagnostic testing is an important part of the evaluation/management of allergic patients because the history may not be precise enough to identify the specific allergen sensitivity. In addition to providing information about specific sensitivities, allergy diagnostic tests have some predictive value in terms of future risk of developing an allergic condition and the severity/persistence of the allergic disease. The two most commonly used methods of confirming allergen sensitization are skin testing and measurement of serum-specific IgE. Both methods have similar diagnostic value in terms of sensitivity and specificity, with both parameters varying with the clinical scenario and allergen tested. Currently, there are three US Food and Drug Administration-cleared, serum-specific IgE assays used in the United States. The three assays report comparable analytic sensitivity, with the coefficients of variation of the precision, reproducibility, and linearity being less than 15%. However, comparative studies have demonstrated significant inter-assay variability, suggesting that they detect different populations of IgE antibody in human sera or do not measure the same antibodies with the same efficiency. Current specific IgE assays utilize allergen extract reagents. Testing with these reagents may identify sensitivity to clinically irrelevant allergens. This diagnostic limitation has spurred the development of molecular diagnostic tests, also referred to as component-resolved diagnostics, which utilize purified native or recombinant allergens to detect IgE sensitivity to individual allergen molecules. These advancements in serum IgE testing may enhance the precision of allergy diagnostic testing, which may decrease the need for oral food challenges and improve the specificity of allergen immunotherapy.

Intradermal skin test results correlate with atopy

Intradermal skin testing (IDST) is performed by most allergists, but its value remains controversial. In most previous studies assessing the value of IDST, a positive result was based on a 5- to 6-mm wheal and erythema. While a subject's immediate reaction upon allergen exposure is a common endpoint to determine "allergy," additional known allergic phenomena such as the delayed or late-phase response to allergen exposure suggest that correlation only with current history or acute challenge may result in an incorrect labeling of false-positive results when, in fact, there is a physiologic response to exposure, albeit a reaction not immediately evident. We conducted a retrospective study to determine if positive IDST reactions represent nonspecific irritation or if they correlate with atopy. We retrospectively reviewed the records of 100 patients who had undergone skin prick testing (SPT) and IDST and compiled data on their age, sex, diagnosis, and number of skin and intradermal reactions. Results were analyzed according to a general linear model to see if the development of a positive IDST result correlated with atopy (defined as SPT positivity). We found statistically significant differences between SPT-positive and -negative patients with regard to diagnoses of asthma, rhinitis, or both (p=0.008). Controlling for asthma and rhinitis, we also found a significant association between atopy and a positive IDST result; among atopic (SPT+) patients, a mean of 25.9% of IDST results were positive, compared with a rate of only 6.7% IDST positivity among the nonatopic (SPT-) patients (p<0.0001). We conclude that IDST is more commonly positive in atopic (SPT+) than nonatopic (SPT-) patients, suggesting that a positive IDST represents genuine atopy and bona fide sensitization rather than nonspecific irritation.

Correlation analysis of two serum-specific immunoglobulin E test systems and skin-prick test in allergic rhinitis patients from northeast China

BACKGROUND

Skin-prick testing (SPT) is the most common screening method for allergy evaluation. The detection of serum-specific immunoglobulin E (sIgE) is also commonly used. The sensitivity and specificity of these testing methods may vary due to type of causative allergen and type of allergic manifestation. The purpose of this study was to evaluate the correlation between two methods of measuring sIgE (AllergyScreen [Mediwiss Analytic GmbH, Moers, Germany] and ImmunoCAP [Pharmacia, Uppsala, Sweden]) and SPT for the diagnosis of allergic rhinitis (AR).

METHODS

All 216 patients who were referred to the allergist for suspected AR from June to October 2009 had SPT and the two serological tests. One hundred fifty-eight patients had a positive clinical history and a related positive SPT. The SPT was used as reference standard, and we selected three allergens (Dermatophagoides pteronyssinus, mugwort, and ragweed), which were common in fall in northeast China, to analyze the correlation of the two serum tests and SPT.

RESULTS

Compared with the SPT, the diagnostic indexes (accuracy, sensitivity and specificity) of the AllergyScreen system and the ImmunoCAP system were 0.819 versus 0.810, 0.780 versus 0.872, and 0.862 versus 0.741, respectively. The accuracy was similar between the two systems (p > 0.05). The ImmunoCAP system method had a higher sensitivity (p < 0.01). The AllergyScreen system had a higher specificity (p < 0.01).

CONCLUSION

These data support that the AllergyScreen system and ImmunoCAP system can identify potentially significant allergens in the diagnosis of AR in patients from northeastern China.

Physico-chemical features of the environment affect the protein conformation and the immunoglobulin E reactivity of kiwellin (Act d 5)

BACKGROUND

Allergy diagnostic systems sometimes give false positive or negative results. In this respect, the influence of protein conformational changes on the allergen-IgE interaction sites is worthy to be investigated.

OBJECTIVE

To investigate the influence of different experimental conditions on the structural properties and IgE reactivity of kiwellin (Act d 5) as a model system.

METHODS

Act d 5 was purified from the natural source. To study its conformational features, experiments of circular dichroism (CD) in different media were performed. The IgE reactivity was investigated by skin testing, immunoblotting and ISAC microarray system, in a population of kiwifruit allergic subjects.

RESULTS

CD experiments indicated that Act d 5 has a mainly helical structure and the conformation is strongly affected by the experimental conditions. The protein is more structured in low polarity media and at acidic pH values, similar to those of the natural source. Eleven subjects of 29 (38%) allergic to kiwifruit were positive to purified natural Act d 5 by skin test. Among them, three patients (10%) showed a reaction only to Act d 5 at pH 4.5, and three (10%) showed a reaction only to the allergen in standard neutral conditions. No one of the 11 subjects with positive skin test recognized Act d 5 immobilized on the ISAC system. Eight of nine subjects detected Act d 5 by IgE immunoblotting. One subject did not recognize the sequence epitopes of Act d 5 in IgE immunoblotting experiments and reacted to the skin test only when the allergen was in acidic conditions.

CONCLUSIONS AND CLINICAL RELEVANCE

The conformation and IgE reactivity of Act d 5 are affected by the physico-chemical characteristics of the solvent. These findings suggest that the assay conditions influence the results of the diagnostic systems by modulating the pattern of exposed antigenic epitopes.

Pest and allergen exposure and abatement in inner-city asthma: a work group report of the American Academy of Allergy, Asthma & Immunology Indoor Allergy/Air Pollution Committee

Our work group report details the importance of pest allergen exposure in inner-city asthma. We will focus specifically on mouse and cockroach exposure. We will discuss how exposure to these pests is common in the inner city and what conditions exist in urban areas that might lead to increased exposure. We will discuss how exposure is associated with allergen sensitization and asthma morbidity. Finally, we will discuss different methods of intervention and the effectiveness of these tactics.

Role of mouse allergens in allergic disease

Mouse allergen has long been recognized as an important cause of occupational allergy and asthma, but only recently has it been implicated in asthma and allergic diseases in community settings. Recent studies have established that mouse allergen is detectable in most US homes, with strikingly high levels in some inner cities. Inner city homes in major northeastern and midwestern US urban centers have levels as much as 100-fold higher than those found in other geographic regions. In addition, about 25% of inner city children with asthma have evidence of IgE sensitization to mouse. Several studies have shown that the combination of sensitization and exposure to higher levels of mouse allergen is associated with substantial asthma morbidity, including hospitalizations. Integrated pest management is efficacious in reducing mouse allergen levels and is recommended for sensitized patients with asthma. However, its impact on clinical outcomes has not yet been proven.

Comparison of wheat and rye flour solutions for skin prick testing: a multi-centre study (Stad 1)

BACKGROUND

Skin prick testing (SPT) is the basic method for diagnosing IgE-mediated allergies. However, skin reactivity is related to the quality of allergen extracts, which are often poorly defined for occupational allergens.

OBJECTIVE

To compare wheat and rye flour SPT solutions from different producers.

MATERIALS AND METHODS

Standardized SPTs were performed in seven allergy centres with wheat and rye flour solutions from four producers in 125 symptomatic bakers. Optimal cut-off levels for weal sizes were assessed with the Youden Index. Comparisons between SPT results of different solutions were made with flour-specific IgE (sIgE) as the gold standard. Sensitivities, specificities, positive and negative predictive values, and test efficiencies were calculated and compared with McNemar and chi(2)-tests. The influence of the choice of the gold standard (sIgE or challenge) test was examined for 95 subjects. Additionally, SPT solutions were analysed for protein and antigen content.

RESULTS

The optimal cut-off level for all SPT solutions was a weal size of >or=1.5 mm. While differences between wheat and rye flours were small, differences between producers were important. Variability of sensitivities (0.31-0.96), negative predictive values (0.42-0.91), and test efficiencies (0.54-0.90) were higher than variations of specificities (0.74-1.00) and positive predictive values (0.88-1.00). Similar results were obtained when using challenge test results as the gold standard. Variability could be explained by the different antigen contents of the SPT solutions.

CONCLUSION

There is a wide variability of SPT solutions for wheat and rye flour from different producers, mainly with respect to sensitivities, negative predictive values, and test efficiencies. Improvement and standardization of SPT solutions used for the diagnosis of baker's asthma are highly recommended.

Pearls and pitfalls of allergy diagnostic testing: report from the American College of Allergy, Asthma and Immunology/American Academy of Allergy, Asthma and Immunology Specific IgE Test Task Force

The intended purpose of this monograph is to provide a general overview of allergy diagnostics for health care professionals who care for patients with allergic disease. For a more comprehensive review of allergy diagnostic testing, readers can refer to the Allergy Diagnostic Practice Parameters. A key message is that a positive allergy test result (skin or blood) indicates only the presence of allergen specific IgE (called sensitization). It does not necessarily mean clinical allergy (ie, allergic symptoms with exposure). It is important for this reason that the allergy evaluation be based on the patient's history and directed by a health care professional with sufficient understanding of allergy diagnostic testing to use the information obtained from his/her evaluation of the patient to determine (1) what allergy diagnostic tests to order, (2) how to interpret the allergy diagnostic test results, and (3) how to use the information obtained from the allergy evaluation to develop an appropriate therapeutic treatment plan.

The role of intradermal skin testing in inhalant allergy

OBJECTIVE

To provide an overview of the role of intradermal skin testing (IDST) in inhalant allergy.

DATA SOURCES

A literature search was conducted in MEDLINE to identify peer-reviewed articles related to IDST using the following keywords: skin testing, intradermal, intracutaneous, aeroallergen, and inhalant allergen. In addition, references cited within these articles were also reviewed.

STUDY SELECTION

Articles were selected based on their relevance to the topic.

RESULTS

The use of IDST for inhalant allergy varies widely among allergists. When performed, it is necessary to use a 100- to 1,000-fold dilution from the stock allergen extract. IDST is used routinely in the standardization of extracts in the United States. With a negative skin prick test result, a positive IDST result has low agreement with in vitro and challenge results and generally adds little to the diagnostic evaluation. In contrast, a negative IDST result generally has a high negative predictive value. Only a few inhalant allergens have been evaluated with challenge models for IDST. A summary of the data is also presented in tabular form.

CONCLUSIONS

Most of the literature suggests that with a negative skin prick test result, a positive IDST result adds little to the diagnostic evaluation of inhalant allergy. However, additional studies are necessary using challenge models for less potent and nonstandardized inhalant allergens (molds, trees, dog, weeds).