Diagnosis Of IgE-mediated Allergy Research Articles

Sensitization to Food and Aero-Allergens in Children with Coeliac Disease Assessed with the Use of a Multiplex Molecular Diagnostic Technique

(1) Background. Coeliac disease (CD) often co-occurs with autoimmune conditions or genetic syndromes, but there are few studies on the co-existence of CD and immunoglobulin E (IgE)-mediated allergies. The purpose of this study was to assess sensitization to food and aero-allergens in pediatric patients with CD. (2) Methods. A multiplex ALEX®2 test was used to determine specific IgEs (sIgEs). (3) Results. The study included 108 children newly diagnosed with CD. Allergen extract- and/or allergen molecule-sIgEs were detected in 49.1% of children. Most children (41.5%) were sensitized to both inhalant and food allergens. The three most common aero-allergens (timothy pollen, ryegrass, silver birch) were molecules Phl p 1, Lol p 1, and Bet v 1. The most common food allergens (hazelnut, apple, and peanut) were Cor a 1, Mal d 1, and Ara h 8 molecules of the PR-10 subfamily. Patients were not sensitized to cereal allergens containing gluten. Spearman’s rank correlation analysis of sensitized patients showed a significant positive relationship (r = 0.31) between the patients’ age and the occurrence of positive sIgEs (≥0.3 kUA/L) for inhalant allergen molecules (p = 0.045). In sensitized patients, mainly symptoms of inhalant allergy were observed, such as hay fever, conjunctivitis, and bronchial asthma. (4) Conclusions. The current study indicates the co-occurrence of IgE sensitization to food and inhalant allergens in children with CD. The study highlights the need to take a closer look at the diagnosis of IgE-mediated allergy in patients with CD, which may help in their care and lead to a better understanding of the relationship between CD and IgE-mediated allergy.

Synthesis of skeletally diverse β-lactam haptens for the in vitro diagnosis of IgE-mediated drug allergy

Skeletally diverse compounds derived from β-lactam antibiotics were synthesized to generate antigens for the in vitro diagnosis of IgE-mediated allergy.

Sensitivity and specificity of standardised allergen extracts in skin prick test for diagnoses of IgE-mediated respiratory allergies

BackgroundSkin prick tests (SPTs) are essential for the diagnosis of IgE-mediated allergy and are influenced by extract quality, biological potency and concentration of allergen.MethodsIn this open multicentre study 431 patients, aged 18–64 years were enrolled. Patients had a history of IgE-mediated allergy and a sensitisation (previous positive SPT of any manufacturer) against at least one of the investigated allergens: 6-grass pollen, house dust mite, birch and mugwort pollen. In our study, these allergens were tested in five concentrations each. To establish the optimal trade-off between sensitivity and specificity, the area under the receiver operating characteristic (ROC) curve was estimated by comparing the outcome of the SPT with three methods referred to as ‘reference methods’ (specific IgE, clinical case history and a previous SPT).ResultsFor all allergens and reference methods, the area under the ROC curves were highly significant (p < 0.001). Specific IgE reference method resulted in the largest area under the curve (AUC) for all allergens (0.80–0.90) followed by previous SPT (0.70–0.87) and case history (0.65–0.74). Sensitivity of SPT increased with increasing concentration and specificity decreased. For all allergens, compared to specific IgE, the highest sensitivity (specificity at least 80%) was observed for the SPT solution of 50,000 Standardised Units (SU)/mL (grass pollen, birch pollen, house dust mite and mugwort).ConclusionIn this study, with a large number of patients, it was demonstrated that clinical case history, previous SPT and specific IgE measurement could all be used as reference methods for the assessment of sensitivity/specificity of SPT solutions. The comparison of SPT with specific IgE resulted in the largest AUC. The highest sensitivity was observed for the SPT solution of 50,000 SU/mL.Trial registration EudraCT: 2006-005304-14.

A new framework for the interpretation of IgE sensitization tests.

IgE sensitization tests, such as skin prick testing and serum-specific IgE, have been used to diagnose IgE-mediated clinical allergy for many years. Their prime drawback is that they detect sensitization which is only loosely related to clinical allergy. Many patients therefore require provocation tests to make a definitive diagnosis; these are often expensive and potentially associated with severe reactions. The likelihood of clinical allergy can be semi-quantified from an IgE sensitization test results. This relationship varies though according to the patients' age, ethnicity, nature of the putative allergic reaction and coexisting clinical diseases such as eczema. The likelihood of clinical allergy can be more precisely estimated from an IgE sensitization test result, by taking into account the patient's presenting features (pretest probability). The presence of each of these patient-specific factors may mean that a patient is more or less likely to have clinical allergy with a given test result (post-test probability). We present two approaches to include pretest probabilities in the interpretation of results. These approaches are currently limited by a lack of data to allow us to derive pretest probabilities for diverse setting, regions and allergens. Also, cofactors, such as exercise, may be necessary for exposure to an allergen to result in an allergic reaction in specific IgE-positive patients. The diagnosis of IgE-mediated allergy is now being aided by the introduction of allergen component testing which may identify clinically relevant sensitization. Other approaches are in development with basophil activation testing being closest to clinical application.

Modern diagnosis of IgE-mediated allergy – molecular diagnosis of allergies

Diagnostic difficulties resulting from the imperfections of natural allergen extracts inspired to use genetic engineering techniques to produce recombinant allergens or obtaining highly purified components (component) allergen. This led to the development of modern diagnostic technique in allergy or molecular diagnostics. The basis for understanding the molecular diagnosis of allergies is to know the properties of allergens. Each allergen is composed of various proteins known. component capable of sensitizing allergen, and each component includes a plurality of epitopes that can be divided into one species-specific epitopes, and the identical amino acid structure of the epitopes derived from different species. Specific epitopes are responsible for primary sensitization, while the epitopes with similar structures are responsible for cross-reactions. Finding sensitization several epitopes is a strong indication of the occurrence of much more dangerous allergic reactions than only one epitope. In addition, molecular diagnosis of allergies allows for personalized diagnosis of allergic patients. It enables the assessment of individual risk of allergic symptoms and allows you to distinguish the original from allergy symptoms caused by cross-reactions. It should be noted, however, that the diagnosis of allergy should be based on a comprehensive evaluation of the results and their confrontation with data from the interview. The mere detection of allergen-specific IgE antibodies, even the method of molecular diagnostics, without the presence of clinical symptoms does not confirm an allergy or illness. Only goes to confirm that the body of such a person is allergic and that the symptoms of this condition may at some point reveal but not necessarily.

IgE antibodies in occupational asthma

To evaluate recent data on the causative role of specific IgE antibodies, as well as the performance of IgE diagnostic tests, in allergic occupational asthma induced by high (HMW) or low-molecular-weight (LMW) agents. Skin prick testing (SPT) and specific IgE assays are useful to document allergy to most HMW allergens and some LMW agents. These tests, however, are limited by the lack of standardized and commercially available reagents. There is a wide variability among the quality of occupational allergen extracts used for SPT and the sensitivity of several SPT solutions is low. In addition, many individuals with allergen-specific serum IgE and/or positive SPT to specific HMW allergens do not have clinical symptoms. Sensitization or allergenic cross-reactivity to allergens or epitopes from unrelated sources may interfere in the diagnosis of IgE-mediated allergy, giving rise to false-positive results, particularly when cross-reactive carbohydrate determinants (CCDs) are involved. The immune responses to these ubiquitous structures may interfere with the diagnosis of occupational allergy. Component-resolved diagnosis of IgE-mediated allergic diseases (occupational and nonoccupational) using panels of native or recombinant allergens, or micro-arrayed allergens, have been proposed to identify specific molecules responsible for these disorders and to overcome false-positive in-vitro test results. Improvement and standardization of SPT solutions for occupational allergens are highly recommended. More refined diagnostic tools than specific IgE measurements are being developed, such as inhibition assays of IgE binding to CCDs with specific carbohydrate molecules, and component-resolved diagnosis.

In vitro diagnosis of IgE-mediated allergy: breakthroughs in the last decade

Background This article briefly reviews the historical development, present status and perspectives of the diagnosis of IgE-mediated allergy. After more than a century of relying on skin testing and 40 years of relying on quantification of specific IgE antibodies for the diagnosis of IgE-mediated allergy, clinicians now have access to different novel in vitro diagnostics in the form of component-based assays and flow-assisted quantification of activated basophils. Although these techniques already constitute key advances in the diagnosis of allergy, it is anticipated that future developments, such as epitope mapping and identification of novel basophil activation markers, might further improve management of the allergic patient. In this context, the recent development of a flow cytometric technique to analyze histamine release at a single cell level might represent a significant step forward. IgE-mediated allergies constitute an important and increasing health problem with significant morbidity and potential mortality. Correct diagnosis with identification of all offending allergens is an absolute prerequisite for appropriate and potentially life-saving preventive measures or the initiation of allergen-specific immunotherapy. The diagnostic algorithm for IgE-mediated allergy involves a thorough clinical history that is documented by the demonstration of allergen-specific IgE (specific IgE) antibody by either in vivo skin testing (prick/intradermal) or a serologic assay. Although these tests can provide useful information, they do not demonstrate an absolute predictive value and the results are not always unequivocal. In these cases, where there exists a discrepancy between history and results from quantification of sIgE and/or skin tests, additional tests such as mediator release assays or (double-blind placebo-controlled) challenge tests have long been used to establish correct diagnosis. During the last decade two novel in vitro assays have entered the allergy diagnostics arsenal, that is, component-resolved allergy diagnosis (CRD) and the basophil activation test by flow cytometry.

Diagnostic value of Alt a 1, fungal enolase and manganese-dependent superoxide dismutase in the component-resolved diagnosis of allergy to pleosporaceae

Over the last decades, genomics and proteomics have contributed to the current knowledge of individualized allergenic components and their potential use in the diagnosis of IgE-mediated allergies. Recent investigations have demonstrated that Alt a 1 should be considered as a relevant allergen of the Pleosporaceae group and that enolase is the main allergen involved in the cross-reactivity to fungi. However, the real utility of these allergens as tools for the diagnosis of allergy to Alternaria is still unclear. To demonstrate the current value of the available fungal allergen panel and the need to build an accurate mould allergen array for the diagnosis of allergy to Pleosporaceae. Specific IgEs to individual mould allergens and allergenic mould extracts were evaluated using the ImmunoCAP™ system in 30 patients allergic to Alternaria and in 100 blood donors. Cross-reactivity studies were performed by Fluoro Enzyme ImmunoAssay (FEIA) and FEIA inhibition using individual allergens and allergenic extracts. Two-dimensional electrophoresis associated with a MALDI-TOF analysis was carried out to identify new allergen molecules. All allergic patients had positive specific IgE responses to several moulds from different taxonomical families. Classic and molecular diagnosis demonstrated that 23% of patients had multi-sensitization. The current commercially available fungal allergen array was not sufficient to establish an accurate diagnosis. Unexpected correlations between Alternaria or Alt a 1 and Curvularia or Cladosporium stimulated the investigation of a more accurate allergen panel. A manganese-dependent superoxide dismutase (MnSOD) homologous to Asp f 6 was identified as a new IgE-binding molecule from Alternaria alternata. Alt a 1 is the marker for allergy to Pleosporaceae, not including Curvularia. MnSOD can explain 6.6% of allergy to Alternaria without Alt a 1 sensitization and should be included together with Alt a 1 and fungal enolase in the molecular array for the diagnosis of allergy to Pleosporaceae.

The performance of a component‐based allergen‐microarray in clinical practice

Currently, the diagnosis of IgE-mediated allergy is based on allergen-specific history and diagnostic procedures using natural allergen extracts for in vivo and in vitro tests. The aim of the study was to comparatively analyse a new component-based allergen-microarray and the 'quasi-standard' ImmunoCAP for their clinical relevance in patients with allergic rhinoconjunctivitis to five aeroallergens [house dust mite (HDM), cat dander, birch, grass and mugwort pollen] in a prospective, double-centre study. We enrolled 120 subjects at the two study centres. Allergic patients were defined as having an allergen-specific history plus a concomitant positive skin-prick test (SPT) to natural allergen extracts and specific serum IgE was measured by both methods. Each allergen was analysed separately. The microarray performed equally well in receiver-operating characteristic curve (ROC) analyses when compared with the CAP in cat (23 allergic vs 97 non-allergic, ROC area under the curve microarray 0.950 vs CAP 0.894, P = 0.211), birch (31/89, 0.908 vs 0.878, P = 0.483) and grass pollen (47/73, 0.923 vs 0.915, P = 0.770). It was slightly less sensitive in HDM-allergic subjects (26 allergic vs 94 non-allergic, ROC area microarray 0.808 vs CAP 0.911, P = 0.053) and displayed a reduced sensitivity in the mugwort pollen-allergic patients (17/103, 0.723 vs 0.879, P = 0.032). Component-based testing and the whole-allergen CAP are equally relevant in the diagnosis of grass-, birch- and cat-allergic patients. Although slightly less sensitive, the microarray is sufficient for the diagnosis of HDM-allergic patients, but needs alternative and/or additional components for detecting mugwort allergy.

The Performance of a New Component-Based Allergen-Microarray in Clinical Practice

RATIONALE: Currently the diagnosis of IgE-mediated allergy is based on the allergen-specific history and diagnostic procedures using natural allergen extracts for in vivo and in vitro tests. The aim of the study was to comparatively analyse a new allergen-microarray and the ‘quasi-standard’ ImmunoCAP® for their clinical relevance in patients with allergic rhinoconjunctivitis to 5 aeroallergens [house dust mite (HDM), cat, birch, grass and mugwort pollen] in a prospective, double-centre study.

Tests cutanés allergologiques. Nourrisson et jeune enfant asthmatiques

Skin tests represent a major tool in the diagnosis of IgE mediated-allergy. The main indication is the measure of atopy during infancy and early childhood, as a predictive factor of the development of asthma. When atopic eczema is present, skin testing can provide a diagnosis of food allergy. Skin tests are easily done, without absolute contraindications. The epidemiological knowledge helps to choose the allergens to test. The skin-prick test method is well standardized and must be rigorous because of the hyporeactivity of the infant skin. Results are always confounded with positive and negative control solutions. The interpretation of pricks tests must be careful, standing out a clinical allergy (when clinical allergic symptoms are presents) from a sensitization (atopy). The predictive value of a positive skin test is discussed: predisposition to asthma, association with severe asthma, predisposition to acute bronchiolitis during an epidemic of respiratory virus. A positive skin test to food allergen would predict a later pneumallergen sensitization.

Detection of Basophil Activation by Flow Cytometry in Patients with Allergy to Muscle-relaxant Drugs

ALLERGIC or pseudoallergic reactions that occur during anesthesia have been increasing over the last few years. 1 Muscle-relaxant drugs are responsible for at least half of these life-threatening adverse reactions. 1,2 The diagnosis of drug allergy is mainly based on a detailed clinical history, positive skin tests, and detection of specific immunoglobulin E (IgE). Nevertheless, the biologic results are not always closely correlated with clinical assessment of the disease, and discrepancies between skin tests and specific IgE are reported, 2,3 In these cases, in vitro investigations to identify the responsible drug are needed, and the histamine release (HR) test is usually performed. 2 HR reflects basophil degranulation, but the very small number of circulating basophils is a limitation to this test, and its clinical benefit remains controversial. Because flow cytometry is a valuable tool for identifying cell populations even at low concentrations, we developed a tricolor flow cytometric method (FCM) for the study of allergen-induced basophil activation. 4 Briefly, identification of basophils is based both on CD45 expression (a common leukocyte antigen) and on the presence of IgE on the cell surface, because basophils express high-affinity receptor for IgE. Cell activation on allergen or drug challenge is assessed by the expression of CD63 on the plasma membrane. 5 After the publication of preliminary data (only focused on usual allergens), we initiated studies to evaluate the usefulness of the method in the diagnosis of drug allergy. We report here results of the first four cases of allergy to muscle-relaxant drugs since this FCM was introduced in our laboratory. The patients were recruited from different associated hospitals in Lyon, France, and rapidly developed clinical features evocative of anaphylactic reaction after induction of anesthesia, e.g., hypotension, bronchospasm, and cutaneous signs. Investigations of the responsible drug were performed in the outpatient unit of the Department of Anesthesia (screening for drug allergy unit) at least 2 months after the allergic reaction. Skin prick and intradermal reaction (IDR) tests 3 were performed using various dilutions of drug solutions, specific IgE antibodies (against ammonium group) were measured using radioallergosorbent techniques (Capsystem; Pharmacia, Uppsala, Sweden), histamine was measured using a radioimmunoassay (Immunotech, Marseille, France), and HR test was considered positive when superior to 10% of total HR. Basophil degranulation by FCM was detected by CD63 expression on the cell surface. A positive threshold is defined with a negative control without any drug. Results are positive when > 10% of basophils express CD63.

Comparison of two diagnostic tests for canine atopy using monoclonal anti-IgE antibodies.

In 66 dogs of various races consulting the veterinary clinic for skin problems suspicious of atopic dermatitis, parallel skin tests with two commercial brands of allergens and serological tests with the CMG IMMUNODOT system and with an ELISA assay using monoclonal anti-IgE antibodies were performed. The most frequent sensitivities found were towards house dust (44%) and storage mites (50%). Depending upon the cut-off point chosen, the CMG IMMUNODOT test was shown to have sensitivity, in respect to the skin test, varying from 54 to 100%, in an inverse relationship to specificity. The ELISA assay was found to be slightly less sensitive. These investigations also revealed some major discrepancies in skin test results among allergen extracts of different origins, confirming that skin test results should no longer be considered as the sole 'gold standard' in diagnosis of IgE-mediated allergy. The experience gained confirms that modern serological tests using monoclonal anti-IgE antibodies for detection of allergen-specific IgEs in the dog are useful in the diagnosis of dog allergy.

Diagnosis of IgE‐mediated allergy in the upper respiratory tract

A statistical analysis was made of data concerning diagnosis of IgE-mediated allergy in the upper respiratory tract in 292 patients. A study was made of: skin test, total and specific IgE (RAST), X-sinus, red blood investigation, and cytology of nasal smear. It appears that screening for the presence of an IgE-mediated allergy in the upper respiratory tract can be performed efficiently with a limited number of skin tests (rye grass, timothy, birch, house dust mite and cat). In this study a greater number of skin tests (15 instead of 5) yielded little additional information (in 2% of the patients). A rather poor correlation between skin test and RAST was found.

Comparison between RAST and Pharmacia CAP system: A new automated specific IgE assay

RAST represents the standard technique to titrate serum-specific IgE and was found to have a higher efficiency in the diagnosis of IgE-mediated allergy than other in vitro tests. Pharmacia CAP system (CAP) is a new solid-phase immunoassay, fully automated, used for the titration of specific IgE antibodies. Results are listed in kilounits per liter, equilibrated against the World Health Organization standard for IgE. RAST and CAP were compared in 106 unselected patients (6 to 59 years) characterized by a detailed clinical history and skin prick tests with standardized allergen extracts. IgE to cat, Dermatophagoides pteronyssinus, Alternaria, orchard grass, olive, and Parietaria pollen were tested; 470 tests were run. The specificity, sensitivity, and efficiency of both in vitro tests ranged from 85.5% to 100% except for olive pollen, in which the sensitivity of both in vitro tests was low (68.2% for the new test and 63.6% for RAST). Except for orchard-grass pollen, the sensitivity and specificity of CAP were better than that of RAST. There was a highly significant correlation between both tests ( r range, between 0.864 to 0.987). CAP competes favorably with RAST and has the advantage of being automated and eliciting results in kilounits per liter.

3. Skin tests for diagnosis of IgE-mediated allergy

3. Skin tests for diagnosis of IgE-mediated allergy