CD63 expression on basophils as a tool for the diagnosis of pollen-associated food allergy: sensitivity and specificity

Identification and Characterization of Pectate Lyase as a Novel Allergen in Artemisia sieversiana Pollen

INTRODUCTION

Artemisia species are widely spread in north hemisphere. Artemisia sieversiana pollen is one of the common pollen allergens in the north of China. At present, seven allergens were identified and had been listed officially from A. sieversiana pollen, but the remaining allergens are still insufficiently studied, which need to be found.

METHODS

Pectate lyase was purified from the extracts of A. sieversiana pollen by anion exchange, size exclusion, and HPLC-hydrophobic interaction chromatography. The gene of A. sieversiana pectate lyase (Art si pectate lyase) was cloned and expressed in Escherichia coli. The enzyme activity and circular dichroism (CD) spectrum of natural and recombinant proteins were analyzed. The allergenicity of Art si pectate lyase was characterized by enzyme-linked immunosorbent assay (ELISA), Western blot, inhibition ELISA, and basophil activation test. The allergen's physicochemical properties, three-dimensional structure, sequence profiles with homologous allergens and phylogenetic tree were analyzed by in silico methods.

RESULTS

Natural Art si pectate lyase (nArt si pectate lyase) was purified from A. sieversiana pollen extracts by three chromatographic strategies. The cDNA sequence of Art si pectate lyase had a 1191-bp open reading frame encoding 396 amino acids. Both natural and recombinant pectate lyase (rArt si pectate lyase) exhibited similar CD spectrum, and nArt si pectate lyase had higher enzymatic activity. Moreover, the specific immunoglobulin E (IgE) binding rate against nArt si pectate lyase and rArt si pectate lyase was determined as 40% (6/15) in patients' serum with Artemisia species pollen allergy by ELISA. The nArt si pectate lyase and rArt si pectate lyase could inhibit 76.11% and 47.26% of IgE binding activities to the pollen extracts, respectively. Art si pectate lyase was also confirmed to activate patients' basophils. Its structure contains a predominant motif of classic parallel helical core, consisting of three parallel β-sheets, and two highly conserved features (vWiDH, RxPxxR) which may contribute to pectate lyase activity. Moreover, Art si pectate lyase shared the highest sequence identity of 73.0% with Art v 6 among currently recognized pectate lyase allergen, both were clustered into the same branch in the phylogenetic tree.

CONCLUSION

In this study, pectate lyase was identified and comprehensively characterized as a novel allergen in A. sieversiana pollen. The findings enriched the allergen information for this pollen and promoted the development of component-resolved diagnosis and molecular therapy of A. sieversiana pollen allergy.

Recent advances in the management of nut allergy

Peanut/tree nut allergy is common and has been associated with particularly severe reactions. Epidemiological data have shown that the prevalence ranges between 0.05% and 4.9% for tree nut and between 0.5% and 3% for peanut. These large variations can be explained by differences in the age of included patients and the geographical region. In addition, the food consumption modality (ie, raw versus roasted) plays a major role, as heat treatment has the capacity to modify the allergenicity of nuts and legumes. Nut allergies tend to persist into adulthood and consequently have a high impact on quality of life.

Recently, it has been demonstrated that a significant proportion of nut allergic patients are able to tolerate other nuts. As opposed to the avoidance of all nuts, this approach is currently proposed in several tertiary allergy centers. However, diagnosis of nut allergy is particularly difficult due to co-sensitization leading to high rate of false positive skin prick tests and/or specific IgE to whole allergen extracts. The use of component resolved diagnosis leads to major improvement of diagnosis, particularly to distinguish between primary and secondary nut allergies. The basophil activation test has been suggested to be useful but is still used mainly as a research tool. Thus, diagnosis remains mainly based on the oral food challenge, which is considered as the gold standard.

Regarding treatment, avoidance remains the cornerstone of management of nut allergy. Oral immunotherapy is increasingly proposed as an alternative management strategy.

Effect of tyrosinase and caffeic acid crosslinking of turbot parvalbumin on the digestibility, and release of mediators and cytokines from activated RBL-2H3 cells

Turbot can induce allergy in susceptible individuals due to the presence of parvalbumin (PV), a major fish allergen. This study aimed at evaluating the digestibility and the ability of PV to elicit the release of cellular degranulation, following treatment with tyrosinase (PV-Tyr), caffeic acid (PV-CA) and in combination (PV-Tyr/CA), using in vitro digestion and RBL-2H3 (passive rat basophil leukemia) cell line. The digestion assay products revealed that the stability of PV in simulated gastric fluid (SGF) was stronger, while in simulated intestinal fluid (SIF) was rather weak. Western blot analysis revealed that the IgG-binding abilities of the cross-linked PV were markedly reduced. Moreover, crosslinking hampered the release of cellular degranulation process in RBL-2H3 cell lines. PV-Tyr/CA showed highly significant reduction in the release rate of β-hexosaminidase (66.02%), histamine (35.01%), tryptase (29.25%), cysteinyl leukotrienes (29.72%), prostaglandin D₂ (34.96%), IL-4 (43.99%) and IL-13 (38.93%) and shown potential in developing hypoallergenic fish products.

Making the Most of In Vitro Tests to Diagnose Food Allergy

Various in vitro tests assess different aspects of the underlying immune mechanism of IgE-mediated food allergy. Some can be used for diagnostic purposes; specific IgE to allergen extracts is widely available; specific IgE to allergen components is used in most specialist centers, and the basophil activation test is becoming increasingly used clinically. IgE to allergen peptides, T-cell assays, allergen-specific/total IgE ratios, and allergen-specific IgG4/IgE ratios are currently reserved for research. Different factors can modulate the likelihood of IgE-mediated food allergy of a given allergy test result, namely, the patients' age, ethnicity, previous allergic reaction to the identified food, concomitant atopic conditions, and geographical location, and need to be taken into account when interpreting the allergy test results in the clinic. The importance of the specific food, the clinical resources available, and patient preferences are additional aspects that need to be considered when deciding whether an oral food challenge is required to reach an accurate diagnosis of IgE-mediated food allergy.

Road map for the clinical application of the basophil activation test in food allergy

The diagnosis of IgE‐mediated food allergy based solely on the clinical history and the documentation of specific IgE to whole allergen extract or single allergens is often ambiguous, requiring oral food challenges (OFCs), with the attendant risk and inconvenience to the patient, to confirm the diagnosis of food allergy. This is a considerable proportion of patients assessed in allergy clinics. The basophil activation test (BAT) has emerged as having superior specificity and comparable sensitivity to diagnose food allergy, when compared with skin prick test and specific IgE. BAT, therefore, may reduce the number of OFC required for accurate diagnosis, particularly positive OFC. BAT can also be used to monitor resolution of food allergy and the clinical response to immunomodulatory treatments. Given the practicalities involved in the performance of BAT, we propose that it can be applied for selected cases where the history, skin prick test and/or specific IgE are not definitive for the diagnosis of food allergy. In the cases that the BAT is positive, food allergy is sufficiently confirmed without OFC; in the cases that BAT is negative or the patient has non‐responder basophils, OFC may still be indicated. However, broad clinical application of BAT demands further standardization of the laboratory procedure and of the flow cytometry data analyses, as well as clinical validation of BAT as a diagnostic test for multiple target allergens and confirmation of its feasibility and cost‐effectiveness in multiple settings.

Effect of malonaldehyde cross-linking on the ability of shrimp tropomyosin to elicit the release of inflammatory mediators and cytokines from activated RBL-2H3 cells

BACKGROUND

Malonaldehyde, the primary by-product of lipid peroxidation in food, modifies the structural and functional properties of proteins by cross-linking. The aim of this study was to investigate the effect of malonaldehyde on the allergenicity of shrimp tropomyosin.

RESULTS

RBL-2H3 cells, a model of type I allergic reactions, were sensitised with sera from patients allergic to shrimp, and were stimulated with native and cross-linked tropomyosin. Release of inflammatory mediators such as β-hexosaminidase, histamine, tryptase, cysteinyl leukotriene, and prostaglandin D2 was clearly suppressed in a manner that depended on the extent of tropomyosin cross-linking. Release of interleukin-4 (IL-4) and IL-13 was similarly decreased. Notably, cells sensitised with one patient's serum released IL-4 at comparable levels in response to native and cross-linked tropomyosin.

CONCLUSION

Cross-linking strongly modulates the ability of shrimp tropomyosin to induce release of inflammatory cytokines and mediators from activated RBL-2H3 cells. © 2016 Society of Chemical Industry.

Assessing basophil activation by using flow cytometry and mass cytometry in blood stored 24 hours before analysis

BACKGROUND

Basophil activation tests (BATs) have promise for research and for clinical monitoring of patients with allergies. However, BAT protocols vary in blood anticoagulant used and temperature and time of storage before testing, complicating comparisons of results from various studies.

OBJECTIVE

We attempted to establish a BAT protocol that would permit analysis of blood within 24 hours of obtaining the sample.

METHODS

Blood from 46 healthy donors and 120 patients with peanut allergy was collected into EDTA or heparin tubes, and samples were stored at 4°C or room temperature for 4 or 24 hours before performing BATs.

RESULTS

Stimulation with anti-IgE or IL-3 resulted in strong upregulation of basophil CD203c in samples collected in EDTA or heparin, stored at 4°C, and analyzed 24 hours after sample collection. However, a CD63^hi population of basophils was not observed in any conditions in EDTA-treated samples unless exogenous calcium/magnesium was added at the time of anti-IgE stimulation. By contrast, blood samples collected in heparin tubes were adequate for quantification of upregulation of basophil CD203c and identification of a population of CD63^hi basophils, irrespective of whether the specimens were analyzed by means of conventional flow cytometry or cytometry by time-of-flight mass spectrometry, and such tests could be performed after blood was stored for 24 hours at 4°C.

CONCLUSION

BATs to measure upregulation of basophil CD203c and induction of a CD63^hi basophil population can be conducted with blood obtained in heparin tubes and stored at 4°C for 24 hours.

Basophil activation test: food challenge in a test tube or specialist research tool?

Oral food challenge (OFC) is the gold-standard to diagnose food allergy; however, it is a labour and resource-intensive procedure with the risk of causing an acute allergic reaction, which is potentially severe. Therefore, OFC are reserved for cases where the clinical history and the results of skin prick test and/or specific IgE do not confirm or exclude the diagnosis of food allergy. This is a significant proportion of patients seen in Allergy clinics and results in a high demand for OFC. The basophil activation test (BAT) has emerged as a new diagnostic test for food allergy. With high diagnostic accuracy, it can be particularly helpful in the cases where skin prick test and specific IgE are equivocal and may allow reducing the need for OFC. BAT has high specificity, which confers a high degree of certainty in confirming the diagnosis of food allergy and allows deferring the performance of OFC in patients with a positive BAT. The diagnostic utility of BAT is allergen-specific and needs to be validated for different allergens and in specific patient populations. Standardisation of the laboratory methodology and of the data analyses would help to enable a wider clinical application of BAT.

Years in Review: Recent Progress in Cellular Allergology

This review highlights the recent key advances in the biology of CD4⁺ effector T cells, antigen-presenting cells, Th17 and T regulatory cells, as well as immediate effector cells, such as mast cells, basophils and eosinophils, which are critically contributing to the better understanding of the pathophysiology of allergic diseases and are helping to improve their diagnosis and therapy. Some of the key advances with a direct impact on allergic asthma research and treatment are summarized.

Food allergy testing

Food allergy (IgE-mediated hypersensitivity) is a common clinical problem affecting approximately 15% of children in the Western world. These hypersensitivity reactions tend to be "immediate" (typically within minutes of food exposure), and clinical features may range from mild to life threatening (anaphylaxis). Detailed clinical history is critical to correct diagnosis. Available laboratory tests have limitations not least poor positive predictive value and limited repertoire. Laboratory tests should support clinical diagno sis not vice versa.

EAACI food allergy and anaphylaxis guidelines: diagnosis and management of food allergy

Food allergy can result in considerable morbidity, impact negatively on quality of life, and prove costly in terms of medical care. These guidelines have been prepared by the European Academy of Allergy and Clinical Immunology's (EAACI) Guidelines for Food Allergy and Anaphylaxis Group, building on previous EAACI position papers on adverse reaction to foods and three recent systematic reviews on the epidemiology, diagnosis, and management of food allergy, and provide evidence-based recommendations for the diagnosis and management of food allergy. While the primary audience is allergists, this document is relevant for all other healthcare professionals, including primary care physicians, and pediatric and adult specialists, dieticians, pharmacists and paramedics. Our current understanding of the manifestations of food allergy, the role of diagnostic tests, and the effective management of patients of all ages with food allergy is presented. The acute management of non-life-threatening reactions is covered in these guidelines, but for guidance on the emergency management of anaphylaxis, readers are referred to the related EAACI Anaphylaxis Guidelines.

Basophil activation test with food additives in chronic urticaria patients

The role of food additives in chronic urticaria (CU) is still under investigation. In this study, we aimed to explore the association between food additives and CU by using the basophil activation test (BAT). The BAT using 15 common food additives was performed for 15 patients with CU who had a history of recurrent urticarial aggravation following intake of various foods without a definite food-specific IgE. Of the 15 patients studied, two (13.3%) showed positive BAT results for one of the tested food additives. One patient responded to monosodium glutamate, showing 18.7% of CD203c-positive basophils. Another patient showed a positive BAT result to sodium benzoate. Both patients had clinical correlations with the agents, which were partly determined by elimination diets. The present study suggested that at least a small proportion of patients with CU had symptoms associated with food additives. The results may suggest the potential utility of the BAT to identity the role of food additives in CU.

Non-celiac wheat sensitivity as an allergic condition: personal experience and narrative review

OBJECTIVES

Non-celiac wheat sensitivity (NCWS) is a newly described clinical entity characterized by symptoms, which can involve the gastrointestinal tract, the nervous system, the skin, and other organs. There is little data on the pathogenesis of NCWS and it is probable that different pathogenic mechanisms are involved in the different clinical manifestations of the disease. The only common denominator of NCWS "syndrome" is wheat consumption: the symptoms disappear on exclusion of wheat from the diet, and reappear on wheat consumption. The objective of this study was to review our prior data regarding NCWS and to review relevant medical literature regarding NCWS, with particular attention to the hypothesis that NCWS patients could suffer from non-immunoglobulin E (IgE)-mediated wheat allergy.

METHODS

We reviewed our data on 276 patients diagnosed with NCWS by means of double-blind placebo-controlled (DBPC) wheat challenge. The data indicating a possible wheat allergy diagnosis were examined and other data in the literature were reviewed; we review the role of serum immunoglobulin G antibodies and the basophil activation assay in food allergy, and the histology findings in the food allergy diagnosis.

RESULTS

The comparison between patients suffering from NCWS and presenting with irritable bowel syndrome (IBS) and controls with IBS not due to NCWS showed that NCWS was characterized by: a personal history of food allergy in the pediatric age (0.01), coexistent atopic diseases (0.0001), positive serum anti-gliadin (0.0001) and anti-betalactoglobulin (0.001) antibodies, positive cytofluorimetric assay revealing in vitro basophil activation by food antigens (0.0001), and a presence of eosinophils in the intestinal mucosa biopsies (0.0001).

CONCLUSIONS

Patients with NCWS and multiple food sensitivity show several clinical, laboratory, and histological characteristics that suggest they might be suffering from non-IgE-mediated food allergy. However, other pathogenic mechanisms need to be considered.

Beyond skin testing: state of the art and new horizons in food allergy diagnostic testing

Food allergy affects approximately 1% to 10.8% of the general population, and its prevalence seems to be increasing. An accurate diagnosis is particularly important because a misdiagnosis could lead to life-threatening reactions or to unnecessary restrictive diets. However, allergy tests currently used in clinical practice have limited accuracy, and an oral food challenge, considered as the gold standard, is often required to confirm or exclude a food allergy. This article reviews several promising novel approaches for the diagnosis of food allergy, such as new molecular diagnostic technologies and functional assays, along with their potential clinical applications.

Food allergy: from diagnosis to treatment

Adverse food reactions, an adverse health effect arising from an immune or nonimmune response that occurs reproducibly on the exposure to a given food, can be divided into toxic and hypersensitivity reactions. When an immunologic mechanism has been shown, hypersensitivity food reactions should be referred to as food allergy that may be IgE- or non-IgE-mediated. Food allergy diagnosis is mainly guided by a correct and accurate history and physical examination, thus leading to prick test and elimination diets. The treatment gold standard is still represented by an elimination diet together with antihistamines and corticosteroid usage in order to reduce the gastrointestinal and potentially life-threatening systemic symptoms. Other treatments are currently under investigation with promising results.

Impact of thermal processing and the Maillard reaction on the basophil activation of hazelnut allergic patients

Food allergy, an abnormal immunological response due to sensitization to a food component, has become an important health problem, especially in industrialized countries. The aim of this study was to investigate the impact of thermal processing and glycation on the basophil activation by hazelnut proteins using a basophil activation test. Patients with systemic allergic reactions (SR; n=6) to hazelnut as well as patients with an isolated oral allergy syndrome (OAS; n=4) were investigated. Thermal processing of hazelnut proteins either in the presence or absence of wheat proteins did not result in major changes in the stimulatory activity of the basophils for patients with SR or OAS. For the patients with OAS, incubation of hazelnut proteins with glucose led to complete depletion of the stimulatory activity of the basophils. An increase in stimulatory activity of the basophils for two out of six patients with SR was observed. For the other four patients slight or complete abolition of the stimulatory activity was observed. These results indicate that some patients with SR to hazelnut are at risk when exposed to hazelnut proteins, even in processed foods.

A mutant of the major melon allergen, Cuc m 2, with reduced IgE binding capacity is a good candidate for specific immunotherapy

Hypoallergenic mutants with reduced IgE-binding capacity but which show a similar T-cell response to the corresponding natural allergen are ideal tools for immunotherapy, for preventing a possible anaphylactic shock. An IgE conformational epitope has been identified in Cuc m 2, the major allergen and profilin from melon. Since this epitope is highly conserved in most pollen profilins, it may contribute to an explanation of cross-reactivity between pollen and food profilins. Mutants (Mut 1 and Mut 2) were generated by changing specific residues of the Cuc m 2 epitope to alanine, produced in Escherichia coli, and purified by chromatographic methods. Mut 1 showed a slight reduction in IgE binding but an allergenic activity that was similar to recombinant Cuc m 2, as measured by basophil activation test (BAT) and skin prick test (SPT). By contrast, Mut 2 displayed a substantial reduction in IgE-binding capacity (57%) and positive responses, as determined by BAT (33%) and SPT (50%), when compared to those of rCuc m 2. However, the T-cell proliferation and cytokine production induced by Mut 2 and rCuc m 2 were similar. Thus, this mutant represent potential candidate for immunotherapy of profilin allergies.

Allergenic activity of different tomato cultivars in tomato allergic subjects

BACKGROUND

Tomatoes (Solanum lycopersicum) are consumed worldwide and their amount of consumption is associated with the prevalence of tomato allergy. Therefore, identification of tomato cultivars with reduced allergenicity would potentially increase the quality of life of affected subjects.

OBJECTIVE

In this study, we examined the allergenic and biological activity of two different tomato cultivars in tomato allergic subjects.

METHODS

Twenty-five subjects with tomato allergy were identified using double-blind, placebo-controlled food challenges (DBPCFC). We applied skin prick test (SPT) and further DBPCFC to investigate the clinical differences between two tomato cultivars ('Reisetomate' and 'Matina'). To examine the molecular basis of allergenic activity, immunoblotting and basophil activation test (BAT) were performed.

RESULTS

The cultivar 'Reisetomate' induced significantly less positive skin reactions (P = 0.045) and elicited fewer symptoms after oral challenge compared with 'Matina' (P = 0.047). Molecular assessment revealed that IgE-binding profiles were variable on an interindividual basis, but no major differences between 'Reisetomate' and 'Matina' were detectable. In contrast, BAT underpinned the clinical differences evoked by the different tomato cultivars and showed a left-shift of the dose-response curve obtained for 'Matina' extract (P = 0.046).

CONCLUSIONS AND CLINICAL RELEVANCE

Tomato cultivars promote a distinct clinical reactivity in tomato allergic subjects, demonstrated using SPT, DBPCFC and BAT. The molecular background for these differences could not be clarified, as the IgE-binding profiles did not reveal significant alterations. This might be due to instabilities of physicochemical sensitive proteins and/or different isoform expression of allergens.

Utility of the peripheral blood basophil histamine release test in the diagnosis of hen's egg, cow's milk, and wheat allergy in children

BACKGROUND

The diagnosis of food allergy (FA) is made by oral food challenge tests (OFCs) that occasionally produce serious symptoms in patients; therefore, whether to perform OFCs should be carefully considered. The utility of the histamine release test (HRT) in the diagnosis of childhood FA has not been fully examined.

METHODS

Sixty-four subjects with suspected hen's egg allergy, cow's milk allergy (CMA), and wheat allergy (WA) were enrolled. The diagnosis of FA was made based on the outcomes of OFCs or a convincing history of symptoms after food ingestion within 6 months before or after sample collection. HRT was performed using an HRT Shionogi kit. The threshold of histamine release (HRT threshold), which was defined as the minimum concentration of food antigen to induce a 10% net histamine release, was analyzed in association with FA diagnosis.

RESULTS

Receiver operating characteristic analysis showed that the HRT threshold was useful in the diagnosis of heated egg allergy (HEA), raw egg allergy (REA), CMA, and WA. We were able to determine the cutoff value for the HRT threshold in relation to outcomes of OFCs. The cutoff value was 6 ng/ml of egg white antigen in HEA and REA (p < 0.01), 40 ng/ml of milk antigen in CMA (p < 0.01), and 500 ng/ml of wheat antigen in WA (p < 0.05). The efficiency was 70.3% for HEA, 78.0% for REA, 77.6% for CMA, and 70.7% for WA.

CONCLUSIONS

We conclude that the HRT threshold measurement for egg white, milk, and wheat antigen is related to outcomes of OFCs and is useful in determining when OFCs should be performed.

Food allergy: which tests are worth doing and which are not?

Adverse reactions to foods may arise by a variety of mechanisms, both immune (IgE and non-IgE) and non-immune mediated. This article considers those assays useful in the diagnosis of Type 1 hypersensitivity to foods (IgE-based) and, importantly, discusses those assays where evidence is lacking for their use. In all cases of suspected food allergy, a full clinical history is indispensable in facilitating diagnosis. Total serum IgE is not a suitable screen for food allergy. Suspect allergens may be confirmed by either skin prick testing or serological assays for specific IgE. Several studies suggest concentrations of food-specific IgE at which there is a high probability of reaction on food challenge. These cut-off levels are now being used by physicians to direct clinical advice. However, it is important to note that not all studies agree on these limits and the chosen cut-off is dependent on the population studied and the assay used.

Age-related sensitization profiles for hazelnut (Corylus avellana) in a birch-endemic region

BACKGROUND

Symptoms of hazelnut allergy seem related to geographic and possibly age variations in allergen recognition.

OBJECTIVE

To investigate sensitization profiles of hazelnut allergy in different age groups in a birch-endemic region using component resolved diagnosis (CRD) by microarray.

METHODS

Sixty-five patients with hazelnut allergy, 27 healthy control individuals tolerant to hazelnut, and 34 birch pollen allergic but hazelnut tolerant individuals were included. All blood samples were analyzed using ISAC microarray.

RESULTS

Twenty-nine patients with hazelnut allergy suffered from a systemic reaction (17 preschool children with a median age of 2 years, six school children, and six adults), whereas 36 patients reported an oral allergy syndrome (OAS; three preschool and nine school children and 24 adults). In the hazelnut allergic preschool children with systemic reactions, 65% were sensitized to Cor a 9, 12% to Cor a 8, 18% to Cor a 1.04, 6% to Cor a 1.0101, and 29% to Bet v 1. Of the school-aged systemic reactors, 50% were sensitized to Cor a 9, 17% to Cor a 8, 50% to Cor a 1.04 and Cor a 1.0101, and 67% to Bet v 1. In adults with hazelnut allergy, 3.3% were sensitized to Cor a 9, 6.7% to Cor a 8, 90% to Cor a 1.04 and Bet v 1, and 87% to Cor a 1.0101. In regard to systemic reactors in this group, 17% were sensitized to Cor a 9, 33% to Cor a 8 and Cor a 1.0101, and 50% to Cor a 1.04 and Bet v 1. In the patients with OAS, irrespective the age group, all were sensitized to Bet v 1 and over 97% to Cor a 1.04 and Cor a 1.0101. No sensitization to Cor a 9 or Cor a 8 was found in patients with only an OAS. Of the patients with birch pollen allergy, tolerant to hazelnut, none were sensitized to Cor a 9 or Cor a 8, 56% to Cor a 1.0101, 82% to Cor a 1.04, and 92% to Bet v 1. In healthy controls, no sensitization to components of hazelnut, hazel pollen or birch pollen was demonstrable.

CONCLUSION

Hazelnut allergy in a birch-endemic region exhibits age-related sensitization profiles with distinct clinical outcomes that can be identified using CRD. The majority of hazelnut allergic preschool and school children in a birch-endemic region show systemic reactions on consumption of processed hazelnut, mostly being sensitized to the hazelnut legumin-like allergen Cor a 9 but unrelated to birch pollen allergy. In contrast, adults generally suffer from an OAS apparently as a result of cross-reactivity between Cor a 1.04 from hazelnut and Bet v 1 from birch pollen.

Validation of basophil CD164 upregulation for pollen allergy diagnosis

The aim of the study was to evaluate the sensitivity and specificity of allergen-induced basophil CD164 upregulation in patients with seasonal allergic rhinitis caused by allergy to grass pollens. This study was performed in 24 patients with allergy to grass pollens, and in 25 healthy controls. The protocol for allergen-induced basophil CD164 upregulation consisted of whole blood samples processing and staining with anti-CCR3/anti-CD164 antibodies added to a buffer at the beginning of stimulation. We observed dose-dependent allergen-induced basophil CD164 upregulation with 100% of specificity in both used allergen concentrations (12 and 1.2 ng/ml). Higher allergen concentration resulted in 100% and lower concentration in only 70.83% sensitivity. We have observed in the patients statistically significant correlations between anti-IgE stimulation and both allergen concentrations (for 12 ng/ml, r = 0.71, p < 0.0001; and for 1.2 ng/ml, r = 0.64, p < 0.001). We conclude that assessment of allergen-induced basophil CD164 upregulation is a very useful method for in vitro determination of allergy to grass pollens. This method seems to be a very promising tool in laboratory testing of allergies to other allergens.

Oral allergy syndrome: a clinical, diagnostic, and therapeutic challenge

OBJECTIVES

To provide a review of the literature and discuss the clinical, pathophysiologic, diagnostic, and therapeutic challenges of oral allergy syndrome (OAS).

DATA SOURCES

English-language publications on OAS (and pollen-food allergy syndrome) were identified through MEDLINE and through the reference lists of each identified article and review.

STUDY SELECTION

Articles pertaining to OAS with respect to its varied clinical presentation, underlying pathophysiology, available and investigational diagnostic testing, and evidence-based treatment options were selected.

RESULTS

OAS occurs in patients with a prior cross-reactive aeroallergen sensitization and clinically presents with initial oralpharyngeal symptoms after ingestion of a triggering fruit or vegetable. Although controversial, these symptoms may progress to systemic symptoms outside the gastrointestinal tract in 8.7% of patients and anaphylactic shock in 1.7%. OAS's underlying pathophysiology may play a role in clinical presentation and outcome, depending on whether the cross-reactive protein is a heat-labile PR-10 protein, a partially labile profilin, or a relatively heat-stable lipid transfer protein. Diagnostic testing is variable based on the underlying food tested, but fresh food skin prick test typically has the highest sensitivity. Treatment centers on avoidance and the consideration of self-injectable epinephrine. Because of its relationship with a cross-reactive aeroallergen sensitization, subcutaneous immunotherapy and sublingual immunotherapy have also been therapeutically tried with mixed results.

CONCLUSION

OAS is a challenging diagnosis to the practicing allergist because of its many clinical, diagnostic, and therapeutic considerations. Understanding these challenges and their underlying mechanisms can facilitate a knowledgeable approach to treating an oral allergy patient.

Detection and quantification of drug-specific T cells in penicillin allergy

Drug allergic reactions presenting as maculo-papular exanthema (MPE) are mediated by drug-specific T cells. In this study, the frequency of circulating specific T cells was analyzed by interferon-gamma (IFN-gamma) enzyme-linked immunospot assay in 22 patients with an allergic MPE to amoxicillin (amox). Amox-specific circulating T cells were detected in 20/22 patients with frequencies ranging from 1 : 8000 to 1 : 30 000 circulating leucocytes. No reactivity was observed in 46 control patients, including 15 patients with immunoglobulin E-mediated allergy to amoxicillin, 11 patients with a history of drug-induced MPE but tolerant to amoxicillin and 20 healthy individuals. Furthermore, amox-specific T cells were still detectable several years after the occurrence of the allergic reaction even after strict drug avoidance. Finally, analysis of drug-specific T cells in one patient allergic to ticarcillin (a penicillin antibiotic distinct from amox) revealed the presence of IFN-gamma-producing T cells reactive to ticarcillin and several other betalactam antibiotics, suggesting that the IFN-gamma ELISPOT assay is able to detect T cell cross-reactivity against chemically related drugs. These findings confirm that drug-induced MPE is associated with the presence of specific T cells in blood and further suggest that the IFN-gamma ELISPOT is a sensitive assay which could improve the diagnosis of betalactam allergy.

Negativization rates of IgE radioimmunoassay and basophil activation test in immediate reactions to penicillins

BACKGROUND

Skin test sensitivity in patients with immediate allergy to penicillins tends to decrease over time, but no information is available concerning in vitro tests. We analysed the negativization rates of two in vitro methods that determine specific immunoglobulin E (IgE) antibodies, the basophil activation test using flow cytometry (BAT) and the radioallergosorbent test (RAST), in immediate allergic reactions to penicillins.

METHODS

Forty-one patients with immediate allergic reactions to amoxicillin were followed up over a 4-year period. BAT and RAST were performed at 6-month intervals. Patients were randomized into groups: Group I, skin tests carried out at regular intervals; Group II, skin tests made only at the beginning of the study.

RESULTS

Differences were observed between RAST and BAT (P < 0.01), the latter showing earlier negativization. Considering different haptens, significant differences for the rate of negativization were only found for amoxicillin (P < 0.05). Comparisons between Groups I (n = 10) and II (n = 31) showed a tendency to become negative later in Group I with RAST.

CONCLUSIONS

Levels of specific IgE antibodies tended to decrease over time in patients with immediate allergic reactions to amoxicillin. Conversion to negative took longer for the RAST assay, although the differences were only detected with the amoxicillin hapten. Skin testing influenced the rate of negativization of the RAST assay, contributing to maintenance of in vitro sensitivity. Because of the loss of sensitivity over time, the determination of specific IgE antibodies to penicillins in patients with immediate allergic reactions must be done as soon as possible after the reaction.

Abordagem laboratorial no diagnóstico da alergia alimentar

OBJETIVO: Revisar os exames laboratoriais disponíveis utilizados no diagnóstico da alergia alimentar mediada ou não por IgE. FONTES DE DADOS: Artigos publicados em base de dados PubMed e Embase (língua inglesa e portuguesa) nos últimos dez anos. As palavras-chave utilizadas como fonte de busca foram "alergia alimentar", "diagnóstico" e "laboratório", isolados e/ou associados. SÍNTESE DOS DADOS: A abordagem diagnóstica das reações alérgicas a alimentos inclui história clínica completa, estudos laboratoriais, dietas de eliminação e desencadeamentos cegos com alimentos. Recentemente, a medida quantitativa de anticorpos IgE específicos a alimentos tem mostrado ser mais preditiva de alergia alimentar sintomática mediada por IgE. Níveis séricos de IgE específica a alimento que excedam os valores diagnósticos indicam que o paciente tem chance maior que 95% de apresentar uma reação alérgica se ingerir o alimento em questão. Estes "valores de decisão" foram definidos para alguns alimentos e resultados inconsistentes são obtidos ao se estudar diferentes populações. Os desencadeamentos com alimento, especialmente o duplo-cego controlado por placebo (DADCCP), representa a maneira mais confiável de estabelecer ou descartar o diagnóstico de hipersensibilidade alimentar. CONCLUSÕES: Número crescente de aquisições tem melhorado o valor preditivo de alguns testes laboratoriais empregados no diagnóstico de alergias alimentares. Entretanto, até hoje, não há teste in vitro ou in vivo que mostre correlação completa com a clínica da alergia alimentar. O DADCCP continua sendo o padrão-ouro no diagnóstico definitivo de alergia alimentar específica. São necessárias, urgentemente, novas abordagens diagnósticas válidadas em pacientes com alergia alimentar confirmada por DADCCP positivo.

Flow cytometry for basophil activation markers: the measurement of CD203c up-regulation is as reliable as CD63 expression in the diagnosis of cat allergy

The flow cytometric basophil activation test (BAT), based on the detection of allergen-induced CD63 expression, has been proved effective in the diagnosis of various IgE-mediated allergies. However, there is not yet consensus about the suitability of CD203c expression as a specific basophil activation marker and its diagnostic reliability. The goal of the present study was to compare measurement of CD63 and CD203c expression using BAT in a model of cat allergy and to determine optimal experimental conditions for both markers. Heparinized whole blood samples from 20 cat allergic patients and 19 controls were incubated with Fel d1 (relevant allergen) or anti-FcepsilonRI (positive control) either in IL-3 or IL-3-free conditions. An optimal gating of basophils was achieved in triple staining protocols: anti-IgE PE/anti-CD45 PerCP/anti-CD63 FITC or anti-IgE FITC/anti-CD45 PerCP/anti-CD203c PE. We demonstrated that IL-3 significantly enhanced CD63-induced expression by basophils obtained from cat allergic patients in response to Fel d1. Sensitivity was found to be 100%. The CD203c protocol, when performed under IL-3-free conditions, also demonstrated 100% sensitivity. Only one of the control subjects was positive in both tests. In conclusion, using well-defined experimental conditions, the measurement of CD203c up-regulation on basophils in response to specific allergens is as reliable as CD63-BAT for the in vitro diagnosis of patients with IgE-mediated allergy.

[In vitro allergy testing]

Along with the history, skin tests and provocation tests, in vitro test procedures are essential for the adequate care for patients with allergies. While serological investigations of immediate-type allergic reactions primarily detect allergen-specific IgE antibodies, basophil activation tests with different read-out parameters are available for cellular diagnosis of immediate-type reaction patterns. If clinically necessary, further immunological methods (i. e. immunoblots, lymphocyte transformation tests) can be employed. New options are provided by allergen microarray technology, which makes it possible to determine not only the specific antigenic protein but also to analyze different epitopes.

Allergen-specific IgE testing in the diagnosis of food allergy and the event of a positive match in the bioinformatics search

Current documents on risk assessment of genetically modified foods recommend including IgE-binding tests on sera from allergic patients. However, there is no generally accepted recommendation on technical aspects of the testing procedures or on the interpretation of the results, despite that fact that both false positive and false-negative results may be caused by variability of the test procedures. The present article discusses the state-of-the-art of serological test procedures for qualitative and quantitative determination of specific IgE and interpretation of test results. It is emphasized that the use of sera from clinically well-characterized subjects is of high importance. In the case of a positive test result, the biological activity of the detected IgE antibodies, i. e., the potential to trigger mediator release from basophils or mast cells in an allergen-specific manner, should be taken into account. However, present data also indicate that validation of such mediator release tests is required, both in terms of experimental protocols and with respect to correlation of the test results with the clinical situation. Further studies are also required to prove the usefulness of targeted serum screening, i. e., the testing of gene products from organisms not known to be allergenic with sera from subjects allergic to related species.

Flow-assisted allergy diagnosis: current applications and future perspectives

Physicians predominantly rely upon quantification of serum-specific immunoglobulin E (IgE) and/or skin test to confirm clinically suspected IgE-mediated allergy. However, for various reasons, identification of the offending allergen(s) and potentially cross-reactive structures is not always straightforward. Flow-assisted allergy diagnosis relies upon quantification of alterations in the expression of particular basophilic activation markers. Actually, upon challenge with a specific allergen, basophils not only secrete quantifiable bioactive mediators but also upregulate the expression of different markers which can be detected efficiently by flow cytometry using specific monoclonal antibodies. Currently, the technique has been applied in the investigation of IgE-mediated allergy caused by classical inhalant allergens, food, Hevea latex, hymenoptera venoms and drugs. It is also appreciated; the technique proves valuable in the diagnosis of non-IgE-mediated (anaphylactoid) reactions such drug hypersensitivity and the detection of autoantibodies in certain forms of chronic urticaria. This review will not address immunologic features, characteristics and general pitfalls of flow-assisted analysis of in vitro-activated basophils as summarized elsewhere. After a recapitulation of the principles and some specific technical issues of flow-assisted analysis of in vitro-activated basophils, we principally focus on the current clinical and research applications of the basophil activation tests. Personal experience of both research groups is provided, where appropriate. Finally, a viewpoint on how the field might evolve in the following years is provided.

Comparision of two-flow cytometry methods for basophil degranulation in patients sensitized to grass pollen

BACKGROUND

Two-flow cytometry methods for quantification of degranulated basophil after allergen-specific activation were discussed. The methods are discerned by used membrane receptors--FcepsilonRI or IL-3Ralpha Our goal was to evaluate the diagnostic potential of the methods and to correlate them to allergen-specific IgE detection and skin prick test (SPT).

METHODS

Patient's and control's groups were studied with Bulgarian grass pollen allergen B1 simultaneously by flow cytometry kits: Basotest and BD FastImmune test. Allergy diagnosis was based on clinical history and SPT. The determination of specific IgE was performed by ELISA--RIDASCREEN.

RESULTS

There were no significant differences between the patient's results from Basotest and FastImmune (P>0.05). A significant correlation between values, analyzed by Basotest and by FastImmune was found (r=0.88). The sensitivity and specificity of the Basotest, FastImmune, specific IgE and SPT were 85%, 72%, 92% and 92% sensitivity and 100%, 92%, 100% and 85% specificity respectively. The efficiency was between 82% and 97%. There were a significant correlation between the specific IgE and flow cytometry tests: tau=0.92 (Basotest) and tau=0.71 (FastImmune) and a moderate significant correlation between the SPT and the in vitro tests: tau=0.26 (Basotest) and tau=0.31 (FastImmune).

CONCLUSION

The successful use of the Bulgarian grass pollen allergen B1 and both flow cytometry tests was presented. These methods could be as specific tools for IgE-mediated diagnosis especially FastImmune in the case of low IgE receptor expression.

Diagnostic tests based on human basophils: potentials, pitfalls and perspectives

Human basophils are important tools for studying immediate-type hypersensitivity reactions since they release a variety of mediators (e.g., histamine, leukotriene C4, IL-4 and IL-13) following allergen triggering. Several diagnostic tools have been introduced that measure either leukotriene production or the upregulation of surface markers (CD63 and CD203c) from these cells after antigen stimulation. However, a broad variability in basophil activity exists between different basophil donors and different antigens within one donor. This manifests itself in terms of their reactivity (maximum secretory response), based on the intracellular signaling of the basophils studied, and in terms of their sensitivity. The latter is governed by the number of IgE receptors per basophil, the ratio of antigen-specific IgE to total IgE, and by the number of cell surface antigen-specific IgE molecules for half-maximal responses, termed 'intrinsic sensitivity'. These variables give rise to shifts in the dose-response curves which, in a diagnostic setting where only a single antigen concentration is employed, may produce false-negative data. Thus, in order to meaningfully utilize the current basophil activation tests for diagnostic purposes, each allergen should be pre-evaluated separately in order to determine a suitable stimulation range. Additionally, anti-IgE or anti-FcepsilonRIalpha antibodies should serve as positive controls, bearing in mind that 10-20% of basophil donors are not responsive to IgE-mediated stimulation. Diagnostic studies using CD63 or CD203c in hymenoptera, food and drug allergy are critically discussed. Basophil-based tests are indicated for allergy testing in selected cases but should only be performed by experienced laboratories.

Evaluation of basophil activation in food allergy: present and future applications

PURPOSE OF REVIEW

The diagnosis of immediate hypersensitivity relies on specific IgE and history. Because of low specificity, however, provocation challenges are often necessary. Furthermore, IgE testing does not predict features such as reaction severity; nor can it discriminate cross-reactivity from multiple sensitizations. Direct and passive basophil activation tests may address these needs. In addition, measuring basophil activation ex vivo may be useful for monitoring patients with food allergies.

RECENT FINDINGS

Several papers using basophil activation tests demonstrate comparable sensitivity and specificity to current testing for food allergy. Flow-based basophil activation tests have also been used to assess functional characteristics of patient IgE. Finally, several activation phenotypes have been identified as markers of allergic inflammation in vivo; these phenotypes appear to correspond to earlier reports of spontaneous histamine-releasing basophils in patients with active allergic inflammation.

SUMMARY

Although in their early stages, direct basophil activation tests may prove to be useful in the clinic. Indirect basophil activation studies are useful when applied to compare functional aspects of IgE. Identification of basophil activation ex vivo is a promising approach for monitoring allergic inflammation.

Detection of Anisakis simplex-induced basophil activation by flow cytometry

BACKGROUND

Laboratory diagnosis of anisakidosis is based on specific serum IgE detection. Recently, detection of allergen-induced basophil activation by flow cytometry has been proposed as a valuable tool for allergy diagnosis.

OBJECTIVE

To evaluate if detection of Anisakis-induced basophil activation by flow cytometry is a useful tool in the diagnosis of Anisakis allergy.

METHODS

Patients with Anisakis allergy (A.s.+, n = 37), patients reporting chronic urticaria or abdominal pain unrelated to fish ingestion (A.s.-, n = 51), and healthy controls (n = 12) were studied. Specific IgE to Anisakis simplex (A. simplex) was quantified with CAP-FEIA method, and basophil activation test was performed with three different concentrations of an Anisakis crude extract. Basophil gating was performed with CD123 and HLA-DR, and cellular activation was measured with CD63.

RESULTS

A.s.+ patients showed significantly higher age and total IgE levels than did the A.s.- patients. Specific IgE to A. simplex correlated with the activated basophil percentages obtained with 15 microg/mL (r = 0.80; P < 0.001), 1.5 microg/mL (r = 0.84; P < 0.001), and 0.15 microg/mL (r = 0.82; P < 0.001) of A. simplex crude extract. Nine individuals (3 in the A.s.+ group and 6 in the A.s.- group) were nonresponders to basophil stimulation with anti-IgE. Five A.s.- patients showed positive IgE values to A. simplex while the basophil activation test was negative. According to the receiver operating characteristics curves performed between A.s.+ vs. A.s.- and A.s.+ vs. healthy controls, the cutoff for a positive basophil activation test was >or=21% (specificity = 96%, sensitivity = 100%), and 16% (sensitivity and specificity of 100%) respectively. When nonresponders were included in the A.s.+ vs. A.s.- analysis, sensitivity decreased to 95%. Multivariate logistic analysis showed that the specific basophil activation was a factor independently associated with clinical symptoms of A. simplex allergy.

CONCLUSIONS

Detection of A. simplex-induced basophil activation by flow cytometry is a useful laboratory technique for the diagnosis of anisakidosis, supplementing specific IgE determinations.