In vitro diagnosis of Hymenoptera venom allergy and further development of component resolved diagnostics

A film-linked electrostatic self-assembly microfluidic chip

This article proposes a film-linked electrostatic self-assembly microfluidic chip for the first time, designed to be ready-to-use. Barrier films are used to isolate the gas/liquid path microchannels and the pre-stored reagents of the chip before use. Through the linkage design between the film materials, the motion of barrier films is linked to the structural changes inside the chip. Under the combined action of the rebound force of the elastic substrate, the electrostatic adsorption force between the substrates, and the reaction force of the elastic film, the elastic substrate and the liquid storage substrate are instantly bonded, and the self-assembly of the chip is completed within 1 s. By using six independently output programmable sequences to perform the sequential quantitative pumping of pre-stored reagents, the transfer and mixing of samples and pre-stored reagents are automatically driven in a confined space, which greatly reduces the contamination risk and loss rate of samples/reagents, and improves the accuracy and reproducibility of test results. In addition, the microfluidic multi-step reaction driven in parallel can avoid liquid reflux, accurately control the amount of reactant transfer, and realize the quantitative detection of samples. Multiple reactions can be performed synchronously without interference, saving the test time. Since each gas path is independently controllable, the chip can be extended to a variety of biochemical reactions and has the potential to detect a variety of substances.

[Basophil activation test to follow-up of patients treated with hymenoptera venom immunotherapy: a review of current evidence]

Hymenoptera venom immunotherapy (HVI) is a long-term effective treatment to avoid new systemic reactions in patients with Hymenoptera allergy. The sting challenge test is considered the gold standard to confirm the tolerance. However, the use of this technique is not generalized in clinical practice, being the basophil activation test (BAT), which functionally explores allergen response, an alternative that does not entail any of the provocation risks associated with the sting challenge test. This study reviews the publications that used the BAT to follow up and evaluate the success of the HVI. Studies assessing the changes between a baseline BAT before the start and BATs performed between the starting and maintenance phases of the HVI were selected. Ten articles were found, comprising information from 167 patients, of which 29% used the sting challenge test. The studies concluded the importance of evaluating the responses with submaximal allergen concentrations, which reflect basophil sensitivity, to monitor the HVI using the BAT. It was also observed that changes in the maximum response (reactivity) could not reflect the clinical status of tolerance, particularly in the initial phases of HVI.

IgE allergy diagnostics and other relevant tests in allergy, a World Allergy Organization position paper

Currently, testing for immunoglobulin E (IgE) sensitization is the cornerstone of diagnostic evaluation in suspected allergic conditions. This review provides a thorough and updated critical appraisal of the most frequently used diagnostic tests, both in vivo and in vitro. It discusses skin tests, challenges, and serological and cellular in vitro tests, and provides an overview of indications, advantages and disadvantages of each in conditions such as respiratory, food, venom, drug, and occupational allergy. Skin prick testing remains the first line approach in most instances; the added value of serum specific IgE to whole allergen extracts or components, as well as the role of basophil activation tests, is evaluated. Unproven, non-validated, diagnostic tests are also discussed. Throughout the review, the reader must bear in mind the relevance of differentiating between sensitization and allergy; the latter entails not only allergic sensitization, but also clinically relevant symptoms triggered by the culprit allergen.

Component-resolved diagnosis in hymenoptera allergy

Component-resolved diagnosis based on the use of well-defined, properly characterised and purified natural and recombinant allergens constitutes a new approach in the diagnosis of venom allergy. Prospective readers may benefit from an up-to-date review on the allergens. The best characterised venom is that of Apis mellifera, whose main allergens are phospholipase A2 (Api m1), hyaluronidase (Api m2) and melittin (Api m4). Additionally, in recent years, new allergens of Vespula vulgaris have been identified and include phospholipase A1 (Ves v1), hyaluronidase (Ves v2) and antigen 5 (Ves v5). Polistes species are becoming an increasing cause of allergy in Europe, although only few allergens have been identified in this venom. In this review, we evaluate the current knowledge about molecular diagnosis in hymenoptera venom allergy.

Venom immunotherapy in patients with allergic reactions to insect stings

INTRODUCTION

Allergy to Hymenoptera (Apis mellifera, Vespula species, Polistes species, Vespa crabro) venom can be safely and effectively treated by venom immunotherapy (VIT), which in the 40 years since its introduction has been able to prevent reactions to stings, and to treatment as well, though systemic reactions, occasionally severe, are possible. Areas covered: We reviewed the recent literature on VIT by searching in PubMed for the terms 'venom immunotherapy' and 'Hymenoptera venom immunotherapy' to highlight the current status of VIT and the likely development in the coming years. Expert commentary: VIT, provided the correct choice of the venom and adequate venom preparations and maintenance doses are used, is a treatment of great value in preventing systemic reactions to Hymenoptera stings. A 5-year duration ensures a prolonged tolerance to stings following VIT discontinuation, unless patients suffer from mastocytosis. In fact, due to reports of fatal reactions after stopping VIT, patients with mastocytosis, or with very severe reactions to stings, need an indefinite duration of treatment.

Which immunotherapy product is better for patients allergic to Polistes venom? A laboratory and clinical study

BACKGROUND

Venom immunotherapy (VIT) is highly effective in preventing allergic reactions to insect stings, but the appropriate venom must be used to achieve clinical protection. In patients with multiple positive results to venoms, molecular allergy diagnostics or CAP-inhibition may identify the causative venom. Concerning allergy to venom from Polistes spp. it has been proposed that only the European species P. dominulus should be used for VIT. However, this recommendation is not present in any international guideline. Using both laboratory and clinical data, we aimed to evaluate the reliability of this proposal.

METHODS

We performed an in vitro study using CAP-inhibition to determine sensitization of 19 patients allergic to Polistes venom. The clinical study included 191 patients with positive tests to Polistes treated with VIT, 102 were treated with P. dominulus and 89 were treated with a mix of American Polistes (mAP).

RESULTS

The difference in % of inhibition was significant concerning inhibition of P. dominulus sIgE by P. dominulus venom (79.8%) compared with inhibition by mAP venom (64.2%) and not significant concerning the inhibition of mAP sIgE by P. dominulus venom (80.1%) and by mAP venom (73.6%). Instead, the clinical protection from stings was not statistically different between the two kinds of venom.

CONCLUSION

The data from CAP inhibition would suggest that the choice of either P. dominulus venom or mAP venom for VIT is appropriate in patients with CAP inhibition higher than 70%, but the clinical data show the same odds of protection from stings using for VIT P. dominulus or mAP venom.

Coping with cross-reactive carbohydrate determinants in allergy diagnosis

A relevant proportion of allergy diagnosis is accomplished by in vitro determination of specific immunglobulin E (sIgE) to extracts from suspected allergens. Such extracts inevitably contain glycoproteins, which may react with patients' IgE. In the case of plant and insect allergens, the relevant epitope structure is an α-1,3-fucose on the Asn-linked sugar residue of so-called N-glycans. Due to their wide distribution, N-glycans carrying this epitope are known as "cross-reactive carbohydrate determinant(s)" (CCD[s]). About 15 years of awareness allow the conclusion that anti-CCD IgE does not cause noticeable clinical symptoms. In consequence, diagnostic results arising from CCD reactivity must be rated as false positives. With up to 30 % of CCD reactive patients, this can be regarded as a serious problem. Another cross-reactive carbohydrate determinant became notorious as a potential cause of anaphylactic reactions to a recombinant glycoprotein drug carrying α-1,3-galactose. This galactose-containing determinant (GalCD, galactose containing cross-reactive carbohydrate determinant) was supposed as a trigger for delayed allergic reactions to red meat in several cases. Thus, α-1,3-galactose may have clinical relevance in certain cases - possibly as a result of tick bites. Often, however, GalCDs probably cause false-positive results with milk and meat extracts. No clear evidence for the role of other non-human carbohydrate structures such as N-glycolylneuraminic acid as CCD has been presented so far. Remedies for sIgE based in vitro diagnosis come in the form of non-glycosylated recombinant allergen components or of specific CCD inhibitors. The high potential of recombinant allergens is optimally realized in the context of component resolved diagnosis using allergen arrays with more than 100 components, whereas CCD inhibitors increase the specificity of conventional extract-based diagnosis. Reagents for the detection and inhibition of CCDs from plants and insects have been developed, whereas tools for GalCDs of milk and meat lag behind.

In vitro Diagnosis of Immediate Drug Hypersensitivity: Should We Go with the Flow

BACKGROUND

Diagnosis of immediate drug hypersensitivity reactions (IDHRs) is based upon history taking, skin prick or intradermal tests and quantification of specific immunoglobulin E (IgE) antibodies. Unfortunately, this is often insufficient to correctly identify patients with IgE-mediated IDHRs and is impossible in the case of non-IgE-mediated IDHRs. Drug provocation tests (DPT) are considered the 'gold standard' diagnostic but are not always possible, for ethical and practical reasons. Therefore, the validation of new cellular tests such as basophil activation testing (BAT) was necessary. This review focuses on the applications of BAT in IDHRs.

METHODS

A literature search was conducted, using the words basophil, flow cytometry, immediate drug allergy and drugs; this was complemented by the authors' own expertise.

RESULTS

BAT/HistaFlow® is a useful diagnostic tool in IDHRs, mainly used to diagnose allergy to neuromuscular blocking agents (NMBAs), antibiotics, nonsteroidal anti-inflammatory drugs (NSAIDs) and iodinated radiocontrast media. Its sensitivity varies between 50 and 60%, and specificity attains 80%, except for with quinolones and NSAIDs.

CONCLUSIONS

The diagnostic utility of BAT (and to lesser extent HistaFlow) has been demonstrated and is mostly applied in IDHRs. However, larger-scale collaborative studies are necessary to optimize test protocols and validate the entry of BAT as a diagnostic instrument in drug allergy.

Anaphylaxis to insect venom allergens: role of molecular diagnostics

Anaphylaxis due to Hymenoptera stings is one of the most severe consequences of IgE-mediated hypersensitivity reactions. Although allergic reactions to Hymenoptera stings are often considered as a general model for the underlying principles of allergic disease, diagnostic tests are still hampered by a lack of specificity and venom immunotherapy by severe side effects and incomplete protection. In recent years, the knowledge about the molecular composition of Hymenoptera venoms has significantly increased and more and more recombinant venom allergens with advanced characteristics have become available for diagnostic measurement of specific IgE in venom-allergic patients. These recombinant venom allergens offer several promising possibilities for an improved diagnostic algorithm. Reviewed here are the current status, recent developments, and future perspectives of molecular diagnostics of venom allergy. Already to date, it is foreseeable that component-resolution already has now or will in the future have the potential to discriminate between clinically significant and irrelevant sensitization, to increase the specificity and sensitivity of diagnostics, to monitor immunotherapeutic intervention, and to contribute to the understanding of the immunological mechanisms elicited by insect venoms.

Stinging insect allergy: current perspectives on venom immunotherapy

Systemic allergic reactions to insect stings affect up to 5% of the population during their lifetime, and up to 32% of beekeepers. Such reactions can be fatal, albeit very rarely, and fear of a further systemic reaction (SR) can lead to significant anxiety and quality of life impairment. A recent Cochrane systematic review confirmed that venom immunotherapy (VIT) is an effective treatment for people who have had a systemic allergic reaction to an insect sting. VIT reduces risk of a further SR (relative risk 0.10, 95% confidence interval 0.03-0.28), but VIT also reduces risk of a future large local reaction, and significantly improves disease-specific quality of life. However, health economic analysis showed that VIT is generally not cost effective for preventing future SRs; most people are stung infrequently, most SRs resolve without long-term consequences, and a fatal outcome is extremely rare. VIT only becomes cost effective if one is stung frequently (eg, beekeepers) or if quality of life improvement is considered. Thus, for most people with insect sting allergy, anxiety and quality of life impairment should be the overriding consideration when making treatment decisions, highlighting the importance of a patient-centered approach. Areas which need to be explored in future research include efforts to improve the safety and convenience of VIT such as the use of sublingual immunotherapy; quality of life effects of venom allergy in children and adolescents as well as their parents; and the optimal duration of treatment.

Molecular allergy diagnosis: status anno 2015

IgE antibodies play a key role in type I allergic reactions. Today, different in vitro immunoassays for allergen-specific IgE antibodies are available. However, some major issues should be taken into account for correct interpretation of specific IgE (sIgE) antibody results, as these assays do not demonstrate absolute positive and negative predictive values. Therefore, additional diagnostic tests are needed to make the correct diagnosis. During the last two decades significant progress in biochemistry and molecular biology enabled the detection and quantification of sIgE antibodies to allergen protein components and epitope-emulating peptides, also called molecular allergy diagnosis or component resolved diagnosis (CRD). In contrast to conventional sIgE antibody assays, molecular allergy diagnosis makes it possible to discriminate between genuine allergy and merely sensitisation, to establish personalized sensitization patterns and to assess the individual risk of severity of an allergic reaction and finally it helps us to predict the natural course. In this review the use of CRD in inhalant, food, latex and hymenoptera venom allergy will be discussed. The primary focus will be on the most relevant clinical applications of CRD rather than to describe all the currently available allergen components and epitopes. Appropriate experience of our own research group is provided.

Fifty years of allergy: 1965-2015

The last 50 years in allergy could almost be considered the first 50 years. Over this time period, we have witnessed the emergence of allergy as a subspecialty, have seen and continue to observe a tremendous change in prevalence of allergic disease and have gained insight into the mechanisms that underlie allergic predisposition and disease manifestation. We have improved the care of children with many forms of allergic disease and now sit poised to be able to alter the natural history of allergic disease with the use of specific immunotherapy. There is much left to do in the next 50 years including understanding what underlies both the predisposition to atopic disease and its natural resolution and identifying the environmental cofactors involved in the 'allergic epidemic' and therefore targets for effective primary prevention.

A Pitfall to Avoid When Using an Allergen Microarray: The Incidental Detection of IgE to Unexpected Allergens

The introduction of new laboratory techniques to detect specific IgE antibodies against single allergen molecules rather than whole extracts represents a significant advance in allergy diagnostics. The advantages of such component-resolved diagnosis can be summarized as follows: (1) the ability to identify the truly responsible allergens in polysensitized patients, whether they be genuine (causing specific sensitization to their corresponding allergen source) or primary (the original sensitizing molecule); (2) distinguishing these allergens from simply cross-reactive components; (3) improving the appropriateness of the prescribed specific immunotherapy; and (4) identifying a risk profile for food allergens. Component-resolved diagnosis is performed using either a singleplex (1 assay per sample) platform or a multiplex (multiple assays per sample) platform. Using an immuno solid-phase allergen chip microarray that falls into the latter category--it currently tests sensitivity to 112 allergens--may lead to a pitfall: detecting IgE to unexpected allergens, such as Hymenoptera venom. In fact, testing insect venom sensitivity in individuals with no history of reactions to stings is contrary to current guidelines and presents the physician with the dilemma of how to manage this information; moreover, this may become a legal issue. Based on what is currently known about venom allergy, it remains likely that a positive sensitization test result will have no clinical significance, but the possibility of reacting to a future sting cannot be completely ruled out. Because this problem has not been previously encountered using the more common allergy tests, no indications are currently available on how to effectively manage these cases.