New frontiers in allergen standardization

Chinese Guideline on allergen immunotherapy for allergic rhinitis

The present document is based on a consensus reached by a panel of experts from Chinese Society of Allergy (CSA) and Chinese Allergic Rhinitis Collaborative Research Group (C2AR2G). Allergen immunotherapy (AIT), has increasingly been used as a treatment for allergic rhinitis (AR) globally, as it has been shown to provide a long-term effect in improving nasal and ocular symptoms, reducing medication need, and improving quality of life. AIT is currently the only curative intervention that can potentially modify the immune system in individuals suffering from AR and prevent the development of new sensitization and the progression of disease from AR to asthma. Although the use of AIT is becoming more acceptable in China, to date no AR immunotherapy guideline from China is available for use by the international community. This document has thus been produced and covers the main aspects of AIT undertaken in China; including selection of patients for AIT, the allergen extracts available on the Chinese market, schedules and doses of allergen employed in different routes of AIT, assessment of effect and safety, patients' administration and follow-up, and management of adverse reactions. The Chinese guideline for AR immunotherapy will thus serve as a reference point by doctors, healthcare professionals and organizations involved in the AIT of AR in China. Moreover, this guideline will serve as a source of information for the international community on AIT treatment strategies employed in China.

Standardization and Regulation of Allergen Products in the European Union

Product-specific standardization is of prime importance to ensure persistent quality, safety, and efficacy of allergen products. The regulatory framework in the EU has induced great advancements in the field in the last years although national implementation still remains heterogeneous. Scores of methods for quantification of individual allergen molecules are developed each year and also the challenging characterization of chemically modified allergen products is progressing. However, despite the unquestionable increase in knowledge and the subsequent improvements in control of quality parameters of allergen products, an important aim has not been reached yet, namely cross-product comparability. Still, comparison of allergen product potency, either based on total allergenic activity or individual allergen molecule content, is not possible due to a lack of standard reference preparations in conjunction with validated standard methods. This review aims at presenting the most recent developments in product-specific standardization as well as activities to facilitate cross-product comparability in the EU.

Standardization of allergen products: 2. Detailed characterization of GMP-produced recombinant Phl p 5.0109 as European Pharmacopoeia reference standard

BACKGROUND

The Biological Standardization Programme of the European Directorate for Quality of Medicines and Healthcare (EDQM) aims at the establishment of well-characterized reference standards based on recombinant allergens and validated assays for the quantification of major allergen content. The objective of this study was to examine the detailed physicochemical and immunological characterization of recombinant Phl p 5.0109, the second available allergen reference standard.

METHODS

Recombinant Phl p 5.0109 PP5ar06007 was produced under GMP conditions and analyzed by an array of physicochemical and immunological methods for identity, quantity, homogeneity, and folding stability in bulk solution, as well as thermal denaturation, aggregation state, and biological activity when formulated for long-time storage.

RESULTS

PP5ar06007 revealed as a highly homogeneous, monomeric, well-folded preparation of rPhl p 5.0109, as documented by mass spectrometry, SDS-PAGE, isoelectric focusing, size-exclusion chromatography with light scattering, circular dichroism, and infrared spectroscopy. Upon storage at +4°C, PP5ar06007 retained the monomeric state for at least 2 months. A protein quantity of 1.56 ± 0.03 mg/ml was determined by amino acid analysis in PP5ar06007, and its biological activity was shown to be comparable to natural Phl p 5 in terms of basophil activation and T-cell reactivity.

CONCLUSIONS

Recombinant Phl p 5.0109 PP5ar06007 was characterized extensively at the physicochemical and immunological level. It revealed to be a highly stable, monomeric, and immunologically equivalent of its natural counterpart. PP5ar06007 is now available as European Pharmacopoeia allergen reference standard for grass pollen products.

Control Process for Manufacturing and Standardization of Allergenic Molecules

It is widely accepted that the success of the allergen immunotherapy (AIT), beyond clinical parameters such as dose, dosage regimen, or compliance, depends on the quality and composition of the final products used in the vaccines. Allergenic vaccines are pharmaceutical preparations derived from the natural sources which contain the allergenic components responsible for allergic sensitization. The selection of the appropriate allergenic sources must be a requirement. They suffer a dramatic transformation during the manufacturing process which renders a biologically standardized final product. The inclusion of the appropriate control analyses in the manufacturing process has demonstrated to be an efficient method to guarantee the quality and homogeneity of the final product as well as being a very useful tool for saving time and money. In this context, in the last years, the Regulatory Agencies have released specific guidelines to guarantee the manufacturing of the most appropriate products for the treatment of patients.

Authorised allergen products for intracutaneous testing may no longer be available in Germany: Allergy textbooks have to be re-written

BACKGROUND

Beside the skin prick test, the intracutaneous test represents the most important skin test method for detecting type-1 allergies. With the incorporation of European directives into national law, test allergens used for allergy diagnosis are deemed medicinal products within the meaning of the German Medicinal Products Act (Arzneimittelgesetz) and therefore require marketing authorisation for distribution in Germany. The high costs of acquiring and maintaining these authorisations have lead to no new finished intracutaneous test products being authorized in Germany for more than 20 years. Instead, most manufacturers have voluntarily withdrawn their existing marketing authorisations for intracutaneous test extracts. The last manufacturer to offer approved finished allergen products for intracutaneous tests recently announced that it would now cease production and distribution of these solutions.

METHODS

Research on the current European and German legislation; selective literature search in Medline, including national and international guidelines and Cochrane meta-analyses; licensing information on the Paul-Ehrlich-Institute homepage (www.pei.de) as well as in the Bundesanzeiger (Federal Gazette).

RESULTS

According to information on www.pei.de, marketing authorisations still existed as of 31.01.2015 for intracutaneous test solutions of six grass/cereal/herbal pollens, seven tree pollens, ten food allergens, twelve moulds and yeasts as well as two fungal mixtures, five house dust and storage mites and five animal epithelia/danders, all held by only one company in Germany. These marketing authorisations were granted between 16th March 1987 and 17th January 1992; more recent marketing authorisations do not exist.

CONCLUSIONS

European legislation and the associated increase in production and licensing costs have already lead to numerous suppliers withdrawing their marketing authorisation for diagnostic test allergens - marketing authorisations for 443 diagnostic allergens were voluntarily withdrawn by manufacturers in 2013 alone. If the announced restrictions on the allergen portfolio go ahead, considerable problems in the management of allergy patients in Germany due to the discontinuation of the intracutaneous test are likely to be encountered. Moreover, the fact that a diagnostic procedure that has been established for decades seems set to disappear quite simply because all the requisite substances vanish from the market in one fell swoop may well be without parallel in modern medicine. The situation for skin prick test allergens is less dramatic, although, here again, the available range is becoming increasingly limited.

Biochemical and immunological analysis of mould skin prick test solution: current status of standardization

BACKGROUND

Sensitization prevalence to moulds reached from less than 10% in the general population to more than 25% in atopic and/or asthmatic subjects. To diagnose IgE-mediated mould sensitization, skin prick test (SPT) and specific IgE (sIgE) measurement are recommended. However, concordance of SPT and sIgE results is often less than 50% and standardization of the extracts is required to achieve reliable test results.

OBJECTIVE

The aim of our study was to analyse mould SPT solutions (SPTs) with respect to quantity and quality of protein, antigen and human IgE-binding content as a prerequisite for further in vivo studies.

METHODS

Commercial SPTs of Alternaria alternata, Aspergillus fumigatus, Cladosporium herbarum and Penicillium chrysogenum from six manufacturers as well as two in-house extracts from Aspergillus versicolor were investigated. Protein-, antigen- and IgE-binding contents were quantified by Bradford assay, sandwich ELISA and IgE-ImmunoCAP-inhibition tests. Protein composition and IgE and IgG binding were analysed by SDS-PAGE and immunoblotting, respectively.

RESULTS

Median protein concentrations were similar in all mould SPT extracts (90-110 μg/mL). In contrast, antigen contents and IgE-binding capacity showed a high variability with median antigen values from 4 to 118 μg/mL and IgE inhibition results between 30 to 95%. Whereas almost all SPTs of A. alternata and A. versicolor showed complete sIgE inhibition with mean values > 80%, only three extracts for A. fumigatus, two extracts for C. herbarum and none of the tested extracts for P. chrysogenum exceeded 50% sIgE reduction. Quantitative amounts of protein, antigenic and IgE-binding structures were not comparable with the quality of the corresponding protein or immunoblot pattern, with the exception of A. alternata SPTs.

CONCLUSIONS AND CLINICAL RELEVANCE

Commercially available mould SPT extracts showed high variability raising the question of comparability and reliability of SPT results. Possible consequences for diagnostic test outcome will be investigated in the next step.

Component-resolved diagnosis in pediatric allergic rhinoconjunctivitis and asthma

PURPOSE OF REVIEW

The aim of this review is to update readers on the growing impact of a molecular approach (CRD) to the diagnosis and treatment of children with respiratory allergies

RECENT FINDINGS

A large panel of highly purified natural or recombinant species-specific and cross-reacting allergenic molecules is now available for clinical purposes. Species-specific molecules allow identifying specific sensitization toward a given allergenic source. Cross-reacting molecules allow interpreting polysensitization patterns that cannot be detailed using routine skin prick tests or specific IgE tests based on allergenic extracts. These molecular tools are transforming and improving the interpretation of clinical and laboratory tests used to define patients' IgE-sensitization profile.

SUMMARY

The accurate dissection of the IgE repertoire offers new possibilities in the diagnosis, prophylaxis and treatment of pediatric allergic rhinoconjunctivitis and asthma.

Generation and characterization of anti-chitinase monoclonal antibodies

Class IV chitinase, an allergenic protein of Vitis vinifera (grape), was purified by anion exchange chromatography and used for immunization of Balb/c mice. Monoclonal antibodies (MAbs) were raised by hybridoma technology using Sp2/0 myeloma cells. Finally after three limiting dilutions, six stable clones were generated. Antibody isotyping showed that IgG(2a), IgG(2b), and IgM were produced by one, two, and three of the clones, respectively. All of the MAbs had kappa light chain. The affinities were in the range of 3 × 10(8) to 1.2 × 10(9) M(-1). The MAbs were specific for grape chitinase as confirmed by Western blotting. In conclusion, we successfully produced several MAbs against grape class IV chitinase, which could be used for assessment of this allergen in different grape cultivars.

The frontiers of mass spectrometry-based techniques in food allergenomics

In the last years proteomic science has started to provide an important contribution to the disclosure of basic aspects of food-related diseases. Among these, the identification of proteins involved in food allergy and their mechanism of activation of toxicity. Elucidation of these key issues requires the integration of clinical, immunological, genomic and proteomic approaches. These combined research efforts are aimed to obtain structural and functional information to assist the development of novel, more reliable and powerful diagnostic protocols alternative to the currently available procedures, mainly based on food challenge tests. Another crucial aspect related to food allergy is the need for methods to detect trace amounts of allergenic proteins in foods. Mass spectrometry is the only non-immunological method for high-specificity and high-sensitivity detection of allergens in foods. Nowadays, once provided the appropriate sample handling and the correct operative conditions, qualitative and quantitative determination of allergens in foods and ingredients can be efficiently obtained by MALDI-TOF-MS and LC-MS/MS methods, with limits of detection and quantification in the low-ppb range. The availability of accurate and fast alternatives to immunological ELISA tests may also enable the development of novel therapeutic strategies and food processing technologies to aid patients with food allergy or intolerance, and to support allergen labelling and certification processes, all issues where the role of proteomic science is emerging.

Regulatory environment for allergen-specific immunotherapy

Products for specific immunotherapy (SIT) are medicinal products according to the European Regulations. To obtain a marketing authorization (MA) within the European Community, the quality, safety and efficacy have to be proven. During the development phase of a medicinal product, applicants have the opportunity to apply for scientific advice by national competent authorities or the European Medicines Agency (EMA) to compile a suitable development plan for the examination of quality and performance of nonclinical and clinical trials. Moreover, a paediatric investigation plan has to be submitted to the Paediatric Committee of the EMA and has to be approved before submission of an application for MA. Several regulatory procedures exist for obtaining a MA in the European Community. The national procedure leads only to marketability in one country whereas the Mutual Recognition, the Decentralized and Centralized Procedures (CP) are intended for MA in several or all member states of the European Union. The CP is mandatory for certain medicinal products, for example for drug substances derived by biotechnological processes such as recombinant allergens. Named Patient Products for SIT are a specialty because they are manufactured on the basis of an individual prescription and marketed without a MA.

Comparison of skin prick tests with specific serum immunoglobulin E in the diagnosis of fungal sensitization in patients with severe asthma

BACKGROUND

It has been shown that patients with allergic bronchopulmonary aspergillosis (ABPA) and patients with severe asthma with fungal sensitization (SAFS) can benefit from antifungal therapy. It is not known whether allergy skin prick tests (SPT) or specific IgE tests are more sensitive in the identification of patients who are sensitized to fungi and who are therefore candidates for antifungal therapy.

OBJECTIVES

To compare SPT and specific serum IgE tests for fungal sensitization in patients with severe asthma.

METHODS

We have undertaken SPT and specific serum IgE tests to six fungi (Aspergillus fumigatus, Candida albicans, Penicillium notatum, Cladosporium herbarum, Alternaria alternata and Botrytis cineria) and specific serum IgE test for Trichophyton in 121 patients with severe asthma (British Thoracic Society/SIGN steps 4 and 5).

RESULTS

Sixty-six percent of patients were sensitized to one or more fungi based on SPT and/or specific serum IgE results. Positivity to SPT and/or specific serum IgE was as follows: A. fumigatus 45%, C. albicans 36%, P. notatum 29%, C. herbarum 24%, A. alternata 22%, B. cineria 18%, Trichophyton 17% (specific serum IgE only). Concordance between the tests was 77% overall but only 14-56% for individual fungi. Twenty-nine (24%) patients were sensitized to a single fungus and seven (6%) were sensitized to all seven fungal species. Fifty percent of patients were sensitized to fungal and non-fungal extracts, 21% were sensitized only to non-fungal extracts, 16% were sensitized only to fungal extracts and 13% had no positive tests.

CONCLUSION

This study is consistent with previous reports that fungal sensitization is common in patients with severe asthma. At present, it remains necessary to undertake both SPT and specific serum IgE testing to identify all cases of fungal sensitization. This may be important in the identification of patients with ABPA and SAFS who may benefit from antifungal therapy.