Allergen standardization

Allergen immunotherapy (AIT) and diagnostic tests are based on well qualified allergen extracts, which are derived from biologic organisms. The allergenicity of the extracts is markedly affected by the climate, soil, year of production, storage methods, and manufacturing processes. Thus, standardization is a crucial process to guarantee the clinical efficacy and safety of the treatment and diagnostic reagents in allergic diseases. There are 2 different standardization processes, one is In vivo and the other is in vitro standardization. In vivo standardization is done by skin prick or intradermal tests. For in vitro standardization, measurements of weight/volume and protein nitrogen units have been widely used since the early period of AIT. In the 1970s, immunological methods such as radial immunodiffusion, enzyme-linked immunosorbent assay (ELISA) inhibition test and basophil activation test were developed. Allergen potency measured by ELISA inhibition test reflects the potency measured by skin tests and has been widely used for quality control of batch-to-batch variation. Recently, standardizations focused on the major allergen content of extracts have developed. Standardization for major allergens requires reliable reference materials (RMs) made of recombinant allergens and 2-site ELISA kits. However, only a few reliable RM and 2-site ELISA kits are available. For the standardization process, allergen RMs are essential. The Center for Biologics Evaluation and Research of the U.S. Food and Drug Administration provides 19 allergen RMs, and our research team also proved 9 RMs which are important in Korea. In conclusion, allergen standardization is an essential process for the development of reliable treatment and diagnostic reagents, and allergy specialist should be familiar with the concept of allergen standardization.

Standardization of Weed Pollen Extracts, Japanese Hop and Mugwort, in Korea

PURPOSE: Japanese hop (Humulus spp.) and mugwort (Artemisia spp.) are notable causes of autumn pollinosis in East Asia. However, Japanese hop and mugwort pollen extracts, which are widely used for the diagnosis, have not been standardized. This study was performed to standardize Japanese hop and mugwort pollen extracts. MATERIALS AND METHODS: Allergen extracts were prepared in a standardized way using locally collected Humulus japonicus and purchased Artemisia vulgaris pollens. The immunoglobulin E (IgE) reactivities of prepared extracts were compared with commercial extracts via IgE immunoblotting and inhibition analyses. Intradermal skin tests were performed to determine the bioequivalent allergy unit (BAU). RESULTS: The IgE reactive components of the extracts via IgE immunoblotting were similar to those of commercial extracts. A 11-kDa allergen showed the strongest IgE reactivity in Japanese hop, as did a 28-kDa allergen in mugwort pollen extracts. Allergenic potencies of the investigatory Japanese hop and mugwort extracts were essentially indistinguishable from the commercial ones. Sums of erythema of 50 mm by the intradermal skin test (SigmaED50) were calculated to be 14.4th and 13.6th three-fold dilutions for Japanese hop and mugwort extracts, respectively. Therefore, the allergenic activity of the prepared extracts was 90827.4 BAU/mg for Japanese hop and 34412 BAU/mg for mugwort. CONCLUSION: We produced Japanese hop and mugwort pollen extracts using a standardized method. Standardized Japanese hop and mugwort pollen extracts will facilitate the production of improved diagnostic and immunotherapeutic reagents.

Allergen standardization of whole body extract of Korean house dust mite by in vivo method / 천식및알레르기

BACKGROUND AND OBJECTIVE: House dust mites have been known as the most important allergens in respiratory allergic disease. Since environmental factors may have influences on the pathogenesis of allergic disease, the study using Korean house dust mites for immune and biologic reactions in house dust mite-sensitive allergic disease is considered as significant. MATERIAL AND METHOD: We made two in-house allergenic extracts of Korean house dust mites (D. farinae and D. pteronpsssinus) and performed this study for the allergen standardization by in vivo methods and for the evaluation of the reliabilities for clinical applications. RESULT: As a results of biologic standardization using skin prick test teachnique, the activity of 1: 1,500w/v of D. farinae extract was estimated 1,000 biology unit(BU), concentration that elicits a wheal of the same size as that of histamine dihydrochloride 1mg/ml. The activity of 1: 1,000w/v of D. pteronyssinus was condiered as 1,000BU. The activity of 1:100w/v of both D. farinae and D. pteronpssiuns extracts were considered as 100,000 Allergy Unit(AU), based on intradermal skin testing of 30 subjects with strong sensitive reaction. The concordant rates between results of skin prick test done with 5,000BU/ml concentration of in-house allergenic extracts and thoae with the commercially available allergen(Bencard Co., UK) were 84.6% and 81.0% for D. farinae and D. pteronpssinus, respectively. The wheal erythema size and A/H ratios induced by in-house extracts were significantly correlated with those induced by Bencard allergen. CONCLUSION: This results suggest that in-house extracts of the whole bodies of two house dust mites have good allergenic activities in vivo. It is considered to be clinically useful and reliable allergenic extracts.