Allergen standardization

ABSTRACT

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.