A. Standardization of Allergenic Extracts Labeled """"""""No US Standard of Potency"""""""": Standardization efforts have focused on eight grasses (Timothy, Kentucky Blue (June), Perennial Rye, Bermuda, Redtop, Orchard, Sweet Vernal and Meadow Fescue), three cockroaches (German, American and Oriental), and birch tree pollen. Serum from allergic individuals is identified by Blotted IsoElectric Focusing-LIGHT (BIEF-Light) and purchased to establish a serum pool. Candidate references are selected by scanning available extracts and comparing their IsoElectric focusing (IEF) and BIEF-Light patterns. Each reference extract is purchased from commercial manufacturers so that it will be submitted for clinical testing under IND to determine its Bioequivalent Allergy Units (BAU). Companies must then submit extracts analyzed for their IsoElectric focusing pattern, total protein content by ninhydrin, and RAST or ELISA relative potency compared to the CBER reference extracts, or the specific allergen content is determined by RID. B. In Vitro Testing for the Standardization of Grass Pollen Extracts: All grass pollen extracts submitted for approval under a PLA supplement are tested in vitro for relative potency by ELISA, for similarity to the CBER reference by IEF and BIEF-Light and for total protein content by Ninhydrin C. Surveillance of Standardized Allergenic Extracts: In order to facilitate the standardization of extracts and stability testing of standardized extracts, the Allergenic Products Testing Laboratory (APTL) currently supplies all references to the companies. Ongoing testing is needed to replenish laboratory supplies for each of these items. Stringent test parameters are maintained when replacing a reference reagent to minimize reference-to-reference variation.
