Quantitation of the major fungal allergens, Alt a 1 and Asp f 1, in commercial allergenic products

Background: Alternaria is one of the most important fungi associated with a llergic disease, whereas Aspergillus fumigatus is involved in a broad spect rum of pulmonary diseases. Currently, fungal extracts used for diagnosis in the United States are unstandardized, and their allergenic content cannot be compared directly. Objective: The goal of this study was to compare the variability of major a llergen levels among US allergenic products derived from fungi: specificall y, Alt a 1 levels in Alternaria alternata extracts, and Asp f 1 levels in A fumigatus extracts. Methods: A novel a-site monoclonal antibody ELISA was used for measuring Al t a 1 using recombinant Alt a 1 as a standard. Asp fl was also measured by ELISA, Allergenic products produced by 8 US manufacturers over a 2-year per iod were compared, as were multiple lots produced by a single company, Results: Alt a 1 levels in Alternaria extracts from 8 companies produced in 1998 and 1999 ranged from less than 0.01 to 6.09 mug/mL (mean 1.4 +/- 1.6 mug/mL, n = 15), In general, Alt al levels were consistent within and betwe en companies (1.4 +/- 1.1 mug/mL, n = 27), with 21 of 32 (66%) of all extra cts tested containing 0.7 to 2 mug/mL Alt a 1, Aspergillus extracts showed much greater variability in Asp fl levels, with extracts from 8 companies c ontaining from less than 0.1 to 64 mug/mL Asp fl (mean 16.3 +/- 23.9 mug/mL , n = 15), Overall variability was greater for Aspergillus products within and between manufacturers (22 +/- 22 mug/mL Asp f 1, a = 20), Conclusions: ELISA-based assays for specific allergens showed greater consi stency among allergenic products derived from Alternaria than from Aspergil lus, These assays should facilitate improved quality control and standardiz ation of fungal allergen extracts and lead to the development of more consi stent products for clinical use.