MONOCLONAL ANTIBODY-BASED ASSAY FOR ALT A1, A MAJOR ALTERNARIA ALLERGEN

Background: Allergenic materials from Alternaria are significant cause s of human disease. One 31-kD glycoprotein, designated Alt al, has bee n described previously as being a significant allergen. Objectives: Th e purpose of this study is to characterize purified Alt al and to prov ide a method for measuring it in laboratory and environmental samples. Methods: Monoclonal antibodies directed to the purified allergen were produced and used to construct a double monoclonal assay for Alt al. The purified allergen detected by this assay was tested for IgE bindin g in vitro and in vivo. Results: Purified allergen detected by this as say was shown to bind IgE from patients sensitive to Alternaria and ga ve a positive skin test in 15 of 16 patients skin test reactive to com mercial Alternaria extracts. The assay is sensitive to Alt al concentr ations as low as 0.2 mu g/mL and is very specific for the allergen. Th e three commercial Alternaria extracts assayed contained measurable qu antities of the allergen varying from 12 to 84 mu g/mL. Conclusions: A lt al is a significant Alternaria allergen. The ability to measure thi s allergen may assist in standardizing Alternaria extracts and lead to an understanding of the significance of exposure to this allergen.