Isolation and characterization of the main allergen of Dermatophagoides farinae by monoclonal antibodies that recognize IgE related epitopes

Abstract

Mouse monoclonal antibodies (MAbs) with different specificities against Dermatophagoides farinae (D.farinae) extract have been obtained. Fifteen of these antibodies reacted with allergen molecules contained in D. farinae and D. pteronyssinus extracts, immunoprecipitating the main allergen of D. farinae (DF29) and homologous allergen of D. pteronyssinus (DP28). In addition, the monoclonal antibody MADF2 immunoprecipitated DF29 together with two other polypeptides (mol. wt 20,000 and 40,000) from D. farinae extracts. Five monoclonal antibodies (MADF2, MADF5, MADF9, MADF10 and MADF 13) were selected to study their epitope specificity and the relationship of the epitope location on the allergen with the IgE binding site. By cross-inhibition studies two different epitopes and two partly overlapping determinants were found. In addition, two of these epitopes, those defined by MADF 13 and MADF5, are close to, or overlapping, IgE binding site(s) on the allergen molecule. DF29 allergen from D. farinae extract was purified by affinity chromatography using MADF5 coupled to Sepharose. The purified allergen had capacity to bind mite specific human IgE and demonstrated an allergenic activity of up to 70% of total extract of D. farinae. These results indicate that DF29 molecule is the main allergen from D. farinae extracts.