ALKALINE SERINE PROTEINASE - A MAJOR ALLERGEN OF ASPERGILLUS-ORYZAE AND ITS CROSS-REACTIVITY WITH PENICILLIUM-CITRINUM

Background: Aspergillus species are common indoor airborne fungi and h ave been considered as causative agents of human allergic disorders. H owever, allergens of different Aspergillus species have not been effec tively characterized. The object of this study was to identify and cha racterize IgE-binding components of Aspergillus oryzae. Methods. Aller gens of A. oryzae were identified by immunoblot analysis using sera fr om asthmatic patients. The N-terminal amino acid sequences of allergen s thus identified were determined by Edman degradation. The antigenic and the allergenic cross-reactivities between allergens of different f ungi were analyzed by immunoblotting and immunoblot inhibition analysi s, respectively, using a monoclonal antibody (MoAb) 55A against the 33 -kD major allergen of Penicillium citrinum and a mixture of IgE-contai ning asthmatic serum samples. Results: Thirteen components of A. oryza e ranging in apparent molecular weight from 16 to 42 kD react with IgE antibodies. A 34-kD component that showed intense IgE-binding reactiv ity and was detectable in the highest frequency in our asthmatic serum samples tested was considered a major allergen of A. oryzae. The 34-k D component also reacted with MoAb 55A. Results from immunoblot inhibi tion studies also demonstrated the IgE cross-reactivity between the 34 -kD major allergens of A. oryzae and P citrinum. In addition, the sequ ence of the N-terminal 18 amino acid residues of the 34-kD major aller gen of A. oryzae was found to be identical to that of the alkaline ser ine proteinase from the same Aspergillus species. Conclusion: The 34-k D major allergen of A. oryzae is an alkaline serine proteinase. There is IgE cross-reactivity between the major serine proteinase allergens of A. oryzae and P. citrinum.