Aspergillus fumigatus allergen I, a major IgE-binding protein, is a member of the mitogillin family of cytotoxins.

Abstract

A major-kD-IgE-binding protein from Asperigillus fumigatus (Asp fI) has been purified. Partial amino acid sequencing oif Asp f I showed extensive sequence homology (95%) between Asp f.I and a cytotoxin (mitogillin) produced by A. restrictus. Cross inhibition radioimmunoassay using murine monoclonal antibody and human IgG and IgE antibodies showed that Asp fI and mitogillin were antigenically indistinguishable. Furthermore, both proteins inhibited protein synthesis in vitro by >90%. Asp fI was expressed in A. fumigatus but not in seven other Aspergillus species. The results suggest that Asp. fI could play a dual role in the pathogeneis of A. fumigatus-related diseases by promoting colonization through cytotoxic activity and by causing inflammatory reactions involving IgE antibodies.