Molecular and immunological characterization of Asp f 34, a novel major cell wall allergen of Aspergillus fumigatus.
BACKGROUND
Although fungal spores have been recognized as triggers of respiratory allergy and asthma, only two allergenic fungal cell wall components have so far been described.


METHODS
Eighty-one sequences derived from an Aspergillus fumigatus cDNA library encoding putative allergens were examined for the presence of cell wall components. A new allergen (Asp f 34) was evaluated by Western blots, enzyme-linked immunosorbent assay (ELISA), peripheral blood mononuclear cell (PBMC) proliferation assays, and skin prick test (SPT).


RESULTS
The cDNA encoding Asp f 34 contained an open reading frame predicting a protein of 185 amino acids with a molecular weight of 19.38 kDa, showing sequence homology to phiA, an essential protein for the formation of conidia in the genus Aspergillus. The recombinant Asp f 34 was binding IgE from sensitized individuals in Western blots. An ELISA survey showed that 94% of the ABPA and 46% of the A. fumigatus-sensitized individuals tested had Asp f 34-specific serum IgE. Asp f 34 induced allergen-specific proliferation exclusively of PBMCs from patients sensitized to the allergen. Eight patients with anti-Asp f 34 serum IgE tested reacted positively in SPT, whereas four A. fumigatus-sensitized individuals without Asp f 34-specific IgE and eight healthy controls scored negatively.


CONCLUSIONS
A cell wall protein of the phialides of A. fumigatus was identified as a major allergen. Asp f 34 belongs to the Aspergillus-specific proteins of the phiA family and has relevant potential for a specific diagnosis of Aspergillus sensitization.
Department Molecular Allergology, Swiss Institute of Allergy and Asthma Research, University of Zürich, Zürich, Switzerland.
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Glaser
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Kirsch
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Zeller
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Menz
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Rhyner
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Crameri
D000328:Adult; D000368:Aged; D000485:Allergens / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D000595:Amino Acid Sequence; D000908:Antibodies, Fungal / Q000276:immunology; D000918:Antibody Specificity; D001229:Aspergillosis, Allergic Bronchopulmonary / Q000175:diagnosis / Q000276:immunology*; D001232:Aspergillus fumigatus / Q000276:immunology*; D002455:Cell Division / Q000276:immunology; D002473:Cell Wall / Q000276:immunology*; D003001:Cloning, Molecular; D005260:Female; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D017386:Sequence Homology, Amino Acid; D012882:Skin Tests
D000485:Allergens; D000908:Antibodies, Fungal; D005656:Fungal Proteins; D011994:Recombinant Proteins; D007073:Immunoglobulin E