Cladosporium herbarum and Pityrosporum ovale allergen extracts share cross-reacting glycoproteins.
BACKGROUND
Patients sensitized to airborne fungi such as Alternaria alternata and Cladosporium herbarum often also show positive skin prick test results and specific serum IgE antibodies to a yeast, Pityrosporum ovale. We examined whether part of the IgE binding to these fungi is explained by cross-reacting mould and yeast allergens.


METHODS
Serum samples from 36 patients with positive skin prick test to A. alternata or C. herbarum were analyzed for IgE antibodies to fungal extracts by ELISA and immunoblot analysis. Cross-reactivity between mould and yeast extracts was studied by ELISA and immunoblot inhibition assays. In further analysis, the mannan-containing glycoproteins were removed from the yeast extract by concanavalin A-Sepharose chromatography, and the IgE binding properties of the extracts were compared.


RESULTS
Serum IgE reactivity to P. ovale was found in 40% of the mould-sensitized patients. The IgE antibody binding to A. alternata and C. herbarum moulds was partially inhibited by the yeast P. ovale in ELISA and immunoblot inhibition assays. When the glycoproteins were removed from the extract, cross-reactivity was markedly reduced.


CONCLUSIONS
Part of the IgE binding to mould and yeast allergen extracts is due to cross-reacting glycoproteins. False-positive IgE and skin prick test results should be taken into account in the diagnosis of mould allergy.
Unit of Excellence in Immunotoxicology, Finnish Institute of Occupational Health, Helsinki, Finland. Marina.Leino@ttl.fi
Marina
M
Leino
Kari
K
Reijula
Soili
S
Mäkinen-Kiljunen
Tari
T
Haahtela
Mika J
MJ
Mäkelä
Harri
H
Alenius
D000485:Allergens / Q000276:immunology* / Q000378:metabolism; D000946:Antigens, Fungal / Q000276:immunology / Q000378:metabolism; D001666:Binding Sites, Antibody; D002963:Cladosporium / Q000276:immunology*; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D005656:Fungal Proteins / Q000276:immunology* / Q000378:metabolism; D006023:Glycoproteins / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D007073:Immunoglobulin E / Q000378:metabolism; D008290:Malassezia / Q000276:immunology*
D000485:Allergens; D000946:Antigens, Fungal; D005656:Fungal Proteins; D006023:Glycoproteins; D007073:Immunoglobulin E