Mold Allergens and Their Importance in Molecular Allergy Diagnosis

Abstract

Currently, 111 fungal allergens are identified and listed in the World Health Organization/International Union of Immunological Societies (WHO/IUIS) allergen database, including allergens from molds (n = 81), yeasts (n = 18), dermatophytes (n = 4), and mushrooms (n = 8) of 29 different fungal species. The biological function of 91 fungal allergens is known and 73 of these belong to the most prominent mold allergen families. For the molecular allergy diagnosis of fungal sensitization, only eight single allergens from three mold species are commercially available. Recombinant (r) Alt a 1 is the major allergen for the species Alternaria alternata and one of the two for this species that is commercially available. The other is rAlt a 6, an enolase with potential cross-reactivity to other fungal, food, and latex allergens. Commercially available allergens of Aspergillus fumigates are rAsp f 1, 2, 3, 4, and 6. The combination of specific immunoglobulin (Ig)E to rAsp f 2, 4, and 6 acts as an especially strong indicator of allergic bronchopulmonary aspergillosis (ABPA). Finally, Cla h 8 is the major allergen for Cladosporium herbarum that is available in a recombinant form. It is a dehydrogenase with apparent cross-reactivity to other dehydrogenases. With only eight recombinant allergens available, there is a need to increase the limited range of commercially provided single mold allergens with, e.g., typical marker allergens lsuch as serine proteases. Furthermore, crude extracts must be standardized, at least for their allergen content and composition, in order to have validated allergen extracts for diagnosis and therapy.