Allergens in Fungi

Abstract

Fungi can be divided into three types based on the environment in which they exist, namely outdoor fungi, indoor fungi, and residential fungi. The major outdoor fungi are Cladosporium and Alternaria, whereas Aspergillus and Penicillium are indoor fungi. It is known that the conidia of these fungi function as aeroallergens, and may correlate with both onset and exacerbation of allergic diseases, such as allergic rhinitis and bronchial asthma. As different fungal allergens have common structures, such as proteases and heat shock proteins, the characteristics of fungal allergens exhibit allergenic cross-reactivity, not only between fungi, but also between other species. As a result of this cross-reactivity, patients who are sensitized to fungi exhibit a higher degree of polysensitization compared with monosensitization. On the other hand, Cla h2 and Alt a1 are fungi-specific allergens. Alt a1 is the major Alternaria allergen. As Alt a1 is comprised of proteins specific to Alternaria, the degree of monosensitization to Alternaria is higher than those of other fungal allergens. Mala S11 and Mala S13 are major allergens in Malassezia, which is a residential fungus, and exhibit antigen cross-reactivity between enzymes from humans. As a result, Malassezia is known to be associated with exacerbation of atopic dermatitis.