[The role of fungal allergy in bronchial asthma]

Fungus is known to be one of the causative allergens inducing bronchial asthma as are housedustmites, pollen and pet dander. Outdoor airborne fungi such as Cladosporium, Alternaria, Penicillium and Aspergillus are important inducing IgE antibody formation. In addition to these common fungi, the indoor fungi Aspergillus restrictus, Neurospora and Eurotium are important allergenic fungi which have recently been identified. The yeast Candida albicans, is a common commensal of the human oral and vaginal mucosae and gastrointestinal tract and part of the normal flora, is known as one of the main allergens causing bronchial asthma. We examined the allergenicity of mannan (Mn) as a cell-wall constituent and acid protease (CAAP) as a secreted enzyme of C. albicans. We previously reported cases of atopic asthma caused by CAAP and stressed the role of CAAP as an important allergen in mucosal allergy to C. albicans 9). The levels of the antibodies to these antigens in the sera of asthmatic patients who showed positive immediate intradermal response to crude C. albicans (n=86) were measured. Anti-Mn IgE and IgG antibody levels were measured by liquid-phase assay (AlaSTAT). Anti-CAAP and anti-crude C. albicans IgE and IgG antibody levels were measured by RAST and AlaSTAT. Anti-Mn A and anti-Mn B IgE antibody titers were strongly correlated (r=0.87), while anti-Mn A and anti-CAAP IgE titers were not correlated. However, all of the anti-Mn A IgE positive sera and all of the anti-CAAP IgE positive sera were positive for IgE to crude-C. albicans. This indicates that both Mn and CAAP are C. albicans-related allergens. Titers of IgG antibodies to Mn A and crude C. albicans were highly correlated (r=0. 90). Results of inhibition assays performed using other fungal antigens as inhibitors showed that Mn is a cross reactive allergen among different fungi and that CAAP is a C. albicans specific allergen causing human mucosal allergic reaction.