Molds and Respiratory Allergy - Part 1

Abstract

Allergic reactions to molds were defined more than three hundred years ago, but the importance of mold allergy has been undervalued for a long time. Mold allergens essentially cause respiratory symptoms in sensitized individuals. Molds cultivate best in warm, damp, and humid conditions, and they spread and replicate by making spores. The genera of molds causing allergy and allergy-related problems most often are Alternaria alternate, Cladosporium herbarium, Aspergillus fumigates and Penicillium. Of the estimated number of more than 1 million different fungal species, approximately 80 species have been linked with respiratory allergy. Alternaria is the most -known and well-studied mold species associated with fungal allergy in the literature. Although the sensitization prevalence to commercial extracts is approximately 3% in epidemiologic studies, in selected allergic patients, especially with asthma, the sensitization rate increases up to 30%. Sensitization to molds is more prevalent in individuals living in damp dwellings compared to subjects living in residential properties without any sign of dampness. Alternaria alternate is the best known to be related to immunologically base respiratory tract symptoms in children and adults, although Cladosporium, Aspergillus and Penicillium have also been held responsible to varying degrees. Molds are known to cause a variety of immune effects, including diminishing Th1-type response while not diminishing or even stimulating Th2-type reactivity. Besides asthma development, several studies have also shown that severity of asthma correlates significantly with measures of total humidity and fungal growth in the house. Diagnosing mold allergy with skin prick testing is still problematical by absence of standardized allergenic extracts, possible many allergenic epitopes and fear about the poor sensitivity of the immediate coetaneous hypersensitivity reaction. However, molecular cloning techniques have allowed researchers to separate DNAs coding for fungal allergens and to produce a better panel of recombinant allergens for the diagnosis of mold allergy;