Challenges associated with indoor moulds: Health effects, immune response and exposure assessment

Assessment of the health effects of indoor moulds is complicated by the diversity of mould species found in homes and the limitations of current methods to determine exposure. Thus it is difficult to establish whether there is a relationship between mould exposure and disease. Allergic respiratory diseases are commonly caused by Alternaria, Aspergillus, Cladosporium and Penicillium spp. IgE-mediated sensitization to these moulds is a strong risk factor for asthma: IgG and IgE antibody responses to Aspergillus fumigatus are common in patients with other respiratory diseases, including allergic bronchopulmonary aspergillosis and cystic fibrosis. Several important mould allergens have been cloned with different biologic functions. These allergens can also serve as immunologic markers which may be associated with disease activity. Evidence for health effects associated with exposure to mould toxins e.g. from Stachybotrys spp. is less compelling. Recently, several new technolgies have been introduced which could be applied to mould exposure assessment. Ion-charging devices can silently sample air within homes and have been successfully used to monitor animal allergens. Fluorescent multiplex array technology is being used to make quantitative measurements of five to ten allergens simultaneously on dust samples. The development of monospecific (monoclonal or polyclonal) antibodies to specific fungal antigens or allergens will facilitate more accurate assessments of the mould burden in homes, schools and commercial buildings. The application of these techniques in well-designed clinical studies will enable better understanding of the health effects of moulds.