Bioaerosols and respiratory health

M4.1 ATOPIC AND NON-ATOPIC RESPONSES TO FUNGAL SPORES IN ANIMALS AND HUMANS

W. Eduard.Department of Occupational Hygiene, National Institute of Occupational Health, Oslo, Norway

Introduction: Fungal spores are ubiquitous in the environment and healthy people are well adapted to cope with inhaled spores of most species. Occupational exposure levels may be much higher than outdoor levels, especially at workplaces where mouldy materials are handled. Febrile reactions are relatively common in such occupations, which usually are related to episodes with high exposures resulting in attacks of toxic and allergic alveolitis. Exposure levels in other workplaces are much lower, even below outdoor levels. However, respiratory symptoms such as Sick Building syndrome and asthma have been related to indoor environments of humid buildings. Atopy seems to play a role in these responses, while atopic disease is rare in the high exposed populations. Scientific evidence for atopic and non-atopic responses to fungal spores is therefore presented.

Methods: A literature search of experimental, clinical, and epidemiological studies of fungal spores was conducted and further references were obtained from reviewed papers.

Results: The defence against fungal spores observed in single exposure in vivo studies is dominated by non-adaptive responses. Alveolar macrophages bind fungi with innate receptors, as the TLR receptors, and phagocytise and kill the spores. In vivo studies using repeated exposures show atopic responses, as increase in eosinophilic granulocytes and IL-4, besides neutrophilic inflammation. In one study viable spores induced an atopic response whereas a non-atopic response was observed with killed spores. This is further supported by allergen production by germinating spores, and in vitro studies with dendritic cells …