Antibody response to long-term and high-dose mould-exposed sawmill workers

Exposure to moulds is thought to cause adverse health effects ranging from vague subjective symptoms to allergy and respiratory diseases. Until now, most studies have been emphasizing low levels of exposure. In Norwegian sawmills during the 1980s, extensively high spore counts up to 10(7) spores/m3 air were reported. By using serum samples obtained from sawmill workers during that period, in addition to control sera, we studied the antibody response of all classes and IgG subclasses to Rhizopus microsporus at different levels of exposure. Antigen specificity was further studied by Western blotting. Exposure to R. microsporus was accompanied by R. microsporus-specific antibody production against a wide range of antigenic components most likely of both protein and carbohydrate nature. Increasing levels of mould-specific IgG1, IgG2, IgG4 and IgA antibodies were associated with increased exposure, while the highest levels of exposure were associated with a somewhat reduced level of mould-specific IgE antibodies. In conclusion, the present study strongly suggests that high mould exposure can induce a strong IgG and IgA response in a dose-dependent manner.