Murine Respiratory and Immunological Responses to the Inhaled Aerosols of Stachybotrys chartarum Extract.

Acute effects of repeated inhalation exposure to Stachybotrys chartarum extract (Sc) on the respiratory tract were investigated in Sc-immunized (group Sc/Sc) and non-immunized (PBS/Sc) mice. Control animals were exposed to aerosolized water (PBS/water) and one group was immunized against Sc but not exposed via the airways (Sc/-). Immune responses, measured as the production of total IgE and Sc-specific IgA, IgG1 and IgG2a antibodies, the cytokines IL-4, IL-10 and IFN-γ by spleen cells, spleen cell proliferation and signs of inflammation in the respiratory tract were studied. Inhalation of Sc aerosols (but not water) induced sensory irritation in both the Sc-immunized and non-immunized mice on every exposure. Spleen cells from Sc/Sc mice exhibited higher proliferation indices and production of IL-10 and IL-4 compared with the responses in the other groups. Sc immunization increased serum antibody levels except for IgA. Inhalation of Sc increased IgG2a in Sc-immunized mice and decreased IgE levels in the non-immunized mice. Clear signs of inflammation were not detected in tissue samples of the upper respiratory tract in the exposed groups, whereas mild focal lung inflammation was observed in the Sc/Sc mice and one PBS/Sc mouse. As a conclusion, inhalation of Sc aerosols caused sensory irritation in the murine airways. Cytokine production and Sc-specific proliferative responses were activated in spleen cells of Sc-immunized mice, whereas only the level of IgG2a antibody was increased. [ABSTRACT FROM AUTHOR]