Inhalation of stable dust extract prevents allergen induced airway inflammation and hyperresponsiveness.

Background: Recent epidemiological studies have shown that growing
up on a traditional farm provides protection from the development
of allergic disorders such as hay fever and allergic asthma. We
present experimental evidence that substances providing protection
from the development of allergic diseases can be extracted from
dust collected in stables of animal farms. Methods: Stable dust was
collected from 30 randomly selected farms located in rural regions
of the Alps (Austria, Germany and Switzerland). The dust was
homogenised with glass beads and extracted with physiological
sodium chloride solution. This extract was used to modulate immune
response in a well established mouse model of allergic asthma.
Results: Treatment of mice by inhalation of stable dust extract
during sensitisation to ovalbumin inhibited the development of
airway hyperresponsiveness and airway eosinophilia upon challenge,
as well as the production of interleukin 5 by splenocytes and of
antigen specific IgG1 and IgE. Dust extract also suppressed the
generation of human dendritic cells in vitro. The biological
activity of the dust extract was not exclusively mediated by
ipopolysaccharide. Conclusions: Stable dust from animal farms
contains strong immune modulating substances. These substances can
interfere with the development of both cellular and humoral
immunity against allergens, thus suppressing allergen
sensitisation, airway inflammation, and airway hyperresponsiveness
in a murine model of allergic asthma.