Researchers in Germany have isolated the substance in cowshed dust that possibly protects farm children from developing allergies and allergic asthma -- namely the plant sugar molecule arabinogalactan. If high concentrations are inhaled during the first year of life, it inhibits the immune system from excessive defense reactions. There are large quantities of this molecule in forage crops such as the Meadow Foxtail (Alopecurus pratensis). Researchers have now demonstrated experimentally that the molecule affects immune system cells.