September 2, 2010

Strange BiologyImmunity Down on the Farm

Children that grow up on a farm develop fewer allergies. (Photo credit: Steve Baccon/Digital Vision/Getty Images)

The incidence of allergies and allergic asthma is higher in children raised in urban and suburban neighborhoods. But children who are raised on a farm or spend a significant portion of their early years in the presence of farm animals have a much lower incidence of these ailments. Why is this? Researchers in Europe may have found the answer.

Extensive research in Europe has shown that the prevalence of hay fever, asthma, and allergies is significantly lower among the children of farmers when compared to children who have not grown up on a farm. Research also indicates that children exposed to farm milk during their first year of life also have a significantly lower incidence of asthma, allergies, and hay fever. Those children exposed to both livestock stables and farm milk during their first year of life had the lowest incidence of these three ailments.

In addition, research shows that exposure during pregnancy to farm life also provides allergen immunity to a mother’s unborn child. In a Swiss study published in 2006, researchers found that the greater the number of farm animals a woman came in contact with during her pregnancy, the greater the allergen immunity expressed in her child.

Though scientists recognized the correlation between living on a farm as a child and a reduced incidence of allergies and asthma, they could not point to what exactly led to the development of the immunity. However, recent research has begun to shed light on this phenomenon.

In a study published in the Journal of Allergy and Clinical Immunology, scientists reported that they had isolated a substance in cowshed dust that provides protection to children growing up on farms from developing allergies and allergic asthma. In their study, the researchers analyzed the composition of dust collected from livestock stables from German, Austrian, and Swiss farms. They found that the majority of the dust was made up of plant substances. In addition, more than 10 percent of these plant substances were comprised of a single plant sugar molecule called arabinogalactan. This molecule is a component in forage crops such as meadow foxtail.

Research indicates that a substance in forage crops may inhibit the development of allergies. (Photo credit: Image Source/Alamy)

In the second part of their study, the scientists examined the reaction of the immune system of mice to possible allergens in the presence of arabinogalactan. They found that the nerve cells changed their behavior when arabinogalactan was present. This chance in behavior caused the nerve cells to produce a transmitter that prevents the immune system from reacting to the allergens. Interestingly, the arabinogalactan only prevents the immune system from overreacting in the presence of allergens; it does not prevent the immune system from reacting as it normally would to pathogens.

Buoyed by these findings, the researchers are interested in continuing their study of arabinogalactan and its role in allergen immunity. They are especially interested in determining if arabinogalactan could be used in the prevention or treatment of allergies and allergic asthma.

More to Explore

• What protects farm children from hay fever: The protective substance slumbers in cowshed dust
• Farm animals 'reduce allergies'
• Why Old McDonald had a farm but no allergies: genes, environments, and the hygiene hypothesis
• Farm studies in allergy and their potential connection to auto immune diseases

Last updated September 2, 2010 | Comments (7) | Permalink | Strange Biology