Researchers at the University of Bristol School of Veterinary Sciences and collaborators have provided some of the first evidence growing up on a farm helps the immune system develop and regulate and reduces the incidence of immunological diseases.
According to the research team, immunological (or allergic) diseases, including asthma and eczema, have been rising throughout the urbanized, industrialized western world, becoming a major medical challenge this century, but their new study has demonstrated that simply growing up in a complex farming environment might reduce immunological responses to unfamiliar food proteins by increasing the number immune response-limiting regulatory T-lymphocytes, Bristol University announced about the findings documented in the journal Allergy and Clinical Immunology.
For this study, a group of piglets -- animals oft used by scientists as translational models for humans because they share many aspects of genetics and physiology -- were nursed on a farm while their siblings were fed formula milk under isolated, hygienic conditions in an experiment designed to reflect the environmental extremes human infants face.
The researchers found that the farm-nursed piglets had fewer T-lymphocytes overall, compared to their isolated sisters and brothers, and the "dirty piglets" had significantly more immune response-calming, inflammation-inhibiting regulatory T-lymphocytes.
This ratio shift in the amounts of stimulatory and regulatory T-lymphocytes appeared to affect the piglets' immune functioning, with the farm-reared group exhibiting decreased antibody responses to new food proteins that were introduced while they were weaned, according to the team.
School of Veterinary Sciences research associate Marie Lewis, the team leader, explained the significance of this study's findings:
"Many large-scale epidemiological studies have suggested that growing up on a farm is linked to a reduced likelihood of developing allergic disease. However, until now, it has not been possible to demonstrate direct cause and effect: does the farm environment actively protect against allergies, or are allergy-prone families unlikely to live on farms?"
According to team, next research steps include determining which, and to what extent, various farm-associated factors -- such as nutrition, maternal and social interactions, antigens from bedding and aerial contaminants -- might be contributing to this immune system boost, and discovering the underlying mechanisms at play that could lead to new clinical interventions during infancy to prevent immune diseases from developing as children grow up.