Children who grow up on farms, have older siblings, or have furry pets in their homes all seem to have lower risk for atopic diseases. Two U.S. farming communities, the Amish of Indiana and the Hutterites of South Dakota, have similar genetic backgrounds but different farming practices; the Amish still live on traditional single-family dairy farms, whereas the Hutterites practice large-scale mechanized farming. In previous studies, Amish schoolchildren had lower prevalence of asthma (5% vs. 21%) and allergic sensitization (7% vs. 33%) compared with Hutterite schoolchildren. In the current study, researchers explored what immunological mechanisms might account for this difference.
Immunological and genetic testing was performed in 30 randomly selected children from each community, and dust samples were collected from homes. None of the Amish children had asthma, whereas six Hutterite children did, and the rate of allergic sensitization was higher among Hutterite children. Endotoxin levels were seven times higher in Amish homes, and innate immunity–related cytokine levels were higher in the blood of Amish children. When Amish, but not Hutterite, house dust was administered to mice intranasally, it inhibited airway inflammation, and this effect was blunted in mice who were deficient in toll-like receptor signaling.
Editor Disclosures at Time of Publication