Another interesting article in Science News, Oct3, 2015 page 8. This one titled "How farm life can prevent allergies". The caveat on this article is that the science is based on experiments with mice; but, seems to be supported by a study of 1,707 children in fours countries which shows the same link between being exposed to barn dust and resulting allergy resistance.
Scientists have known for a long time that farm life seems to protect kids from developing asthma and hay fever. The study with mice may have found the link between barn dust and allergy resistance. Mice exposed to the dust developed resistance to house dust mites which otherwise produce asthma in mice.
Analysis of mouse lung tissue revealed that Trifaip3, the gene for making the enzyme A20, had switched on. A20 tells cells to not react and thus prevents triggering immune system unnecessarily. The A20 enzyme removes ubiquitin, a molecule that sticks to proteins and can signal cells to dial up inflammation.
The dust ingredient may be a bit of bacteria called endotoxin. That alone would trigger the same response in mice as the air loaded with fine cow manure particles.
Frankly, I can understand the above, but have insufficient knowledge to determine if this somewhat exotic and also primitive science is significant or not. The same appears to be strue of Stewart Levine of the National Heart, Lung and Blood Institute in Bethesda, Md. says it explains a lot, but still does not know if he himself would put a kid in a barn to test this.
Meanwhile those of us still around cattle and barn dust and who have probably been exposed to it since early childhood may owe any resistance to allergies we have to that early exposure. I suspect we will learn more about the connection between dried cow manure and allergy resistance in the future.
***Stay tuned even if you would rather have allergies than ever get even close to barn dust--- Doug Wiken