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JACI Highlights - April 2009Farm exposure while pregnant may prevent development of allergy in childrenBianca Schaub, MD, Jing Liu, MD, Sabine Höppler, Isolde Schleich, Jochen Huehn, MD, Sven Olek, PhD, Georg Wieczorek, PhD, Sabina Illi, PhD, Erika von Mutius, MD, MSc Previous studies have shown that life on a farm protects against the development of atopic disease, or allergy. In this article, published in the April 2009 issue of The Journal of Allergy and Clinical Immunology, Schaub et al. suggest a new mechanism by which maternal farm exposure in pregnancy changes the baby’s immune responses. One fascinating thought is that maternal farm exposure in pregnancy may reflect a “natural model of immunotherapy,” potentially including a selection of natural stimuli in addition to allergens and shaping a child’s immune system at an early stage. Two factors seem to be particularly important for this effect. First, an early influence on the fetus’ immune system during pregnancy seems to have a strong effect on reducing later allergy development. Second, microbial exposure has been identified as a crucial “entity of allergy-protective exposure.” The microbial exposure refers to several germs found in barns and stables including on livestock, as well as milk straight from the cow. The researchers identified one cell population, the so-called regulatory T cells (a unique group of immune cells that balance immune responses) that were different in infants of farming and non-farming mothers. These regulatory T cells were higher in number and better in function in infants whose mothers were exposed to a traditional farming environment during pregnancy. Thus, in this sensitive period of fetal immune development, exposure to a farm environment impacts the fetal immune system. While it is remarkable that effects before birth may be capable of causing a long-lasting immune effect, the complex underlying mechanism is not completely understood. Long-term follow-up of the children born to farming mothers is needed to determine whether this specific modulation of regulatory T cells before birth truly guides a child’s immune system at later age and persists to protect against atopic disease throughout life. Perhaps this “natural model of allergy-protection” will lead to backyard farms cropping up in cities and suburbs. |
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