The longitudinal cohort study, led by Kirsi Järvinen-Seppo at the University of Rochester Medical Center and published in Science Translational Medicine, compared infants from Old Order Mennonite (OOM) farm families in New York's Finger Lakes region with urban and suburban infants in Rochester. Researchers followed mothers and babies from pregnancy through the first year and collected cord blood, infant blood, stool, saliva and human milk to profile immune development and antibodies.
Farm-exposed infants showed evidence of earlier maturation of the antibody-producing system: they had more "experienced" B cells, including higher numbers of memory and IgG+ B cells, and higher IgG and IgA in blood, saliva and stool. OOM mothers had higher IgA in milk. The team measured egg-specific IgG4 and IgA in infant blood and milk and then tracked egg allergy development. "We saw a continuum: the more egg-specific antibodies in breast milk, the less likely babies were to develop egg allergy," Järvinen-Seppo says. She notes the study cannot prove causality.
The researchers also found different antibody patterns to environmental allergens at birth: OOM infants had higher IgG and IgG4 to dust mites and horse, while urban infants had higher antibodies to peanut and cat. Detection of food antigens and antigen-specific IgA in cord blood suggests possible in-utero exposure shaping early immunity. The team highlighted several lifestyle differences that may contribute:
- Daily contact with farm animals and environmental microbes
- Use of well water and lower use of certain antibiotics
- Longer or more frequent breastfeeding and distinct gut microbiome patterns
URMC has started a randomized clinical trial that will assign pregnant women to regularly eat egg and peanut during late pregnancy and early breastfeeding or to avoid them. The trial will monitor maternal antibody levels and infant allergy outcomes to test whether maternal diet and milk antibodies add protection beyond early food introduction.
Difficult words
- longitudinal — study that follows people over time
- cohort — group of people studied together
- antibody — protein made by immune system against substancesantibodies
- b cell — type of white blood cell making antibodiesB cells
- cord blood — blood taken from newborn's umbilical cord
- in-utero — happening before birth, while in the womb
- randomized clinical trial — study that randomly assigns treatments to participants
- microbiome — community of microorganisms living in a body habitat
- antigen — substance that triggers an immune responseantigens
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- How might daily contact with farm animals and environmental microbes influence an infant's immune development?
- What are possible benefits and limitations of assigning pregnant women to eat or avoid certain foods in a clinical trial?
- What does the detection of antigen-specific IgA in cord blood suggest about exposure before birth?
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