PURPOSE OF THE STUDY.
To determine whether early intestinal bacterial colonization patterns are associated with B-cell activation and maturation.
The study evaluated 65 healthy Swedish infants (33 boys and 32 girls) born at term in rural areas in southwest Sweden. These infants were part of a prospective newborn/infant cohort that was followed to investigate the relation between intestinal bacterial colonization and pattern and maturation of the immune system.
Cord blood samples from newborn children and peripheral blood samples from children at 3 to 5 days, 1 month, 4 months, 18 months, and 36 months of age were obtained. Phenotypic characterization of the circulating B cells by flow cytometry was performed within 72 hours after venipuncture. Fecal samples were obtained at 1, 2, 4, and 8 weeks of age and cultured quantitatively for major groups of aerobic and anaerobic bacteria.
At both 4 months and 18 months of age, children colonized with Escherichia coli and/or bifidobacteria during the first 8 weeks of life had significantly higher numbers of CD27+ memory B cells than did noncolonized children. Early colonization with Staphylococcus aureus was associated with low numbers of CD27+ memory B cells at 4 months of age.
The results of this study showed that early colonization of the gut microflora with different species of bacteria affects B-cell activation and maturation. E coli and bifidobacteria colonization may lead to more B-cell activation and maturation, whereas S aureus colonization may lead to lower counts of circulating memory B cells.
This study was the first to demonstrate that gut bacterial colonization may affect B-cell activation and maturation in humans. The study showed that early colonization of the gut with S aureus, which is increasingly common with improved sanitary conditions in the Western world, is associated with lower counts of circulating memory B cells in infants, whereas early colonization with E coli and bifidobacteria is associated with B-cell activation and maturation. The study team suggests that S aureus colonization may reflect low diversity of gut microbiota and E coli and bifidobacteria colonization may reflect greater diversity of gut microbiota. Whether either the gut microbiome or lower levels of B-cell activation and maturation in early life are risk factors for developing allergic disease is unknown, but evidence linking either to allergic disease would support the conduct of prevention studies aimed at increasing the diversity of the gut microbiome.
- Copyright © 2012 by the American Academy of Pediatrics