Higher B-cell activating factor levels at birth are positively associated with maternal dairy farm exposure and negatively related to allergy development.
BACKGROUND
A high proportion of circulating immature/naive CD5(+) B cells during early infancy is a risk factor for allergy development. B-cell activating factor (BAFF) is an important cytokine for B-cell maturation.


OBJECTIVE
We sought to investigate whether BAFF levels are related to environmental exposures during pregnancy and early childhood and whether BAFF levels are associated with postnatal B-cell maturation and allergic disease.


METHODS
In the FARMFLORA study, including both farming and nonfarming families, we measured BAFF levels in plasma from mothers and their children at birth and at 1, 4, 18, and 36 months of age. Infants' blood samples were also analyzed for B-cell numbers and proportions of CD5(+) and CD27(+) B cells. Allergic disease was clinically evaluated at 18 and 36 months of age.


RESULTS
Circulating BAFF levels were maximal at birth, and farmers' children had higher BAFF levels than nonfarmers' children. Higher BAFF levels at birth were positively associated with proportions of CD27(+) memory B cells among farmers' children and inversely related to proportions of CD5(+) immature/naive B cells among nonfarmers' children. Children with allergic disease at 18 months of age had lower cord blood BAFF levels than nonallergic children. At birth, girls had higher BAFF levels and lower proportions of CD5(+) B cells than boys.


CONCLUSIONS
Farm exposure during pregnancy appears to induce BAFF production in the newborn child, and high neonatal BAFF levels were associated with more accelerated postnatal B-cell maturation, which lend further strength to the role of B cells in the hygiene hypothesis.
Department of Rheumatology and Inflammation Research, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. Electronic address: anna-carin.lundell@rheuma.gu.se.
Anna-Carin
AC
Lundell
Department of Pediatrics, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
Bill
B
Hesselmar
Department of Rheumatology and Inflammation Research, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
Inger
I
Nordström
Department of Infectious Diseases, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
Ingegerd
I
Adlerberth
Department of Infectious Diseases, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
Agnes E
AE
Wold
Department of Rheumatology and Inflammation Research, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
Anna
A
Rudin
D000328:Adult; D053264:B-Cell Activating Factor / Q000097:blood* / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D018956:CD5 Antigens / Q000097:blood / Q000276:immunology; D002675:Child, Preschool; D003612:Dairying; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006967:Hypersensitivity / Q000097:blood / Q000276:immunology; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D018811:Maternal Exposure; D011247:Pregnancy / Q000097:blood* / Q000276:immunology; D011446:Prospective Studies; D012737:Sex Factors; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7 / Q000097:blood / Q000276:immunology
D053264:B-Cell Activating Factor; D018956:CD5 Antigens; C505719:TNFSF13B protein, human; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7
B-cell activating factor; Prospective birth cohort; allergy; dairy farm; hygiene hypothesis; immature/naive B cells; memory B cells; pregnancy; sex