Maternal obesity is a condition with increasing prevalence worldwide, that correlates with negative infant outcomes. Here we performed an observational cross-sectional study, where peripheral blood and colostrum samples from 37 mothers with BMI between 18.5-25 or > 30 kg/m2 (21 and 16 mothers, respectively) were collected 24-48 h postpartum. B lymphocyte subpopulations were investigated using flow cytometry. IgG, IgA, and IgM concentrations, and antibody production from colostrum-resident B cells were quantified. Overall, naïve B lymphocytes were the most abundant subtype in peripheral blood, while CD27-IgD- double-negative B cells were the most frequent in colostrum. The colostrum from mothers with BMI > 30 kg/m2 contained significantly more IgG-secreting colostrum-resident B cells, more total IgG, and less total IgA. Mothers with BMI > 30 kg/m2 who had been vaccinated with the Pfizer BioNTech bivalent vaccine during the third trimester of pregnancy (n = 8) did not show higher IgA or IgG antibody responses against SARS-CoV-2 RBD in either tissue types compared to unvaccinated mothers, contrasting with mother of BMI between 18.5-25 kg/m2 (n = 7). This is the first characterization of B lymphocyte subpopulations and antibodies in the colostrum of mothers with obesity. This work uncovers maternal obesity as a possible modifier of humoral immune components in colostrum.
Keywords: Antibodies; B lymphocytes; Colostrum; IgA; IgG; Obesity.
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