Background: Human milk antibodies specific to allergen enhance immunological tolerance in neonates by educating their immature mucosal immunity. The impact of restricting food allergens in diet and maternal factors on the levels of allergen-specific antibodies in human milk remains unclear. We aimed to evaluate the influence of the maternal avoidance diet of cow's milk on the titers of IgG, SIgA/IgA, and IgM specific to β-lactoglobulin (BLG) in human milk. Materials and Methods: Human milk samples were collected from 26 women nonrestricting cow's milk and 11 women restricting cow's milk. The titers of IgG, SIgA/IgA, and SIgM/IgM specific to BLG were measured using ELISA. Results: BLG-specific IgG titers were 2.9-fold higher in women nonrestricting cow's milk than those restricting cow's milk in their diet (p = 0.026), but BLG-specific SIgA/IgA and SIgM/IgM titers were comparable between these two groups. BLG-specific IgG was positively correlated with BLG-specific SIgA/IgA titers in milk from mothers nonrestricting cow's milk (p = 0.0007) but did not correlate for mothers restricting cow's milk. BLG-specific SIgA/IgA titer decreased with increasing postpartum time in milk from women restricting cow's milk (p = 0.019). Type of delivery, infant gender, maternal age, and probiotic intake did not influence the BLG-specific antibody titers. Conclusions: This study reveals that the secretion of BLG-specific IgG in human milk increases in women nonrestricting cow's milk compared with women restricting cow's milk. The role of breast milk allergen-specific antibodies on the neonatal gut (crosstalk with immune and epithelial cells) remains to be investigated.
Keywords: allergens; breastfeeding; cow's protein-free diet; food antigens; immunological tolerance; neonatal gut.