Role of maternal elimination diets and human milk IgA in the development of cow's milk allergy in the infants

Summary Background The role of maternal avoidance diets in the prevention of food allergies is currently under debate. Little is known regarding the effects of such diets on human milk (HM) composition or induction of infant humoral responses. Objective To assess the association of maternal cow's milk (CM) avoidance during breastfeeding with specific IgA levels in HM and development of cow's milk allergy (CMA) in infants. Methods We utilized HM and infant serum samples from a prospective birth cohort of 145 dyads. Maternal serum and HM samples were assessed for casein and beta‐lactoglobulin (BLG)‐specific IgA and IgG by ELISA; 21 mothers prophylactically initiated a strict maternal CM avoidance diet due to a sibling's history of food allergy and 16 due to atopic eczema or regurgitation/vomiting seen in their infants within the first 3 months of life. Infants' sera were assessed for casein and BLG‐specific IgG, IgA and IgE; CMA was confirmed by an oral food challenge. The impact of HM on BLG uptake was assessed in transcytosis assays utilizing Caco‐2 intestinal epithelial cell line. Results Mothers avoiding CM had lower casein‐ and BLG‐specific IgA in HM than mothers with no CM restriction (P = 0.019 and P = 0.047). Their infants had lower serum casein‐ and BLG‐specific IgG1 (P = 0.025 and P