Impact of pertussis-specific IgA, IgM, and IgG antibodies in mother's own breast milk and donor breast milk during preterm infant digestion.

Pertussis-specific antibodies from mother's breast milk were stable during infant digestion, whereas anti-pertussis IgA and IgG from donor breast milk decreased in gastric contents. The constant region and variable region of pertussis-specific antibodies and the maternal immunization (previous infections and vaccinations) appear to be the critical factors for their stability to proteolytic digestion and pasteurization. Pertussis-specific antibodies from either mother's breast milk or donor breast milk survived during preterm infant digestion and both types of milk will compensate for the lower IgG transplacental transfer in preterm infants compared with term infants.