A. - Defense Agents in Human Milk

Abstract

This chapter discusses defense agents in milk. There has been a growing realization that breastfeeding not only provides the nutritional requirements of the infant, but also supplies a host of defense factors for the protection of the recipient and/or the mammary gland. In this chapter, a summary of the current information concerning the molecular forms, concentrations in milk during the several phases of lactation, biological activities, fate in the recipient infant, and in vivo functions of the defense agents in human milk is provided. Many whey proteins in human milk have direct antimicrobial properties. Lysozyme is found in relatively high concentrations in external secretions including human milk. Specific antibodies in human milk arise from a triggering of enteromammary and bronchomammary immune pathways. Human milk mucins have recently been reported to be antimicrobial. Human milk may also protect by supplying defense agents from substrates that are partially digested in the recipient's alimentary tract. Living white blood cells are present in human milk particularly during the first 3 or 4 months of lactation. One of the extraordinary features of the protection afforded by human milk is the virtual absence of clinical signs of inflammation during the gastrointestinal infections. In addition, human milk contains a host of anti-inflammatory agents, some that double as antimicrobial factors.