The Ecology of Breastfeeding and Mother-Infant Immune Functions

Abstract

Science and society are increasingly aware of the relationship between the environment and the immune system, and how this relationship can impact chronic and infectious health outcomes. A growing body of evidence points to early infancy as a critical window for immunological development. During this time, infants are bombarded with information about the world around them: friendly and not-so-friendly microorganisms from complementary foods, mothers’ milk, and exposure to new people and places. Contact with local exposures is hypothesised to explain differences in immunological profiles between populations, a concept known as ecological immunity. The evolved flexibility in human immune responses is an adaptive mechanism that protects infants from the diseases that are present in their unique environment while priming them to coexist with benign microbes. The mother-infant immune nexus, linked by shared breastfeeding and shared experiences, forms the basis for this early ecology. This chapter reviews the shared mother-infant immune system, focusing on ecological and developmental variation in the immune systems of mothers, infants, and milk. Cytokines, immunoglobulins, and other immunologically active proteins in milk will be discussed, as well as our growing understanding of the microbiome and how it is integrated into the body via breastfeeding and the immune system. This chapter highlights the importance of embodied immune systems, the implications of ecological difference in exposure for understanding immune-mediated chronic health problems, and a new model of shared maternal-infant life histories that recognises the shared maternal-infant immune system.