Cytokines in Human Breast Milk: Immunological Significance for Newborns

Mother's milk represents a fundamental step in the proper development of newborn immunity. Development in research on human lactation has contributed to knowledge about the significance of breast milk for the infant and the effects of different immunological components. Breast milk contains immune modulating agents, especially cytokines and growth factors, which can act at the level of gastrointestinal mucosa. In this review, we present the involvement of cytokines as mediators of newborn immunity in human breast milk. We searched the electronic literature PubMed and Embase for all relevant articles, using “human breast milk”, “immunity” and “cytokines” words. The search was limited to English- language papers. Of the studies with the same or overlapping data published by the same investigators, we selected the most recent with the largest number of subjects. Several growth factors and cytokines are present in breast milk with capacity to persist in the infant gut and exert their activities. The mechanism by which the ingestion of human milk modifies immunologic defense against such pathogens remains elusive. There are many additional factors present in breast milk which have as yet unexplained functions and benefits to the infant. It is known that cytokines and their receptors are critical in the mucosal immunity in newborns. Hence, the promotion of breastfeeding is very important for at least the first six months of life of the neonate, during which the child does not have a developed immune system.