Abstract • 65

Human milk contains living white cells which consist mainly of macrophages, polymorphonuclear neutrophils and lymphocytes. Both PMN neutrophils and macrophages have been found to phagocytose and kill bacteria and fungi and elicit antibody dependent cytotoxicity. Human milk macrophages contain intracellular IgA and have been found to produce host resistance factors, including lysozyme, lactoferrin, complement components and cytokines. Human milk T-lymphocytes are mainly CDW29+ "memory" cells, which respond to a variety of bacterial and viral antigens. Furthermore, these cells elaborate cytokines and growth factors. B-lymphocytes produce specific IgA antibodies in human milk. In experimental animals human milk cells have been found to survive the G.I. tract, stick to the intestinal mucosa and transverse it thus offering not only local but also systemic immune protection.

In conclusion human milk cells offer protection to the vulnerable recipient newborn by transmitting immunocompetence and by promoting the maturation of its G.I. tract.