SPECTRUM OF IMMUNOMODULATING AGENTS IN HUMAN-MILK

Because breast-fed infants are at less risk from certain chronic disea ses that are immunologically mediated and because the immune system of infants appears to be altered by breast-feeding, investigations have been conducted to ascertain whether human milk contains immunomodulati ng agents. In addition to certain peptide and nonpeptide hormones, gro wth factors, other proteins and peptides, lipids and nucleotides, the most represented group of immunomodulating agents so far discovered in human milk is the family of the cytokines. The cytokines that have be en to date measured in human milk are interleukin (IL)-1 beta, IL-6, I L-10, granulocyte colony-stimulating factor, macrophage colony-stimula ting factor, tumor necrosis factor alpha, transforming growth factor b eta 2, inteferon-gamma, and the chemokines IL-8, growth-related peptid e alpha, monocyte chemotactic protein 1 and the factor termed ''regula ted upon activation, normal T cell expressed and secreted,'' more wide ly known as RANTES. The spectrum, origins and physical distributions o f these agents in human milk are under investigation. Certain cytokine s including IL-6, IL-8, and macrophage colony-stimulating factor are p roduced by mammary gland epithelial cells. There is also evidence that some cytokines such as IL-6, IL-10 and tumor necrosis factor-alpha ar e compartmentalized and thus protected from digestion in the recipient . That may bear upon the possible in vivo function of those agents. Th e in vivo role of the immunomodulating agents has not, however, been d irectly demonstrated. The information will be critical to understandin g how breast-feeding exerts long-term immunologic effects upon the rec ipient infant.