The mammary gland-infant intestine immunologic dyad.

The human infant has a very small immune system and needs the support of the mother with the transplacentally arrived IgG antibodies to protect tissues with inflammatogenic and energy-consuming defense. The mucous membranes, where most infections occur, need support via the specialized secretory IgA antibodies and the many other mucosal defense mechanisms provided via the mother's milk. This defense is not inflammatogenic and energy-consuming. We learn about additional defense factors in the milk, like the anti-secretory factor, which seems to protect against diarrhoea. The milk contains numerous growth factors and cytokines, like leptin, which may promote the development of the intestine as well as the immune system. Results are appearing giving interesting evidence for enhanced protection against infection also after the termination of breastfeeding. This may occur via the priming of the infant's immune system after uptake of anti-idiotypic antibodies and lymphocytes from the milk. A breastfeeding motivation study in a large Pakistani village resulted in a 50% decrease of diarrhoea and infant mortality. Deep interviews with the mothers and the traditional birth attendants suggested that even better results may be obtained.