Bacterial Imprinting of the Neonatal Immune System: Lessons From Maternal Cells?

We examined the presence of a natural bacterial inoculum in breast milk and its intracellular transport from the maternal intestine to the breast through the circulation.

Breast milk and peripheral blood were collected aseptically from healthy donors at various times after delivery, and the presence of viable bacteria was determined through plating. Temporal temperature gradient gel electrophoresis was used to examine the bacterial ribosomal DNA content in milk cells, maternal peripheral blood mononuclear cells, and feces and in corresponding infant feces. Blood from nongravid nonlactating women served as control samples. Bacterial translocation to extraintestinal tissues was also evaluated in virgin, pregnant, and lactating mice.