Fetus' Immune System Halts Attack on Cells from its Mother

Repost from AAAS Science Roundup

Tolerating Maternal Influences

A baby developing in the womb receives vital nutrients from its mother, but also some of her cells. Researchers have long known about such maternal crossover cells, but have been unable to explain why they are able to escape attack by the baby's immune system. In a Report in the 5 Dec 2008 Science, Mold et al. provided new insight into the capabilities of the human fetal immune system. The researchers found that substantial numbers of maternal cells cross the placenta to reside in fetal lymph nodes and that this crossover spurs the baby to produce regulatory T cells -- white blood cells whose job it is to suppress fetal immune responses -- that persist at least until early adulthood.

As noted in an accompanying News story by M. Leslie, the work "suggests a new mechanism for how the human immune system learns to spare the body's own tissues, a tolerance that breaks down in autoimmune diseases." Lead author Jeff Mold discussed the findings in a related podcast interview.