Cell 'bodyguards' protect fetus in the womb.

The article reports a study by molecular biologists showing that regulatory T-cells, or T_reg cells, play a role in ensuring a pregnant woman's body does not reject the embryo. The study, detailed on a web page from the journal "PLoS ONE," showed that chemical signalers called chemokines summon T-cells to the uterus, where they suppress the activity of immune cells that might otherwise attack the embryo. In mice, chemokine levels were showed to be linked to the menstrual cycle.