Ever wonder why your immune system doesn’t reject your fetus as a foreign entity they way it could reject a transplanted organ? OK, yeah, me neither. But once I heard the question I was puzzled by it. Why does the immune system the leave the fetus alone?
Several years ago, Erlebacher and his research team found that T cells, poised to attack the fetus as a foreign body, were somehow unable to perform their intended role. The finding prompted the researchers to wonder if perhaps there was some sort of barrier preventing the T cells from reaching the fetus. They turned their attention to studying the properties of the decidua, the specialized structure that encases the fetus and placenta, and there, in a mouse model, they found new answers.
The research team has discovered that the onset of pregnancy causes the genes that are responsible for recruiting immune cells to sites of inflammation to be turned off within the decidua. As a result of these changes, T cells are not able to accumulate inside the decidua and therefore do not attack the fetus and placenta.
Specifically, they revealed that the implantation of an embryo changes the packaging of certain chemokine genes in the nuclei of the developing decidua’s stromal cells. The change in the DNA packaging permanently deactivates, or “silences,” the chemokine genes. Consequently, the chemokines are not expressed and T cells are not recruited to the site of embryo implantation.
I think the layman’s explanation for all of that is that there’s some kind of genetic force field that surrounds the fetus that blocks immune cells from attacking it. Like a Jedi defense or something.
Regardless of what the technical explanation is, this knowledge sounds pretty darn exciting to me. It could potentially have implications for women who have trouble carrying pregnancies to term. And any new knowledge of the immune system could cause a ripple effect into all kinds of disease research. If we can figure out what turns immune cells off and on under various circumstances, maybe we can figure out how to make them work to defeat cancer or HIV or even the common cold. Here’s hoping this is one of those discoveries that opens a whole new world of cures!