Miscarriage and natural killer (NK) cells - Everything you know is wrong

Miscarriage and natural killer cells - Dr Randy Morris MD-The BOARD CERTIFIED fertility expert with weekly TTC tips on InfertilityTV

If you have suffered a #miscarriage or multiple miscarriages chances are you've gone online and done a Google search to try to figure out what the cause for the losses. And if you did that, you probably came across some web pages that talked about natural killer cells. This probably terrified you because what sounds scarier than “killer” cells attacking your pregnancy.

Here is the basic idea. You have a blood test to look at how many natural killer cells there are. If your levels are high that means you're at greater risk for having a miscarriage. In order to prevent miscarriage you do a really expensive therapy called intravenous immunoglobulin or IVIG. Unless you do this you are doomed to have miscarriages over and over. Sounds reasonable right? Unfortunately it is completely wrong.

Natural killer cells are one type of white blood cell and are therefore part of the immune system. They circulate in the blood and they can also be found in the uterine lining. In the blood, natural killer cells work as an early defense to destroy cells infected with viruses and cancer cells.

However in the uterus, these cells are not cell killers...in fact, they are distinctly different than the natural killer cells in the blood and have a completely different function. So let's not call them natural killer cells any more... let's refer to them as scientists do which are NK cells.

The most recent research suggests that NK cells in the uterus are essential to allow the embryo to implant and allow the placenta to grow in the uterus. In fact, uterine NK cells increase in number after ovulation around the time that an embryo is expected to implant. These levels stay high during early pregnancy. So measuring the number of NK cells in the blood or in the uterus is a useless test.

So what are all these NK cells doing in the uterus? In order to answer that question we need to ask another question first and that is how is it that an embryo which is foreign to the mother is not rejected by her immune system like a liver or a kidney transplant? The answer is that the mother’s immune system somehow learns not to reject an embryo. This is called immune tolerance. Recent evidence suggests that uterine NK cells are involved in the process of allowing immune tolerance to embryos.

In certain cases, based on the mother's genetic makeup and the father's genetic makeup, the mother may fail to develop tolerance to an embryo. There may be some embryos which therefore get rejected by the mother's immune system. this may be more likely to occur in situations like egg donation where there is twice as much tissue which is foreign to the mother. This is an area of active research.

In the meantime don't waste time and money doing blood tests for NK cells or biopsies of the uterus for NK cells. And certainly don't have treatments like IVIG which are risky and unproven.


Increase your "Infertelligence" TM

Subscribe to Infertility TV now!!!
A new episode of Infertility TV is broadcast weekly every Thursday afternoon

or visit our website at IVF1.com

*******************************************
Do you want to become a patient at IVF1?
*******************************************

Register online here:
https://patient.ivf1.com/PatientPorta...

Or call:
630-357-6540