Natural Killer Cells and Recurrent Miscarriage

How can natural killer cells (NK cells) cause RPL?

There are several different types of cells used by the immune system to attack a foreign "invader" these are part of two systems, the innate (first responders) and the acquired(second responders). The first group are where the Natural Killer Cells are. It is not clear where the site of attack on an embryo or invading vasculature of the embryo that a NK cell attack occurs or if that even happens at all. It may be that elevated blood NK cells are just a sign of a problem or that they act to prevent the suppressive effects of the "protective" or T regulator cells. These "blood" or peripheral NK cells are often confused with the most important Natural Killer cells called "uterine" NK cells whose "activation" is in fact CRITICAL for a correct implantation to occur. High levels of "activated" blood or peripheral NK cells or failure to properly activate Uterine NK cells (of which there are many known causes that we can now diagnose and treate) continue to cause multiple miscarriages until corrected. Certain tests can determine whether or not peripheral NK cells are activated and also whether the mother is predisposed to "failed" activation of the Uterine NK cells.

Another type of cell significant in the immune evaluation is the T cell. These may attack an embryo either by direct contact or by releasing certain chemicals. T cells can also carry messages to other cells to attack, including the B cells – those with the primary function of producing antibodies. It is possible to measure a number of these cells which may have been activated to potentially mount an immune response against the embryo. This may help predict impending immune rejection of an embryo.

Reproductive Immunology: Providing Success After Multiple Miscarriages

When you work with Dr. Braverman and our team, we will conduct thorough testing regarding the presence of these attacking cells and apply treatment to counteract each as needed. There is an additional type of cell called a natural killer T cell (NKT cell), which is a combined form of these two types and can be responsible for an inflammatory immune response in the mother that can also itnerfere with the ability to generate tolerance for the embryo by the maternal immune system. It seems to be even more potent that the NK cell in generating an inflammatory response by the mother. When NKT levels rise, this may show that an immune response to the embryo is taking place; when they fall after treatment, it can be an excellent indication of a successful treatment. In fact, this is how we can monitor its effectiveness. Again it must be reiterated , that to date there has been no site of attack on the embryo by NK or NKT cells so it is quite possible that they are a sign of a problem but not the cause albeit some indirect mechanism.

Contact our infertility practice at Braverman IVF & Reproductive Immunology for a thorough examination of cell activity relating to your miscarriages.