Natural Killer (NK) Cells are lymphocytes in the same family as T and B cells, coming from a common progenitor. NK cells are best known for killing virally infected cells, and detecting and controlling early signs of cancer. As well as protecting against disease, specialized NK cells are also found in the placenta and may play an important role in pregnancy.
NK CELLS AND FERTILITY
NK cells are the major lymphocyte population (up to 70%) in the lining of the uterus during implantation and during early pregnancy. They are the major population, a source of immunoregulatory cytokines and play an important role in the regulation of the maternal immune response to fetal allograft, implantation and maintenance of pregnancy.
NK cell dysfunction leads to both problems with conception and some complications of pregnancy. Infertility caused by NK-cell activity can be manifest as failed embryo transfers or lack of spontaneous pregnancy after at least 1 year of attempts to conceive. Some scientists even suggest that abnormalities in NK cell function play an important role in the development of preeclampsia.
NK cell testing is not routinely used in infertility diagnosis. It can be performed when standard tests (hormonal, imaging, etc.) cannot explain the cause of infertility.
It is advisable to administer immunological tests (including NK cell activity testing) in:
- Women with a history of consecutive miscarriages and stillbirths.
- Women with bleeding during the current pregnancy and a history of a previous miscarriage.
- Women with preeclampsia in previous or current pregnancies.
- Intrauterine growth restriction of the fetus in a previous or current pregnancy. This is a condition in which the fetus lags behind in growth compared to the norm for its gestational age.
INCREASED NK CELL ACTIVITY – IS THERE A TREATMENT?
There are several options for treating increased NK cell activity. One of them is the infusion of intravenous IgG immunoglobulins. These are antibodies obtained from of donor plasma, which have a beneficial effect on infertility caused by immunological problems.