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NK клетки


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 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:

  1. Women with a history of consecutive miscarriages and stillbirths.
  2. Women with bleeding during the current pregnancy and a history of a previous miscarriage.
  3. Women with preeclampsia in previous or current pregnancies.
  4. 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.

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.



Д-р Милен Карагеоргиев


Interview with Dr. Milen Karageorgiev

What made you become part of the New Life team?

New Life attracted me in the first place with the team of specialists working in the clinic. I know each of my colleagues personally, long before I became part of the New Life family. I admire the professionalism and desire of the team and their dedication of achieving every patient`s dream of having a child.  Obstetrics and gynecology is my vocation and I think I can be extremely helpful to many women and couples with pregnancy monitoring, treatment or when there are problems with conceiving. I am more than happy to be part of this modern structure with first-class equipment and the soul that the team brings. Last but not least is the feeling that this is my place. The clinic prvides my patients everything I think they would need. We work with the National Health Insurance Fund, monitor pregnancies, conduct treatments of infertility, in vitro procedures and pay special attention to one recently discussed topic – egg donation. The clinic is an outstanding innovator in this area and I think that the donation program without the need of waiting to find a suitable donor is something we all needed – we as doctors and on the other hand the patients. For all of us, time is precious and we should not waste it in waiting.

Tell us something more about your interest in the field of reproductive medicine. How it all started?

I was raised to respect, appreciate and love the family institution. And yes, I call it an institution because for me it is the driving factor in the life of every person – from early childhood to old age. We are designed to rely on each other, to support and love one another. In recent years, in my practice as an obstetrician-gynecologist, I have observed more and more young people and families having problems with conceiving. This is what made me turn to reproductive medicine. I love working and communicating with young people – I accept them not only as patients but also as friends. As a result of lifestyle, work, school, stress and emotions, first Health problems appear at a very early age. I believe that a young person and a specialist like me can be in help of many patients thanks to my professional attitude, easy communication and the needed attention paid to all those who trust me.

What advice would you give to young people with reproductive problems?

In the first place do not to give up. The path is not easy and requires a lot of trust and support from the partner, family and doctor. As banal as it sounds, there is a solution to every problem. In the clinic we start by diagnosing the problem itself and with the help of medicine and technology we find the right solution. At the first consultation, I always advise my patients to calm down as a beginning. In life, not everything goes according our plan or when we want. Sometimes success requires a little help and personal effort. The first step is to become aware of the problem, followed by a consultation with a specialist who will suggest an appropriate solution. As my advice to all of you is – Dear Friends, don’t wait for too long.

How do you deal with the constant stress? Getting up in the late hours of the night when you are called from the hospital and generally the work as an obstetrician-gynecologist, which definitely keeps your mind awake even when you sleep?

This vocation and moral duty does not weigh on me at this stage. I’m used to live like this, that at any moment the phone can ring and I have to go to the hospital. I am extremely grateful to my family for understanding all that because they are the ones who suffer the most from my lack of holidays, dinners or occasions that I should attend. I used to get up in the middle of dinner or when I have to leave a restaurant as soon as I ordered. These situations are a lot, but I have never regretted even for a moment about my choice of profession. The key is in planning. When I need a break, I plan at least six months ahead and for no longer than a week. My job is extremely responsible and many people rely on me.

What about the postpartum depression? How does a woman recover after a natural birth? Are there any problems in sexual life after birth?

We always advise our patients not to accept the new member of the family as the most important unit, but as an addition to the family, without forgetting the people around them and the normal way of life. This is the key to avoid depression. When the intimate emotions between the partners are back, they should not have any sexual problems after the birth, especially when everything went normal. If there is a depression or any other problem of which the woman is aware of, a talk to a specialist is needed. Here is a piece of advice to the male half, too – Men, observe your wives, if you notice a change in their behavior or feel that something is wrong, please support them and seek adequate help to cope together.




In our previous article, „Male Abstinence and Pregnancy,“ we talked about the fact that long-term abstinence in men is associated with increased percentage of sperm with fragmented DNA.

But what does DNA fragmentation actually mean? Which men should do a DNA fragmentation test?

The standard semen analysis provides information on the three main parameters measuring a man’s fertility – concentration, motility and morphology of sperm. However, the spermogram does not provide information on the percentage of sperm with fragmented DNA in the man’s semen. The integrity of the genetic material (DNA) of sperm can be disrupted due to the action of chemicals, smoking, high fever, free radicals released during normal metabolism, and others. High rates of DNA fragmentation (≥ 30%) are associated with poorer embryo quality and miscarriages.

Indications for research

The DNA fragmentation test is recommended for patients with normal spermogram parameters who, together with their partner are with uncleared infertility factor or have undergone multiple failed assisted reproductive procedures.

The test can also be performed on patients with abnormalities in the basic parameters examined in the spermogram. Although the cause of infertility in men described as a male factor is considered to be known, a DNA fragmentation test may be ordered at the discretion of the treating physician. This usually happens when there are more than 3 failed in vitro procedures or several miscarriages. The test is also recommended in case of preconditions in the men`s working environment such as exposure to chemicals, fever and examples.

In such cases, the detection of an increased percentage of sperm with fragmented DNA means that a change in lifestyle is needed. This includes not only avoiding working environment risk, but also leading a healthier lifestyle and consuming much more foods rich in antioxidants.

A test for DNA fragmentation of sperm is done with a pre-arranged appointment at the clinic, as the result is ready on the next day.