The Role of NK Activated Cells in Infertility, RSAs, and Failed IVFs
The number and the activation of the NK cells are the different markers, but very important for the reproductive infertility issue in terms of infertility, RSAs, and failed IVFs. Natural Killer (NK) cells are a lymphocyte subset that express CD56+ on their cell surface. They are large granular lymphocytes that arise from the bone marrow and circulate peripherally before localizing to specific tissues. NK cells are the most prevalent lymphocyte population in secretory endometrium and in decidua of early pregnancy. They are believed to play a role in regulating trophoblastic cell migration.
The NK cell activation assay tests the killing function of circulating NK cells as well as the ability of interleukin-2 (IL2) to stimulate and intravenous immunoglobulin (IVIg) to suppress that activity. NK activity can be measured as a bioassay that determines the ability of activated NK cells to kill their target (K562 cell line).
Increased peripheral and endometrial NK killing activity has been demonstrated among patients undergoing in vitro fertilization (IVF) who experienced spontaneous pregnancy loss or IVF failure. Interestingly, 40% of patients undergoing IVF with a diagnosis of endometriosis displayed increased NK activity. Identification of patients with increased NK cell activity will allow appropriate treatment for those who will benefit from it. Because the levels of the NK cells is totally different marker compared to the NK activation test, a professional medical approach is performed in this case, where specific treatment is applied to the woman according to the diagnostic test’s evaluation.