The Role of Uterine Natural Killer Cells in Maternal–Fetal Immune Tolerance and Recurrent Pregnancy Loss
DOI:
https://doi.org/10.5281/zenodo.20466059Keywords:
Uterine Natural Killer Cells, Maternal-Fetal Immune Tolerance, Recurrent Pregnancy Loss, Reproductive Immunology, Embryo ImplantationAbstract
Recurrent pregnancy loss represents a major challenge in reproductive medicine, significantly affecting the physical and emotional health of women and couples. Among the mechanisms involved in its pathogenesis, uterine Natural Killer (uNK) cells have gained increasing attention due to their essential role in maternal-fetal immune tolerance and pregnancy maintenance. This study aimed to analyze the participation of uNK cells in normal pregnancy and their association with recurrent pregnancy loss. An integrative literature review was conducted using national and international scientific databases. A total of 55 potentially relevant studies were identified, of which 9 met the eligibility criteria and were included in the final analysis. The selected studies demonstrated that uNK cells actively participate in embryo implantation, spiral artery remodeling, angiogenesis, placentation, and fetal growth, while also playing a central role in the modulation of maternal immune responses. Quantitative and functional alterations in these cells were frequently associated with recurrent pregnancy loss, including increased cytotoxic activity, dysregulated cytokine production, and impaired trophoblast invasion. Despite these findings, significant controversies remain regarding their use as diagnostic biomarkers and therapeutic targets. It is concluded that uNK cells are essential regulators of maternal-fetal immune tolerance and may contribute to recurrent pregnancy loss when their physiological functions are disrupted. Further studies are required to establish their clinical and therapeutic applicability.
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Copyright (c) 2026 Luise D'Avila Lopes
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