To investigate the local natural killer (NK) activity of the peritoneal fluid mononuclear cells (PFMC).
DESIGN
Patients
In a prospective way, the NK activity (K562-assay) was measured in peripheral blood (PB) and peritoneal fluid (PF) of 44 women who underwent a laparoscopy for infertility and/or pain at the University Hospital of Gasthuisberg, Leuven, Belgium.
Main Outcome Measure
The NK activity of peripheral blood mononuclear cells and PFMC, the number and concentration of PFMC, the percentage of lymphocytes versus macrophages by May-Grünwald-Giemsa staining and the estradiol and progesterone concentration of the PF were correlated together and with the severity of endometriosis.
Results
We demonstrated that there is a significant NK activity in PF and that this activity is decreased in women with endometriosis. This defect was more pronounced in the follicular phase of the cycle compared with the postovulatory phase. In PB of the same 44 women, the decreased NK activity correlated with the severity of the disease. This confirms our previous report on another 34 women.
Conclusions
The NK activity is decreased in women with endometriosis and correlated significantly with the severity of the disease in both the PB and PF of women with endometriosis.
PMID 1633893 1633893 DOI 10.1016/s0015-0282(16)55224-8 10.1016/s0015-0282(16)55224-8
Cite this article
Oosterlynck, D. J., Meuleman, C., Waer, M., Vandeputte, M., & Koninckx, P. R. (1992). The natural killer activity of peritoneal fluid lymphocytes is decreased in women with endometriosis. Fertility and sterility, 58(2), 290-295. https://doi.org/10.1016/s0015-0282(16)55224-8
Oosterlynck DJ, Meuleman C, Waer M, Vandeputte M, Koninckx PR. The natural killer activity of peritoneal fluid lymphocytes is decreased in women with endometriosis. Fertil Steril. 1992;58(2):290-295. doi:10.1016/s0015-0282(16)55224-8
Oosterlynck, D. J., et al. "The natural killer activity of peritoneal fluid lymphocytes is decreased in women with endometriosis." Fertility and sterility, vol. 58, no. 2, 1992, pp. 290-295.
The role of natural killer (NK) cells in the decreased cellular immunity of women with endometriosis was investigated. DESIGN, SETTING, Thirty-four women were investigated prospectively before a CO2-laser laparoscopy for infertility and/or pain at the University Hospital Gasthuisberg. Endometriosis was scored blindly. The cytotoxicity, directed against the endometrium, was mediated by NK cells because this cytotoxicity could be removed by treating the effector cells with the NK-specific anti-Leu-11b monoclonal antibody. Consequently, we evaluated prospectively in those women the lymphocyte-mediated cytotoxicity toward NK sensitive (K562-assay) and autologous endometrial target cells. The NK activity (K562-assay) and the cytotoxicity against autologous endometrial cells were similarly decreased in women with endometriosis and correlated with the severity of the disease. Using heterologous effector cells, the decreased chromium release in women with endometriosis was less pronounced but still present. The decreased cytotoxicity to endometrial cells in women with endometriosis is mainly because of a defect in NK activity but is also partially because of a resistance of the endometrium to NK cytotoxicity.
Practice Committee of the American Society for Reproductive Medicine, 2026·Fertility and Sterility
Current strategies for the assessment and treatment of recurrent pregnancy loss are discussed. This replaces the previous document, titled, "Evaluation and treatment a committee opinion," last published in 2012.
This narrative review examines the evidence for medical optimization of inflammatory conditions, vitamin deficiencies, endocrine disorders, immune dysregulation, oligo-ovulation, and luteal phase factors to improve fertility outcomes in women attempting to conceive through natural or timed intercourse. Overall, there is a paucity of data with respect to these categories among patients pursuing timed intercourse, precluding our ability to draw strong recommendations. However, there is strong evidence supporting treatment of endocrine disorders, specifically overt thyroid dysfunction and hyperprolactinemia, as well as oligo-ovulation. Conversely, treatment of subclinical hypothyroidism is not recommended. The current data are insufficient to support empiric use of antiinflammatory medications, corticosteroids, thyroid hormones, or vitamins or supplements to improve chances of pregnancy in a general infertility population.
Restorative Reproductive Medicine (RRM) aims to restore fertility by diagnosing and treating the underlying causes of infertility. RRM is frequently promoted as an alternative to assisted reproductive technology (ART), despite uncertainty regarding its comparative effectiveness and safety. Where delayed childbearing and infertility are becoming more common, reliance on optimization of natural physiology alone may delay effective treatment and compromise reproductive outcomes. A systematic review of the current evidence comparing RRM to either ART or unassisted conception is, therefore, essential to inform clinical practice, guideline development, and shared decision-making for patients experiencing infertility. To assess the effectiveness and safety of RRM approaches, evaluated as a whole, rather than as individual components, compared with ART and medically unassisted conception in couples experiencing infertility. A systematic literature search of MEDLINE, Embase, CENTRAL and the Journal of Restorative Reproductive Medicine from inception to 28 November 2025. We included randomized control trials (RCTs) or nonrandomized comparative studies evaluating reproductive and safety outcomes of RRM as a unified treatment, compared with either ART or expectant management (attempted medically unassisted conception). Two reviewers independently screened titles, abstracts and full texts with disagreements resolved by a third reviewer. We retrieved 724 records, of which 16 studies underwent full-text review. No RCTs or comparative observational studies were identified. All 16 full-text studies were excluded for an ineligible study design (no control group); most were cohort studies in which all participants underwent RRM. Ten studies reported reproductive outcomes; nine of these made claims regarding the benefits or effectiveness of RRM. None of these claims were supported by the study designs used, as the lack of a comparison group precludes reliable estimation of treatment effects. Consequently, these studies cannot provide valid estimates of RRM success rates, nor permit any meaningful inference about its effectiveness relative to unassisted conception or ART. Large-scale RCTs or prospective cohort studies reporting effectiveness and safety outcomes are required to inform evidence-based fertility guidelines. There are no comparative studies to support reliable estimates of the safety and effectiveness of RRM compared with ART or medically unassisted conception for couples experiencing infertility.