Natural Killer (NK) cells are cytotoxic effector lymphocytes with the ability to lyse target cells in a major histocompatibility complex (MHC) class I-independent manner and without the need for prior antigen exposure. Data strongly suggested that NK cells play an important role in human reproduction and disturbance in their function can favor development of the gynecological disorders. In our study the role of NK cells in pathogenesis of endometriosis is reviewed and summarized from available literature. Endometriosis is related to a defect of NK cell cytotoxicity function in the ability to eliminate endometrial cells in ectopic sites. Alternations of the innate immunity mediated by NK cells may promote impairments or disrupt functions of adaptive immunity, which can contribute to development and progression of endometriosis and infertility associated with endometriosis. Aberrant immune responses by NK cells in affected women may represent risk factors for endometriosis and the repaired function can be a new treatment target of the affected women.

Background: The most important proinflammatory cytokine is interleukin (IL)‐1β, however its precursor, prointerleukin‐1β (proIL‐1β), can also potentiate inflammatory state. The aim of this study was to explore the involvement of proIL‐1β in pathogenesis of endometriosis. For this purpose, we evaluated concentrations of proIL‐1β, IL‐1β, and soluble IL‐1 receptor type 2 (sIL‐1R2) in peritoneal fluid (PF) and macrophage culture medium of women with endometriosis.Methods: PF from 55 women with and without endometriosis was collected during laparoscopy. Peritoneal macrophages were cultured in basal and stimulated with lipopolysaccharide (LPS) conditions. Concentrations of cytokines were measured with enzyme‐linked immunosorbent assays (ELISA).Results: PF proIL‐1β and IL‐1β levels in endometriosis women were higher than in the control. Higher basal and stimulated macrophage secretion of cytokines in endometriosis patients than in the control was observed. However, in endometriosis, there was a higher level of proIL‐1β than for the mature molecule. Additionally, lower PF and macrophages culture medium sIL‐1R2 levels were observed in women with endometriosis.Conclusions: Abnormal proIL‐1β concentration in PF and higher macrophage secretion can escalate peritoneal inflammation and endometriosis formation. The results are presented as a total IL‐1β, which is a sum of proIL‐1β and IL‐1β, and we believe that it reflects the actual cytokine production. The imbalance among all studied cytokines in endometriosis may be linked with an ability to transform acute inflammation to the chronic inflammation.