Evaluation of the natural killer cell subsets and their relationship with serum interferon gamma and vitamin D levels in women with stages III and IV endometriosis: A case-control study.

Background: Natural killer (NK) cells play a critical role in the pathogenesis of endometriosis. Moreover, a normal vitamin D level is remarkably associated with an optimal immune response. So, there may be a probable relationship between these factors and the endometriotic women.

Objective: This study aimed to evaluate the percentage of NK cells and their subsets and their relationship with serum levels of vitamin D and interferon-gamma (IFN-γ) in women with endometriosis.

Materials and methods: In this case-control study, 29 women with stage III-IV endometriosis and 30 healthy controls were enrolled. The study was conducted in the Immunology Department of Isfahan University of Medical Sciences, Isfahan, Iran between November 2021 and June 2022. The percentage of NK cells and their subsets, including CD56 ${\hspace{0.5em}}^{\text{dim}}$ CD16 ${\hspace{0.5em}}^{+}$ , CD56 ${\hspace{0.5em}}^{\text{bright}}$ CD16 ${\hspace{0.5em}}^{-}$ and CD56 ${\hspace{0.5em}}^{\text{bright}}$ CD16 ${\hspace{0.5em}}^{\text{bright}}$ were measured in the peripheral blood samples using flow cytometry. Serum levels of vitamin D and IFN-γ were also measured using the enzyme-linked immunosorbent assay.

Results: The mean percentage of NK cells in women with endometriosis increased significantly compared to the control group (p = 0.03). The percentage of CD56 ${\hspace{0.5em}}^{\text{dim}}$ CD16 ${\hspace{0.5em}}^{+}$ (p = 0.007) and CD56 ${\hspace{0.5em}}^{\text{bright}}$ CD16 ${\hspace{0.5em}}^{\text{bright}}$ (p = 0.043) increased significantly in women with endometriosis in comparison with the control group, but the percentage of CD56 ${\hspace{0.5em}}^{\text{bright}}$ CD16 ${\hspace{0.5em}}^{-}$ subset was not significantly different. No relationship was observed between NK cells and their subsets with vitamin D and IFN-γ in the studied groups.

Conclusion: The study of NK cell subsets and their related factors can be useful in assessing and treating women suffering from endometriosis. However, more comprehensive studies are required to draw definitive conclusions about these observations.