Evaluation of NKT Cell Percentage and Function and Its Relationship with Serum IFN-γ and Vitamin D Levels in Women with Recurrent Spontaneous Abortion and Recurrent Implantation Failure

Background Mothers experiencing recurrent spontaneous abortion (RSA) along with repeated implantation failures (RIF) could potentially have abnormalities in their immune systems. Vitamin D is known as a crucial immunomodulatory agent. This study aimed to assess the ratio of Natural Killer T-cells (NKTs) and the correlation between this ratio with serum vitamin D levels among women with RSA and RIF. Methods In this research, blood samples were collected from both patients and a group of healthy individuals. The flow cytometry technique was used to determine the proportion of NKT and activated NKT cells. Additionally, Vitamin D and IFN-γ levels were measured using the ELISA technique. Results The mean ratio of NKT cells and IFN-γ levels increased significantly in those women with RSA relative to our healthy control group [( P < 0.018) and ( p < 0.031), respectively]. Nevertheless, women in the RIF and control groups did not show any significant differences. Serum vitamin D levels significantly decreased in RIF ( p < 0.04) and RSA ( p < 0.01) groups relative to the control group . Conclusions It was found that increasing ratio as well as inflammatory activity of NKT cells correlated with repeated miscarriage. Reduced vitamin D levels could cause immune system disorder along with pregnancy complications.