NK and T Cell Subtypes in the Endometrium of Patients with Recurrent Pregnancy Loss and Recurrent Implantation Failure: Implications for Pregnancy Success.

BACKGROUND: RPL and RIF are challenges in reproductive medicine. The immune system plays a pivotal role in endometrial receptivity, successful implantation, and pregnancy complications. Immunological changes have been associated with RPL and RIF. Understanding immune dysregulation especially in NK and T cell subtypes may lead to better diagnostic concepts and treatments. From July 2019 to August 2020 patients with RPL and RIF underwent a standardized diagnostic procedure including endometrial biopsies. Immune cell analysis was performed using flow cytometry. Patients were contacted in March 2023 and interviewed concerning their pregnancy outcomes following diagnostics. RESULTS: Out of 68 patients undergoing endometrial biopsies, 49 patients were finally included. Live birth rates were high with 72% in RPL and 86% in RIF. Immune cell analysis revealed that patients with RPL had more cytotoxic CD56(dim)CD16(high) cells, while RIF patients had more CD56(+) uNK cells. RPL patients with pregnancy complications showed increased NKT cell percentages. CONCLUSION: Our findings suggest specific immune changes in RPL and RIF patients, offering potential therapeutic targets. Tailored immunotherapy based on endometrial immunophenotyping might be an option, but further research is needed.