The immune cell profile of menstrual blood is distinct in women using oral contraceptive pills or IUD

Menstrual blood has been shown to be an excellent method to non-invasively study the uterine immune environment. In this study, we investigated whether menstrual effluent from patients using oral contraceptive pill (OCP) or copper intra-uterine device (IUD) can also be used for research into fertility issues. Menstrual effluent was collected during the first 24 h of menstruation using a menstrual cup, from women using OCP (n=5), copper IUD (n=3), and no contraceptives (n=5). Menstrual blood-derived endometrial cells were isolated and stained with monoclonal antibodies to identify NK, B and T cells using flowcytometry. High dimensional flowcytometry data revealed significantly low abundances of endometrial CD56BrightCD16-NK cells in women using OCP compared to non-contraceptive users, while the same pattern was not observed in copper IUD users. Additionally, OCPs users had significantly high amounts of endometrial Tregs than the other two groups. We did not observe any difference in the abundances of conventional T and B cell subsets between groups; however, copper IUD users displayed significantly increased frequencies of proliferating (Ki67+) CD8+T cells in comparison to non-contraceptive users and OCP users. OCP usage has a significant impact on the frequencies of various menstrual blood-derived immune cell subsets. The immune cell profile of copper IUD users was more comparable to non-contraceptive users; however, the increased presence of proliferative CD8+ T cells might suggest the reaction toward copper. Due to its significant impact on the immune cell profile, usage of OCP or IUD needs to be an exclusion criterion for further research into fertility issues.