EXPRESSION AND T CELL REGULATORY ACTION OF THE PD-1 IMMUNE CHECKPOINT IN THE OVARY AND FALLOPIAN TUBE
This study was initiated to better understand how native ovary and fallopian tube cells interact with resident immune cells. Ovarian and fallopian tube samples were obtained, and PD-1 and ligan protein expression were assesed. Human follicular fluid was also obtained, of which protein expression was assessed, and treated with human T-cells to measure interferon gamma. Findings from this study suggest that soluble and membrane bound PD-1 pathway proteins are expressed in non-lymphoid/non-myeloid cells of the human ovary and were found in the fluid collected from peri-ovulatory follicles in egg retrieval procedures during IVF. Specifically, PD-1, PD-L2, and PD-L1, were present in the human ovarian cortex pre- and post-menopausally in various amounts. After menopause, PD-L1 was found distributed in the cortex more extensively compared to pre-menopause. Results also suggest that these ligands are present in human follicular fluid at levels capable of activating T-cells. The findings indicate that the PD-1 pathway dually helps to protect the ovary, oocytes, and embryos in the fallopian tubes from autoimmune reactions while also functioning as a protective immune system against infection.