en Molecular & Cellular Immunology Molecular & Cellular Immunology Original Article Original Article <span style="font-family:Tahoma;"><span style="font-size:12px;"><span style="unicode-bidi:embed"><span style="line-height:107%">Polycystic ovary syndrome is a low-grade inflammatory state with increased serum levels of TNF-&alpha;. The present study has compared the inflammatory responses to breast cancer cell lines in women with PCOS with healthy women. Peripheral blood mononuclear cells (PBMCs) isolated from 50 women with PCOS and 50 healthy controls were cultured in the trans-well co-culture system. These cells were stimulated with two distinct breast cancer cell lines. The proliferation of PBMCs, CD3+CD8+T cell percentages, and tumor necrosis factor-alpha (TNF-&alpha;) concentration were evaluated after 48 and 72 hours of incubation. TNF-&alpha; concentration and the proliferation rate of PBMCs after 48 hours of incubation significantly increased in the PCOS group. However, after 72 hours, TNF-&alpha; secretion significantly decreased in the PCOS group. The ability of PBMCs to produce TNF-&alpha; decreased gradually in women with PCOS. When the effects of low-grade inflammation and endocrine conditions on the cells decrease, the inability of PBMCs to create an inflammatory response will be altered<span dir="RTL" lang="FA">.</span></span></span></span></span> Inflammatory response, polycystic ovary syndrome, TNFα, breast cancer 70 80 http://ijmcmed.org/browse.php?a_code=A-10-5374-1&slc_lang=en&sid=1 Fatemeh Rezayat f.rezayat1991@gmail.com 100319475328460032696 100319475328460032696 No Department of Immunology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Mehri Hajiaghayi MEHRI.HAJIAGHAYI@gmail.com 100319475328460032697 100319475328460032697 No Department of Immunology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Nazanin Ghasemi nazanin.ghasemi69@gmail.com 100319475328460032698 100319475328460032698 No Department of Immunology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Mehrnaz Mesdaghi mehrnaz_mesdaghi@yahoo.com 100319475328460032699 100319475328460032699 No Department of Immunology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Fahimeh Ramezani Tehrani ramezani@endocrine.ac.ir 100319475328460032700 100319475328460032700 Yes Reproductive Endocrinology Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Nariman Mosaffa yasamaryan@gmail.com 100319475328460032701 100319475328460032701 No Department of Immunology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.