Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 19 5 2020 10 18 484 496 EN Nishtman Heidari Student Research Committee, Kurdistan University of Medical Sciences, Sanandaj, Iran AND Department of Immunology and Hematology, Faculty of Medicine, Kurdistan University of Medical Sciences, Sanandaj, Iran Mobin Mohammadi Department of Immunology and Hematology, Faculty of Medicine, Kurdistan University of Medical Sciences, Sanandaj, Iran AND Cancer and Immunology Research Center, Research Institute for Health Development, Kurdistan University of Medical Sciences, Sanandaj, Iran Mohammad Ali Rezaee Zoonosis Research Center, Research Institute for Health Development, Kurdistan University of Medical Sciences, Sanandaj, Iran AND Department of Medical Laboratory Sciences, Faculty of Paramedical, Kurdistan University of Medical Sciences, Sanandaj, Iran Abbas Ali Amini Department of Immunology and Hematology, Faculty of Medicine, Kurdistan University of Medical Sciences, Sanandaj, Iran AND Cancer and Immunology Research Center, Research Institute for Health Development, Kurdistan University of Medical Sciences, Sanandaj, Iran Shohreh Fakhari Department of Immunology and Hematology, Faculty of Medicine, Kurdistan University of Medical Sciences, Sanandaj, Iran AND Cancer and Immunology Research Center, Research Institute for Health Development, Kurdistan University of Medical Sciences, Sanandaj, Iran Mohammad Rahmani Department of Immunology and Hematology, Faculty of Medicine, Kurdistan University of Medical Sciences, Sanandaj, Iran AND Zoonosis Research Center, Research Institute for Health Development, Kurdistan University of Medical Sciences, Sanandaj, Iran 2019 09 04 2020 06 22 Co-inhibitory molecules modulate immune responses. Immunomodulatory properties of mesenchymal stem cells (MSCs) turn them into ideal candidates for cell therapy. This study was designed to investigate the immunomodulatory effect of adipose-derived stem cells (ASCs) on inflammatory environment of a co-culture of allogenic peripheral blood mononuclear cells (PBMCs) in a two-way mixed leukocyte reaction (twMLR) setting. ASCs were co-cultured with allogenic PBMCs in twMLR setting for four days. The proliferation of peripheral blood mononuclear cells (PBMCs), levels of interleukin (IL)-10, and expression of interferon-gamma (IFN-γ), B7-1, cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), programmed death-ligand 1 (PD-L1), +, and CD200R1 genes, as well as cell surface expression of CD200 and CD200R1, were measured in twMLR as control, and co-culture groups on days 0, 2 and 4 of the experiment. The proliferation of PBMCs was suppressed on days 2 and 4 of co-culture. The expression of CD200 (p=0.014), CD200R1, CTLA-4, and PD1 genes increased on days 2 and 4 of the co-culture compared to twMLR. CD200 expressing PBMCs decreased by 1.75% on day 2 of the co-culture but increased by 6.23% on day 4 of the co-culture (p=0.013) compared to the same days of twMLR. IL-10 levels increased in the co-culture supernatants on days 2 and 4 compared to twMLR (p<0.05). Our results showed that ASCs upregulate the CD200/CD200R1 axis more than PD-1/PD-L1 and CTLA-4/B7-1 pathways in the twMLR. Also, elevated expression of CD200R1 in the final day of co-culture was similar to PD-1 expression pattern. This finding suggests a role for the CD200/CD200R1 axis in later modulation of the immune response. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/2509