Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 17 2 2018 04 28 151 157 EN Tahereh Khamechian Department of Pathology, Kashan University of Medical Sciences, Kashan, Iran Behnaz Irandoust Department of Pathology, Kashan University of Medical Sciences, Kashan, Iran Hanieh Mohammadi Student Research Committee, Kashan University of Medical Sciences, Kashan, Iran Hassan Nikoueinejad Nephrology and Urology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran Hossein Akbari Department of Biostatistics and Public Health, Faculty of Health, Kashan University of Medical Sciences, Kashan, Iran 2017 03 07 2017 07 19 In recent years, it has been recognized that regulatory T cells (Tregs) play a critical role in maintaining immune tolerance. Moreover, the expression of two markers named Helios and neurophilin-1 (NRP-1) has been highlighted in such cells. Helios, an intracellular transcription marker, largely differentiates twomost operative sub group of Tregs, namely naturally occurring (nTreg) and induced (iTreg) Tregs, and NRP-1 is reckoned as a membranous activity marker of Tregs. We aimed to count peripheral mononuclear cells expressing such markers in a group of type 1 diabetes patients to elucidate the possible role of Tregs in the pathogenesis of such disease and its complications. Blood samples from 61 adult patients with type 1 diabetes and 61 sex and age-matched healthy controls were tested to count two types of Tregs, namely naturally occurring and inducible types, according to the expression of cell surface markers of CD4/CD25/CD47–FITC/PE/APC and intracellular markers of FoxP3/Helios–PE-CY5/eFlour450 by flow cytometry, respectively.We also investigated the relation between expression of such markers with HbA1c, urine albumin/creatinine ratio (UACR), and common carotid intima thickness (CIMT). The circulatory frequency of both Helios+ and Helios- T-cells were significantly decreased in patients compared to those in healthy controls (p<0.001). There was also a significant decrease in circulatory frequency of Helios+ NRP-1+ and Helios- NRP-1+ cells in the patients compared to controls (p=0.029). According to expression of Helios and NRP-1 markers, the number and function of both Tregs were decreased in diabetic patients. Moreover, the neurophilin expression was inversely associated with complications of type 1 diabetes. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/1353 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/1353/816