Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 17 5 2018 10 14 453 463 EN Behnaz Esmaeili Immunology Department, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran AND Immunology, Asthma and Allergy Research Institute (IAARI), Tehran University of Medical Sciences, Tehran, Iran Parvin Mansouri Skin and Stem Cell Research Center, Tehran University of Medical Sciences, Tehran, Iran Alipasha Meysamie Department of Community and Preventive Medicine, Tehran University of Medical Sciences, Tehran, Iran Maryam Izad Immunology Department, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran 2017 10 08 2018 02 04 Memory regulatory T cells (Tregs) has been demonstrated to produce IL-17 in Psoriasis. Forkhead box P3 (Foxp3) has been demonstrated not to be reliable marker to evaluate Treg cells. Effector CD4+T cells also express Foxp3 after activation. Human T helper-17 cells (Th-17) express high level of surface CD26, while regulatory T cells are CD26 negative or low and this phenotype is stable even after activation of Treg cells. In this study, we aimed to analyze IL-17 producing Treg cells using CD26. Memory T cells were isolated from 10 patients with psoriasis and 10 controls. Ex vivo stimulated IL-17 producing regulatory (Forkhead Box P3 (Foxp3)+CD25+CD26-/low) and effector (Foxp3+CD25+CD26hi) memory T cells were analyzed by flow cytometry. IL-23, IL-6, TNFα, TGFβ and IL-17 cytokine levels were also evaluated. No significant difference in IL-17+memory regulatory T cells was seen between patients and controls (p=0.19). A significant decrease in the percentage of IL-17 producing CD26hi effector memory T cells was observed in patients (p=0.04). However, the percentage of these cells was not different between patients with mild or severe form of psoriasis compared to controls (p=0.13). We could not find any significant difference regarding IL-23, IL-6, TNFα, TGFβ and IL-17 cytokine levels in plasma and cell culture supernatant samples between patients and controls. Taken together, our results showed a reduced IL-17 producing effector memory CD26hi T cells in patients with psoriasis compared to controls. However, IL-17 producing memory regulatory CD4+T cells of patients showed no significant difference from that of controls.  https://ijaai.tums.ac.ir/index.php/ijaai/article/view/1683 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/1683/1364