Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 19 1 2020 02 01 65 73 EN Parya Basimi Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Firouzeh Akbari Asbagh Department of Obstetrics and Gynecology, Yas Hospital, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Mir Saeed Yekaninejad Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Mojgan Asadi Diabetes Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran Ali Dabbagh Department of Cardiac Anesthesiology, Anesthesiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran Farangis Najafi Arbastan Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Samira Rajaei Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran 2019 05 05 2019 07 09 Thyroid autoimmunity, being recognized by the presence of auto-antibodies against thyroid peroxidase (TPO) and thyroglobulin, has known to be associated with increased risk of recurrent spontaneous abortion (RSA), even in euthyroid subjects. There was no robust evidence regarding T cell deviations in anti-TPO positive RSA patients. The aim of this study was to investigate if the numbers of different CD4+T  subsets were different in women who experienced RSA and have an anti-TPO antibody from those without autoantibody and normal fertile women or not. In this study, peripheral blood samples were obtained from three groups of women (age: 20-35 years) including RSA anti-TPO positive (n=17), RSA anti-TPO negative (n=27), and fertile (n=29) groups. The frequency of T helper (Th) 1, Th2, Th17, and regulatory T cells (Tregs) and also, the proportions of Th1/Th2 and Th17/Treg were measured by flow cytometry and compared between groups in different menstrual phases. The findings indicated elevated levels of Th1 in anti-TPO+ RSA in comparison with those without anti-TPO (p-value: 0.004), exclusively in the luteal phase. Other T cell subsets were different only between RSA and control groups. Also, the Th1/Th2 and Th17/Treg ratios were increased in both RSA groups compared to fertile women. The only subset of CD4+ T cell different between RSA groups (i.e. with and without anti-TPO) was Th1 cells. Other CD4+ T cells’ deviations including Th2, Th17, and Treg cells could be related to the presence of abortion, regardless of the underlying thyroid autoimmunity state. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/2388