ORIGINAL ARTICLE HTLV-1 seroprevalance in sarcoidosis. A clinical and laboratory study in northeast of Iran Massoud SAGHAFI, Zahra REZAIEYAZDI, Shima NABAVI, Zahra MIRFEIZI, Maryam SAHEBARI and Masoumeh SALARI Rheumatic Diseases Research Center, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran Abstract Aim: Sarcoidosis is an autoimmune multiorgan granulomatosis disease with unknown origin. Some environ- mental factors such as viruses may induce the disease in genetically susceptible individuals. Human T cell lym- photropic virus type 1 (HTLV-1) can dysregulate the human immune system and the role of this virus in the pathogenesis of autoimmune diseases has been investigated and documented, such as in uveitis. In this study, we have focused on the seroprevalence of HTLV-1 in sarcoidosis in comparison to the normal population in the northeast of Iran, an endemic area for HTLV-1. Methods: This cross-sectional study enrolled 125 patients with established sarcoidosis to evaluate the frequency of HTLV-1 and compare it with the normal population of Mashhad, Iran. Participants’ blood samples were ana- lyzed for HTLV-1 antibody by an enzyme-linked immunosorbent assay kit. Positive results were confirmed by polymerase chain reaction method. Finally, data were analyzed using SPSS 11. Results: Among sarcoidosis patients 106 (84.8%) patients had a history of acute course and 19 (15.2%) had chronic sarcoidosis. Four percent of the patients versus 2.12% of the Mashhad population were HTLV-1 positive with no statistical difference (P = 0.201). In age- and sex-matched selected controls, 3.6% were HTLV-1 positive again with no statistical difference by sarcoidosis group (P = 0.52). There was no statistical difference between arthritis, erythema nodusom, uveitis, constitutional symptoms, abnormal chest radiography (parahilar lym- phadenopathy) and computed tomography scan findings, respiratory symptoms, sex, the course of the sarcoido- sis in HTLV-1 positive and negative sarcoidosis patients. Conclusion: The frequency of HTLV-1 in 125 sarcoidosis patients was 4%. In comparison with prevalence of HTLV-1 in Mashhad, HTLV-1 seroprevalence did not show any significant difference. Key words: HTLV-1, human T-cell lymphotropic virus type 1, Lofgren’s syndrome, sarcoid arthropathy, sarcoidosis. INTRODUCTION Sarcoidosis is an immune-mediated disease, which is diagnosed through non calcified granulomas and with a classic antigenic T helper-1 immune response. 1 Its prevalence varies throughout the world. The etiology of sarcoidosis is still unknown. 1,2 Previous studies have brought up organic and inor- ganic environmental factors, occupational factors and various micro-organisms, especially viral agents, as the causative factors for sarcoidosis. 3 As the lung is affected in over 90% of sarcoidosis cases, environmental agents which enter the body through inhalation have been introduced as predisposing factors for disease. 4 Correspondence: Dr Maryam Sahebari and Masoumeh Salari, Rheumatic Diseases Research Center (RDRC), Ghaem Hospital, School of Medicine, Mashhad University of Medical Sciences, Mashhad 9176699199, Iran. Emails: sahebarim@mums.ac.ir and salarim@mums.ac.ir © 2017 Asia Pacific League of Associations for Rheumatology and John Wiley & Sons Australia, Ltd International Journal of Rheumatic Diseases 2017