Marta Imamura,1 Rosa Alves Targino,1 Wu Tu Hsing,2,3 Satiko Imamura,1 Raymundo Soares Azevedo,3 Lucy Santos Villas Boas,4 Tania Regina Tozetto-Mendoza,5 Fábio Marcon Alfieri,1,6 Thais Raquel Filippo,1 Linamara Rizzo Battistella1,71Clinical Research Center, Institute of Physical Medicine and Rehabilitation, University of São Paulo Medical School, São Paulo, 2Division of Physical Medicine, Center for Acupuncture, Institute of Orthopedics and Traumatology, University of São Paulo, São Paulo, 3Department of Pathology, University of São Paulo, São Paulo, 4Laboratory of Medical Investigation LIM-52-HCFMUSP, Institute of Tropical Medicine, University of São Paulo, São Paulo, 5Tropical Laboratory of Hematology/Medical Research Laboratory-LIM 52, Institute of Tropical Medicine, University of São Paulo, São Paulo, 6Program of Master in Health Promotion, São Paulo Adventist University Center, São Paulo, 7Department of Legal Medicine, Medical Ethics, Social and Labor Medicine – Medicine School, University of São Paulo, São Paulo, BrazilIntroduction: Fibromyalgia and osteoarthritis may present a relationship with the concentration of cytokines. The aim of this study was to compare the serum concentrations of IL-12p70, tumor necrosis factor, IL-10, IL-6, IL-1ß, and IL-8 in patients with knee osteoarthritis and fibromyalgia.Materials and methods: The study included 53 women (71.2±7.6 years old) diagnosed with knee osteoarthritis with moderate-to-severe pain (visual analog scale >4) for at least 3 months. Sixty women (54.1±8.1 years old) diagnosed with fibromyalgia according to the American College of Rheumatology criteria and with moderate-to-severe pain (visual analog scale >4) also participated in this study. For the dosage of cytokines, blood was collected in the morning: 5 mL from the cubital vein. The material was centrifuged at 4°C, separated into 100 µL aliquots and stored at -80°C until processing. Serum concentrations of the studied cytokines were assessed using the BD Cytometric Bead Array method. Data were analyzed with Student’s t-test and the Mann–Whitney U test.Results: We found higher levels of IL-6, IL-10, and IL-1ß in fibromyalgia patients. After adjustment of age as a covariate, there was no statistically significant difference in the concentration of any cytokine between fibromyalgia and knee osteoarthritis patients.Conclusion: Patients with knee osteoarthritis and fibromyalgia with the same duration and intensity of pain demonstrate similar concentrations of cytokines. Aging may play a role in cytokine profile, a finding not so extensively addressed in the literature and one that should be further investigated.Keywords: cytokines, osteoarthritis, fibromyalgia, agin