Activities of enzymes that hydrolyze adenine nucleotides in lymphocytes from patients with rheumatoid arthritis Jeandre Augusto dos Santos Jaques 1,2 , Lara Vargas Becker 1,2 , Viviane do Carmo Gonçalves Souza 2 , Cláudio Alberto Martins Leal 1 , Tatiana Montagner Dalcin Bertoldo 2 , Kelly de Vargas Pinheiro 2 , Vera Maria Morsch 1 , Maria Rosa Chitolina Schetinger 1 and Daniela Bitencourt Rosa Leal 2 * 1 Centro de Ciências Naturais e Exatas, Departamento de Química, Universidade Federal de Santa Maria, RS, Brazil 2 Centro de Ciências da Saúde, Departamento de Microbiologia e Parasitologia, Universidade Federal de Santa Maria, RS, Brazil The purpose of this study was to investigate the activities of ecto-nucleoside triphosphate diphosphohydrolase (E-NTPDase; EC 3.6.1.5; CD39) and adenosine deaminase (E-ADA; EC 3.5.4.4) in lymphocytes from patients with rheumatoid arthritis (RA). Thirty patients diagnosed with RA through American College of Rheumatology criteria as well as 30 healthy patients were selected. Peripheral blood lymphocytes were isolated, and E-NTPDase and E-ADA activities were assayed. The results demonstrated an increased E-NTPDase activity (both ATP and ADP as substrates) and a decreased E-ADA activity in RA patients. These data suggest an organic effort to preserve the adenosine level, which is known to have anti-inflammatory and analgesic properties, working as a potent suppressor of immune response. Copyright © 2012 John Wiley & Sons, Ltd. key words—rheumatoid arthritis; E-NTPDase; E-ADA; nucleotides; lymphocytes INTRODUCTION Rheumatoid arthritis (RA) is a systemic, inflammatory, autoimmune disorder characterized by predominant synovial proliferation, bone destruction and degradation of articular cartilage. 1 It is known that the synovial fluid of RA patients is enriched by immune cells such as neutrophils, macro- phages, dendritic cells and T lymphocytes, which contribute in many ways to the chronicity of disease. 2 Furthermore, many studies have described a pro-inflammatory profile of cytokines expression in these patients. 3–7 Extracellular adenine nucleotides are signalling molecules that play an important role in the immune response regula- tion. 8 Adenine nucleotides (ATP, ADP and AMP) and their nucleoside derivative, adenosine, are important molecules in the mediation of many biological and pathological events. 9 These molecules are dynamically controlled during inflamma- tion by a group of membrane-bound enzymes expressed in immune cells. 10 The enzyme ecto-nucleoside triphosphate diphosphohydrolase (E-NTPDase; EC 3.6.1.5; CD39) cata- lyses the sequential hydrolysis of ATP nucleotides to ADP and AMP, ecto-5 0 -nucleotidase (EC 3.1.3.5; CD73) catalyses the hydrolysis of AMP to adenosine, 11 and ecto-adenosine deaminase (E-ADA; EC 3.5.4.4) catalyses the irreversible deamination of adenosine and deoxyadenosine to inosine and deoxyinosine, respectively. 12 Considering that RA is characterized by a systemic inflammatory and autoimmune response and the involve- ment of purinergic system in the modulation of these events, the purpose of this study was to investigate the activity of E-NTPDase and E-ADA in lymphocytes from patients with RA to achieve better comprehension of their immune status. MATERIALS AND METHODS Chemicals The substrates ATP, ADP and adenosine, as well as Trizma base, Coomassie Brilliant Blue G and bovine serum albumin, were obtained from Sigma Chemical Co. (St. Louis, MO, USA), and K 2 HPO 4 was acquired from Reagen. All chemicals used in this experiment were of the highest purity. Patients and samples Thirty RA patients of both sexes (5 men, 25 women) (age 49.77  12.11 years) from the UFSM University Hospital (HUSM) were selected for the study, together with a control group that consisted of 30 healthy subjects (5 men, 25 women) (45.31  8.96 years) (Table 1). The diagnostic of RA was performed in accordance with the criteria of the American College of Rheumatology, which is based on the confirmed presence of synovitis in at least one joint, absence of an *Correspondence to: Daniela Bitencourt Rosa Leal, Departamento de Microbiologia e Parasitologia/CCS/UFSM—Universidade Federal de Santa Maria (UFSM), Prédio 20—Sala 4102, RS, Brazil. E-mail: dbitencourtrosaleal@gmail.com Received 5 April 2012 Revised 7 August 2012 Accepted 10 September 2012 Copyright © 2012 John Wiley & Sons, Ltd. cell biochemistry and function Cell Biochem Funct 2013; 31: 395–399. Published online 16 October 2012 in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/cbf.2910