Adenosine Deaminase Activity and its Isoenzyme Pattern in Patients with Juvenile Rheumatoid Arthritis and Systemic Lupus Erythematosus

Abstract

Adenosine deaminase (ADA) is involved in purine metabolism and plays a significant role in the mechanisms of the immune system. The aim of this study was to investigate the activity of total ADA (tADA) and its isoenzymes ADA1 and ADA2 in serum and peripheral blood lymphocytes (PBLs) of children with juvenile rheumatoid arthritis (JRA) and systemic lupus erythematosus (SLE) in different phases of the diseases. The study comprised 34 patients with rheumatic disease, 24 with JRA and 10 with SLE, and 64 healthy controls. The tADA activity and its isoenzymes were measured in serum and PBLs of all patients by the method of Giusti and by the presence or absence of EHNA (erythro-9-(2-hydroxy-3-nonyl)adenine) during the active phase of the disease (before treatment), as well as during remission and relapse. Our data show that increased tADA activity in the serum and PBLs of patients with JRA and SLE is correlated mainly to increased levels of ADA2 activity in serum and ADA1 activity in PBLs. It also closely correlates with clinical disease activity and relapse. The cause of this increased tADA/ADA2 activity in serum and tADA/ADA1 activity in PBLs in JRA and SLE remains to be elucidated. Nevertheless, it may be noted that the measurement of tADA activity, together with ADA2 activity in serum and tADA with ADA1 activity in PBLs, could offer a biochemical approach to the assessment of the pathophysiology of JRA and SLE. Also, tADA and its isoenzymes could be used as alternative parameters representing disease activity.

Serum Adenosine Deaminase as Inflammatory Marker in Rheumatoid Arthritis

“…Similar findings were reported earlier [5]. Although the exact cause of increase in ADA levels is not known, the activity may be increased due to its release from damaged cells and increased cellular proliferation in RA [15]. Synthesis of CRP in liver is triggered by pro inflammatory cytokines released from monocyte and/or macrophages.…”

Dosagem sérica de adenosina deaminase em lúpus eritematoso sistêmico: ausência de associação com atividade de doença

“…Esse resultado diverge da maioria dos trabalhos publicados (18,19,20) , o que pode ser explicado pela diferença nas diversas populações estudadas ou pela falta de padronização da técnica de dosagem sérica da ADA. Existem vários kits comercializados para a dosagem desta enzima, os quais não são detalhados nos trabalhos publicados, o que pode dificultar a comparação dos resultados entre os mesmos.…”

Human ADA2 belongs to a new family of growth factors with adenosine deaminase activity

“…HIV-1-infected T-cells [14] and B-cells [12] might also be a source of ADA2 in plasma. ADA2 activity is profoundly elevated in plasma from patients suffering from liver diseases, such as chronic hepatitis and cirrhosis, AIDS, adult T-cell leukaemia, acute lymphoblastic leukaemia, tuberculosis and diabetes mellitus [4,[15][16][17]. However, it is puzzling that ADA2, an enzyme more abundant in plasma than in ADA1, has a Michaelis constant K m = 2 mM, which is several orders higher than the concentration of adenosine in plasma (0.1 µM) [18], suggesting that the rate of adenosine deamination catalysed by ADA2 is close to zero at physiological adenosine concentrations.…”