ABSTRACT
Sickle cell anemia (SCA) is characterized by hemoglobin polymerization that results in sickle-shaped red blood cells. The vascular obstruction by sickle erythrocytes is often inflammatory, and purinergic system ecto-enzymes play an important role in modulating the inflammatory and immune response. This study aimed to evaluate the E-NTPDase and E-ADA activities in lymphocytes of SCA treated patients, as well as verify the cytokine profile in this population. Fifteen SCA treated patients and 30 health subjects (control group) were selected. The peripheral lymphocytes were isolated and E-NTPDase and E-ADA activities were determined. Serum was separated from clot formation for the cytokines quantification. E-NTPDase (ATP and ADP as substrate) and E-ADA (adenosine as substrate) activities were increased in lymphocytes from SCA patients (P<0.001). The TNF-α and IL-6 serum cytokines showed decreased on SCA patients comparing to control (P<0.001). The regulation of extracellular nucleotides released in response to hypoxia and inflammation through E-NTPDase and E-ADA enzymes represent an important control of purine-mediated in the SCA disease, avoiding elevated adenosine levels in the extracellular medium and consequent organ injuries in these patients. The pro-inflammatory cytokines decreased levels by use of hydroxyurea occur in attempt to reduce the pro-inflammatory response and prevent vaso-oclusive crisis.
Subject(s)
Adenosine Deaminase/blood , Adenosine Triphosphatases/blood , Anemia, Sickle Cell/blood , Anemia, Sickle Cell/enzymology , Cytokines/blood , Lymphocytes/enzymology , Adolescent , Adult , Anemia, Sickle Cell/therapy , Case-Control Studies , Female , Humans , Male , Middle Aged , Treatment Outcome , Young AdultABSTRACT
NTPDase (EC 3.6.1.5) is an enzyme that hydrolyzes extracellular nucleoside tri- and/or diphoshates forming AMP that can serve as a substrate for an ecto-5'-nucleotidase (EC 3.1.3.5) with liberation of adenosine, a modulator of vascular tone and inhibitor of platelet aggregation. These enzymes also occur in lymphocytes playing an important role in immune function. In this study, it was investigated if anti-HIV therapy could affect NTPDase activity in human lymphocytes. Samples of lymphocytes were incubated with different concentrations of anti-HIV drugs and NTPDase activity was determined by colorimetric assay with quantification of inorganic phosphate released. There is not significant difference of NTPDase activity among samples with therapeutic doses of anti-HIV drugs tested when compared with controls. NTPDase activity in peripheral human lymphocytes is not altered by anti-HIV therapy.
Subject(s)
Anti-HIV Agents/pharmacology , Antigens, CD/metabolism , Apyrase/metabolism , Lymphocytes/drug effects , Adult , Anti-HIV Agents/administration & dosage , Colorimetry , Dose-Response Relationship, Drug , Female , Humans , In Vitro Techniques , Lymphocytes/enzymology , MaleABSTRACT
Infection with the human immunodeficiency virus (HIV) results in alterations in immune cells such as an increase or decrease of cytokine secretion and immunodeficiency. HIV causes a state of chronic cellular activation that can induce apoptosis in lymphocyte T-helpers, making the patient susceptive to opportunistic infections. The biochemical mechanisms involved in this immune response to HIV have been researched. Here, we have shown for the first time that ATP and ADP hydrolysis are essential for the immune response to HIV. Our results clearly indicate an increase of NTPDase-1 (EC 3.6.1.5) activity in lymphocytes of HIV-positive patients, confirmed by an enhanced CD39 expression on its surface. These results suggest that NTPDase-1 may be important to keep an adequate balance between the generation and consumption of ATP and to preserve cellular integrity and immune response to the HIV infection.