title: Reduced purine 5'-nucleotidase activity in lymphocytes of patients with systemic lupus erythematosus: results of a pilot study.
abstract: OBJECTIVE
  To investigate purine metabolism in patients with systemic lupus erythematosus (SLE) for possible abnormalities that might be related to their overall impaired immune function.
  
  
  METHODS
  This pilot study included 17 patients with SLE (2 men, 15 women). Enzyme activities of the purine enzymes 5'-nucleotidase (5'NT), purine nucleoside phosphorylase (PNP), and hypoxanthine-guanine-phosphoribosyltransferase (HGPRT) were measured in peripheral blood mononuclear cells (PBMC) and also in fractions of T cells (differentiation antigen CD3+) (n = 12) and B cells (CD19+) (n = 9). The activity of the thiopurine enzyme thiopurine-methyltransferase (TPMT) was measured in red cell lysate. Routine blood tests and indices of disease activity were measured as well. Results were compared with those of healthy volunteers.
  
  
  RESULTS
  Compared with their controls, the female SLE patients had a more than 50% reduced activity of 5'NT in the T cell fraction (p = 0.001) and in PBMC (p < 0.000). 5'NT activity was also lower in B cells, but this was not statistically significant. Enzyme activities did not correlate with indices of disease activity, disease duration or the B cell/T cell ratio and no influence of medication was found.
  
  
  CONCLUSIONS
  Reduced lymphocyte 5'NT activity is a novel finding in SLE. These results indicate that purine metabolism in SLE may be disturbed. Consequences of a low 5'NT activity may be an intracellular accumulation of (deoxy)purine nucleotides and a reduction of adenosine production. It is hypothesised that these factors may play a part in the overall impaired immune function and in the chronicity of inflammation in SLE.
authors.affiliation: Department of Rheumatology, University Hospital Nijmegen, The Netherlands.
authors.forename: J N
authors.initials: JN
authors.lastname: Stolk
authors.forename: D G
authors.initials: DG
authors.lastname: de Koning
authors.forename: A H
authors.initials: AH
authors.lastname: Pennings
authors.forename: R A
authors.initials: RA
authors.lastname: De Abreu
authors.forename: L B
authors.initials: LB
authors.lastname: van de Putte
authors.forename: A M
authors.initials: AM
authors.lastname: Boerbooms
mesh_terms: D000328:Adult; D000368:Aged; D018941:Antigens, CD19; D001402:B-Lymphocytes / Q000201:enzymology / Q000276:immunology; D017252:CD3 Complex; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000201:enzymology*; D008180:Lupus Erythematosus, Systemic / Q000201:enzymology* / Q000276:immunology; D008297:Male; D008875:Middle Aged; D009708:Nucleotidases / Q000378:metabolism*; D010865:Pilot Projects; D013601:T-Lymphocytes / Q000201:enzymology / Q000276:immunology
chemical_list: D018941:Antigens, CD19; D017252:CD3 Complex; D009708:Nucleotidases; C029296:purine 5'-nucleotidase