title: Tuberculous effusion: ADA activity correlates with CD4+ cell numbers in the fluid and the pleura.
abstract: BACKGROUND
  Adenosine deaminase (ADA) is a commonly used marker in the diagnosis of tuberculous effusion and there is evidence that its production is linked to T cells and monocytes. Data on the correlation between ADA and T cells or macrophages in tuberculous effusions are conflicting. Furthermore, no studies have examined a possible correlation between pleural tissue infiltration and ADA.
  
  
  OBJECTIVE
  We undertook this study to examine cell subsets in the fluid and the pleura in tuberculous effusion and their correlation to ADA. The use of cell subsets as a marker in the differential diagnosis was also examined.
  
  
  METHODS
  Pleural fluid from 36 patients with tuberculous and 34 patients with malignant effusion as well as pleural tissue biopsies from 16 patients with tuberculous pleurisy were examined. The APAAP and the avidin-biotin complex immunocytochemical methods were used to examine CD4+ T cells and macrophages (CD68+), while ADA activity was measured by the Giusti colorimetric method.
  
  
  RESULTS
  Our results showed that, in pleural fluid, CD4+ cells and ADA were significantly higher in tuberculous compared to malignant effusion (p<0.001 for all measurements). In pleural tissue biopsies, macrophages were the predominant cells but CD4+ T cells were also abundant. A significant correlation was found between ADA and CD4+ numbers in pleural fluid and tissue (r=0.45, p<0.01; r=0.75, p<0.001, respectively). ADA had high sensitivity and specificity for differential diagnosis while cell subsets did not.
  
  
  CONCLUSIONS
  These results indicate that ADA activity correlates to CD4+ T cell infiltration in the pleura and the fluid. Moreover, ADA but no cell subsets may be used as markers of tuberculous effusion.
authors.affiliation: Respiratory Medicine Department, Medical School, Athens University, Athens, Greece. mgaga@med.uoa.gr
authors.forename: M
authors.initials: M
authors.lastname: Gaga
authors.forename: G
authors.initials: G
authors.lastname: Papamichalis
authors.forename: P
authors.initials: P
authors.lastname: Bakakos
authors.forename: P
authors.initials: P
authors.lastname: Latsi
authors.forename: I
authors.initials: I
authors.lastname: Samara
authors.forename: N G
authors.initials: NG
authors.lastname: Koulouris
authors.forename: N
authors.initials: N
authors.lastname: Alchanatis
authors.forename: D
authors.initials: D
authors.lastname: Orphanidou
mesh_terms: D000243:Adenosine Deaminase / Q000378:metabolism*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015703:Antigens, CD / Q000276:immunology; D015214:Antigens, Differentiation, Myelomonocytic / Q000276:immunology; D015415:Biomarkers / Q000378:metabolism; D001706:Biopsy; D018791:CD4 Lymphocyte Count; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000473:pathology*; D003937:Diagnosis, Differential; D045604:Extracellular Fluid / Q000166:cytology / Q000201:enzymology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008264:Macrophages / Q000276:immunology; D008297:Male; D008875:Middle Aged; D010994:Pleura / Q000473:pathology; D010996:Pleural Effusion / Q000201:enzymology* / Q000209:etiology / Q000473:pathology; D016066:Pleural Effusion, Malignant / Q000201:enzymology / Q000473:pathology; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D014397:Tuberculosis, Pulmonary / Q000150:complications* / Q000201:enzymology / Q000473:pathology; D000097382:CD68 Molecule
chemical_list: D000243:Adenosine Deaminase; D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D015415:Biomarkers; C067980:CD68 antigen, human; D000097382:CD68 Molecule