Objectives: Neopterin is produced by stimulated macrophages under the influence of gamma interferon of lymphocyte origin. It is regarded as a biochemical marker of cell-mediated immune response. This study was designed to assess the diagnostic value of pleural fluid neopterin levels in tuberculous pleurisy in comparison with adenosine deaminase activity.
Design and methods: Pleural fluid adenosine deaminase (ADA) activity and neopterin levels were measured in 16 patients with tuberculous pleurisy (TP) and 19 patients with malignant pleurisy (MP). ADA activity was determined by a colorimetric method, whereas neopterin levels were determined by a reversed-phase liquid chromatography technique. All values were given as median (min-max).
Results: The mean age was 45.43+/-20.39 years in the TP group and 60.42+/-11.02 years in the MP group (p=0.026). The median pleural fluid ADA activity was 51.75 U/L (3.50-62.40 U/L) in the TP group and was 2.30 U/L (1-8.20 U/L) in the MP group. The difference was statistically significant (p<0.001). The median pleural fluid neopterin levels were 13.15 nmol/L (1.86-59.50 nmol/L) and 2.44 nmol/L (0.92-27.60 nmol/L) in the TP group and the MP group, respectively (p=0.021). In order to evaluate the diagnostic value of pleural fluid neopterin concentrations, receiver-operating-characteristic curve analysis was performed.
Conclusion: Pleural fluid neopterin concentration is significantly higher in TP when compared to MP, however when compared, its clinical use as a diagnostic marker is not valuable as ADA.