Are soluble IL-2 receptor and IL-12p40 levels useful markers for diagnosis of tuberculous pleurisy?

Background: The differential diagnostic utilities of the levels of soluble interleukin (IL)-12p40 and the IL-2 receptor in sera and pleural effusions were evaluated in patients with exudative pleural effusions. Methods: We enrolled a total of 120 patients with exudative pleural effusions. The clinical, radiological, and histopathological diagnoses were tuberculous pleurisy in 52, malignant pleurisy in 39, and parapneumonic effusions in 29 patients. Results: We measured serum IL-12p40 and adenosine deaminase (ADA) levels in patients with tuberculous pleurisy and in a control group treated for pleural effusion to determine if such levels were useful in the diagnosis of pleural effusion (p < 0.005). Definite microbiological or histopathological diagnoses of tuberculous pleurisy or pleural effusion were recorded, and we found that ADA and serum soluble IL-2 receptor levels aided in diagnosis (p < 0.001). The levels of ADA and soluble IL-2 in pleural effusions afforded sensitivities and specificities of 84.62% and 82.69% and of 70.59% and 80.88%, respectively. The soluble IL-2 receptor level afforded a sensitivity and specificity of 82.69% and 52.9%. IL-12p40 levels in pleural effusions and sera afforded sensitivities and specifi cities of 80.77% and 80.77% and of 60.29% and 39.71%, respectively. Conclusion: Soluble IL-2 receptor levels in patients with tuberculous pleurisy serve as markers of disease in non-endemic countries, similarly to ADA levels.