Diagnostic value of Interleukin 12 p40 in tuberculous pleural effusions

¹ Complejo Hospitalario Universitario de Santiago de Compostela
² Servicio de Neumología y Servicio de Análisis Clínicos

^* To whom correspondence should be addressed. E-mail: luis.valdes.cuadrado{at}sergas.es.

	Abstract

The diagnosis of tuberculous pleural effusion (TBPE) is frequently problematic. Several markers of TBPE in pleural fluid have been evaluated, with different results.

Pleural effusions from 96 patients were classified on the basis of definitive diagnosis as tuberculous (39), neoplastic (42) or parapneumonic (15). Adenosine deaminase (ADA), ADA isoform 2 (ADA-2), interferon (IFN-), CD3⁺ DR⁺ T lymphocytes (CD3⁺ DR⁺ T), and interleukin 12 p40 (IL-12 p40) were determined in all 96 effusions. The efficiency of IL-12 p40 for diagnosis of tuberculous pleural effusions (TBPEs) was evaluated in comparison with those of the other parameters; by comparing the areas under their receiver operating characteristics (ROCs).

With the threshold value of 550 pg·mL^-1 for IL-12 p40, had a sensitivity of 92.3% (36/39); specificity of 70.2% (17 false positives). The misclassification rate of IL-12 p40 was significantly greater than those of ADA-2 and ADA. Among TBPEs, ADA correlated significantly with ADA-2; and IFN- with ADA and IL-12 p40.

Although tuberculous pleural effusions show values of IL-12 p40 significantly higher than neoplastic and parapneumonic fluids, it is less efficient than ADA, ADA-2 and IFN-. Its routine determination is accordingly not justified.