[Comparative study of soluble interleukin 2 receptor and adenosine deaminase levels in tuberculous and other etiologies pleural fluids].

In order to better understand the immunological mechanisms involved in host protection against Mycobacterium tuberculosis infection, we studied soluble interleukin 2 receptor (sIL-2R) concentration in tuberculous pleural exudates as well as in pleural fluids of non-mycobacterial etiology. We collected pleural fluid from 40 patients: 10 with tuberculous bacterial pneumonia and 10 with trasudate. Soluble IL-2R was measured in the stored specimens using a standard ELISA technique. In patients with tuberculosis, sIL-2R in pleural fluid was 14,666 +/- 5,634 U/ml, significantly higher than was detected in any other group, being 4,341 +/- 2,655 U/ml in pneumonic exudates, 5,542 +/- 3,682 U/ml in neoplastic exudates and 1,377 +/- 125 in trasudates (p < 0.001). Also, an excellent correlation was demonstrated between adenosine-desaminase (ADA) and sIL-2R in tuberculous pleural fluids, with p < 0.001 and r = 0.805. In pleuropulmonary tuberculosis, compartmentalization of the immune response in the pleural space is responsible for the significantly higher levels of sIL-2R that were found in tuberculous pleural liquids compared with the ones detected in other diseases. This observation, as well as the demonstration of a good correlation between sIL-2R and ADA, suggest the possible usefulness of this molecule as an additional marker in the differential diagnosis of pleural effusions, though in the present study it appears to be less reliable than ADA.