Objective: Tuberculosis, the leading cause of death among infectious diseases worldwide, is a major cause of lymphocytic exudative pleural effusion. T-helper 1 cytokines, including interferon-gamma (IFN-gamma), interleukin (IL)-12p40 and IL-18 are predominantly associated with cell-mediated immune responses, and play an important role in immunity to Mycobacterium tuberculosis.
Design: We studied 55 patients presenting with pleural effusion at the National Sanyo Hospital between April 2000 and September 2001 (42 men and 13 women; mean age 67 years). Twenty patients (36%) had tuberculous pleurisy, while 18 (33%) had malignant effusions and 17 (31%) had an effusion with another aetiology. Pleural fluid concentrations of IL-12p40 and IL-18 as well as IFN-gamma measured by enzyme-immunoassays.
Results: Concentrations of all three cytokines were significantly higher in tuberculous than other pleural effusions. Significant correlations were evident between IFN-gamma and IL-12. We found particularly high concentrations of IL-12p40 and IFN-gamma in tuberculous patients with high fever.
Conclusion: The results indicate that T-helper 1 cytokines are involved in intrapulmonary cellular immune responses to M. tuberculosis, and suggest that the interactions between them may play an important role in the pathogenesis and severity of the pleural effusion. Understanding the development of this response may enhance our understanding of the pathogenesis of tuberculous pleural effusion and suggest new therapies.