[Determination and significance of interleukin-16 in tuberculous and malignant pleural effusion]

Abstract

Objective: Interleukin-16 (IL-16) is a chemoattractant of CD4+ lymphocytes, and it has been implicated in the pathogenesis of various inflammatory diseases. The aim of the present study was to measure IL-16 in pleural effusions caused by tuberculosis and malignancy and its relationship with cell and differential counts as well as lymphocyte subsets.

Methods: Pleural effusion and venous blood samples were collected from 32 patients with tuberculous pleuritis and 30 lung cancer patients with malignant effusion. Analysis of pleural effusion for total leukocytes and cell differentials of leukocytes was performed. Three-color flow cytometry was performed to determine T lymphocyte subsets in cell pellets of pleural effusion. The concentration of IL-16 in cell-free supernatants of pleural effusion and sera was measured by a sandwich enzyme-linked immunosorbent assay.

Results: In all the studied patients, the level of IL-16 was significantly higher in pleural effusion than in serum. The levels of IL-16 were significantly higher in tuberculous than in malignant effusions. In pleural effusion, positive correlations were found between the IL-16 levels and total cell counts, lymphocytes, CD3+ T cells, as well as CD4+ T cells.

Conclusions: Compared to malignant pleural effusion, IL-16 appeared to be increased in tuberculous pleural effusion. The pleural effusion IL-16 levels were positively related to the numbers of CD4+ T cells, suggesting that IL-16 might be capable of inducing CD4+ T cell infiltration into pleural space.