Evaluation of a new inflammatory molecule (triggering receptor expressed on myeloid cells-1) in the diagnosis of pleural effusion

Background and objective: The triggering receptor expressed on myeloid cell-1 (TREM-1) is a newly discovered molecule that is associated with the inflammatory response to microorganisms. We investigated the role of surface and soluble TREM-1 in differentiating different disease entities in pleural effusion formation. Methods: Sixty-seven patients with pleural effusion due to transudate (14), malignancy (15), tuberculous pleuritis (16), para-pneumonic effusion (10) and empyaema (12) were included in this study. Surface TREM-1 was measured by flow cytometry and was expressed as mean fluorescence intensity and soluble TREM-1 was measured by ELISA and expressed as pg/mL. Results are given as mean levels SEM. Results: Surface TREM-1 was measured in 24 patients and the levels were highest in parapneumonic effusion (30.0 +/- 8.4) and lowest in malignant pleural effusion (5.2 +/- 1. 1) and tuberculous pleuritis (5.2 +/- 2.4). Soluble TREM-1 was highest in effusions of infectious aetiology (para-pneumonic effusion (979.4 +/- 229.6) and empyaema (1712.6 +/- 299.5)) and lowest in non-infectious effusions (transudate (81.2 +/- 4.5 pg/mL) and malignancy R 11.3 +/- 20.7). At a cut-off value of 114 pg/mL, soluble TREM-1 yielded a sensitivity of 87.5% and a specificity of 89.7% in differentiating non-infectious effusion from tuberculous pleuritis. At a cut-off value of 374 pg/mL, sTREM-1 yielded a sensitivity of 93.8% and a specificity of 90.9 in differentiating tuberculous pleuritis from bacterial pleural effusion. Conclusion: Soluble and surface TREM-1 are valuable markers in establishing the aetiology of pleural effusions.