Evaluation of the Triggering Receptor Expressed on Myeloid Cells-1 (TREM-1) as a Diagnostic Tool for Patients With Pleural Effusion

The triggering receptor expressed on myeloid cells-1 (TREM-1) is a member of the immunoglobulin superfamily, and its expression is upregulated on phagocytic cells in the presence of bacteria or fungi. Several experiments by Bouchon and colleagues showed that TREM-1 mediates the acute inflammatory response to microbial products. Human tissues infected with bacteria are infiltrated with neutrophils and macrophages that express high levels of TREM-1. Conversely, TREM-1 is only weakly expressed in samples from patients with noninfectious inflammatory disorders. In addition, TREM-1 is shed from the membrane of activated phagocytes and can be found in a soluble form in body fluids. The presence of a soluble form of TREM-1 in samples of bronchoalveolar lavage fluid from mechanically ventilated patients has been shown to be a good indicator of infectious pneumonia.