PURPOSE: TREM-1 is a recently described glycoprotein receptor of the immunoglobulin superfamily, which is expressed on cell membranes of granulocytes, monocytes, and a subset of macrophages. Engagement of TREM-1 has been reported to trigger synthesis of pro-inflammatory cytokines in response to microbes and play an important role in the innate immune response. A soluble form of TREM-1 (sTREM-1) is shed from the membranes of activated phagocytes. sTREM-1 has been shown to be a marker of infectious inflammation in models of sepsis and ventilator associated pneumonias. In the present study we investigated whether levels of sTREM-1 in pleural fluid would aid in the diagnosis of parapneumonic effusions.
METHODS: Pleural fluid from forty patients who had undergone a thoracentesis were included in the study. The etiology of the pleural effusions was as follows: Parapneumonic(n=10); Malignant(n=10); CHF(n=10); PostCABG(n=10). Pleural fluid was analyzed for RBC count, WBC count and differential, LDH, Protein and Glucose and categorized as exudate or transudate using Light's criteria. sTREM-1 assay was performed on these samples using quantitative sandwich ELISA.
RESULTS: 1)sTREM-1 levels were significantly higher in Parapneumonic effusions compared to other etiologies (p<0.001). For a cutoff value of 675 pg/ml, sTREM-1 had a sensitivity of 90% (95% confidence interval 55 to 99%); specificity of 87% (95% confidence interval 69 to 96%); positive likelihood ratio of 6.75; and negative likelihood ratio of 0.115.2) There was a significant correlation between total and absolute neutrophil counts and sTREM-1.3)There was no significant correlation between the lymphocyte count,LDH or protein and sTREM-1.
CONCLUSION: Levels of sTREM-1 are increased in parapneumonic effusions and may prove to be of diagnostic value. Whether the levels may help in distinguishing complicated from simple parapneumonic effusions needs further studies.
CLINICAL IMPLICATIONS: sTREM-1 may prove to be a diagnostic marker and aid in distinguishing parapneumonic effusions from other exudative pleural effusions.
DISCLOSURE: Faisal Bhutta, No Financial Disclosure Information; No Product/Research Disclosure Information