Investigation of CD14 with Toll-like Receptor Expression in Pleural Effusion for the Detection of Thoracic Disorders and Malignancies

Introduction: The accumulation of fluid in the pleural space indicates the presence of systemic orlocal disease. Pleural exudates (PE) contain immune cells and characterization of the cellularcomposition of such exudates may provide insight into the relevant pathophysiological mechanismsand the functional state of these cells. Tuberculosis and cancer represent the main causes of pleuralexudates. In both cases, the pleural fluid is generally lymphocytic, with a predominance of T-cells,particularly CD4-positive T-cells. The etiology of pleural effusions (PEs) varies, and a percentage ofPEs remains unexplained.Aim of Study: Our aim was to characterize the clinical and cytomorphologic features of TB andthoracic malignancy associated PEs, using flow cytometric analysis.Materials and Methods:15 PE samples were obtained from patients aged 25-65 years withsuspected TB (9 cases) or malignancy (6 cases) and 5 healthy control (HC) based on history, clinicaland laboratory evaluation. Cells were stained with CD3, CD4, CD8, CD14, CD19 and TLR-2, -4and -9 Abs labeled with various florochromes for 30 min and 10000 events counted by flowcytometry.Results: Increased numbers of CD14 cells with lower expression of TLR2, -4 and -9 were observedon the monocytes from malignant PEs in comparison with TB PE samples.CD4+, CD3+CD45RO+and CD20+CD25+ populations were lower in malignancy samples when compared to TB samples.In PEs from patients with confirmed pulmonary TB, high levels of IFN-g and CD3+, CD4+ andCD8+ cells with lower CD14+ levels were detected.Discussion:Flowcytometric evaluation of immune cells in PE shows differential numbers ofspecific immune cells with specific innate immune markers such as TLRs.This may be useful fordifferential diagnosis between malignancies and TB.