T Helper Cell Subsets in the Pleural Fluid of Tuberculous Patients Differentiate Patients With Non-Tuberculous Pleural Effusions

Background: Tuberculous pleural effusion (TPE) is one of the most common forms of extrapulmonary tuberculosis (Tb). Patients with TPE or malignant pleural effusions (MPE) frequently have a similar lymphocytic pleural fluid profile. Since the etiology of PE in various diseases is different, identifying the cellular components may provide diagnostic clues for the understanding pathogenesis. Objective: We determined the frequency of T helper (Th) subtypes in the PEs for differentiation of Tb and non-Tb patients. Methods: 30 patients with TPE, 30 patients with MPE, 14 patients with empyema (EMP) and 14 patients with parapneumonic effusion (PPE) were enrolled between Dec 2018- Dec 2019. 5 ml fresh PE in tubes containing heparin as an anticoagulant was obtained from patients. The frequency of CD4+IL-9+, CD4+IL-22+, CD+IL-17+ and regulatory T-cells CD4+CD25+ FOXP3+ (Treg) were determined by flow cytometry. Results: Treg cells have a lower frequency in TPE patients (4.2 (0.362-17.24) compared with non-TPE patients (26.3 (3.349 – 76.93, P<0.0001). The frequency of CD4+IL-9+ cells were significantly lower in TPE patients (3.67 (0.87 – 47.83) compared with non-TPE groups (13.05 (1.67 – 61.45), P<0.0001). On the contrary, there was no significant difference in the frequency CD4+IL-17+ and CD4+IL-22+ cells between TPE and non-TPE patients. (P=0.906 and P=0.2188). Conclusion: Treg cells and CD4+IL-9+ cells may differentiate TPE from non-TPE patients. However, these results need validation in an independent large cohort.