Differential T helper cell response in tuberculous pleuritis

Purpose: This study was conducted to understand the in vivo and in vitro immune responses and to find whether there exists any difference in the systemic and localized immune responses in tuberculous pleuritis.
Methods: The in vivo levels of IFN-γ and IL-4 were compared in plasma (BL) and pleural fluid (PF) of 47 tuberculous (TB) and 31 nontuberculous pleuritis (Non-TB) patients. In vitro cytokine response to various mycobacterial antigens was studied in 19 TB patients by ELISA . Both ex vivo and in vitro cytokine responses were further ascertained by intracellular cytokine staining on purified CD4⁺ T cells from pleural fluid mononuclear cells (PFMC) of 10 TB patients.
Results: The ex vivo results showed a significant increase in IFN-γ levels and higher IFN-γ ⁺ T cells in PF. On the other hand, in vitro results showed simultaneous increase in both IFN-γ and IL-4 levels in the supernatants of antigen stimulated PFMC. Similarly antigen specific increase was observed in both IFN-γ ⁺ and IL-4⁺ T cells in all cultured conditions. However, the percentile increase was more in IL-4 secreting T cells, significant for PPD stimulation ( P < 0.05), indicating that in vitro cellular response was dominated by Th2 type.
Conclusions: These results showed a differential T-helper response in TB pleuritis suggestive of predominant Th1 in vivo and mixed response (Th1 and Th2) under in vitro conditions.