Serial anti-tuberculous immune responses during the follow-up of patients with tuberculous pleurisy

Little is known about the decay kinetics of interferon (IFN)-gamma response and its influencing factors in tuberculous pleurisy. We enrolled thirty-two patients with tuberculous pleurisy prospectively and followed up at month 0, 6, and 9, at which time peripheral venous blood was drawn for interferon gamma release assay (IGRA) by means of QuantiFERON-TB Gold In-Tube (QFT-GIT). Demographic and clinical data were captured. To identify significant predictive factors influencing the IFN-gamma response, multiple linear regression analyses were performed. Percentage of CD4+, CD8+, Vgamma2Vdelta2 T cells and Treg cells were measured by flow cytometry. The percentage of QFT-GIT-positive patients at baseline, month 6 and month 9 were 96.9% (30/32), 90.6% (29/32) and 84.4% (27/32), respectively. Quantitative IFN-gamma response at baseline were significantly correlated with symptom duration (P = .003, R = 0.261) and age (P = .041, R = 0.132). Besides, the decreases of the IFN-gamma response at month 6 and month 9 were positively correlated with the IFN-gamma level at baseline. The dynamic tendency of the percentages of Treg cells was similar to the IFN-gamma responses at each time-point. Quantitative IFN-gamma response could be influenced by host immune status, instead of disease burden and anti-tuberculosis treatment. IGRA is probably not a useful biomarker of treatment efficacy in tuberculous pleurisy.