Reduced CD27 expression on antigen-specific CD4+ T cells correlates with persistent active tuberculosis.

Objective: CD27, a member of the tumor necrosis factor receptor family, has important role in generation of T cell immunity. In this study, association of CD27 expression on mycobacterial antigen-specific CD4+ T cells with pulmonary tuberculosis (TB) was investigated.

Methods: Mycobacterial antigen-specific CD4+ T cells were identified based on CD154 expression and CD27 expression on antigen-specific CD4 T cells was analyzed by flow cytometry.

Results: Compared with tuberculin-positive controls, patients with bacterial culture-positive pulmonary TB had significantly reduced CD27 expression on antigen-specific CD4 T cells. The persistent active TB patients had much lower percentages of CD27+ antigen-specific CD4 T cells than culture-positive new TB patients (P=0.008) and healthy controls (P=0.005). Logistic regression analysis on frequencies of CD27-expressing antigen-specific CD4 T cells and TB patients' clinical characteristics indicated that low percentage of CD27+ antigen-specific CD4 T cells correlated significantly with persistent active tuberculosis (P=0.002, odds ratio=19.6).

Conclusions: It is concluded that frequency of CD27+ antigen-specific CD4 T cells could be used as an immunological marker for persistent active TB.