Performance of peripheral blood T-SPOT.TB and cerebrospinal fluid interferon-γ in the diagnosis of tuberculous meningitis / 中华传染病杂志

ABSTRACT

Objective To evaluate the performance of peripheral blood T-SPOT.TB and cerebrospinal fluid (CSF) interferon (IFN)-γ detection in the diagnosis of tuberculous meningitis (TBM).Methods Among the 182 consecutive cases with suspected TBM in Huashan Hospital from March 2011 to March 2013,30 patients were included in the case group according to the latest diagnostic criteria of TBM.Thirty-nine patients diagnosed with non-tuberculous meningitis were included in the control group.T-SPOT.TB was employed to detect tuberculosis-specific IFN-γ-secreting T cells in the peripheral blood.And IFN-γ in CSF was detected simultaneously by enzyme-linked immunosorbent assay (ELISA) without antigen stimulation.The CSF was collected from 10 patients of TBM group after anti tuberculosis treatment for 4 weeks to observe the dynamic changes.The t-test was used for analysis of continuous variables with normal distribution and Kruskal-Wallis test was used for analysis of variables with abnormal distribution.Results ()f the 30 TBM cases,6 were confirmed cases and 24 were highly suspected cases.The control group was comprised of 12 viral encephalitis,16 suppurative meningitis and 11 cryptococcal meningitis.The positive rate of T-SPOT.TB was significantly higher in TBM group compared with control group (70％ vs 13％,x2 =12.15,P＜0.01).The mean concentration of CSF IFN γ of TBM group was 244.35 pg/mL,which was significantly higher than that of control group 9.48 pg/mL (Z=-4.646,P＜0.01).The CSF IFN-γ was significantly decreased after 4 weeks of treatment (271.02 pg/mL vs 81.36 pg/mL,Z=-3.099,P=0.002).The sensitivity and specificity of peripheral blood T-SPOT.TB in the diagnosis of TBM were 70％ and 87％,respectively.The area under the receiver operating characteristic (ROC) curve of CSF IFN-γ for TBM diagnosis was 0.819; the optimal cut-off point was 81.36 pg/mL; the corresponding sensitivity and specificity were 83 ％ and 85 ％,respectively.Conclusion Both the detection of peripheral blood T-SPOT.TB and CSF IFN-γ are of great importance for the diagnosis of TBM.Dynamic observation of CSF IFN-γ is important for disease monitoring.