Positive interferon-gamma release assay results are correlated with paradoxical reaction in tuberculous meningitis

Background: Evidence suggests that T cell-based interferon-γ release assays (IGRAs) may be useful for the diagnosis of tuberculosis. The present study aims to investigate the clinical significance of blood T-SPOT.TB assay, a commercially available IGRAs, in tuberculous meningitis (TBM) patients. Methods: Records of consecutive TBM and non-TBM meningitis patients admitted from July 2011 to March 2016 at a tertiary hospital were retrospectively reviewed. Clinical and magnetic resonance (MR) findings, as well as T-SPOT.TB results were comprehensively assessed. Results: A total of 61 TBM patients and 85 non-TBM meningitis patients were enrolled. The sensitivity and specificity of T-SPOT.TB for TBM patients were 62.3% and 72.9%, respectively. Positive T-SPOT.TB results were related to diagnostic category (P=0.015), TB outside of the central nervous system (CNS) (P=0.002), active TB outside of CNS (P=0.009), hydrocephalus (P=0.039) and basal exudates (P=0.031) on MR, and paradoxical reaction to anti-tuberculosis drugs (P=0.032). The logistic regression analysis showed that TB outside of CNS was the only independent predictor for positive T-SPOT.TB (P=0.013). Conclusion: These results collectively indicate that blood T-SPOT.TB should be supplementary for the diagnosis of TBM, rather than serving as a single test to diagnose or exclude the disease. However, positive T-SPOT.TB results may reflect typical clinical and MR features of TBM. Moreover, positive results are associated with paradoxical reaction to treatment, which is related to immune status to tuberculosis infection. Thus, T-SPOT.TB results provide potentially useful information for the consideration of immune-modulating therapy.