The mechanisms underlying the increase of Th17 in CNS in neurosyphilis need to be further elucidated. Because Th17 response may induce the immune-mediated CNS injury, we further evaluated the relationship between IL-17 and the clinical outcome of neurosyphilis. Since longer time would be required to clear a higher number of T. pallidum burden, the likelihood of normalization of CSF VDRL reactivity at the end of the observation would be lower. Because the sample size is limited (the number of subjects included in the regression analyses was only ranged from 21 to 44 patients in this study), a large sample study is needed to further understanding the true immune response at different stages of neurosyphilis and its clinical significance. ...our findings demonstrate that neurological damage in syphilis patients is associated with increased CSF Th17/IL-17 response.