BackgroundChemokine ligand 13 (CXCL13) is believed to play a role in the recruitment of B cells in the central nervous system during neuroinflammation. Neurosyphilis is a group of clinical syndromes of the central nervous system caused by Treponema pallidum (T. pallidum) infection. The relationship between CXCL13 and neurosyphilis still needs further study. In our study, CSF and serum CXCL13 concentrations were detected among 40 neurosyphilis patients, 31 syphilis/non-neurosyphilis patients, 26 non-syphilis/other central nervous system diseases patients. Serum CXCL13 concentrations were detected in 49 healthy persons. All enrolled persons were HIV-negative. Receiver operating characteristic (ROC) analysis was performed to determine the threshold value that could distinguish neurosyphilis from syphilis.ResultsWe found that the CSF CXCL13 concentrations and CXCL13 quotient (QCXCL13) were significantly increased in neurosyphilis patients compared to syphilis/non-neurosyphilis (χ2 = 21.802, P < 0.001) and non-syphilis patients (χ2 = 7.677, P = 0.002). ROC curve analyses revealed that CSF CXCL13 concentrations and QCXCL13 could serve as valuable biomarkers for differentiating neurosyphilis from non-neurosyphilis/syphilis.ConclusionsThe CSF CXCL13 and QCXCL13 could serve as valuable biomarkers for differentiating neurosyphilis from non-neurosyphilis/syphilis in HIV-negative patients.