CXCL13 and syphilis: We 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).