The chemokine CXCL13 is elevated in the cerebrospinal fluid of patients with neurosyphilis

BACKGROUND: The chemokine CXCL13 has been discussed as a diagnostic parameter with high specificity for Lyme neuroborreliosis (LNB) and as a marker of disease activity. Neurosyphilis and LNB share similar characteristics. We investigated retrospectively CXCL13 levels in the cerebrospinal fluid (CSF) of patients with neurosyphilis at initial diagnosis and during treatment. RESULTS: Five patients with neurosyphilis were identified retrospectively using an electronic database in a tertiary care hospital from 2005 to 2012. CXCL13 levels were measured using an ELISA. Five patients with definite LNB and 10 patients with multiple sclerosis (MS) served as controls. Median CXCL13 levels at baseline were 972 pg/mL for neurosyphilis patients, 8,000 pg/mL for LNB patients, and 7.8 pg/mL for MS patients. Patients with LNB and neurosyphilis showed significantly higher CXCL13 levels in their CSF compared to MS patients (p < 0.05, p < 0.001, respectively). CXCL13 levels in the CSF declined during treatment. CONCLUSION: CXCL13 levels in the CSF of patients with neurosyphilis can be as high as in patients with LNB, exceeding the proposed threshold of 250 pg/mL for the diagnosis of LNB. Patients with encephalitic/myelitic syndromes appear to have especially high levels of CXCL13. Clinicians should be aware that high levels of CXCL13 are not found exclusively in LNB but also in other infectious diseases of the CNS.