[CXCL13: a biomarker for acute Lyme neuroborreliosis: investigation of the predictive value in the clinical routine].

BACKGROUND

The level of CXCL13 is a cerebrospinal fluid (CSF) biomarker for acute Lyme neuroborreliosis (LNB) with a high sensitivity. As the concentration rapidly declines during antibiotic therapy CXCL13 can also be used as a follow-up parameter. However, CXCL13 is not yet in use as a routine parameter due to concerns about the specificity.

OBJECTIVES

The sensitivity, specificity and predictive value of CXCL13 in the clinical routine work-up of suspected LNB was analyzed.

MATERIAL AND METHODS

Since July 2010 the CSF of all patients (n = 204) with suspected acute LNB was not only analyzed for the routine parameters (i.e. pleocytosis and intrathecal production of Borrelia-specific antibodies, AI) but also for CXCL13. In cases of incongruent findings, a follow-up puncture after antibiotic therapy was carried out. The cut-off level for acute LNB was set at 250 pg/ml.

RESULTS

This study included 179 patients who were not pretreated with antibiotics. Of these patients 15 suffered from definite LNB, 3 had a probable LNB and all had a CXCL13 value above the cut-off level. Only 2 of the 161 patients with a non-LNB diagnosis (both with a lymphoma) had a CXCL13 value in the CSF higher than 250 pg/ml. Especially noteworthy were two patients without pleocytosis in the CSF but with CXCL13 levels above the cut-off level in whom LNB could be confirmed in the follow-up CSF analysis.

CONCLUSIONS

The biomarker CXCL13 has a higher sensitivity (100 % vs. 87 %) with a specificity (99 %) comparable with the established diagnostic markers for LNB, e.g. CSF pleocytosis and Borrelia-AI in the investigated patient population. The negative predictive value of CXCL13 is 100 %. Therefore, a normal CXCL13 level virtually excludes LNB. In the clinical routine CXCL13 is a valuable and practical diagnostic marker for LNB and can even detect an acute LNB in patients without CSF pleocytosis.