The aims of the study were to determine and compare the concentration of CXCL13 in cerebrospinal fluid (CSF) of patients with Lyme neuroborreliosis (LNB) and various other neurological disorders applying a Luminex based assay and ELISA, and to find factors associated with CXCL13 concentration. CSF samples obtained from four clinically well-defined groups of patients (proven LNB, suspected LNB, tick-borne encephalitis (TBE), and aseptic meningitis/meningoencephalitis other than TBE) - 25 samples per group - were analyzed. The performance of the Luminex recomBead CXCL13 assay (Microgen, Neuried, Germany) and ELISA (Euroimmun, Lübeck, Germany) was assessed by receiver operating characteristics. CXCL13 cut-off values were presented as functions of CSF lymphocyte/monocyte counts. Demographic variables, CSF findings, and history of erythema migrans were assessed as possible predictors for CXCL13 CSF concentrations by a general linear model. The calculated cut-off values determined by the maximum of the Youden index were >131 pg/mL for recomBead and >259 pg/mL for the ELISA. RecomBead showed a sensitivity of 88% (68.8-97.5%) and a specificity of 94% (83.5-98.7%). For the ELISA the corresponding values were 84% (63.9-95.5%) and 98% (89.4-99.9%). The CXCL13 concentration positively correlated with CSF lymphocyte/monocyte count and Borrelia-specific intrathecal antibody index (p < 0.05). High CXCL13 concentrations were only found in the group with proven LNB. CXCL13 levels above cut-off value were established in some patients with viral meningitis/meningoencephalitis but were not detected in patients with suspected LNB without pleocytosis. Applying a linearized cut-off of the CXCL13 concentration in the CSF which is dependent on the CSF cell count is a novel approach in the laboratory diagnosis of LNB.
Keywords: Aseptic meningitis; CXCL13; Cerebrospinal fluid; Lyme neuroborreliosis; Tick-borne encephalitis; recomBead assay.
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