title: A prospective study on the role of CXCL13 in Lyme neuroborreliosis.
abstract: BACKGROUND
  The definite diagnosis of acute Lyme neuroborreliosis (LNB) requires detection of an increased Borrelia burgdorferi-specific antibody index (AI). The B burgdorferi AI, however, is negative in up to 20% of patients with early LNB and can remain elevated for years after adequate therapy; both of these factors can make the diagnosis difficult. Recent retrospective studies suggested the chemokine CXCL13 as a potential biomarker for LNB. To evaluate its diagnostic value, we conducted a prospective study.
  
  
  METHODS
  From March 2008 to August 2009, CSF and serum samples from all patients in whom a B burgdorferi-specific AI was requested (n=692) and CSF analysis revealed CSF pleocytosis (n=192) were included in the study. Because of the low number of patients with untreated LNB, 13 additional retrospectively selected samples of patients with untreated LNB were added. CXCL13 concentrations were measured by ELISA and receiver operating characteristic curves were generated.
  
  
  RESULTS
  CSF CXCL13 was highly elevated in all patients with untreated acute LNB (mean=15,149 pg/mL) compared with that in the patients without LNB (mean=247 pg/mL). At a cutoff of 1,229 pg/mL, the sensitivity of CXCL13 was 94.1%, which is higher than the AI (85.7%). Only 7 patients (5 with a CNS lymphoma and 2 with bacterial meningitis) had a CXCL13 level above the cutoff, resulting in a specificity equal to the AI of 96.1%.
  
  
  CONCLUSIONS
  CXCL13 shows high sensitivity and specificity for acute, untreated LNB. This novel marker appears to be helpful in clinically atypical cases and, in particular, in early stages of the disease when the B burgdorferi AI is (still) negative.
authors.affiliation: Department of Neurology, Klinikum Grosshadern, Ludwig-Maximilians-University, Munich, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Schmidt
authors.forename: A
authors.initials: A
authors.lastname: Plate
authors.forename: B
authors.initials: B
authors.lastname: Angele
authors.forename: H-W
authors.initials: HW
authors.lastname: Pfister
authors.forename: M
authors.initials: M
authors.lastname: Wick
authors.forename: U
authors.initials: U
authors.lastname: Koedel
authors.forename: T A
authors.initials: TA
authors.lastname: Rupprecht
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000906:Antibodies / Q000097:blood; D015415:Biomarkers / Q000134:cerebrospinal fluid; D025065:Borrelia burgdorferi / Q000276:immunology*; D054382:Chemokine CXCL13 / Q000134:cerebrospinal fluid*; D003937:Diagnosis, Differential; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D020852:Lyme Neuroborreliosis / Q000097:blood / Q000134:cerebrospinal fluid* / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012680:Sensitivity and Specificity
chemical_list: D000906:Antibodies; D015415:Biomarkers; C110663:CXCL13 protein, human; D054382:Chemokine CXCL13