Acronym for "C-X-C motif chemokine 13". CXCL-13 is a 109 amino acid protein that acts as a chemoattractant (BLC) and a B cell-attracting chemokine 1 (BCA-1). CXCL13 belongs to the "Intercrine alpha family" also called "chemokine CXC". It acts chemotactically for B lymphocytes but not for T lymphocytes, monocytes and neutrophils and binds to BLR1/CXCR5. CXCL-13 labels follicular T cells. CXCL13 is considered a possible biomarker for systemic lupus erythematosus.
In recent years, it has been shown that the chemokine CXCL13 rises significantly in the CSF of almost all patients with acute neuroborreliosis, even before a specific antibody response is generated. Immediately after the start of antibiotic administration, the chemokine level drops again very quickly, long before the CSF pleocytosis regresses. Studies on patients with suspected neuroborreliosis showed sensitivities/specificities of 100%/99% and positive or negative predictive values of 88% and100%, so that the parameter can be helpful in unclear cases of very early neuroborreliosis (Lintner H et al. 2020). It should be noted that the CXCL13 value is not specific for neuroborreliosis; elevated CSF values have also been found in neurolues, tuberculous meningitis and CNS lymphomas. Furthermore, the determination - including cut-off - has not yet been generally standardized. The CXCL13 level in the CSF correlates with the "disease activity" of neuroborreliosis and can be diagnostically helpful in individual cases.