Given the well-known problem with sensitivity of ELISAs for CXCL13 and the low levels of CXCL13 in the CSF in MS patients relative to LNB, we proceeded to attempt to develop a Luminex assay, the SinglePlex assay for CXCL13 available from Bio-Rad (Hercules, CA, USA) in the hope that we would achieve improved sensitivity. The gene discussed is CXCL13; the disease is myeloid sarcoma.