Since CXCL13 is the ligand for the receptor CXCR5, and CXCR5 is primarily expressed by B cells, and since B cell depletion is a powerful therapy to decrease inflammatory events in MS, it is possible that the intrathecal production of CXCL13 functions to increase CNS inflammatory activity solely by recruiting B cells to the CNS. Here, CXCL13 is linked to myeloid sarcoma.