CXCL13 and myeloid sarcoma: By contrast, CSF concentrations of CXCL13 were clearly higher in patients with active disease in our study and in a previous study.10 The number of gadolinium contrast-enhancing lesions also correlated moderately with CSF concentrations of CXCL13 in another study.27 In the context of MS, the cellular source of CSF CXCL13 has convincingly been shown to be infiltrating monocytes/macrophages.6 The rapid normalization of CSF CXCL13 after AHSCT indicates that this process has halted.