Some investigators described an association between TNF CSF levels and MS activity, but this association was not reproduced by other authors.11,12 Interleukin 6 (IL-6)is another pro-inflammatory cytokine, and some studies showed a mild elevation of CSF IL-6 during MS exacerbations.13,14 Chemokine ligand 13 (CXCL13) is a B cell chemoattractant that participates in the formation of B cell follicles, which are important in MS pathophysiology. This evidence concerns the gene CXCL13 and myeloid sarcoma.