In their multicenter cohort study, 81 PPMS patients who were either MRZR-positive or MRZR-negative underwent measurements of CXCL-13 (chemokine CXC ligand 13), BAFF (B cell-activating factor), sBCMA (soluble B cell maturation antigen), CHI3L1 (chitinase-3-like protein 1) in the CSF using ELISA kits and sTACI (transmembrane activator and CAML interactor). Here, CXCL13 is linked to primary progressive multiple sclerosis.