After unblinding categorization of MS patients into active versus inactive groups, TNFα, TNFβ, IL-10, IL-12p40, and CHI3L1 (unadjusted p = 0.0096, 0.0032, 0.0072, 0.0004, and <0.0001, respectively) were significantly elevated in CSF of MS patients with active lesional activity (CELs > 1 or in clinical relapse) compared to patients with inactive lesional activity (CELs = 0 or not in clinical relapse). Here, CHI3L1 is linked to myeloid sarcoma.