CSF3 and multiple sclerosis: The only validated laboratory biomarker for multiple sclerosis diagnosis is the detection of oligoclonal immunoglobulin G (IgG) bands in the CSF3 that support a prominent role of humoral immunity in this disease.4 Moreover, the epidemiological role of the Epstein–Barr virus,5 the presence of B cells and antibody-secreting plasma cells in CNS demyelinated lesions and the efficacy of B cell-depleting treatments6 provide strong evidence for the involvement of B cells and antibodies in multiple sclerosis pathogenesis.7,8