Several studies found alterations in naïve and memory B cells subsets in MS [9]: a higher percentage of naïve B cells expressing CD86 and CCR5 in untreated pwRRMS; increased levels of B cells expressing TNFα, IFNy, IL12 and IL6 in pwPPMS and reduced regulatory B cells expressing IL13, IL10 and TGFβ in pwPPMS compared to HC [26,27]. Here, IL13 is linked to myeloid sarcoma.