This difference is caused by increased CD19+CD138- mature B cells, which are increased in bout-onset MS compared to PPMS (p<0.05) and OND (p<0.001) and CD19+CD138+ plasma blasts, which are increased in bout-onset MS (p<0.001) and PPMS (p<0.05) compared to OND. Here, CD19 is linked to myeloid sarcoma.