CD19 and myeloid sarcoma: We next compared transmigration rates of total CD19+ B cells as well as of CD19+CD27+IgD- class-switched memory B cells and CD19+CD27- naive B cells isolated from blood samples of 18 untreated MS patients (n = 10 in acute relapse; n = 8 in clinical remission) and 15 age- and sex-matched HC.