CD19 and myeloid sarcoma: On the other hand, our data partly contradict the significant decrease of CD19+ B cells in human PBMCs of MS patients receiving FTY720 [37–39] –partly because we still detected a significantly increased number of total B220+ B cells in the spleen, which suggests a B cell-specific effect of FTY720 although this effect might not have been visible to its full extent in the peripheral blood.