CD4 and myeloid sarcoma: In MS patients, Tecfidera alters the composition of peripheral blood leukocytes to promote anti-inflammatory conditions, reducing absolute numbers and percentages of CD8+ T cells, CD45RO+CD4+ memory T cells, Th1 (CXCR3+) and Th17 (CCR6+) CD4+ T cells, memory B cells, and CD16+ CD56low NK cells; and increasing percentages of CD45RA+CD4+ naïve T cells, Th2 (CCR3+) CD4+ T cells, regulatory B cells, and CD16loCD56bright NK cells19.