Upregulation of CXCR4 mRNA was also observed in white blood cells of individuals with MS with a relapsing-remitting disease course (RRMS; n=32) and a secondary chronic progressive disease course (SPMS; n=22), and compared to controls (n=25, ANOVA, RRMS and SPMS each P<0.05) (Fig. 3A, Tables S6 and S7). Here, CXCR4 is linked to myeloid sarcoma.