ABCB1 and myeloid sarcoma: In analyzing CSF cells defined solely by surface expression of CCR6 and CCR2, we found increases in percentages of expressing cells and/or levels of expression for a subset of pathogenicity-associated genes, including ABCB1, BHLHE40, CCR6 and CCR2, CCR5, CXCR6, KLRB1, LTB, and PDCD1, along with relatively high expression of the activation marker, CD69, in the CCR6+CCR2+ subgroup from the MS patients versus the non-MS control participants.