To address whether B-cell maturation is different in the MS brain, we compared the ratios of ex vivo ASCs (CD45+CD19+CD3−CD38highCD27high) and B cells (CD45+CD19+CD3−CD38dim/−) within the viable lymphocyte gate between single cell suspensions from post-mortem blood, CSF, meninges and white matter compartments of 28 late-stage MS donors and 10 non-demented control (NDC) donors using multicolour flow cytometry (Fig. 1a). The gene discussed is PTPRC; the disease is myeloid sarcoma.