Infiltrating lymphocytes are a source of complement proteins in the subarachnoid space (Stahel et al., 1997) and the density of leptomeningeal infiltrates correlates closely with the degree of inflammation, demyelination, and neuro-axonal loss in the MS neocortex, cerebellum, and spinal cord (Magliozzi et al., 2007; Howell et al., 2011, 2015; Reali et al., 2020). This evidence concerns the gene VTN and myeloid sarcoma.