PRF1 and myeloid sarcoma: In analyzing CITE-seq data of CD4+ T cells from the CSF of patients with MS and non-MS control participants, we found that pathogenicity-associated genes identified in EAE in mice, such as BHLHE40, TBX21, and IFNG, as well as a collection of CD8+ T cell-associated genes, including PRF1, granzyme genes, and CCL519,22,30–32, were differentially expressed in CCR6+CCR2+ cell-enriched UMAP clusters, some of which were expanded in the CSF of patients with MS.