CD8A and myeloid sarcoma: Our speculation that these cells transition from the blood into the CNS as part of active CNS inflammation is supported by several previous observations, including pathology studies reporting that active MS brain lesions contain increased numbers of CD8+ T cells characterized as tissue-resident memory CD8+ T cells or mucosal-associated invariant T (MAIT) cells (54, , , , –59), and enriched for CD20-expressing T cells (54, 60).