CD19 and myeloid sarcoma: We next characterized naive CD8+ T cells in peripheral blood from 4 patient cohorts: (a) healthy control subjects, (b) patients who received anti-CD19 CAR T cell therapy (37) for the treatment of B cell malignancies, (c) patients with multiple sclerosis (MS) who received an α4 integrin inhibitor (natalizumab), as a control for MS disease per se, and (d) patients with MS who received B cell–depleting antibody (rituximab or ocrelizumab; Supplemental Table 1).