CD4 and myeloid sarcoma: Differential lymphocyte reconstitution after alemtuzumab treatment may be a biomarker for MS relapse, as patients with active disease showed an accelerated recovery of CD4+ cells (p = 0.001), with a difference in absolute CD4+ counts at 24 months (p = 0.009), while CD4+ counts <388 × 106 cells/mL predicted MRI stability [104].