Expansion of regulatory CD4 T cells (Foxp3+CD25hi, CD25hiCD127lo) has been reported in AHSCT trials in MS, SSc, SLE, and T1D (6, 7, 12–14); however, an equivalent phenotype was not analyzed when this “real-time” flow analysis was initiated at the start of the HALT-MS trial. The gene discussed is CD4; the disease is myeloid sarcoma.