Clinical immune responses in patients treated with prophylactic CD4+ DLI after HLA-DPB1–mismatched URD alloSCT. After a nonmyeloablative conditioning regimen consisting of fludarabine, busulfan, alemtuzumab, and rabbit-derived antithymocyte globulin, patients received a stem cell transplant graft depleted of T cells by in vitro incubation with alemtuzumab. Percentage of donor chimerism (-▪-) in BM (left, Y-axis), absolute numbers of CD3+CD4+ (-●-), and CD3+CD8+ (-○-) T cells (first right, Y-axis [black]) in PB and CMV-DNA (⁠⁠) (log copies/mL) (second right, Y-axis [gray]) after alloSCT for patient 1 (A) and patient 2 (B) are shown (supplemental Methods). Arrows indicate CD4+ DLI infusion. Asterisks and stars indicate the time of diagnosis of acute skin GVHD (21 and 16 days after CD4+ DLI for patients 1 and 2, respectively) and colonic GVHD (35 and 58 days after CD4+ DLI for patients 1 and 2, respectively). § indicates time of detection of CMV infection in colonic biopsy of patient 1 (133 days after CD4+ DLI). Both patients developed CMV reactivation within the first month after alloSCT, which was treated with antiviral drugs (valganciclovir). Both patients cleared CMV reactivation at 2 months after alloSCT but again experienced several episodes of CMV reactivations requiring antiviral treatment after CD4+ DLI. Longitudinal bars indicate duration of antiviral therapy. Patient 2 experienced 1 episode of Epstein-Barr virus reactivation (black bar), which was treated with Rituximab (anti-CD20 monoclonal antibody). The intensity and duration of systemic immunosuppressive treatment is indicated by longitudinal bars. CsA, cyclosporine; MMF, mycofenolate mofetil; PNL, prednisolone.