Lymphodepleting chemotherapy prior to DLI induces greater immune activation than does DLI alone and is manifested as more severe acute GVHD. The Cy/Flu/DLI cohort (n = 15) consisted of 14 matched sibling donors (93%) and one 5 of 6 mismatched HLA-A, -B, -DR (high-resolution typing) unrelated donor. The control cohort receiving DLI without chemotherapy (n = 63) consisted of 49 matched sibling donors (79%, P = NS), 1 single antigen mismatched sibling donor, and 13 unrelated donors (10 6/6 matched and 3 mismatched). GVHD (A-C) and overall survival (D) are shown for patients who received Cy/Flu/DLI compared with those receiving DLI alone for all patients (A-B) or for those patients with non-CML diseases only (n = 35, C-D).