Graft-versus-lymphoma effect of donor lymphocyte infusion in indolent lymphomas relapsed after allogeneic stem cell transplantation.

Donor lymphocyte infusions (DLI) are used to treat relapsed haematological diseases after allogeneic stem cell transplantation (SCT). We treated seven patients with DLI for indolent non-Hodgkin's lymphoma relapsed after SCT. In available blood and bone marrow samples, lymphoma cells were analysed by real-time quantitative polymerase chain reaction of t(14;18)-positive cells in follicular lymphoma, and by immunophenotyping in small lymphocytic lymphoma. Before DLI, three patients were treated with chemo- and/or radiotherapy, and one with rituximab. Evaluable responses to pre-DLI therapy were stable disease in one and partial remission (PR) in two patients. Six patients responded to DLI (complete remission (CR) in four and PR in two). After DLI, acute graft-versus-host disease (GVHD) occurred in 3/6 patients, classified as grade 2, whereas only limited chronic GVHD was seen (n=5). The four continuous CR are lasting for median 65+ (43-89) months. In the remaining patient, not responding to DLI, progressive disease was seen later on; chemotherapy followed by another DLI resulted in CR. In three cases, clinical responses to DLI could be substantiated by molecular or immunophenotypic analysis of lymphoma cells. We conclude that DLI is effective for treatment of indolent lymphoma relapsing after SCT.