Treatment of leukemic relapse following unrelated umbilical cord blood transplantation with interleukin-2: potential for augmenting graft-versus-leukemia and graft-versus-host effects with cytokines

In comparison to bone marrow, umbilical cord blood has decreased intrinsic immune responsiveness allowing transplantation across HLA barriers with low er rates of graft-versus-host disease, However, laboratory models have also suggested that cord blood may be extremely sensitive to stimulation by cyt okines, We report an adult recipient of an ex vivo expanded, HLA-mismatched , unrelated cord blood transplant who experienced a late extramedullary rel apse while still in hematologic remission. Despite demonstrating immune tol erance on minimal immunosuppressive agents, a brief course of intravenous i nterleukin-2 resulted in rapid, aggressive graft-versus-host and graft-vers us-leukemia reactions. This case highlights the potential of cytokine immun omodulation following cord blood transplantation, hut also suggests caution in stimulating these cells.