Our research is devoted to understanding the mechanism of T cell immunity in mediating graft versus leukemia after allogeneic stem cell transplantation, and to understanding immune tolerance. We are focused on how T cells recognize and inhibit the growth of dysplastic and malignant hematopoietic progenitor cells, and we have identified some of the target molecules that are recognized on leukemia. We have translated our discoveries into the clinic by combining vaccination and adoptive cell therapy approaches, and then back into the laboratory by studying patients to determine how immune tolerance contributes to the outgrowth of leukemia after transplantation and immunotherapy. In a new approach, we have raised antibodies to T cell target antigens on leukemia, and these antibodies have activity against leukemia. We believe that novel therapeutic approaches can be developed that combine both humoral and cellular immunity, which could prove to be synergistic. Ultimately, by understanding leukemia immunity and how to elicit and control it, we hope to improve the outcome for patients and to gain insight into mechanisms of T cell immunity.