This Program Project Grant (PPG) seeks continued support for basic and translational clinical studies in the setting of hematopoietic cell transplantation (HCT). These studies serve as a paradigm for cellular therapeutics and the exploration of immune function for the treatment of cancer. The PPG is composed of five interactive Projects and four Cores focused on the themes of graft vs host disease biology and prevention, disease relapse treatment and prevention and immune reconstitution. The Program utilizes innovative animal modeling, imaging, molecular biological assessment of immunoglobulin and T cell receptor sequencing and novel clinical trial interventional studies with highly purified cell populations to explore the fundamental aspects of transplantation biology and improve outcomes for patients undergoing both autologous and allogeneic HCT. The Projects focus on different aspects of immune effector (conventional and memory CD4+ and CD8+ T cells, cytokine induced killer cells) and regulatory (Treg, NK-T) cell biology, vaccination strategies (CpG stimulated cancer cells), common lymphoid progenitor cell biology and immune recovery in a highly interactive and complementary fashion. In each of the Projects both fundamental biological explorations in animal models and clinical translation in phase 1/11 trials are proposed aimed at enhancing the clinical efficacy of HCT. The Projects and Project leaders are highly interactive using similar animal models, imaging strategies, novel approaches to analysis of T cell receptor sequencing to analyze distinct yet iterative approaches to answer fundamental biological questions and explore translation to the clinic. The four Cores provide administrative, clinical trial, molecular, sample distribution and cellular manufacture support. Ou hypothesis is that through the study of the cellular components of hematopoietic and immunological progenitor, regulatory and effector cells will result in novel insights into improvin immune function resulting in more effective therapy for patients with serious hematological malignancies.