Analysis of a chronic myelogenous leukemia patient vaccinated with leukemic dendritic cells following autologous peripheral blood stem cell transplantation.

Dendritic cells (DCs) are believed to be the most potent antigen-presenting cells and may be important in the induction of anti-leukemia specific T cell responses. In this preliminary clinical study, a patient with chronic phase chronic myelogenous leukemia (CML) was vaccinated with autologous leukemic DCs following autologous peripheral blood stem cell transplantation (PBSCT). In an in vitro study, leukemic DCs were generated using granulocyte-macrophage colony-stimulating factor (GM-CSF), tumor necrosis factor-alpha, and interleukin-4 from granulocyte colony-stimulating factor (G-CSF)-mobilized PBSC fraction of this patient, and were found to be Ph1+, and to possess the morphologic and phenotypic characteristics of mature DCs. These cells could also elicit antigen specific immune responses, including a vigorous cytotoxicity specific to CML cells. In the clinical experiment, we obtained evidence that infused leukemic DCs could induce T cell clones expressing the same T cell receptor usage as a cytotoxic T cell line, suggesting that the immune repertoire includes tumor-reactive T cells. These cytotoxic T lymphocytes are activated in vivo. The vaccination of leukemic DC caused a decrease in the number of Ph1+ cells in the peripheral blood and bone marrow. These results indicate that the activity is an immunologically mediated phenomenon and vaccination therapy with leukemic DC following autologous PBSCT may be effective in treating CML.