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 ce ll responses. In this preliminary clinical study, a patient with chronic ph ase chronic myelogenous leukemia (CML) was vaccinated with autologous leuke mic DCs following autologous peripheral blood stem cell transplantation (PB SCT), In an in vitro study, leukemic DCs were generated using granulocyte-m acrophage colony-stimulating factor (GM-CSF), tumor necrosis factor-alpha, and interleukin-4 from granulocyte colony-stimulating factor (G-CSF)-mobili zed PBSC fraction of this patient, and were found to be Ph1(+), and to poss ess the morphologic and phenotypic characteristics of mature DCs, These cel ls could also elicit antigen-specific immune responses, including a vigorou s cytotoxicity specific to CML cells. In the clinical experiment, we obtain ed 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 l ymphocytes are activated ill vivo. The vaccination of leukemic DC caused a decrease in the number of Ph1(+) cells in the peripheral blood and bone mar row These results indicate that the activity is an immunologically mediated phenomenon and vaccination therapy with leukemic DC following autologous P BSCT may be effective in treating CML.