We have previously reported that leukemic dendritic cells (DC) can be generated ex vivo from myelomonocytic precursors in chronic myelogenous leukemia. In this study we report the generation of DC from acute myelogenous leukemia (AML) cells and their potent ability to stimulate leukemia-specific cytolytic activity in autologous lymphocytes. DC were generated in vitro using granulocyte-macrophage colony-stimulating factor +interleukin-4 in combination with either tumor necrosis factor- or CD40 ligand (CD40L). Cells from 19 AML patients with a variety of chromosomal abnormalities were studied for their ability to generate DC. In all but 1 case, cells with the morphology, phenotypic characteristics, and T-cell stimulatory properties of DC could be generated. These cells expressed high levels of major histocompatibility complex class I and class II antigens as well as the costimulatory molecules B7-2 and ICAM-1. In three cases these cells were determined to be of leukemic origin by fluorescence in situ hybridization for chromosomal abnormalities or Western blotting for the inv(16) fusion gene product. Autologous lymphocytes cocultured with AML-derived DC (DC-AL) were able to lyse autologous leukemia targets, whereas little cytotoxicity was noted against autologous, normal cells obtained from the patients during remission. We conclude that leukemia derived DC may be useful for immunotherapy of many AML patients.

The success of adoptive immunotherapy for the treatment of leukemia depends on the generation of T cells that can specifically react with malignant cells. Dendritic cells (DCs) are important antigen-presenting cells in the development of antileukemic T-cell responses. In this study, we generated DCs from peripheral blood cells of patients with chronic myelogenous leukemia (CML). CML cells incubated concurrently with granulocyte-macrophage colony-stimulating factor, interleukin-4, and tumor necrosis factor-α in vitro developed morphologic and phenotypic characteristics of DCs. Fluorescence in situ hybridization showed the presence of t(9; 22) in the nuclei of these cells, indicating that they were leukemic in origin. These cells were potent stimulators of lymphocyte proliferation in specific in vitro assays for DC function. Autologous T cells stimulated with in vitro-generated, leukemic DCs displayed vigorous cytotoxic activity against CML cells but low reactivity to major histocompatability complex-matched normal bone marrow cells. Cytotoxic activity against CML targets was fourfold to sixfold higher using DC-stimulated autologous T cells than with autologous T cells expanded by culture with interleukin-2 alone. DC-stimulated T cells also inhibited growth of CML clonogenic precursors in colony-forming assays in vitro. These results suggest that cytokine-driven in vitro differentiation of CML cells results in generation of DCs with potent T-cell stimulatory function. In vitro-generated DCs can be effectively used as antigen-presenting cells for the ex vivo expansion of antileukemic T cells.

We used the fluorescence in situ hybridization (FISH) method to show that chromosome 7 trisomy is associated with the progression of human prostate cancer. Thirty-six specimens including 15 primary prostate carcinomas, 16 metastatic lesions, and 5 normal prostate tissues, as well as 2 prostate carcinoma cell lines of different tumorigenic potential, were examined for chromosome 7 aneuploidy. Our results showed that the androgen-unresponsive tumorigenic cell line PC-3 exhibited a significantly higher ratio of chromosome 7 to total chromosome number than the androgen-responsive nontumorigenic cell line LNCaP (P = 0.001). In prostate specimens, the frequency of trisomy 7 cells was significantly increased (P < 0.05) in the advanced stage tumors (C and DI) but not in the early (B) stage tumors or normal prostatic tissue. Furthermore, metastases showed a higher frequency of trisomy 7 cells than primary tumors (P = 0.005). In 2 patients with paired primary and metastatic tumors, trisomy 7 cells increased from 4-7% in the primary tumors to 42-45% in the metastatic tumor cells in the bone marrow. Therefore, our data suggest that trisomy 7 may be a common feature associated with local and metastatic progression and serve as a novel marker for human prostate cancer progression.

No abstract