Pulsing with Blast Cell Lysate or Blast-Derived Total RNA Reverses the Dendritic Cell-Mediated Increase in Cytotoxic Activity of Cytokine-Induced Killer Cells Against Human Allogeneic Acute Myelogenous Leukemia Cells.

Immunotherapeutic strategies may be a treatment option in patients with refractory acute myelogenous leukemia (AML) or, in cases of complete remission after conventional therapy regimens, may help to reduce disease recurrence or delay time to progression. Because evidence suggests a key role of dendritic cells (DCs) in cancer immunotherapy, we examined cytokine induced killer (CIK) cell responses in vitro after coincubation with autologous peripheral blood monocyte-derived DCs against three cell lines and allogeneic blasts from three patients with de novo AML. Although DCs were unable to enhance CIK cell effects against all three cell lines tested, the cytotoxic activity against the AML cells of the patients increased after coculture with mature DCs, which was significant in two of three patients. However, neither prior pulsing of the DCs with blast cell lysates nor with leukaemic cell-derived total RNA further enhanced the lytic capacity of the CIK cells. On the contrary, pulsing reduced the cytotoxic activity of the effector cells in a concentration-dependent manner. Because this decrease of allogeneic cytotoxicity was observed, we conclude that monocyte-derived DCs may be useful in autologous or allogeneic vaccine strategies for the treatment of AML or in priming donor lymphocytes in vitro, but unfractionated antigens as pulsing agents may have inhibitory effects on T cell efficiency and their employment in immunotherapeutic strategies for AML seems questionable.