Generation of Leukaemia-Derived Dendritic Cells (DCleu) to Improve Anti-Leukaemic Activity in AML: Selection of the Most Efficient Response Modifier Combinations.

Dendritic cells (DC) and leukaemia derived DC (DCleu) are potent stimulators of anti-leukaemic activity in acute myeloid leukaemia (AML) and can be generated from mononuclear cells in vitro following standard DC/DCleu-generating protocols. With respect to future clinical applications though, DC/DCleu-generating protocols specifically designed for application in a whole-blood-(WB)-environment must be established. Therefore, we developed ten new DC/DCleu-generating protocols (kits; Kit-A/-C/-D/-E/-F/-G/-H/-I/-K/-M) for the generation of DC/DCleu from leukaemic WB, containing calcium-ionophore, granulocyte-macrophage-colony-stimulating-factor (GM-CSF), tumour-necrosis-factor-alpha, prostaglandin-E1 (PGE1), prostaglandin-E2 (PGE2) and/or picibanil (OK-432). All protocols were evaluated regarding their performance in generating DC/DCleu using refined classification and/or ranking systems; DC/DCleu were evaluated regarding their performance in stimulating anti-leukaemic activity using a cytotoxicity fluorolysis assay. Overall, we found the new kits capable to generate (mature) DC/DCleu from leukaemic WB. Through refined classification and ranking systems, we were able to select Kit-I (GM-CSF + OK-432), -K (GM-CSF + PGE2) and -M (GM-CSF + PGE1) as the most efficient kits in generating (mature) DC/DCleu, which are further competent to stimulate immunoreactive cells to show an improved anti-leukaemic cytotoxicity as well. This great performance of Kit-I, -K and -M in mediating DC/DCleu-based anti-leukaemic immunity in a WB-environment in vitro constitutes an important and directive step for translating DC/DCleu-based immunotherapy of AML into clinical application.

Immunomodulatory kits generating leukaemia derived dendritic cells do not induce blast proliferation ex vivo: IPO-38 as a novel marker to quantify proliferating blasts in acute myeloid leukaemia.

(Leukaemia derived) dendritic cells (DC, DCleu) are potent stimulators of anti-leukaemic activity in acute myeloid leukaemia (AML) and can be generated with immunomodulatory kits containing granulocyte-macrophage-colony-stimulating-factor (GM-CSF), prostaglandin-E1 (PGE1), prostaglandin-E2 (PGE2) and/or picibanil (OK-321). Potential adverse effects initiated through kits, especially the proliferation of blasts, must be ruled out to ensure treatment safety. We quantified proliferating blasts with the proliferation markers CD71 and Ki-67 and the novel proliferation marker IPO-38 before and after kit treatment ex vivo. IPO-38 hereby appeared to be the most sensitive marker; a combination with CD71 may add value when assessing proliferation kinetics. Kit treatment did not or only slightly (<5%) induce blast proliferation in most cases. An induction of blast proliferation was only found in single cases and could be compensated by DCleu-induced anti-leukaemic activity in most times. Overall, we appraise kit treatment to be safe in vivo.

Role of Interferon (IFN)α in "Cocktails" for the Generation of (Leukemia-derived) Dendritic Cells (DCleu) From Blasts in Blood From Patients (pts) With Acute Myeloid Leukemia (AML) and the Induction of Antileukemic Reactions.

Strategies to stabilize remissions by specific elimination of residual acute myeloid leukemia (AML) blasts are needed. Leukemia-derived dendritic cell (DCleu/DC) generated from myeloid blasts improve antileukemic T-cell reactivity and install T-cell memory. Interferon (IFN)α-DC methods produce DCleu from chronic myeloid leukemia-patients (pts') blood. Various INFα-containing versus other DC methods were studied to produce DCleu (evaluated by flowcytometry) from AML-pts' blast-containing mononuclear (MNC) or whole blood (WB). After DCleu/DC stimulation in mixed lymphocyte cultures, T cells' potential to gain antileukemic cytotoxicity was studied and correlated with different DC methods and DCleu/DC counts. (1) Generation of DCleu/DC: (a) "IFN-GIT" [containing granulocyte macrophage-colony stimulating factor (GM-CSF)+IFNα+ tumor necrosis factor (TNF)-α] produced DC successfully (≥10% DC, ≥5% DCleu/cells) from AML-MNC (WB) in 54 (56%), "MCM-Mimic" in 76 (75%), "Picibanil" in 83 (64%), and "Calcium-ionophore" in 42 (67%) of cases. Proportions of DC subtypes in MNC (WB) were comparable with all DC methods, (b) IFNα combinations containing only GM-CSF+IFNα or only IFNα showed low efficiency to produce DCleu/DC from MNC (WB) compared with "IFN-GIT." (2) Antileukemic functionality: DCleu/DC-stimulated T cells showed improved leukemia cytotoxicity compared with blast cells or unstimulated T cells. The highest blast proliferation (=insufficient T cells) was seen with "IFN-GIT" DC-stimulated T cells. Probability to respond to immunotherapy or to obtain blast lysis of DC-stimulated T cells correlated with high proportions of DCleu/DC after DC culture, independent of DC-generating methods. (3) Cytokine release profiles: levels of interleukin-6, IFN-γ, and interleukin-2 were significantly lower in DC culture supernatants (from MNC/WB) with "IFN-GIT" compared with "MCM," "Pici," and "Ca" DC supernatants. Our data show that (1) WB culture simulates AML-pts' in vivo situation, (2) DC generation is possible from AML-MNC (WB) with IFNα-containing and other DC methods, (3) successful IFNα-DC generation needs GM-CSF+IFNα+TNF-α (IFN-GIT); however, "IFN-GIT" produces less DCleu/DC compared with other (non-IFNα) DC methods, (4) T cells stimulated with "IFN-GIT"-produced DCleu/DC yielded comparable antileukemic cytotoxicity; however, in cases without achieved blast lysis, an increased blast proliferation was observed.

Paramunity-inducing Factors (PINDs) in dendritic cell (DC) cultures lead to impaired antileukemic functionality of DC-stimulated T-cells.

INTRODUCTION: Paramunity-inducing-Factors (PINDs) consist of attenuated/inactivated viruses of various poxvirus-genera, used in veterinary medicine as non-antigen-specific, non-immunising stimulators of the innate immune system against infectious and malignant diseases. Their danger-signaling-interactions were tested for their capacity to improve leukemic antigen-presentation on DC generated from AML-patients' blasts ('DCleu') and DC-stimulation/activation of antileukemic T-cells. METHODS: We analyzed, whether the addition of PINDs during DC cultures (15 healthy, 22 leukemic donors) and mixed lymphocyte culture (MLC, n = 15) with autologous (n = 6), allogeneic (n = 2) or T-cells after stem cell transplantation (SCT; n = 7) would alter the quality and quantity of DC, the composition of T-cell-subsets, and/or their antileukemic functionality (AF) as studied by FACS and functional Fluorolysis-cytotoxicity-assays. RESULTS: Effects on 1. DC-cultures: PINDs in DC-cultures lead to increased proportions of mature DC and DCleu, but reduced proportions of viable and overall, as well as TLR4- and TLR9-expressing DC. 2. MLC: PINDs increased early (CD8+) T-cell activation (CD69+), but reduced proportions of effector-T-cells after MLC 3. AF: Presence of PINDs in DC- and MLC-cultures reduced T-cells' as well as innate cells' antileukemic functionality. 4. Cytokine-release profile: Supernatants from PIND-treated DC- and MLC-cultures resembled an inhibitory microenvironment, correlating with impaired blast lysis. CONCLUSIONS: Our data shows that addition of PINDs to DC-cultures and MLC result in a "blast-protective-capacity" leading to impaired AF, likely due to changes in the composition of T-/innate effector cells and the induction of an inhibitory microenvironment. PINDs might be promising in treating infectious diseases, but cannot be recommended for the treatment of AML-patients due to their inhibitory influence on antileukemic functionality.