Dendritic cells (DCs) and leukemia-derived DC (DC_leu) are potent stimulators of various immunoreactive cells and they play a pivotal role in the (re-) activation of the immune system. As a potential treatment tool for patients with acute myeloid leukemia, we developed and analyzed two new PGE₁-containing protocols (Pici-_PGE1, Kit M) to generate DC/DC_leu ex vivo from leukemic peripheral blood mononuclear cells (PBMCs) or directly from leukemic whole blood (WB) to simulate physiological conditions. Pici-_PGE1 generated significantly higher amounts of DCs from leukemic and healthy PBMCs when compared to control and comparable amounts as the already established protocol Pici-_PGE2. The proportions of sufficient DC-generation were even higher after DC/DC_leu-generation with Pici-_PGE1. With Kits, it was possible to generate DCs and DC_leu directly from leukemic and healthy WB without induction of blast proliferation. The average amounts of generated DCs and DC_leu-subgroups were comparable with all Kits. The PGE₁ containing Kit M generated significantly higher amounts of mature DCs when compared to the PGE₂-containing Kit K and increased the anti-leukemic-activity. In summary PGE₁-containing protocols were suitable for generating DC/DC_leu from PBMCs as well as from WB, which reliably (re-) activated immunoreactive cells, improved the overall ex vivo anti-leukemic activity, and influenced cytokine-release-profiles.

Integrin beta 7 (β7), a subunit of the integrin receptor, is expressed on the surface of immune cells and mediates cell–cell adhesions and interactions, e.g., antitumor or autoimmune reactions. Here, we analyzed, whether the stimulation of immune cells by dendritic cells (of leukemic derivation in AML patients or of monocyte derivation in healthy donors) leads to increased/leukemia-specific β7 expression in immune cells after T-cell-enriched mixed lymphocyte culture—finally leading to improved antileukemic cytotoxicity. Healthy, as well as AML and MDS patients’ whole blood (WB) was treated with Kit-M (granulocyte–macrophage colony-stimulating factor (GM-CSF) + prostaglandin E1 (PGE1)) or Kit-I (GM-CSF + Picibanil) in order to generate DCs (DC_leu or monocyte-derived DC), which were then used as stimulator cells in MLC. To quantify antigen/leukemia-specific/antileukemic functionality, a degranulation assay (DEG), an intracellular cytokine assay (INTCYT) and a cytotoxicity fluorolysis assay (CTX) were used. (Leukemia-specific) cell subtypes were quantified via flow cytometry. The Kit treatment of WB (compared to the control) resulted in the generation of DC/DC_leu, which induced increased activation of innate and adaptive cells after MLC. Kit-pretreated WB (vs. the control) led to significantly increased frequencies of β7-expressing T-cells, degranulating and intracellular cytokine-producing β7-expressing immune cells and, in patients’ samples, increased blast lysis. Positive correlations were found between the Kit-M-mediated improvement of blast lysis (vs. the control) and frequencies of β7-expressing T-cells. Our findings indicate that DC-based immune therapies might be able to specifically activate the immune system against blasts going along with increased frequencies of (leukemia-specific) β7-expressing immune cells. Furthermore, β7 might qualify as a predictor for the efficiency and the success of AML and/or MDS therapies.

Hypoxia can modulate the immune system by affecting the function and activity of immune cells, potentially leading to altered immune responses. This study investigated the generation of leukemia-derived dendritic cells (DC_leu) from leukemic blasts and their impact on immune cell activation under hypoxic (5–10% O₂) compared to normoxic (21% O₂) conditions using various immunomodulatory Kits. The results revealed that DC/DC_leu-generation was similar under hypoxic and normoxic conditions, with no significant differences observed in frequencies of generated DC/DC_leu. Furthermore, the study showed that the activation of immune cells and their anti-leukemic activity improved when T cell-enriched immunoreactive cells were co-cultured with DC/DC_leu which were generated with Kit I and M compared to the control after mixed lymphocyte cultures. The anti-leukemic activity was improved under hypoxic compared to normoxic conditions after MLC^{WB-DC Kit M}. These findings suggest that DC/DC_leu-cultures of leukemic whole blood with Kits under hypoxic conditions yield comparable frequencies of DC/DC_leu and can even increase the anti-leukemic activity compared to normoxic conditions. Overall, this research highlights the potential of utilizing DC/DC_leu (potentially induced in vivo with Kits) as a promising approach to enhance immune response in patients with acute myeloid leukemia.

T-cell receptor gamma delta (TCR gamma delta) expressing T-cells are known to mediate an MHC-independent immune response and could therefore qualify for immune therapies. We examined the influence of dendritic cells(DC)/antigen presenting cell (APC) generated from blast-containing whole blood (WB) samples from AML and MDS patients on the provision of (leukemia-specific) TCR gamma delta expressing T-cells after mixed lymphocyte culture (MLC). Kit-M (granulocyte-macrophage colony-stimulating factor (GM-CSF) + prostaglandin E1 (PGE1)) or Kit-I (GM-CSF + Picibanil) were used to generate leukemia derived APC/DC (DCleu)from WB, which were subsequently used to stimulate T-cell enriched MLC. Immune cell composition and functionality were analysed using degranulation- (DEG), intracellular cytokine- (INTCYT) and cytotoxicity fluorolysis- (CTX) assays. Flow cytometry was used for cell quantification. We found increased frequencies of APCs/DCs and their subtypes after Kit-treatment of healthy and patients WB compared to control, as well as an increased stimulation and activation of several types of immune reactive cells after MLC. Higher frequencies of TCR gamma delta expressing leukemia-specific degranulation and intracellularly cytokine producing T-cells were found. The effect of Kit-M-treatment on frequencies of TCR gamma delta expressing cells and their degranulation could be correlated with the Kit-M-mediated blast lysis compared to control. We also found higher frequencies of TCR gamma delta expressing T-cells in AML patients samples with an achieved remission (compared to blast persistence) after induction chemotherapy. This might point to APC/DC-mediated effects resulting in the provision of leukemia-specific TCR gamma delta expressing T-cells: Moreover a quantification of TCR gamma delta expressing T-cells might contribute to predict prognosis of AML/MDS patients.