Dendritic Cell Production From Allogeneic Donor CD34+ Stem Cells and Mononuclear Cells for Patients With AML: Cancer Vaccine

Abstract

Background: Active immunotherapy provides better recognition of tumor-related antigens by immune system of patient, enhanced immune system and elimination of malignant cells. This modality employs therapeutic potential of donor specific and tumor specific immune responses. Active immunotherapy targets immunosuppressive and tolerogenic mechanisms suppressed by tumor cells. Aim: T lymphocytes and antigen-presenting cells (dendritic cells) are 2 cell lineages that play crucial role in the battle of organism against cancer. Close similarity between cancer cells and normal cell structure is the most important reason of escape from defense cells, namely T lymphocytes. Stimulation and enhancement of T lymphocytes against cancer cells comprise principal part of therapy. Methods: To generate allogeneic dendritic cells, leukemic stem cells were isolated from bone marrow samples from patients with acute leukemia. Lysate was prepared from leukemic stem cells identified by flow cytometer. Stem cells and mononuclear cells (1 × 10 > 6/kg) obtained from sibling donors by apheresis were separated to produce dendritic cells. For dendritic cell transformation, GM-CSF and IL-4 were added to media where leukemic stem cell lysate from patient and mononuclear cells from sibling donor were treated. From samples taken from the culture medium, after 48, 72 and 96 hours, dendritic cell surface markers (CD80, CD83 and CD86) was assessed by flow cytometry. CD3, CD14, CD19, CD56, CD66b-negative, and HLA-DR, CD86 positive are indicative of immature DC. HLA-DR, CD80 and CD83 positive are indicative of mature DC. Results: Mononuclear cells were detected by 27% among allogeneic hematopoietic cell groups harvested by apheresis. After culture under GMP conditions, mononuclear cell rate was found to be 24% on hours 96 and 120. It was seen that 88% of mononuclear cells transformed to mature dendritic cells after 96 hours culture. Conclusion: In cancer patients, minimal residual disease can be eliminated by active tumor vaccine after reducing tumor burden by standard methods. Tumor vaccine obtained from allogeneic sibling donor can be used in lieu of autologous tumor vaccine and it is thought to be more effective. Allogeneic dendritic cells produced at 37°C in CO2 media under GMP conditions can be used in tumor immunotherapy. More effective method would have been used by employing dendritic cells against cancer stem cells rather than cancer cells itself.

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“…Additional sources of DCs have stemmed from advancements in ex vivo DC derivation. CD34 + hematopoietic stem progenitor cells (HSPCs) from bone marrow and umbilical cord blood can now be used as a DC source material [47,48]. Indeed, HSPCs incubated in a cytokine cocktail of FLT3L, thrombopoietin (TO), and stem cell factor (SCF) can produce APCs with a primary DC phenotype distinct from MoDCs, capable of inducing more robust anti-tumour T cell responses [49,50].…”