Abstract: Objective Investigate the effects of TLR agonists on the morphology and immunophenotype of DC loaded with CD34+leukemia cells. Providing a basis for studying the function of DC, and further explore the enhancement of immunogenicity of leukemia cells in vitro. Methods After signing the informed consent with the patient or the authorized person of the patient, the fresh bone marrow or anticoagulant blood was collected from the patients diagnosed as acute myeloid leukemia (excluding M3, according to FAB classification). The peripheral blood mononuclear cells (PBMC) of CD14 were obtained by density gradient centrifugation and immunomagnetic bead sorting. CD34+leukemia cells were separated by immunomagnetic beads and frozen for further study. DC was obtained in vitro and then DC was fused with apoptotic CD34+ leukemia cells. Different combinations of Toll-like receptor (TLR) agonist (TLR-3 agonist combined with TLR-9 agonist) were used to further mature DC to obtain functional DC, s cellular morphology and immunophenotype were observed. Results ① Under inverted microscope, mature DC cells became larger in volume, semi-suspended, irregular in shape, and had multiple spiny protuberances on the surface with typical morphological features of mature DC.② The expression of CD11c was increased and the expression of CD14 was down-regulated via flow cytometry detection, indicating the transformation of DC.③ Poly I:C combined with TLR9 agonist (CpG ODN) induced the maturation of DC loaded with CD34+ leukemia cells. The positive expression of CD11c, CD86 on the surface of DC was significantly higher than that of single drug group and blank control group, and DC maturation could be further enhanced in combined stimulation group. Thus, the anti-tumor effect was enhanced. Conclusion In this study, TLR3 agonists and TLR9 agonists have clinical application prospects as adjuvants for stimulating DC mature.

Key words: Dendritic cell, Acute myeloid leukemia, Immunotherapy, Toll like receptor 3, Toll like receptor 9