Dendritic cell (DCs) based cytotoxic T lymphocytes (CTLs) are commonly used in immunotherapy due to their specificity. The selection of appropriate cell origin and tumor antigen is the key point. The objective was to culture DCs and CTLs simultaneously from cord blood, and deliver antigen information using tumor derived exosomes.

Material and methods:
Exosomes were collected from the human promyelocytic leukemia cell line HL-60 using ultracentrifugation. Prepared DCs from adherent cord blood mononuclear cells (MNCs) using SCF, GM-CSF, and IN-4. TNF-α and microRNA removed tumor-exosome were used to induce DCs maturation. DCs matured in the presence of HL-60 cell membrane protein extract or no antigen were set as control. CTLs was cultured from non-adherent MNCs by adding IFN-γ, IL-15, SCF, FLT-3L, anti-CD3, anti-CD28 and IL-2. The CTLs were analyzed by flow cytometry, cytotoxicity experiments and ELISA.

DCs can be obtained from cord blood and express costimulatory molecules. After 15 days, the total number of the cells expanded 26.3 times, and more than 82% of the cells expressed CD3+CD8+ in the most amplified HL-60-Ex-DCs-CTL group. These CD3+CD8+ T cells generated by HL-60-Ex-DCs displayed specific cytotoxicity towards HL-60 and low lethality towards unrelated BALL-1 cells. ELISA results showed that the expressions of TNF-α and IFN-γ in HL-60-Ex-DCs or HL-60mPr-DCs activated CTLs were upregulated compared with the control group.

Cord blood CTLs generated by HL-60 derived exosome activated DCs displayed specific cytotoxicity towards HL-60 promyelocytic leukemia cells. Therefore cord blood and tumor derived exosomes provided a good source for adoptive immunotherapy.