Abstract
We previously reported a method to expand human monocytes through lentivirus-mediated introduction of cMYC and BMI1, and we named the monocyte-derived proliferating cells, CD14-ML. CD14-ML differentiated into functional DC (CD14-ML-DC) upon addition of IL-4, resulting in the generation of a large number of DC. One drawback of this method was the extensive donor-dependent variation in proliferation efficiency. In the current study, we found that introduction of BCL2 or LYL1 along with cMYC and BMI1 was beneficial. Using the improved method, we obtained CD14-ML from all samples, regardless of whether the donors were healthy individuals or cancer patients. In vitro stimulation of peripheral blood T cells with CD14-ML-DC that were loaded with cancer antigen-derived peptides led to the establishment of CD4+ and CD8+ T cell lines that recognized the peptides. Since CD14-ML was propagated for more than 1 month, we could readily conduct genetic modification experiments. To generate CD14-ML-DC that expressed antigenic proteins, we introduced lentiviral antigen-expression vectors and subjected the cells to 2 weeks of culture for drug-selection and expansion. The resulting antigen-expressing CD14-ML-DC successfully induced CD8+ T cell lines that were reactive to CMVpp65 or MART1/MelanA, suggesting an application in vaccination therapy. Thus, this improved method enables the generation of a sufficient number of DC for vaccination therapy from a small amount of peripheral blood from cancer patients. Information on T cell epitopes is not necessary in vaccination with cancer antigen-expressing CD14-ML-DC; therefore, all patients, irrespective of HLA type, will benefit from anti-cancer therapy based on this technology.
Highlights
Vaccination therapies that use antigenic peptides, for example, those emulsified in adjuvant or loaded onto dendritic cells (DC), have been broadly used to treat cancer
The capacity of CD14-ML-DC to induce vigorous T cell proliferation and cancer antigen-specific T cells demonstrated in this study indicates a potential value in vaccination therapy
T cells reactive to CDCA1351-359, MART126-35, and IMP3515-523 were induced from peripheral blood CD8+ T cells from the healthy donor 2 that was positive for HLA-AÃ02:01 (Fig 4D and 4E). These results suggest that HLA class I-restricted peptide-loaded CD14-ML-DC were able to stimulate specific CD8+ T cells in autologous CD8+ T cell populations and induce their expansion in the same way as monocytederived DC (mo-DC)
Summary
Vaccination therapies that use antigenic peptides, for example, those emulsified in adjuvant or loaded onto dendritic cells (DC), have been broadly used to treat cancer. During the last two decades, considerable effort has been devoted to identifying cancer antigen-derived CTL epitopes that are restricted to the common alleles of HLA class I, such as HLA-AÃ02:01 [1,2,3,4]. Cancer patients who are negative for common types of HLA class I are excluded from most of the currently conducted vaccination therapies. HLA-AÃ02:01 is the most common class I allele worldwide, gene frequency of HLA-AÃ02:01 is at most 30% in most ethnic groups. A considerable number of patients cannot benefit from current vaccination therapies [1,2,3,4]. If HLA-B-restricted CTLs could be stimulated, the efficacy of anti-cancer vaccination therapies would be improved substantially
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