Dendritic cell (DC) vaccines for cancer immunotherapy have been actively developed to improve clinical efficacy. In our previous report, monocyte-derived DCs induced by interleukin (IL)-4 with a low-adherence dish (low-adherent IL-4-DCs: la-IL-4-DCs) improved the yield and viability, as well as relatively prolonged survival in vitro, compared to IL-4-DCs developed using an adherent culture protocol. However, la-IL-4-DCs exhibit remarkable cluster formation and display heterogeneous immature phenotypes. Therefore, cluster formation in la-IL-4-DCs needs to be optimized for the clinical development of DC vaccines. In this study, we examined the effects of cluster control in the generation of mature IL-4-DCs, using cell culture vessels and measuring spheroid formation, survival, cytokine secretion, and gene expression of IL-4-DCs. Mature IL-4-DCs in cell culture vessels (cluster-controlled IL-4-DCs: cc-IL-4-DCs) displayed increased levels of CD80, CD86, and CD40 compared with that of la-IL-4-DCs. cc-IL-4-DCs induced antigen-specific cytotoxic T lymphocytes (CTLs) with a human leukocyte antigen (HLA)-restricted melanoma antigen recognized by T cells 1 (MART-1) peptide. Additionally, cc-IL-4-DCs produced higher levels of IFN-γ, possessing the CTL induction. Furthermore, DNA microarrays revealed the upregulation of BCL2A1, a pro-survival gene. According to these findings, the cc-IL-4-DCs are useful for generating homogeneous and functional IL-4-DCs that would be expected to promote long-lasting effects in DC vaccines.
Keywords: BCL2A1; cluster control; cluster formation; dendritic cells; immunotherapy; vaccine.