A Rapid, Novel Strategy to Induce Tumor Cell–Specific Cytotoxic T Lymphocyte Responses Using Instant Dendritomas

Abstract

The generation of fused cells between dendritic cells (DC) and tumor cells is a very effective approach for tumor antigen presentation in cancer immunotherapy. However, the application of this approach in clinical studies is limited by the need for established tumor cell lines and the time-consuming procedures for selecting and expanding the fused cells. In the current study, the authors report a rapid, novel approach to produce fused cells between DCs and primary tumor cells from patients with malignant melanoma. Peripheral blood DCs and a primary tumor cell culture were generated from the same patients, labeled with fluorescent green and red dyes, respectively, and fused. The fused cells were isolated by fluorescence-activated cell sorting. Because the fused cells do not need to be expanded, these cell hybrids have been named instant dendritomas. Fluorescence-activated cell sorting analysis showed that instant dendritomas express the key molecules for antigen presentation (HLA-A, B, C; HLA-DR; CD80; and CD86). In vitro studies have shown that instant dendritomas effectively activated autologous CD8+ T lymphocytes to proliferate and secret interferon-gamma. More importantly, the activated CD8+ T lymphocytes effectively lysed the patients' primary tumor cells. This approach represents a practical clinical strategy for cancer immunotherapy.

Antitumor immunopreventive and immunotherapeutic effect in mice induced by hybrid vaccine of dendritic cells and hepatocarcinomain vivo

“…Hybrid vaccine could express some DC characteristics such as membrane molecule MHC-I, II molecule and costimulator, secrete some cell factors which can stimulate the T cell expansion, capture and present endogenous tumor associated antigens derived form parents H 22 cells, so it can efficiently stimulate the immune response [21][22][23][24][25] . There were similar results in other research reports on hybrid vaccines of DC with MC38, NS1, B16 melanoma, RMA-s lymphpma and renal carcinoma [26][27][28][29][30][31][32][33][34][35] . Mice immunized by hybrid vaccine could induce the tumor specific memory T cells, which could quickly be activated and expanded when they contact with tumor antigen again.…”

New strategy for efficient selection of dendritic cell-tumor hybrids and clonal heterogeneity of resulting hybrids

“…For example, DC-tumor hybrids have been purified from nonfused cells and homotypic hybrids based on distinct adhesive properties 11,12,16,22 d or by FACS-or magnetic-based purification after staining with antibodies against DC-specific and/or tumor-specific markers 13,16,18 or following preloading parental cells with different fluorescence dyes. 15,23 These methods, however, fail to distinguish heterotypic DC-tumor hybrids from aggregates of DC and tumor cells or from DC that have incorporated the fluorescence dye leaked from dying tumor cells. Serious doubts have been raised as to the identity of DC-tumor hybrid preparations used in an early clinical trial, 19 leading to the recent retraction of the corresponding publication.…”

“…17,19,21 Several attempts have been made in other studies to purify the DC-tumor hybrid populations based on adhesiveness 11,12,16,22 or by flow cytometric sorting following immunofluorescence staining or preloading with different fluorescence dyes. 13,15,16,18,23 These methods, however, can be problematic because of unavoidable leakage of fluorescence dyes from one cell type to the other and due to technical difficulty to distinguish DC-tumor cell aggregates from the genuine hybrids. Considering the cytotoxic nature of the cell fusion procedures, we predict further that the hybrid preparations may contain DC that have incorporated tumor cell-derived debris.…”

Novel dendritic cell-based vaccination in late stage melanoma

“…Therefore, we developed a novel technique by which hybrid cells can be easily purified from a fusion mixture, instantly and without culture. 61 Hybrid cells are instantly purified from these fusions between DCs and tumor cells. This process allows these dendritomas to retain the characteristics of the tumor cell as well as the ability of the DC to act as an effective APC.…”