Efficient Activation of Autologous Tumor-specific T Cells: A Simple Coculture Technique of Autologous Dendritic Cells Compared to Established Cell Fusion Strategies in Primary Human Colorectal Carcinoma

Abstract

Different technologies have been employed to deliver the whole spectrum of tumor antigens (TAs) to dendritic cells (DCs) to be presented to T cells. These include whole tumor RNA-transfected DCs, preparations of DCs loaded with tumor-derived apoptotic bodies or tumor cell lysates, and DC tumor cell fusions. Early clinical trials have been conducted using such techniques. The presented study was aimed to revisit the necessity of tumor cell manipulation in DC-based immunotherapy strategies for colorectal carcinoma. We investigated a simple coculture method of autologous monocyte-derived DCs and human primary colorectal carcinoma (pCC) in comparison with 2 well-described cell fusion strategies for the efficacy of uptake, processing and presentation of TAs to autologous T cells. Before coculture or fusion, pCC had been cryopreserved without further manipulation. Fluorescence microscopy and flow cytometry analyses of fluorescent dye labeled cells were used for monitoring engulfment of pCC by DCs. The coculture procedure resulted in a double positive cell fraction of up to 22% and thus was comparable to that observed after cell fusion. More important, DCs after coculture with autologous pCC induced significant tumor-specific interferon-gamma-producing autologous T cells in the same number of patients as DC/pCC fusions. Furthermore, tumor-specific major histocompatibility complex class I restricted cytotoxic T lymphocytes were generated by stimulation with DCs cocultured with pCC. In prior studies for human carcinomas coculture techniques were described to be inferior. In contrast, our data strongly suggest that at least for human pCC and autologous DCs this simple coculture method is similarly efficient compared to established fusion techniques.

Efficacy of Dendritic Cells Matured Early with OK-432 (Picibanil®), Prostaglandin E2, and Interferon-α as a Vaccine for a Hormone Refractory Prostate Cancer Cell Line

“…Various methodological improvement, including a range of DC maturation stimulators, maturation times, techniques of tumor antigen loading to DCs, and treatment of tumor cells before tumor antigen loading, have been explored to achieve this aim. While the evidence obtained to date is controversial (6, 7), the efficacy of the fusion procedure is superior to that of the tumor lysate-stimulating method (8, 9). …”

Activation of autologous leukemia‐specific T cells in acute myeloid leukemia: monocyte‐derived dendritic cells cocultured with leukemic blasts compared with leukemia‐derived dendritic cells

“…In all investigated patients a high yield of MoDC could be generated from remission PBMC and these could be differentiated easily to a mature phenotype. To investigate the functional integrity of these remission MoDC we chose a simple coculture assay, recently characterized to be efficient in activating autologous tumor‐specific T cells (21). In all but one of the investigated patients leukemic blast‐specific T cells could be activated as demonstrated by IFN‐γ ELISPOT assays.…”

“…Culture conditions for antigen presentation were chosen to fulfill the criteria for a clinical applicable setting. In addition, the generation of leukemia‐specific antigen presentation was tested after simple coculture of leukemic blasts with DC, a strategy which we recently described to be efficient in activating autologous tumor‐specific T cells (21).…”

Immunologic Monitoring of Cellular Responses by Dendritic/Tumor Cell Fusion Vaccines

“…The efficacy of antitumor immunity induced by DC/tumor fusion vaccines has been demonstrated in murine models using melanoma [24–32], colorectal [17, 30, 31, 33–41], breast [42–47], esophageal [48], pancreatic [49, 50], hepatocellular [51–55], lung [22, 41, 56–59], renal cell [60] carcinoma, sarcoma [61–66], myeloma [67–74], mastocytoma [75], lymphoma [76], and neuroblastoma [77]. The fusion cells generated with human DC and tumor cell also have the ability to present multiple tumor antigens, thus increasing the frequency of responding T cells and maximizing antitumor immunity capable of killing tumor targets such as colon [78–84], gastric [85, 86], pancreatic [87], breast [47, 88–93], laryngeal [94], ovarian [95–97], lung [85, 98], prostate [99, 100], renal cell [101, 102], hepatocellular [103–105] carcinoma, leukemia [106–111], myeloma [112, 113], sarcoma [114, 115], melanoma [116–119], glioma [120], and plasmacytoma [121]. …”