Dendritic cells transfected with a polyepitope DNA construct stimulate an antitumor cytotoxic response in various tumors.

Dendritic cells (DCs) loaded with tumor-associated antigens (TAAs) are known to be crucial for the antitumor response and are still included in various treatment regimens in cancer immunotherapy research. In the present study, a cell-based protocol was evaluated, involving the use of original DNA constructs encoding the wide range of TAA epitopes expressed on different epithelial cancers. The constructs were transfected into in vitro-generated DCs of patients with various types of cancer, including breast, colorectal and non-small cell lung cancer. The direct cytotoxicity assay of effector cells, activated with the transfected DCs, revealed a significant increase in cytotoxicity against autologous tumor cells. The use of DNA constructs encoding a large number of TAAs for insertion into DCs in vitro, aiming to activate a T-cell response may prove to be a reliable and unified approach for immunotherapy and for the prevention of relapse in patients with epithelial cancers.

Comparison of CD4+CD25hiFoxP3+ Treg Induction by pIL-10-Transfected Dendritic Cells in Different Mouse Strains.

Tolerogenic dendritic cells (tolDCs) and T-regulatory cells (Tregs) are involved in maintaining tolerance to self-antigens and foreign antigens. The cells are used as therapeutic tools for inducing tolerance to transplanted organs or tissues. We investigated the possibility of inducing Tregs in splenocyte cultures using DCs transfected with a DNA construct encoding mouse interleukin-10 (DCpIL-10). DCs were derived from bone marrow cells in the presence of rmGM-CSF and rmIL-4 and electroporated with a plasmid encoding mouse IL-10. Furthermore, DCpIL-10 was cocultured with syngeneic splenocytes. The CD4+CD25hiFoxP3+ Treg frequency, IL-10 expression, and inhibition of the mixed lymphocyte reaction were evaluated. C57Bl/6 and CBA mice differ in their initial frequency of CD4+CD25hiFoxP3+ Tregs and baseline IL-10 production. Also, the effectiveness of CD4+CD25hiFoxP3+ Treg upregulation by tolDCpIL-10 was different. In this study, DCpIL-10 from C57Bl/6 mice induced CD4+CD25hiFoxP3+ Tregs in syngenic splenocytes, which was accompanied by an increase in the IL-10 production and a decrease in the proliferation of splenocytes in response to the alloantigen. DCpIL-10 may be used to induce CD4+CD25hiFoxP3+ Tregs and the regulatory potential of splenocytes.

Use of antigen-primed dendritic cells for inducing antitumor immune responses in vitro in patients with non-small cell lung cancer.

Cancer is associated with a reduction in immature and mature circulating dendritic cells (DCs), and with an impaired migratory capacity, compared with healthy donors. Therefore, modern approaches to the in vitro generation of DCs loaded with tumor antigens and their use for inducing antitumor immune responses in vivo are being investigated. The purpose of the present study was to investigate the phenotypic and functional characteristics of peripheral blood DC subsets in patients with non-small cell lung cancer (NSCLC), and the development of an antitumor cytotoxic response by mononuclear cells (MNCs) from patients using in vitro generated antigen-primed DCs. Heparinized peripheral venous blood samples were obtained from 10 healthy donors and 20 patients with a histologically verified diagnosis of NSCLC. The ability of antigen-activated DCs to stimulate the activity of MNCs against autologous tumor cells was evaluated using a cytotoxic test. Peripheral blood DC subsets from patients with NSCLC were identified to be decreased and to exhibit an impaired ability to mature, compared with healthy donors. Furthermore, DCs generated from MNCs from patients with NSCLC were able to stimulate a specific cytotoxic response when loaded with autologous tumor lysates or RNA and matured, in vitro. A perforin and granzyme B-dependent mode of cytotoxicity was primarily induced. The ability of DCs loaded with tumor antigens to increase the cytotoxic activity of MNCs against NSCLC cells in vitro indicates the effective induction and co-stimulation of T lymphocytes by the generated DCs.

Modern strategies and capabilities for activation of the immune response against tumor cells.

Dendritic cells are professional antigen-presenting cells and the most potent stimulators of various immune responses, such as antitumor responses. Modern studies have not shown an effective antitumor immune response development in patients with malignant tumors. The major cause is the decrease in functional activity of dendritic cells in cancer patients through irregularities in the maturation process to a functionally active form and in the antigen presentation process to naive T lymphocytes. This review describes the main stages of cellular antitumor immune response induction in vitro, aimed at resolving the problems that are blocking the full functioning of dendritic cells, and additional stimulation of antitumor immune response.