Minimal residual disease remaining after resection of primary tumors can lead to tumor recurrence and metastasis, increasing mortality and morbidity rates among cancer patients. Thus, there is a need for new technologies for recognition and elimination of single cancer cells remaining in a patient's body after radiation therapy, chemotherapy, or surgical resection. Effector CD8 + T cells, also commonly known as cytotoxic T lymphocytes (CTLs), play a key role in antitumor cellular immunity and, when properly activated, are able to effectively destroy tumor cells. The aims of this study were to obtain CD8 + CTLs specific for the HER2/neu epitopes E75 and E88 and to assess the cytotoxic activity and composition of these cells in terms of the distribution of memory T-cell subsets. We obtained HER2-specific CD8 + T cells and assessed T cell subset distribution among them including naive T cells (T N ), central memory T cells (T CM ), effector memory T cells (T EM ), stem cell-like memory T cells (T SCM ) and terminally-differentiated T cells (T EMRA ) via eight-color flow cytometry. HER2-specific CTLs were largely (~40–50%) represented by T SCM cells, a population capable of mounting pronounced antitumor immune responses due to a combination of effector function and self-maintenance. In comparison with activated peripheral blood mononuclear cells (PBMCs) and bulk CD8 + T cells, HER2-specific CTLs exhibited greater cytotoxicity against the HER2-expressing human breast adenocarcinoma cell line MCF-7 and produced higher levels of IFN-γ in response to tumor cells. We also showed the presence of HER2-specific CTLs in healthy individuals and increase in them in HER2-positive breast cancer patients. Collectively, our results suggest that HER2-specific CD8 + T cells isolated using this approach could be used for adoptive T-cell transfer to eliminate tumor cells and prevent metastasis and relapse in patients with HER2-overexpressing cancers.
Advances in oncoimmunology related to the definition of the basic mechanisms of the formation of antitumor immune response, as well as the opening of tumor-associated antigens recognized by immune cells, allowed to start developing ways to influence the effector cells of the immune system to generate effective antitumor cytotoxic response. We investigated the possibility to stimulate an antitumor response in a culture of mononuclear cells of breast cancer patients by dendritic cells transfected with HLA-A*02:01-restricted DNA constructs. We isolated dendritic cells from peripheral blood monocytes and delivered our constructs to these cells by magnetic transfection. Additionally, a series of experiments with loading of dendritic cells with autologous tumor cell lysate antigens was conducted. We have shown that dendritic cells transfected with the HLA-A*02:01-restricted DNA constructs are effective in inducing an antitumor response in a culture of mononuclear cells of breast cancer patients. Dendritic cells transfected with DNA constructor dendritic cells loaded with lysate antigens revealed a comparable stimulated cytotoxic response of mononuclear cells to these two ways of antigen delivery. We conclude that using DNA constructs in conjunction with patient stratification by HLA type allows the application of transfected DCs as an effective method to stimulate antitumor immunity in vitro.
Recent data on the application of dendritic cells (DCs) as anti-tumor vaccines has shown their great potential in therapy and prophylaxis of cancer. Here we report on a comparison of two treatment schemes with DCs that display the models of prophylactic and therapeutic vaccination using three different experimental tumor models: namely, Krebs-2 adenocarcinoma (primary tumor), melanoma (B16, metastatic tumor without a primary node) and Lewis lung carcinoma (LLC, metastatic tumor with a primary node). Dendritic cells generated from bone marrow-derived DC precursors and loaded with lysate of tumor cells or transfected with the complexes of total tumor RNA with cationic liposomes were used for vaccination. Lipofectamine 2000 and liposomes consisting of helper lipid DOPE (1,2-dioleoyl-sn-glycero-3-phosphoethanolamine) and cationic lipid 2D3 (1,26-Bis(1,2-de-O-tetradecyl-rac-glycerol)-7,11,16,20-tetraazahexacosan tetrahydrocloride) were used for RNA transfection. It was shown that DCs loaded with tumor lysate were ineffective in contrast to tumor-derived RNA. Therapeutic vaccination with DCs loaded by lipoplexes RNA/Lipofectamine 2000 was the most efficient for treatment of non-metastatic Krebs-2, where a 1.9-fold tumor growth retardation was observed. Single prophylactic vaccination with DCs loaded by lipoplexes RNA/2D3 was the most efficient to treat highly aggressive metastatic tumors LLC and B16, where 4.7- and 10-fold suppression of the number of lung metastases was observed, respectively. Antimetastatic effect of single prophylactic DC vaccination in metastatic melanoma model was accompanied by the reductions in the levels of Th2-specific cytokines however the change of the levels of Th1/Th2/Th17 master regulators was not found. Failure of double prophylactic vaccination is explained by Th17-response polarization associated with autoimmune and pro-inflammatory reactions. In the case of therapeutic DC vaccine the polarization of Th1-response was found nevertheless the antimetastatic effect was less effective in comparison with prophylactic DC vaccine.
The level of TNF receptors on various cells of immune system and its association with the gene polymorphism were investigated. Determining the levels of membrane-bound TNFα receptors on peripheral blood mononuclear cells (PBMCs) was performed by flow cytometry using BD QuantiBRITE calibration particles. Soluble TNFα receptor (sTNFRs) levels were determined by ELISA and genotyping was determined by PCR-RFLP. Homozygous TT individuals at SNP −609G/T TNFRI (rs4149570) showed lower levels of sTNFRI compared to GG genotype carriers. Homozygous carriers of CC genotype at SNP −1207G/C TNFRI (rs4149569) had lower expression densities of membrane-bound TNFRI on intact CD14+ monocytes compared to individuals with the GC genotype. The frequency differences in the CD3+ and CD19+ cells expressing TNFRII in relation to SNP −1709A/T TNFRII (rs652625) in healthy individuals were also determined. The genotype CC in SNP −3609C/T TNFRII (rs590368) was associated with a lower percentage of CD14+ cells expressing TNFRII compared to individuals with the CT genotype. Patients with rheumatoid arthritis had no significant changes in the frequencies of genotypes. Reduced frequency was identified for the combination TNFRI −609GT + TNFRII −3609CC only. The polymorphisms in genes represent one of cell type-specific mechanisms affecting the expression levels of membrane-bound TNFα receptors and TNFα-mediated signaling.
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