Development of in vitro laboratory models of the tumor immune microenvironment to evaluate quality parameters and specific efficacy of the dendritic cell vaccine

Purpose of the study: development of in vitro laboratory models to evaluate quality parameters and specific efficacy of dendritic cell vaccine (DCV).Material and Methods. Biological samples of malignant tumor patients treated with autologous dendritic cell vaccine (DC) were included into the study. Immature DCs (n=46) and mature DCs (n=56) were used to induce proliferation of antigen-specific T lymphocytes (n=227). Autologous tumor cells from skin melanoma (n=10) or sarcoma (n=8) patients in the xCELLigence® assay system were used to study the in vitro antitumor cytotoxic activity of generated CTLs (n=18). The secretion of cytokines and cytolytic proteins was studied by multiplex analysis. The subpopulation composition of effector T-lymphocytes was determined by flow cytometry.Results. We revealed that mature DCs (CD83+CD1a-) had a high expression of antigen presenting molecules (HLA-DR) and those providing migration of DCs into lymph nodes (CCR7) as well as costimulatory molecules CD80 and CD86 as compared to immature DCs (CD83-CD1a+). Induction of mature DCs was found to stimulate an increase in the relative content of proliferating T cells compared with stimulation of immature DCs (p<0.001) and specific PTA+ tumor lysate (p<0.001). When studying cytotoxic activity of effector T-lymphocytes, we developed 2D in vitro models using xCELLigence® analytical system and revealed 2 types of interaction: 1) in vitro model № 1 – decrease in cell index (CI) of autologous tumor cell culture in the presence of activated effector T lymphocytes; 2) in vitro model № 2 – no change in CI of autologous tumor cell culture when co-cultured with activated effector T cells compared to control (72 h observation). The results demonstrated cytotoxic activity of antigen-specific T lymphocytes due to high content of terminally differentiated cytotoxic T lymphocytes (TEMRA), GrB-producing CTLs, and cytokine secretion profile.Conclusion. Requirements for the quality of personalized autologous DCs, including control of immunophenotypic characteristics were developed, and functional activity of Tlymphocytes during induction of mature vaccine DCs was evaluated. A laboratory procedure was developed for quantitative assessment of cytotoxic activity of antigen-specific T-lymphocytes against autologous tumor using the xCELLigence® analytical system, thus allowing for personalized monitoring and predicting the effectiveness of DСV treatment.