Reovirus strain R-92 in in vitro generation of tumor-specific T-lymphocytes.

Abstract

e14216 Background: The purpose of the study was to assess the potential of the reovirus strain R-92 for in vitro generation of tumor-specific T-lymphocytes. Methods: The human reovirus strain R-92 used as a master seed strain was previously isolated from a patient with infectious hepatitis and adapted to the growth on the pig embryo kidney cell culture (PEKC); it lost its pathogenicity after multiple passages and was characterized by electron microscopic, serological methods and PCR. HeLa lysate was prepared by the incubation with the R-92 reovirus in medium 199+L-glutamine during 5 days (37оC, 5% СО2), cytopathogenic effect was observed. Immature dendritic cells (DCs) were derived from blood monocytes cultivated for 7 days in presence of IL-4 and GM-CSF. For the DC loading during 48 hours we used: 1. HeLa lysate obtained by repeated freezing and thawing of cells (control); 2. HeLa lysate obtained by co-culturing with reovirus; 3. reovirus cultured in a standard PEKC. To assess the DC ability to activate lymphocytes, they were co-cultured for 5 days in a 3:1 ratio, 1.5x105 of target cells (HeLa) were added (1:1) for 48 hours; number of dead HeLa cells was count. At each stage of the generation of DCs and activated lymphocytes, they were phenotyped by flow cytometry. Results: DC samples 2 and 3 showed increased percentage of activated cells compared to the loaded with the control tumor lysate, CD86 and HLA-DR coexpression was 62 and 69% vs. 25%, respectively; CD83 expression was maximal after DC loading with reovirus (72.9%). After co-culturing of DC with autologous lymphocytes, the highest number of activated CD4+CD38+ and CD8+CD38+, was observed in sample 2, T-regs (CD4+CD25+CD127low) - in the control. The death of target cells cultured with activated lymphocytes obtained by DC samples 2 and 3, was 100%, control sample showed minimal cytotoxicity against HeLa. The number of T-lymphocytes in samples 2 and 3 cultured with HeLa exceeded the control values by 3-10 times. Conclusions: Reovirus R-92 used for the immature DC loading increases their presenting activity. DCs loaded with reovirus HeLa lysate, when co-cultured with lymphocytes, activate CD4+ and CD8+ and suppress T-regs, apparently leading to the total death of target tumor cells.