Anti-tumor effect of dendritic cell vaccines transfected with total RNA of lung adenocarcinoma cell and induced by modified cytokine cocktail in vivo

Objective To investigate the anti-tumor effect of dendritic cell( DC) vaccine induced by different cytokine cocktails on transplanted tumor-bearing nude mice. Methods Peripheral blood mononuclear cells( PBMC) were first isolated from 38 peripheral blood specimens of normal donors who underwent PBSC collection and then were induced into immature DC. DC were transfected with total RNA of human lung adenocarcinoma cell line A549 through electroporation,then stimulated with conventional cytokine cocktail( IL-6,IL-1β,TNF-α,PGE2) and modified cytokine cocktail( IL-1 β,IL-6,TNF-α,PGE2,poly Ⅰ∶ C,Cp G ODN),respectively. Antigen-sensitized DC were co-cultured with autologous T cells to activate antigen specific cytotoxic T lymphocyte( CTL). The phenotypes of T cells were analyzed by flow cytometry,and the secretion of IFN-γ,TNF-α,IL-4,IL-5 and IL-10 from T cells were measured by enzyme-linked immunosorbent assays( ELISA). After establishment of the A549 implanted lung adenocarcinoma model,nude mice were randomly divided into empty control group,immature group,conventional group and modified group( n = 5). Peritumoral injection of CTL was performed on day 15,day 22 and day 29 after inoculation of tumor cells. The volumes and weights of tumors were measured.The expression of COX-2,VEGF,Bcl-2 and Bax in the tumor tissues were determined using immunohistochemistry and Western blotting. Results( 1) The percentage of CD3 + CD8 + T cells in immature group,conventional group and modified group were( 35. 00 ± 3. 24) % vs( 57. 10 ± 2. 69) % vs( 63. 98 ± 1. 96) %( P 0. 05),respectively.( 2) The secretion of IFN-γ in the above groups were( 160. 12 ± 42. 01) pg / m L vs( 263. 17 ± 55. 30) pg / m L vs( 1 034. 30 ± 253.07) pg / m L( P 0. 05); the secretion of TNF-α in the above groups were( 72. 72 ± 9. 13) pg / m L vs( 65. 20 ± 8. 03)pg / m L vs( 295. 89 ± 123. 80) pg / m L( P 0. 05); the secretion of IL-10 in the above groups were( 7. 26 ± 1. 76) pg/ m L vs( 31. 06 ± 4. 19) pg / m L vs( 44. 01 ± 12. 12) pg / m L( P 0. 05). IL-4 and IL-5 in each group were undetectable,showing that T cells in modified group produced much higher levels of Th1 cytokines IFN-γ and TNF-α than immature group and conventional group.( 3) After immunotherapy with CTL,tumor size of nude mice in immature group,conventional group and modified group were( 512 ± 33) mm3vs( 345 ± 63) mm3vs( 203 ± 52) mm3,( P 0. 05),respectively.Moreover,the inhibitive ratio of tumor weight in modified group was the highest at 69. 62%.( 4) The expression of Bax in modified group was significantly up-regulated and the expressions of COX-2,VEGF and Bcl-2 were down-regulated. Conclusion DC vaccines which are electroporated with total RNA of lung adenocarcinoma cell and induced by modified cytokine cocktail can effectively inhibit the growth of lung adenocarcinoma transplanted tumors in nude mice through significant induction on type Th1 immune response and production of effective antigen specific CTL.