Study On The Immune Effects Of RhscIL-12 Engineered Human Dendritic Cells In Antitumor Immune Response

Objective: Constructing of fusion gene of recombinant human single chain IL-12(rhscIL-12) with retrovirus vector and study on the expression of the fusion gene in dendritic cells(DCs) and the immune effection of rhscIL-12 gene transfection to engineered human DCs in antitumor immune response , aiming to pave new way for further clinical biotherapy focal pointing to antitumor engineered human DCs vaccine.Methods: rhscIL-12 was made to recombinate with retrovirus vector. The early replicating progenitors of DCs, which were isolated from healthy persons peripheral blood and stimulated by IL-4, GM-CSF and TNF-α, were transfected with rhscIL-12 recombinant retroviral vector by lipofection. The transfected cells were driven through committed expansion into DCs lineage by adding the above cytokines, and were detected and analyzed by scanning electronic microscope and by flow cytometry with labeled monoclonal antibodies。It shew its role in antitumor immune responses that rhscIL-12 transfected DCs were also used to induce T cell proliferation and differentiation in MLR. Results: After culturing in the cocktail of the cytokines, rhscIL-12 transfected DCs developed and maintained the characteristic morphological and phenotypic features of DCs, and CD80+, HLA-DR+ and CD83+ were displayed on the cultured dendritic cells, 84%, 80%, 85% , respectively ,and CD83+ molecule is a mature mark of dendritic cells. When the DCs were pulsed with a broad spectrum class II epitope antigen ,the IL-12 transfected DCs stimulated the autologous lymphocytes to proliferate to a higher level,and the primed Th cells released more IFN-γ when compared with the effects shown in untransfected DCs. Meanwhile, the production of IL-4 was decreased. Preliminary experiment in subtype system showed that the autologous lymphocytes, primed by IL-12 transfected DCs loaded with class I and class II restricted epitopes, secreted more MHC when they were subsequently co-coltured with target cells. This fact indicated that the specific CTL response was enhanced.Conclusion: Retrovirus vector was fit to transfection of DCs, and engineered DCs was one of effective methods of antitumor biotherapy. rhscIL-12 engineered human DCsenhanced its immune functions to stimulate Th1 cells as well as to induce specific CTL. IFN-γ secretion in mixed lymphocyte reaction(MLR) was dependent on endogenous IL-12 autocrined from DC.