Application Of MHC Complex Liposome In Cancer Immunotherapy

Cancer immunotherapy is a treatment that stimulates body’s own immune system to help recognize and kill tumor cells based on principles of immunology.Because of immunosuppressive effects in patients,the number of specific T cells that can recognize and kill tumor cells is too scarce.Therefore,some current practices required separation of autologous T cells from patients and use different stimulators to expand in vitro and transfer back to the patients.But the induction and cultivation of tumor antigen specific T cells requires lots of time and efforts,and there lacks a direct mechanism to stimulate cancer cell specific T cells.In our study,Major histocompatibility complex(MHC)Class I which plays an important role in antigen presentation was produced in prokaryotic expression system E.coli.We selected epidermal growth factor receptor v III,antigen EGFRv III as our target antigen,and polypeptide sequence LEEKKGNYV derived from EGFRv III as an antigenic polypeptide fragment as well as HLA A*0201 gene which has a relatively high frequency in the Asian population as our research object.After recombinant MHC Class I protein was produced in E.coli,it was conjugated to the surface of liposomes to recognize tumor-specific T cells.Anti-human CD28 antibody was conjugated together as a co-stimulator to achieve synergistic stimulation of tumor antigen specific T cells.We showed that the single-chain fusion protein “polypeptide sequence-Linker 1-β2M-Linker 2-HLA A*0201-BSP” is stable and effective.The fusion protein was conjugated to the surface of liposome by using the biotin-avidin interaction as the first signal to stimulate antigen-specific T cells.At the same time,a biotin-modified Anti-human CD28 antiboy was conjugated together as a second signal to synergistically stimulate T cells.The constructed MHC Complex liposome was used to incubate with CD8 T cells isolated from peripheral blood of patients with grade IV gliomas.Our preliminary data suggested that the MHC Complex liposome we constructed could effectively stimulate EGFRv III mutant tumor antigen-specific T cells in vitro.