Major histocompatibility complex(MHC)class I chain-related protein A(MICA),which is a ligand for human NKG2D,is expressed by a variety of epithelial tumor cells and promotes the activation of natural killer(NK),CD81 and cd-T cells.Although ectopic expression of MICA on tumor cells elicits anti-tumor responses,soluble MICA downregulates the activities of lymphocytes.In this study,we showed that recombinant,immobilized MICA(iMICA)molecules coated on plastic wells weakly promote peripheral NK cell activation,secretion of interferon(IFN)-c and degranulation without inducing apoptosis.In addition,iMICA synergized with IL-15 and soluble 4-1BB ligand(s4-1BBL)to expand NK cells 25-to 42-fold in a 13-day culture,whereas NK cells stimulated only with IL-15 and s4-1BBL expanded 10-to 16-fold.In contrast toNKcells expanded by IL-15 and s4-1BBL stimulation,NKcells expanded long term in the presence of iMICA exhibited increased cytotoxicity against leukemia cells.These results suggest that large numbers ofNKcells with high cytotoxicity can be generated by stimulation with IL-15 and s4-1BBL in the presence of iMICA and that these cells can be used for adoptive cancer immunotherapy.
Weijuan GongWeiming XiaoLi QianChunxiang GongMaozhi HuXianyuan PanMingchun Ji
Artificial antigen-presenting cells are expected to stimulate the expansion and acquisition of optimal therapeutic features of T cells before infusion. Here CD32 that binds to a crystallizable fragment of IgG monoclonal antibody was genetically expressed on human K562 leukemia cells to provide a ligand for T-cell receptor. CD86 and 4-1BBL, which are ligands of co-stimulating receptors of CD28 and 4-1BB, respectively, were also expressed on K562 cells. Then we accomplished the artificial antigen-presenting cells by coupling K32/CD86/4-1BBL cell with OKT3 monoclonal antibody against CD3, named K32/CD86/4-1BBL/OKT3 cells. These artificial modified cells had the abilities of inducing CD8^＋ T cell activation, promoting CD8^＋ T cell proliferation, division, and long-term growth, inhibiting CD8^＋ T cell apoptosis, and enhancing CD8^＋ T cell secretion of IFN-T and perforin. Furthermore, antigen-specific cytotoxic T lymphocytes could be retained in the culture stimulated with K32/CD86/4-1BBL/OKT3 cells at least within 28 days. This approach was robust, simple, reproducible and economical for expansion and activation of CD8^＋ T cells and may have important therapeutic implications for adoptive immunotherapy. Cellular ＆ Molecular Immunology.
Weijuan GongMingchun JiZhengfeng CaoLiheng WangYayun QianMaozhi HuLi QianXingyuan Pan
