摘要
Peptide-MHC class I complex （pMHC） is a specific ligand for TCR recognition, and important for CD8^＋T cell activation. Here we described a genetically engineered divalent class I major histocompatibility complex （MHC） molecule, H-2K^d/IgG2aFc, a fusion protein consisting of the extracellular domains of H-2K^d, a murine MHC class I molecule, and the Fc region of IgG2a. This fusion protein is expected to attach the H-2K^d molecule to the surface of murine macrophage （MФ） through its Fc portion binding to Fc receptor （FcR） of MФ. cDNAs coding for the extracellular domains of H-2K^d and the Fc region of IgG2a were cloned respectively, and then recombined into plasmid pcDNA3.1（＋）. The H-2K^d/IgG2aFc protein was expressed by the plasmid-transfected cell line J558L, and purified from its supernatant with a Staphylococcal Protein A （SPA） column. The fusion protein showed a 58.4 kDa band as revealed by SDS-PAGE and Western blotting with murine IgG-specific antibody, which consists with that expected for extracellular domains of H-2K^d heavy chain plus the Fc region of IgG2a. The sandwich ELISA assay with antibodies specific for Fc portion and for H-2K^d indicated the fusion protein consists of both Fc portion and H-2K^d. Peritoneal MФ of C57BL/6 （H-2K^b） can be stained with H-2K^d specific monoclonal antibody （mAb） after incubated with the H-2K^d/IgG2aFc fusion protein. These results demonstrate the fusion protein can be used to attach the H-2K^d molecule to the surface of murine MФ, and provides a novel means to manipulate the T cell recognized epitope on the surface of murine MФ, which can be applied to activate antigen-specific cytotoxic T lymphocyte （CTL）.
Peptide-MHC class I complex （pMHC） is a specific ligand for TCR recognition, and important for CD8^＋T cell activation. Here we described a genetically engineered divalent class I major histocompatibility complex （MHC） molecule, H-2K^d/IgG2aFc, a fusion protein consisting of the extracellular domains of H-2K^d, a murine MHC class I molecule, and the Fc region of IgG2a. This fusion protein is expected to attach the H-2K^d molecule to the surface of murine macrophage （MФ） through its Fc portion binding to Fc receptor （FcR） of MФ. cDNAs coding for the extracellular domains of H-2K^d and the Fc region of IgG2a were cloned respectively, and then recombined into plasmid pcDNA3.1（＋）. The H-2K^d/IgG2aFc protein was expressed by the plasmid-transfected cell line J558L, and purified from its supernatant with a Staphylococcal Protein A （SPA） column. The fusion protein showed a 58.4 kDa band as revealed by SDS-PAGE and Western blotting with murine IgG-specific antibody, which consists with that expected for extracellular domains of H-2K^d heavy chain plus the Fc region of IgG2a. The sandwich ELISA assay with antibodies specific for Fc portion and for H-2K^d indicated the fusion protein consists of both Fc portion and H-2K^d. Peritoneal MФ of C57BL/6 （H-2K^b） can be stained with H-2K^d specific monoclonal antibody （mAb） after incubated with the H-2K^d/IgG2aFc fusion protein. These results demonstrate the fusion protein can be used to attach the H-2K^d molecule to the surface of murine MФ, and provides a novel means to manipulate the T cell recognized epitope on the surface of murine MФ, which can be applied to activate antigen-specific cytotoxic T lymphocyte （CTL）.
基金
supported by a grant from the National Natural Science Foundation of China(NO.30271201).
