Induction of Anti-Tumor Response in vivo by HSA Gene Transfected Mouse Lymphoma Cell EL-4 / 中国肿瘤生物治疗杂志

A recombinant eukaryotic expression vector containing HSA(Heat-stable Antigen) cDNA and PcDNA 3 plasmid was constructed and then transfected into mouse lymphoma cell line---EL-4 by electroporation. The transfected tumor cells were selected in RPM11640 containing G418 (400?g/ml).HSA expression was detected by FACS using indirect immunofluorescene technique with HSA mAb (Ml/69).To obtain high expression of HSA'EL-4 cells ,the transfected cells were recloned by limiting dilution. In animal experiments, we found that the tumorigenicity of HSA+ EL-4 is weaker than HSA- EL-4(EL-4 or EL-4-v). The size of HSA+ EL-4 tumors were significantly smaller than that of HSA- EL-4 tumors. The tumor growth speed and survival time of tumor-bearing mice are also different. A protective effect against the subsequently challenge with low dose (2 ? 1 03/mouse) wild type tumor cells was found in immunized mice with inactivated HSA+ EL-4 tumor cells but not in those animals immunized with HSA- EL-4 tumor cells. Moreover, HSA+ EL-4 could be used as tumor vaccine to cure the established tumor at the initial stage.

Islet cell antigens and autoantigen(s): Monoclonal antibodies and further characterization.

A novel series of murine monoclonal antibodies to islet cells (I-45, I-51, I-52 and I-39) have been generated using human insulinoma homogenate as the immunogen in order to characterize pathogenetically relevant islet cell autoantigen(s). Differentiation antigens recognized by these islet cell monoclonal antibodies displayed varied cytological distribution (pan-islet or peripheral mantle only). Monoclonal antibody I-45 reacted with all endocrine subsets of the pancreatic islet, similar to the reactivity of islet cell autoantibody positive sera from type I diabetes subjects. Preexposure to pH2 abolished the immunoreactivity of the autoantigen; I-45 antigen was also sensitive to low pH. Preexposure to 100° C for 1 h did not significantly alter the immunoreactivity of islet antigens recognized by ICAb positive patient sera and monoclonal antibody 1-39, thus demonstrating the extraordinary heat stability of the corresponding epitopes; those recognized by I-45 were less heat stable. Islet cells were found to share I-45 differentiation antigen(s)/epitope(s) with other neuroendocrine cells, viz. amerior pituitary, adrenal medulla and gut endocrine cells.