Transfection Efficiency of Ad5F11p-GFP on CIK and NK-92 Cells and Its Influence on Biological Characteristics / 中国实验血液学杂志

<p><b>OBJECTIVE</b>To study transfection efficiency of Ad5F11p-GFP and its influence on biological characteristics of CIK and NK-92 cells in order to predict the application of Ad5F11p vector in immunotherapy.</p><p><b>METHODS</b>Two kinds of immune cells, cytokine-induced killer (CIK) cells and natural-killer (NK) cell line NK-92 cells, were transfected by Ad5F11p-GFP at different multiplicity of transfection (MOI), and untransfected immune cells were used as negative control. GFP expression was determined by flow cytometry, the cell morphology was observed with microscope, the cell proliferation was analyzed by trypan blue staining, specific cytotoxicity of NK-92 cells was determined by LDH assay.</p><p><b>RESULTS</b>About 90% of transfection efficiency for NK-92 cells could be achieved at a MOI of 25, while the transfection efficiency for CIK was less than 40% at a MOI of 200. In addition, the transfection efficiency basically unchanged at the same MOI for 48 h and 96 h, and the immune cells transfected with the virus trended to form agglomeration, displaying slower proliferation, increase of IFN-γ release and enhancement of tumor killing activity.</p><p><b>CONCLUSION</b>Ad5F11p- modified NK-92 shows a good prospect for adoptive immunotherapy.</p>

Expression of ATR-Fc fusion protein in CHO cells / 生物工程学报

ATR-Fc is a fusion protein consisting of extracellular domain of human anthrax toxin receptor (ATR) and a fragment (hinge, CH2, and CH3 domains) of the Fc of human IgG1. The aim of ATR-Fc expression is to get an antibody-like molecule binding to protective antigen (PA), a component of anthrax toxins, this fusion protein may compete with cell surface receptor for PA binding, and block the transport of lethal factor (LF) and edema factor (EF) into cells, thereby act as an antitoxin to prevent and treat anthrax infection. A DNA fragment encoding N-terminal amino acids 1-227 of ATR and human IgG1 Fc was inserted into the Hind III and Not I sites of pcDNA3.1 to generate the eukaryotic vector pcDNA3.1/ATR-Fc for expression of ATR-Fc fusion protein. Using lipofectine-mediated gene transfer technique, pcDNA3.1/ATR-Fc was transfected into CHO-K1 cells. After selected with G418, a recombinant CHO cell line, ATR-Fc-1D5, whose expression level was about 10 - 15 microg/(10(6) cells x d), was established. The recombinant protein expressed by the ATR-Fc-1D5 cells was purified with protein A chromatography. The experimental results demonstrated a direct and specific interaction between ATR-Fc and PA assessed by ELISA.

Single-chain urokinase-type plasminogen activator (scu-PA) purification by immuno-affinity chromatography / 生物工程学报

The only difference of primary structure between single-chain prourokinase (pro-UK or scu-PA) and two-chain urokinase (UK or tcu-PA) is the cleavage of a single peptide bond (Lys158-Ile159) and transform scu-PA into its active two-chain form. A 13-peptide (Thr-Leu-Arg-Pro-Arg-Phe-Lys-Ile-Ile-Gly-Gly-Glu-Cys), which spans the cleavage peptide bond, was synthesized and linked to KLH (Keyhole limpet hemocyanin). The Balb/c mice were immunized by the conjugated protein with proper adjuvant. According to the Kohler and Milstein's methods, a hybridoma cell line G7 secreting monoclonal antibody specific for scu-PA was obtained. The anti-scu-PA McAb, purified from the supernatant of porous microcarrier hybridoma cell culture, was conjugated to CNBr-activated Sepharose 4B to prepare an immuno-affinity chromatography column. The u-PA was purified only by this affinity column from the supernatant of cultivating the u-PA-producing recombinant CHO cell, the u-PA recovery ratio is 90.4%, the purification factor was about 50, with the specific activity of 1.2 x 10(5) IU/mg, the scu-PA ratio in the u-PA product was 96.3%. Compared to immuno-affinity chromatography, the 3-step process for purifying u-PA (cation-exchange column, gel filtration column and benzamidine affinity column) has a u-PA recovery ratio of about 65%, with a specific activity of 1.0 x 10(5) IU/mg, and an scu-PA ratio of about 90%. These results showed that immuno-affinity chromatography is simple to recover u-PA and effective to separate scu-PA from tcu-PA.