• Journal of Microbiology
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• v.45 no.6
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• pp.572-577
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• 2007

To enhance therapeutic potential of murine monoclonal antibody, humanization by CDR grafting is usually used to reduce immunogenic mouse residues. Most humanized antibodies still have mouse residues critical for antigen binding, but the mouse residues may evoke immune responses in humans. Previously, we constructed a new humanized version (AKA) of mouse CC49 antibody specific for tumor-associated glycoprotein, TAG-72. In this study, to select a completely human antibody light chain against TAG-72, guided selection strategy using phage display was used. The heavy chain variable region (VH) of AKA was used to guide the selection of a human TAG-72-specific light chain variable region (VL) from a human VL repertoire constructed from human PBL. Most of the selected VLs were identified to be originated from the members of the human germline VK1 family, whereas the VL of AKA is more homologous to the VK4 family. Competition binding assay of the selected Fabs with mouse CC49 suggested that the epitopes of the Fabs overlap with that of CC49. In addition, they showed better antigen-binding affinity compared to parental AKA. The selected human VLs may be used to guide the selection of human VHs to get completely human anti-TAG72 antibody.

• KSBB Journal
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• v.31 no.1
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• pp.33-39
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• 2016

Developing the method for the selection of animal cell line producing therapeutic monoclonal antibody (mAb) is invaluable as its market is rapidly growing. Although the quality of produced mAb is as important as quantity, however there is no method developed for the selective screening of cell lines on the basis of both quantity and quality. From recent reports, the ratio of light and heavy chain mRNAs of mAb in the cell is a key parameter for the indication of product quality. Therefore, it is obvious that developing the novel method that can detect both light and heavy chain mRNAs in single live cell will provide unprecedented opportunities in bio-industry. Here, we have constructed oligonucleotide probes, molecular beacons for the detection of light or heavy chain mRNAs, respectively, in the live cells producing mAbs. Both beacons showed increased fluorescent intensity after transient transfection of plasmid expressing mAbs analyzed by fluorometer. Flow cytometric analysis clearly demonstrated that both molecular beacons can simultaneously detect the expression of light and heavy chain mRNAs of mAb in the same cell. The technique described in the thesis provides the new direction and concept for developing the method for the smart selection of cell lines producing recombinant proteins including therapeutic mAbs.

• 한국생물공학회:학술대회논문집
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• 2005.04a
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• pp.39-39
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• 2005

Large scale mammalian cell culture has become, over the past two decades, the preferred method to produce therapeutic monoclonal antibodies. In this presentation, I will introduce disposable bioreactor system and analyze key factors and points for consideration during mammalian cell culture process development. Example will be provided highlighting the selection of master cell, culture media and environmental factors based on productivity and product quality.

• Journal of Embryo Transfer
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• v.11 no.1
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• pp.71-80
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• 1996

The envelope of the rnannnalian oocyte plays crucial roles in sperm-oocyte interactions by providing sperm receptors, inducing acrosome reaction and preventing polyspermy. Understanding of properties of the zona pellucida (ZP) is essential for the artificial control of fertility in mammals. This study was carried out to produce and characterize monoclonal antibodies(MAbs) to porcine ZP proteins. Approximately 8,000 ZPs were obtained from follicular oocytes and dissolved in 40$\mu$l of double distilled water. Following immunization through foot-pad injections of Balb /c mice with a ZP solution, the popliteal lymph nodes were recovered at 2 weeks after the last injection. Hybridoma cell lines were established by fusing lymph node cells with P3X63 myeloma cells through selection using HAT medium and screening by immunofluorescence(IF) microscopy on the isolated ZP. Secreted MAbs were found to consist k chains and different heavy chains as evidenced by isotyping. Some of the MAbs demonstrated high specificity to the ZP in IF. The Mabs also showed positive cross reactivity with hamster and mouse eggs, while negative with bovine eggs. The results implicate that the MAbs can be used not only for identification of functional regions of the ZP, but also for elucidation of mechanisms involved in fertilization of mammals. The MAbs will provide basic information on biochemical anatomy of the ZP as well as can be candidates for the future contraceptive vaccines.

• Journal of environmental and Sanitary engineering
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• v.4 no.1 s.6
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• pp.17-28
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• 1989

Having studied the production of monoclonal antibodies for developing a diagnosis medicine which shall be detected by a high-sensitivity test by using Rhodotorula rubra as a fungi-host which had been extracted through biochemical tests and follow-up examinations on Yeast-like fungi obtained from pulmonary tissues of pulmonary tuberculosis patients who had been in Kong ju National Tuberculosis Hospital from Jun. to Dec. in 1987, I. have gained such results as follows: 1. The fusion rate was influenced by feeder cell layers, cell density and time required to the cell fusion with cells in myelona subculture. 2. The fusion rate did not show any significant difference when the cell was applyed with two molecular weights, i.e., 1500 and 4000, of polyethylene glycol. 3. Fused cells after the addition of HAT selection media were bright and round, whereas unfused myelona cells and spleen cells were shrunk and granulated. 4. The cell fusion rate turned out to be about $57.2\%$(150 wells / 264 wells). 5. $10\%$(15 wells / 150 wells) of the positive reaction was detected in monoclonal antibody screening. 6. The titer which had reacted positively to Rhodotorula rubra fungal-host was 800 times in density after the gradual dilution of the produced monoclonal antibodies with Indirect ELISA method. 7. The Strongest specific reaction came out after the peroxidase labelled anti-human Immunogobulin had been applyed to Rhodotorula rubra for activating its nature after making drift with Carbonate-bicarbonate buffer (pH 9.6) and drying completely.

• Journal of Microbiology and Biotechnology
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• v.12 no.1
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• pp.121-129
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• 2002

Using recombinant Chinese hamster ovary (CHO) cells, strategies for developing high producers for the recombinant human Transforming Growth $Factor-{\beta}1$ ($TGF-{\beta}1$) protein are proposed and their physiological characteristics in cell cultures were investigated. $TGF-{\beta}1$ is a pleiotrophic polypeptide involved in various biological activities, including cell growth, differentiation, and deposition of extracellular matrix proteins. The CHO cells included human $TGF-{\beta}1$ cDNA in conjunction with a dihydrofolate reductase (DHFR) gene, which was cotransfected into the cells to amplify the transfected $TGF-{\beta}1$ cDNA. As a first-round screening of the transfected cells, a relatively high $TGF-{\beta}1$-producing cell line was selected, and then, it acquired a resistance to increasing concentrations of methotrexate (MTX) up to $60{\mu}M$,resulting in a significant improvement in its $TGF-{\beta}1$ biosynthetic ability. After applying a monoclonal selection strategy to the MTX-resistant cells, more productive cells were screened, including the APP-3, App-5, and App-8 cell lines. These high producers were compared with two other cell lines (AP-l cell line without amplification of transfected $TGF-{\beta}1$ cDNA and nontransfectant of $TGF-{\beta}1$ cDNA) in terms of cell growth, $TGF-{\beta}1$ productivity, sugar uptake, and byproduct formation, in the presence or absence of MTX in the culture medium. Consequently, both monoclonal selection as well as an investigation of the physiological characteristics were found to be needed for the efficient screening of higher $TGF-{\beta}1$ producers, even after the transfection and amplification of the transfected gene.

• The Plant Pathology Journal
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• v.22 no.1
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• pp.21-27
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• 2006

We immunized BALB/c mice with purified Cucumber green mottle mosaic virus isolate HY1 (CGMMV-HY1). Through the selection of positive clones that were grown on the HAT medium, four sensitive monoclonal clones (CG99-01, CG99-02, CG99-03, and CG99-04) were selected from 500 Hypoxanthine-guanine phosphoribosyltransferase positive hybridoma cells. Four sensitive clones of CGMMV-HYI were determined as IgM type of the subclass of mouse immunoglobulins Ig group. The titer of monoclonal antiserum against CGMMVHY1 was estimated 1:12,800 by the indirect ELISA. Although monoclonal antibodies (MAbs) from CG99-01 and from CG99-04 cross-reacted with Zucchini green mottle mosaic virus and Kyuri green mottle mosaic virus, MAb from the cell line CG99-03 was highly specific to CGMMV. No MAbs cross-reacted with Cucumber mosaic virus-Fny. Only CG99-04 reacted with Pepper mild mottle virus weakly and CG99-02 reacted with both CGMMV and KGMMV. CGMMV was detected from the rind of watermelon fruit by DAS-ELISA of CGMMV-HY1, but not from the flesh of watermelon. Average seed transmission rate of CGMMV in watermelon was $24\%$ from symptomatic watermelon collected from 5 regions of Gyeongnam province. CGMMV was detected by DAS-ELISA with specific MAb of CGMMVHY1 periodically from root stock, during the sequential process for nursery seedling in Haman. Necrotic spots on cotyledons of root stock seedling progressed to reveal the typical symptomatology on the primary leaves of scion upon grafting. Here, we have established MAb based ELISA system, which could accurately detect CGMMV from watermelon seeds, nursery seedlings, transplants and field samples from greenhouse or open out door field as well.

• The Korean Journal of Zoology
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• v.32 no.4
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• pp.412-419
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• 1989

Monoclonal antibodies (MAbs) reacting with the plasmalemma of Amoeba proteus were produced. Specificity of the 3 MAbs was determined by transfer blotting of the SDS polvacryfamide gel. AMS antibody reacted with the mucopolysaccharide bands of the spacer gel, 220 KD and 50 KD proteins of the resolving gel. The maior glycoprotein bands (175 KD, 165 KD) and 50 KD protein of the plasmalemma were recognized by AUG antibody. A third, AMP antibody reacted with the 50 KD protein only. In immunofluorescence microscopy of the enzyme treated cells, the antigens of these MAbs were sensitive to proteases, but not sensitive to neuraminidase. In the assay of cell to substratum attachment after binding with the antibody, AMG and AMP antibodies exerted no effect, but AMS hindered the attachment and cell spreading. Thus the effective components of the plasmalemma in cell to substratum attachment appear to be the mucopolysaccharides and 220 KD protein. The membranes of latex particle infested phagosomes did not show any distinction from the plasmalemma in fluorescence microscopy. Phagosome membranes of amoebae appear to be derived from the plasma membrane without selection in terms of the antigen composition. Amoeba Proteus의 세포막과 반응하는 단세포군 항체를 생산하였다. SDS polyacrylamide gel을 transfer blotting하여 이들 항체의 반응 특이성을 조사해 본 결과 AMS 단항체는 PAS로 염색되는 spacer gel의 mucopolysaccharide 린드, resolving gel의 220 KD 및 50 KD 단백질과 반응하였으며, 세포막의 주요 당단백질인 175 KD 및 165 KD 빈드와 50 KD 단백질은 AMG 단항체에 의해서 인지되었다. 그리고 AMP단항체는 공통인 50 KD 단백질과 특이하게 반응하였다. 효소처리한 아메바의 면역형광칠미경적 조사에서 이들 항체에 대한 항원분자들은 모두 단백질분해효소에 민감하였으며 neuraminidase에 대해서는 변화가 없었다. 이들 항체를 결합시킨 아메바의 용기표면 부착 가능성을 분석한 결과 AMP 및 AMG 단항체는 아무런 영향을 미치지 못하였으며 AMS 단항체는 세포의 용기표면 부착 및 세포의 펴짐을 저해하였다. 따라서 아메바의 용기표면 부착은 mucopolysaccharide 및 220 KD 단백질에 의해서 매게되는 것으로 나타났다. 그리고 latex particle을 담고 있는 식포막은 면역형광형미경적 조사에서 세포막과 차이가 없었다. 따라서 겐포막은 항원 조성에 있어서 비 선택적으로 세포막에서 유도되는 것으로 나타났다.

• Korean Journal of Otorhinolaryngology-Head and Neck Surgery
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• v.61 no.12
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• pp.637-643
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• 2018

Radioimmunotherapy (RIT) is a therapy that takes advantage of the "cross-fire" effect of emitted radiation by radionuclides conjugated to tumor-directed monoclonal antibodies (mAb) (including those fragments) or peptides. While RIT has been successfully employed for the treatment of lymphoma, mostly with radiolabeled antibodies against CD20 [$^{90}yttrium$ ($^{90}Y$)-ibritumomab tiuxetan; $Zevalin^{(R)}$ and $^{131}iodine$ ($^{131}I)-tositumomab$; $Bexxar^{(R)}$], its use in solid tumors is more challenging, so far. Immuno-PET, a tool for tracking and quantification of mAbs with PET in vivo, is an exciting novel option to improve diagnostic imaging and guide mAb-based therapy. RIT in solid tumors including head and neck cancer may be an alternative treatment with advances in various biological, chemical, and treatment procedures, and it may help to reduce unnecessary exposure and enhance the therapeutic efficacy. Also, immuno-PET based on RIT might play an important role in cancer staging, in patients or targets selection of targeted therapeutics and in monitoring the response of targeted therapeutics as precision medicine. In this review, fundamentals of RIT/immune-PET and current knowledge of the preclinical/clinical trials in RIT for solid tumor including head and neck cancer are reviewed.

• Journal of Microbiology and Biotechnology
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• v.10 no.5
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• pp.707-713
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• 2000

Myasthenia gravis (MG) is caused mainly by autoantibodies directed against acetylcholine receptors located in the postsynaptic muscle cell membrane. Using in vitro selection techniques, we isolated an RNA containing 2'-fluoro pyrimidines that can specifically and avidly ($K_d$ ~25 nM) bind rat monoclonal antibody called mAb198, which recognizes the main immunogenic region on the acetylcholine receptors. This RNA can act as a very effective decoy and block mAb198 binding to the receptors in vitro. Furthermore, this RNA decoy can prevent the antigenic modulation of the acetylcholine receptor caused by mAb198 in human muscle cell cultures with and $IC_{50} $of approximately $2.4{\mu}M$. These results indicate that the RNA selected in this study is a more potent decly inhibitor of myashthenic antibodies than the previously identified RNA with 2'-amino pyrimidines [11]. Moreover, this RNA cross-reacts with autoantibodies from patients with MG and can protect human cells from the effects of these antibodies. These observations have important implications for developing an antigen-specific treatment of autoimmune diseases including MG, which is based on decoy RNAs selected in vitro.