Mapping CD20 molecules on the lymphoma cell surface using atomic force microscopy  

作　　者：LI Mi LIU LianQing XI Ning WANG YueChao DONG ZaiLi XIAO XiuBin ZHANG WeiJing 

机构地区：[1]State Key Laboratory of Robotics,Shenyang Institute of Automation,Chinese Academy of Sciences [2]University of Chinese Academy of Sciences [3]Department of Mechanical and Biomedical Engineering,City University of Hong Kong [4]Department of Lymphoma,Affiliated Hospital of Military Medical Academy of Sciences

出　　处：《Chinese Science Bulletin》2013年第13期1516-1519,共4页

基　　金：supported by the National Natural Science Foundation of China (60904095, 61175103);the CAS FEA International Partnership Program for Creative Research Teams

摘　　要：Atomic force microscopy (AFM) was used to locate CD20 molecules on the surface of lymphoma Raji cells. Rituximab (a monoclonal antibody against CD20) molecules were linked onto the AFM tip via a polyethylene glycol (PEG) linker. Raji cells were adsorbed onto glass slides coated with poly-L-lysine. First, the CD20 distribution in a local area of the cell surface was visualized using the AFM lift scan mode. Second, 16 × 16 force curves were obtained from the same cell area to construct the CD20-rituximab binding force map. Finally, free rituximab was added to block the CD20 molecules on the cell surface and the lift phase image and CD20-rituximab force map were obtained again. The experimental results indicated that when the lift height was greater than the length of the PEG linker, no recognition sites were observed in the lift phase image. However, as the lift height decreased to the length of the PEG linker, some recognition sites were observed in the lift phase image and these sites were generally consistent with the pixels in the force map. After blocking, both the recognition sites in the lift phase image and the gray pixels in the binding force map decreased markedly. These results can improve our understanding of the distribution of protein molecules on the cell surface and facilitate further investigations into cellular functions.Atomic force microscopy （AFM） was used to locate CD20 molecules on the surface of lymphoma Raji cells. Rituximab （a mono- clonal antibody against CD20） molecules were linked onto the AFM tip via a polyethylene glycol （PEG） linker. Raji cells were adsorbed onto glass slides coated with poly-L-lysine. First, the CD20 distribution in a local area of the cell surface was visualized using the AFM lift scan mode. Second, 16 x 16 force curves were obtained from the same cell area to construct the CD20- rituximab binding force map. Finally, free rituximab was added to block the CD20 molecules on the cell surface and the lift phase image and CD20-rituximab force map were obtained again. The experimental results indicated that when the lift height was great- er than the length of the PEG linker, no recognition sites were observed in the lift phase image. However, as the lift height de- creased to the length of the PEG linker, some recognition sites were observed in the lift phase image and these sites were general- ly consistent with the pixels in the force map. After blocking, both the recognition sites in the lift phase image and the gray pixels in the binding force map decreased markedly. These results can improve our understanding of the distribution of protein mole- cules on the cell surface and facilitate further investigations into cellular functions.

关 键 词：原子力显微镜 细胞表面 淋巴瘤 分子 测绘 识别位点 单克隆抗体 L-赖氨酸 

分 类 号：R733.1[医药卫生—肿瘤]