目的 :构建抗CD2 0 嵌合抗体Fab片段表达载体 ,并在大肠杆菌中进行高效可溶性分泌表达。方法 :利用PCR方法从抗CD2 0 单链抗体 (ScFv)表达载体上扩增抗CD2 0 抗体轻链可变区基因 (VL)、重链可变区基因 (VH) ,然后将VH、VL 基因重组到Fab表达载体pYZF中 ,构建抗CD2 0 Fab表达载体pYZF1cd2 0 ,并在 2 7C7菌中高效表这。结果 :经Fab表达载体转化的 2 7C7菌株 ,进行表达培养 ,经分离纯化获得具有CD2 0 特异结合活性的Fab片段 ,竞争性免疫荧光抑制实验表明 ,表达产物Fab片段能竞争性抑制鼠源性抗CD2 0 抗体HI47和CD2 0 表达细胞Raji细胞结合。结论 :在大肠杆菌中高效可溶性分泌表达有活性的抗CD2 0 嵌合抗体Fab片段。 OBJECTIVE: To construct a Fab fragment expression vector for anti-CD20 chimeric antibody, which is highly soluble and secretively expressed in E. coli. Methods: The anti-CD20 antibody light chain variable region (VL) and heavy chain variable region (VH) genes were amplified by PCR from the anti-CD20 scFv expression vector. The VH and VL genes Recombined into the Fab expression vector pYZF, the anti-CD20 Fab expression vector pYZF1cd20 was constructed, and the anti-CD20 Fab expression vector was efficiently expressed in the 27C7 strain. Results: The 2 7C7 strain transformed with Fab expression vector was expressed and cultured. The Fab fragment with CD20-specific binding activity was isolated and purified. The competitive immunofluorescence inhibition assay showed that Fab fragment expressed competitively inhibited murine CD20 antibody HI47 and CD20 expressing cells Raji cells. CONCLUSION: Fab fragments of active anti-CD20 chimeric antibody are efficiently secreted and expressed in E. coli.