目的：研究阿糖胞苷(cytarabine，AraC)对白血病细胞共刺激分子B7表达的影响，以及联合双功能抗体antiCD3/antiPgp介导T细胞对耐药白血病细胞的杀伤作用。方法：应用流式细胞术检测白血病细胞株K562和多药耐药白血病细胞株K562/A02细胞经AraC刺激不同时间后B71、B72分子的表达，RTPCR方法检测B71mRNA、B72 mRNA的表达，MTT法检测经AraC刺激的K562和K562/A02细胞对T淋巴细胞增殖的影响。CytoTox 96非放射性细胞毒性分析检测AraC联合antiCD3/antiPgp微型双功能抗体对人外周血淋巴细胞杀伤K562和K562/A02靶细胞的影响。结果：经AraC刺激的K562和K562/A02细胞B71、B72分子的表达较对照组明显升高；MTT结果显示，经AraC刺激的K562和K562/A02细胞能促进T淋巴细胞增殖；AraC联合antiCD3/antiPgp双功能抗体在0.39∶1~25∶1效靶比范围内，随着效靶比的升高，介导T淋巴细胞对K562和K562/A02细胞的杀伤率随之提高，对高表达Pgp的耐药K562/A02细胞尤为明显。结论：AraC可上调白血病细胞B7分子的表达，从而增强antiCD3/antiPgp双功能抗体介导的T细胞对靶细胞的体外杀伤作用。

Objective:To observe the effects of cytarabine (AraC) on B7 expression on leukemia cells, and to study the effects of antiCD3/antiPgp bispecific antibody on the cytotoxicity of T cells against drugresistant leukemia cells. Methods：The expressions of B71 and B72 on K562 (leukemia cells) and K562/A02 cells (drugresistant leukemia cells) were examined by flow cytometry after treatment with AraC for different periods. B71 and B72 mRNA expressions in K562 and K562/A02 cells were detected by RTPCR. The proliferation of T lymphocytes stimulated by AraCtreated K562 and K562/A02 cells was detected by MTT assay. In vitro cytotoxicity of T lymphocytes against K562 and K562/A02 cells was analyzed using CytoTox 96 nonradioactive method after treatment with antiCD3/antiPgp bispecific antibody and AraC. Results:Compared with untreated cells, B71 and B72 expression on AraCtreated K562 and K562/A02 cells was significantly enhanced. MTT results showed that AraCtreated K562 and K562/A02 cells increased the proliferation of T lymhocytes. AraC combined with antiCD3/antiPgp bispecific antibody enhanced the cytotoxicity of T cells against K562 and K562/A02 target cells (T∶target, 0.39∶125∶1), especially when against Pgp positive drugresistant K562/A02 leukemia cells. Conclusion: AraC can upregulate B7 expression on leukemia cells, and when combined with antiCD3/antiPgp bispecific antibody it can enhance the cytotoxicity of T cells against target leukemia cells in vitro.

国家自然科学基金资助项目（No. 30701012）；天津市科技计划资助项目（No. 08ZCKFSH04100）；天津市应用基础研究计划资助项目（No. 07JCZDJC04900）