目的：构建以IL-3为靶向、力达霉素（lidamycin，LDM）为弹头的融合蛋白IL-3-LDM，观察其对多种CD123+白血病细胞的靶向杀伤作用。 方法: 原核表达IL-3-LDP（interleukin 3-lidamycin）融合蛋白，组装活性烯二炔（active enediyne，AE）发色团得到IL-3-LDM。流式细胞术检测不同白血病细胞系（KG1-a、TF-1、M07e、HL-60、K562、Raji）表面CD123分子的表达，并检测融合蛋白IL-3-LDM与各白血病细胞的结合能力；CCK-8检测IL-3-LDM融合蛋白对不同CD123阳性率的白血病细胞的杀伤能力。 结果: 组装活性发色团得到的IL-3-LDM蛋白纯度可达90%以上。急性髓系白血病（acute myeloid leukemia，AML）KG-1a细胞表面CD123阳性率最高（88.9%），其次为MO7e和TF-1细胞（＞75%），再次为HL-60细胞（7.8%），而K562、Raji细胞CD123表达呈阴性。体外IL-3-LDM融合蛋白对CD123+白血病细胞(KG-1a、MO7e、TF-1和HL-60细胞）的结合能力和杀伤效率与细胞表面CD123的阳性率成正比，对于CD123表达率最高的KG-1a细胞，LDM的杀伤强度是多柔比星（adriamycin, ADR)的1 415.8倍，而IL-3-LDM 的杀伤强度又是LDM的9.6倍。 结论: IL-3-LDM融合蛋白可以有效携带细胞毒药物LDM 并高效靶向杀伤CD123+白血病细胞。

Objective: To construct a fusion protein IL-3-lidamycin(IL-3-LDM) with an IL-3 guide and a LDM warhead, and to investigate its targeting cytotoxicity on CD123+ leukemia cells in vivo. Methods: IL-3-LDP (interlekin 3-lidamycin) fusion protein was obtained in a prokaryotic system, and further assembled with active enediyne (AE) to get IL-3-LDM. The expression of CD123 in six leukemia cell lines (KG1-a, TF-1, M07e, HL-60, K562, Raji) was detected by flow cytometry and the binding ability of IL-3-LDM with different leukemia cell lines was examined. The cytotoxicity of IL-3-LDM fusion protein on leukemia cells with different CD123 expression levels was detected by CCK-8. Results: The purity of recombinant protein IL-3-LDM was more than 90% after assembling with AE. The results showed that the CD123 expression ratio was 88.9% on AML (acute myeloid leukemia) KG-1a cells, ＞75% on MO7e and TF-1 cells, 7.8% on HL-60 cells, and negative on K562 and Raji cells. The expression ratio of CD123 on leukemia cells （KG-1a, MO7e, TF-1 and HL-60）was positively related to its binding ability and sensitivity to IL-3-LDM in vitro. The cytotoxicity of LDM on KG-1a cells which expressed the highest level of CD133 was 1 415.8 fold stronger than that of adriamjcin (ADR), and the cytotoxicity of IL-3-LDM was 9.6 fold than that of LDM. Conclusion: IL-3-LDM fusion protein can effectively target cytotoxic drug LDM to kill CD123+ leukemia cells.

国家自然科学基金资助项目（No. 30971291）；天津市科技发展计划资助项目（No. 05YFGZGX02800）