Generation and preclinical characterization of an NKp80-Ig fusion protein for redirection of NK cell against leukemia

【作者】 邓刚； 郑晓东； 魏海明； 田志刚； 孙汭；

【机构】 中国科学技术大学免疫学研究所；

【摘要】 Backgroud:The capability of NK cells to mediate Fc-receptor dependent effector functions like ADCC largely contributes to the clinical application.However,few antibodies targeting leukemia cells are yet available or effective so far.Aim:Given that AICL,an NKp80 ligand,is frequent highly expressed on malignant AML and CML cells and the lack of therapeutic AICL-specific antibodies,we aimed to explore a strategy to reinforce NK anti-leukemia reactivity by combining induction of NK cell ADCC with targeting AICL-expressing leukemia cells using NKp80-Ig fusion proteins.Methods:The binding tests using flow cytometry indicated NKp80-Fc chimera specifically bound to leukemia cell lines,which expressed substantial level of AICL,in a target antigen-specific and dose-dependent manner.Moreover,cell binding assays between NK and leukemia cells displayed that NKp80-Fc significantly increased NK-target cell conjugates.In functional analyses of NK and leukemia cells,treatment with NKp80-Fc clearly induced NK cell ADCC effect.Cell apop-tosis and lysis assays showed that the fusion proteins not only promoted NK-mediated target cell apoptosis in the early stage of cell conjugation,but also enhanced NK cell degranulation and cytotoxicity activity in a target-antigen dependent manner in the relatively late stage of cell conjugation.Results:The bifunctional recombinant fusion protein re-directed NK cells towards leukemia cells by binding to both,tumor cells and NK cells,and triggered NK cell-mediated target cell killing in vitro.Conclusion:Taken together,our results demonstrate that NKp80-Fc fusion proteins can effectively target AICL-expressing leukemia cells for NK anti-tumor reactivity despite the inevitable reduction of activating signals upon binding to AICL.The fusion proteins may thus constitute an attractive means for immunotherapy of leukemia.更多还原

【Abstract】 Backgroud:The capability of NK cells to mediate Fc-receptor dependent effector functions like ADCC largely contributes to the clinical application.However,few antibodies targeting leukemia cells are yet available or effective so far.Aim:Given that AICL,an NKp80 ligand,is frequent highly expressed on malignant AML and CML cells and the lack of therapeutic AICL-specific antibodies,we aimed to explore a strategy to reinforce NK anti-leukemia reactivity by combining induction of NK cell ADCC with targeting AICL-expressing leukemia cells using NKp80-Ig fusion proteins.Methods:The binding tests using flow cytometry indicated NKp80-Fc chimera specifically bound to leukemia cell lines,which expressed substantial level of AICL,in a target antigen-specific and dose-dependent manner.Moreover,cell binding assays between NK and leukemia cells displayed that NKp80-Fc significantly increased NK-target cell conjugates.In functional analyses of NK and leukemia cells,treatment with NKp80-Fc clearly induced NK cell ADCC effect.Cell apoptosis and lysis assays showed that the fusion proteins not only promoted NK-mediated target cell apoptosis in the early stage of cell conjugation,but also enhanced NK cell degranulation and cytotoxicity activity in a target-antigen dependent manner in the relatively late stage of cell conjugation.Results:The bifunctional recombinant fusion protein re-directed NK cells towards leukemia cells by binding to both,tumor cells and NK cells,and triggered NK cell-mediated target cell killing in vitro.Conclusion:Taken together,our results demonstrate that NKp80-Fc fusion proteins can effectively target AICL-expressing leukemia cells for NK anti-tumor reactivity despite the inevitable reduction of activating signals upon binding to AICL.The fusion proteins may thus constitute an attractive means for immunotherapy of leukemia.更多还原