Fusion protein, CD19-targeted CAR and application thereof

The invention belongs to the technical field of tumor cell immunotherapy, and particularly relates to a fusion protein, a CD19-targeted CAR thereof and its application. The fusion protein is SIRP gamma fusion protein and comprises an extracellular fragment, a transmembrane structure and an intracellular signal region. The fusion protein and a CD19-targeted CAR structure are connected to jointly or independently transfect immune cells, the activity of the immune cells in a hypoxia environment is enhanced, the tumor microenvironment is reversed, the influence of inhibitory signals in tumor tissues on the CAR-T function is broken, the effectiveness of CAR-T treatment is achieved, and meanwhile certain safety can be guaranteed. 本发明属于肿瘤细胞免疫治疗技术领域，具体涉及一种融合蛋白及其靶向CD19的CAR及其应用。所述融合蛋白为SIRPγ融合蛋白，包含胞外段、跨膜结构和胞内信号区。该融合蛋白和靶向CD19的CAR结构连接共同或单独转染免疫细胞,该免疫细胞在缺氧环境下活性增强，而且以逆转肿瘤微环境，破除肿瘤组织中抑制性信号对CAR-T功能的影响，实现了CAR-T治疗有效性，同时能够保证一定的安全性。