The application discloses a multifunctional immunoregulatory
fusion protein, a preparation method thereof, NK cells expressing the
protein and application of the
protein. The
fusion protein structure is anti-CD16a VHH-(GGGGS)3-anti-NKG2D VHH-(EAAAK)2-IL-15R beta super
agonist peptide, and the
amino acid sequence is SEQ ID NO:1. The anti-CD16a VHH and the anti-NKG2D VHH synergistically activate
immune effector cells, the IL-15R beta super
agonist peptide strongly activates
effector cells and weakly activates Tregs, and the
linker ensures that the functions of the domains are independent. The
protein can be efficiently prepared, the yield is 155 mg / L, the purity is higher than 95%, the NK cells and CD8 + T cells can be significantly activated, the 24h
lysis rate of the protein on various
tumor cells reaches 87.0%-90.0%
in vitro, the
tumor growth is significantly inhibited
in vivo, the inhibition rate is 81.3%, and the
survival period of tumor-bearing mice is prolonged by more than 60 days. The stability of the NK cells expressing the protein is improved after being treated by MI-3, and the protein provides a high-efficiency and safe candidate
drug for tumor
immunotherapy.