PD-15 fusion protein specifically targeting PD-1 molecule combined with G15Ra-K562 feeder cells to rapidly expand NK/T cells / 中华微生物学和免疫学杂志

ABSTRACT

Objective:To investigate the ability of the anti-PD-1(scFv)/hIL-15 fusion protein(PD-15) to specifically bind to PD-1 in vitro and the effect of the combination of PD-15 with GF-hIL-15Ra-K562(G15Ra-K562) feeder cells to expand NK/T cells. Methods:Overlap PCR was used to construct G15Ra expression vector. pMXs-G15Ra-IP was transfected into K562 by electroporation. G15Ra-K562 feeder cell lines were obtained by limiting dilution method. pUC57-PD-15 was constructed by digestion and ligation. Lipofectamine? 2000 was used to transiently transfect pUC57-PD-15 into HEK293T cells and the conditioned medium containing PD-15 fusion protein was obtained. Density gradient centrifugation was used to obtain human peripheral blood mononuclear lymphocytes(PBMC), and CFSE staining was used to mark active proliferating cells. Flow cytometry was used to detect the ability of PD-15 to specifically bind to PD-1 and its effect on the proliferation of human PBMC and the proportion of different subpopulations of lymphocytes.Results:The feeder cells G15Ra-K562 with high expression of fusion protein G15Ra was successfully constructed. The addition of hIL-15 can increase the ability of G15Ra-K562 to expand human PBMC by more than 5 times( P<0.05). PD-15 fusion protein has PD-1 specific binding ability( P<0.001), combined with G15Ra-K562 can efficiently expand human peripheral blood-derived NK/T cells in vitro( P<0.05). The cells expanded by PD-15 and G15Ra-K562 are mainly natural killing cell, CD8 + T and CD4 + T cells. Conclusions:The PD-15 fusion protein can specifically target the PD-1 molecule and has a strong human peripheral blood-derived NK/T cell expansion ability when combined with G15Ra-K562 feeder cells. These results shed light on selective expansion of PD-1 + lymphocytes in vitro.