FIGURE 1.

Characterization of self-delivered α-PD-1 scFv. (A) Schematic structure of secretory α-PD-1 scFv. (B) Sequences of signal peptides tested. (C) 293T cells were transfected with vectors coding His-tagged α-PD-1 scFv with different leading signals. 48 h later, the supernatants and 293T cells were separately collected and subjected to western blot analysis. (D) The expressions of interested proteins in the supernatants were measured according to gray-values using ImageJ software. Then relative expressions to Secrecon were calculated. (E) PD-1+ or PD-1- 293T cells were incubated with the supernatants from 293T cells expressing α-PD-1 scFv. Then the binding of scFv to cells having different PD-1 expressions were detected with AF488-labeled His tag-specific antibody. Data shown were representative of three independent experiments. *** indicates P < 0.001.