Fig. 3

In vitro characterization of multimodal PD-L1 imaging tools. A SDS-PAGE analysis of the antibody formats before and after sortagging with IH18. After purification using NiNTA beads and SEC, an analytical fraction of mIgG1-IH18 and Fab-IH18 was reacted with 5 kDa mPEG-DBCO to analyze purity and azide functionality. This resulted in the near-quantitative conversion to a fluorescent product of higher molecular weight. Fab-IH18-PEG was produced through large-scale reaction of Fab-IH18 with 20 kDa mPEG-DBCO and subsequently purified using cation exchange chromatography. B Competition assay. Renca cells were incubated with a serial dilution of unlabeled anti-PD-L1 MIH5 (WT) or different antibody-conjugate (mIgG1-IH18, Fab-IH18, Fab-IH18-PEG) concentrations, as well as commercially available anti-PD-L1-PE. Data are presented as mean ± SD, n = 3