Fig. 6: The antigen-binding affinities and specificities of WT and PCP-modified CARs.

a Purified WT and PCP-modified antibodies stained with Coomassie Blue. HC, heavy chain; LC, light chain. b, c Antigen-binding activities of WT and PCP-modified antibodies measured by a cell-based FACS assay using antigen-positive cell lines. Nalm6 cells were used for CD19 antibodies (b), and GD2⁺Nalm6 cells were used for GD2 antibodies (c). EC₅₀, half maximal effective concentration. Data are presented as means with 95% confidence intervals. d Binding activities of GD2^WT and GD2^F4 antibodies against 100 synthetic glycans detected using the glycan array. e Biotin-labeled surface proteins on CD19⁺K562 cells enriched by CD19 antibodies. Cell surface proteins were biotinylated and immunoprecipitated using CD19^WT or CD19^M1 antibodies, followed by detection via Streptavidin-HRP blot. WT K562 cells were included as a negative control. IP, immunoprecipitation. f Binding activities of WT and PCP-modified antibodies against a panel of human cells. MFI, Mean fluorescence intensity. g Schematic model illustrating rational improvement of tonic signaling strength and CAR-T cell fitness.