Fig. 6: Tumor-reactive lymphocyte capture by pAPCs for adoptive cell therapy and neoantigen identification.

A Schematic illustration showing the application of pAPC-mediated lymphocyte capture for improving adoptive T cell therapy. T cells were collected from E.G7-OVA burdened mice receiving ICB therapy, which were expanded for 7 days prior to antigen-specific T cell capture. After expansion, all the T cells underwent isolation by OVA_257–264-loaded pMHC-beads or pAPCs prior to adoptive cell therapy in a E.G7-OVA tumor challenge. B Representative flow cytometric scatter plot showing H-2Kb OVA_257–264-tetramer⁺ CD8⁺ T cells before and after lymphocyte isolation by either pMHC-beads or pAPCs. C Quantification of H-2Kb OVA_257–264-tetramer⁺ CD8⁺ T cells from 4 independent tumor burdened hosts before and after lymphocyte isolation with OVA_257–264-loaded pMHC-beads or pAPCs (Independent biological replicates n = 4). D Evaluation of in vitro tumor-killing capacity of T cells captured with pAPC, pMHC-beads, and non-enriched T cells against E.G7-OVA in various effector-to-target cells (E/T) ratio (Independent biological replicates n = 3). E Tumor growth following adoptive T cell therapy. Mice were inoculated with 5 × 10⁴ E.G7-OVA and received 2 × 10⁶T cells on the following day. The error bars represent mean ± standard error of the mean (SEM). P values from left to right, *p = 0.0156, **p = 0.0023, **p = 0.0074 (n = 6). F Tumor survival curve from (E). Progression-free survival was defined as the time from 5 × 10⁴ E.G7-OVA inoculation until the tumor volume exceeded 500 mm³. Gehan-Breslow-Wilcoxon test were performed. P value from left to right, *p = 0.0349, **p = 0.0015, **p = 0.0017. G Schematic illustration showing the application of pAPCs for capture and identification of neoantigen-specific T cells. T cells collected from MC38-burdened mice receiving ICB therapy underwent lymphocyte capture with Adpgk-loaded, Reps1-loaded pAPCs or control pAPCs with peptide loading. H–K The isolated cells were then stained with neoantigen-specific tetramers for analysis. Flow cytometric analysis of H2-Db Adpgk tetramer-positive T cells (H, I) and H2-Db Resp1 tetramer-positive T cells (J, K) among T cells pools following different preparation protocol. Dashed line indicates detection limit as determined by the average value of tetramer⁺ T cells from non-tumor-burdened mice plus 3 standard deviations. P values from (I) left to right, *p = 0.0373, *p = 0.0374, **p = 0.0073. P values from (K) left to right, *p = 0.0302, *p = 0.0144, *p = 0.0163 (Independent biological replicates n = 5 in naïve mice, n = 8 in the other groups). The error bars represent mean ± standard deviation except in (E). Statistical analyses were performed by two-sided Student’s t tests.