Fig. 3: biNV-IL-15 for multivalent IL-15 self-transpresentation (MIST) and secondary lymphoid organ accumulation.

a Schematic depicting biNV-IL-15 to activate CD8⁺ T cells and stimulate their proliferation. b The direct activation of splenic CD8⁺ T cells harvested from BALB/c mice, 2 × 10⁵ cells were coincubated with various formulations (DC vesicles, IL-15, biNV, IL-15+biNV, and biNV-IL-15) for 7 d. HCP isolated from 4T1 (c–e) and CT26 (f–h) tumor tissue was used for DC priming and DC vesicle isolation for T cell activation, respectively. c, f ELISPOT analysis of IFN-γ and TNF-α spot-forming cells (n = 3/group). Cytolysis rate against 4T1 (d) and CT26 (g) cancer cells with T cells after various activations. The cytolysis efficiency was measured through LDH-releasing cytotoxic assay with effector-to-target cell (E:T) ratios of 5:1, 10:1, 20:1, and 40:1 (n = 3/group). The statistical analysis was performed at the E:T ratio of 40: 1. e, h The flow cytometric detection and mean fluorescence intensity (MFI) of T lymphocyte proliferation with CFSE staining after various treatments (n = 4/group). i Pharmacokinetic profiles of Cy7-labeled IL-15 and biNV-IL-15 by assessing the fluorescence of Cy7 in blood samples at predetermined time points (n = 3/group). j Fluorescence imaging and k quantitative analysis of isolated organs, axillary and inguinal LNs after intravenous injection of Cy7-labeled IL-15 and biNV-IL-15 (n = 3/group). Data represent the mean ± s.d. The p values of biNV-IL-15 to biNV in panels c–h are <0.0001. And the p values of biNV-IL-15 to IL-15+biNV in panels c–h are <0.0001, 0.0004, 0.0002, <0.0001, 0.0001, <0.0001, <0.0001, and <0.0001, respectively. Statistical significance was calculated through one-way ANOVA using a Tukey post-hoc test. Source data underlying panels c–i, k are provided as a Source Data file.