Fig. 1: α-melittin-NPs efficiently flow into the LN and stimulate the activation of APCs.

a Fluorescence images of excised LNs from C57BL/6 mice (n = 4 per group) subcutaneously injected with 20 nmol FITC-melittin, FITC-α-peptide-NPs, and FITC-α-melittin-NPs (quantification was based on the FITC content). ILN, inguinal lymph node. ALN, axillary lymph node. Time points: 3 h and 6 h. b, c Representative histograms (b) and percentages (c) of FITC⁺ RBC at 3 h after s.c. injection (n = 4 biologically independent samples). PLT, platelets. RBC, red blood cell. d, e Flow cytometry (d) and immunofluorescence analysis (e) of the uptake of FITC-melittin, FITC-α-peptide-NPs, and FITC-α-melittin-NPs by the immune cells in ILNs at 3 h after s.c. injection. Blue and magenta represent F4/80⁺ macrophages and CD11c⁺ DCs, respectively, in upper panel and represent CD3⁺ T cells and B220⁺ B cells, respectively, in lower panel. Green represents FITC-labeled melittin, α-peptide-NPs, and α-melittin-NPs. Representative images from three independent experiments are shown. Scale bar, 10 μm. f, g Representative flow cytometry plots (f) and quantitative data (g) for CD80 and CD86 expression on macrophages and DCs in ILNs (n = 4 per group) at 24 h after s.c. injection with 35 nmol melittin, α-peptide-NPs, and α-melittin-NPs (quantification was based on the peptide content). The histograms on the right show the percentage of activated APCs. Data are shown as the mean ± SEM. n.s. not significant, **P < 0.01, ***P < 0.001, and ****P < 0.0001, as analyzed by one-way ANOVA with Bonferroni’s post hoc test (c, d, g). Source data are provided as a Source Data file.