Fig. 8. The long-term immune memory in vivo elicited by antigen-loaded CC OMVs.
a Schema of immune memory analysis. C57BL/6 mice were immunized with the formulations shown in (b) on days 0, 3, and 8. Immune responses were evaluated, and the mice were challenged with B16-OVA cells (2 × 105 cells/mouse, i.v.) on days 60. Lung metastasis was analyzed on day 80. c, d Specific killing ability of splenocytes collected on day 60 toward B16-OVA cells with OVA antigen (c) and MC38 cells without OVA antigen (d) analyzed by CCK-8 assay. e, f Quantitative analysis of tetramer+ T cells in splenocytes (e) and blood (f) on day 60 through flow cytometry. g Flow cytometry analysis of IFNγ+ cytotoxic T lymphocytes in splenocytes re-stimulated with OVA257–264. h The proportion of Tem cells (CD8+CD44+CD62L−) in splenocytes on day 60 (n = 5). I, j Lungs were collected on day 80 and photographed (n = 10). k Schema of tumor rechallenge model. The mice were inoculated with B16-OVA cells and treated with CC-SpT-OVA OMVs vaccine. Then, the survived animals (complete tumor regression) were rechallenged with s.c. injection of B16-F10 and B16-OVA cells on day 60. l B16-OVA or B16-F10 tumor growth curve (B16-OVA (Control), n = 8; B16-OVA (CC-SpT-OVA OMVs), n = 8; B16-F10 (Control), n = 6; B16-F10 (CC-SpT-OVA OMVs), n = 8). The controls were healthy mice without tumor burden. The data are shown as mean ± SD. Statistical analysis was performed by a two-tailed unpaired t test. Source data are provided as a Source Data file.