Extended Data Fig. 4: Capsular polysaccharides of LpIMB19 are primary effector molecules.
a, Frequency of IFNγ+CD8 T cells co-cultured with PBS or live or heat-killed LpIMB19-treated APCs. Naïve CD8 T cells were co-cultured, for 72 hrs with CD11c+ splenic APCs treated as indicated. (n = 3 biological replicates). b, Tumor progression in mice treated with PBS (n = 6 mice) or Live LpIMB19 (n = 6 mice) or heat-killed LpIMB19 (n = 7 mice). c, Transmission electron micrographs of LpIMB19. The presence of a thick capsule around the bacillus is shown. d-f, Frequency of IFN-γ+CD8 T cells, co-cultured with APCs treated with different concentrations of LpIMB19 derived capsular polysaccharide (CPS), membrane-associated proteins, and cell wall peptidoglycans (d) (n = 4 biological replicates); or secreted exo-polysaccharides (EPS) (e) (n = 4 biological replicates); and increasing concentrations of CPS (f) (n = 3 biological replicates). g, CPS biosynthesis gene cluster depicting genes present in LpIMB19 in comparison to type strain L. plantarum WCSF1. LpIMB19 harbors partial cluster 1 with rhamnose synthesis gene rmlC, rmlB, and rmlD and cluster 4, evolutionarily conserved in L. plantarum. Results are pooled from three (a), two (b, d, f) or four (e) independent experiments. Data are Mean ± SEM (a, b, d-f). Statistical analyses were performed by one-way ANOVA with Tukey’s multiple comparison test (a, d-f) or two-way ANOVA (b).
