Figure 1.
Systemic administration of poly-ICLC elicits antitumor effects accompanied with enhanced CD8 T cell tumor infiltrates. (A) Lewis lung carcinoma (LLC) tumor growth in mice after poly-IC stabilized with poly-lysine and carboxymethylcellulose (PICLC) treatment. Wild-type (WT) mice were subcutaneously inoculated on day 0 with 5×105 LLC cells, injected intravenously, intramuscularly or intratumorally with 50 µg PICLC on days 9, 14 and 19 and tumor growth was monitored. Data are shown as tumor average size±SD; n=5 mice per group. ****P<0.0001 (two-way analysis of variance (ANOVA)). (B) B16F10 growth in dendritic cell (DC)-depleted bone marrow chimeric mice. CD45.1 WT mice were irradiated and reconstituted with bone marrow cells from CD11cDTR mice. Two months later, mice were inoculated subcutaneously on day 0 with 3×105 B16F10 cells and treated intravenously with 50 μg PICLC on days 9, 14 and 19 plus 200 µg αPD-L1 monoclonal antibody (mAb) on days 10, 13 and 17 post-tumor inoculation. DCs were depleted in one group by injecting DT 100 ng/mouse on days −2 and 0 of each PICLC injection and the tumor growth was monitored. Data are shown as tumor size±SD; n=5 mice per group. ****P<0.0001 (two-way ANOVA). (C, D) CD8+ T cells and myeloid-derived suppressor cells (MDSCs) infiltration in the tumor after PICLC treatment. (C) Similar experiment to (A), except tumors were harvested 24 hours after the last PICLC injection, dissociated and the percentages of CD8+ T and CD11b+Gr1+ cells of the CD45+/MHC-II-negative populations were assessed in the single cell suspensions. Bars are shown as mean±SD; n=3 mice per group. *P<0.05 by Mann-Whitney unpaired test. (D) Similar experiment to (B), except that 24 hours after the last PICLC injection the percentages of CD8+ T and CD11b+Gr1+ cells were assessed in the single cell suspension. Bars are shown as mean±SD; n=3 mice per group. **P<0.01 by Mann-Whitney unpaired test. ns, not significant.