Figure 5. Thermo-responsive polymer particles (TRPP) permit temperature-dependent particle assembly that leads to persistent innate immune activation and protective CD8 T cell responses.

(a) Schematic of TRPP shown reversibly assembling into particles. (b) Transition temperatures (TT) were empirically determined by measuring the turbidity (OD at 490 nm) of solutions of TRPP in PBS over a range of temperatures. (c) Table summarizing the thermo-responsive properties of select TRPP. (d) TRPP-7/8a and a TRPP control were delivered subcutaneously into both hind footpads of C57BL/6 mice. Popliteal lymph nodes draining the vaccination site were harvested at 24 h (n = 6) and 72 h (n = 4) and then processed to create a cell suspension that was cultured ex vivo for 8h and then evaluated for the presence of IL-12p40 and IP-10 by ELISA. (e, f) C57BL/6 mice (n = 5) received subcutaneous administration of 50 μg of OVA alone or admixed with adjuvant at days 0 and 14. (e) Tetramer⁺ CD8 T cell responses were evaluated at day 24 (n = 5). (f) Mice were challenged intravenously at day 28 with LM-OVA and bacterial burden in spleens was evaluated on day 31 (n = 5). All data are representative of two independent experiments. Data on log scale are reported as geometric mean with 95% CI. Comparison of multiple groups for statistical significance was determined using Kruskal-Wallis ANOVA with Dunn’s post test; ns, not significant (P > 0.05); *, P < 0.05; **, P < 0.01.