Figure 5. IL-15Sa-NG backpacks increase the therapeutic window for adjuvant cytokine delivery during ACT.

B16F10 tumor cells (0.5 × 10⁶) were injected s.c. in Thy1.2⁺ C57Bl/6 mice and allowed to establish tumor for 6 days. Animals were then sublethally lymphodepleted by irradiation on day 6 and received i.v. adoptive transfer of 10×10⁶ activated pmel-1 Thy1.1⁺CD8⁺ T cells on day 7. Animals received sham injections of PBS, T cells only, T cells followed by different doses of i.v. injected free IL-15Sa as single dose (immediately after adoptive transfer) or split into multiple doses (days 7, 10, 13 and 16), or T cells backpacked with aCD45/IL-15Sa-NG at different doses. Body weights and systemic cytokine/chemokine/liver enzyme levels were analysed over time. (a) Experimental timeline and groups. (b) Body weight normalized to day 7 over time for different treated groups. (c-e) Counts of cytokine⁺ endogenous CD8⁺ T cells (c) and ACT CD8⁺ T cells (d) in blood analysed by intracellular cytokine staining and flow cytometry. (e, f) Serum cytokine levels (e) and liver enzymes (f) were measured from samples collected on day 17 or when the mice were euthanized due to toxicity. Data represent the mean ± s.e.m. (n=5 biologically independent animals) and are compared with control group (T cells only) for statistical analyses using One-Way ANOVA and Tukey’s tests; n.d., not detectable. Shown is one representative of two independent experiments.