Fig. 3
The stronger local CD8+ T cell response seen with combinatorial ACT is largely the result of endogenous T cell recruitment. Seven days after tumor inoculation, Ly5.2+ mice were treated with 105 Teff, 105 Tmem, or 5 × 104 Teff + 5 × 104 Tmem derived from Ly5.1+ mice. Melanoma tumors were resected 4 or 14 days after ACT and TIL were harvested for flow cytometric analysis. (a) Representative data demonstrate higher percentages of Ly5.1+/CD8+ T cells in tumors after memory and combinatorial ACT. (b) Analysis of total numbers of Ly5.1+/CD8+ T cell populations showed that significant and durable infiltration of adoptively transferred cells was observed after memory ACT; combinatorial ACT, which used half the number of adoptively transferred Tmem as memory ACT, resulted in smaller numbers of intratumoral Ly5.1+/CD8+ T cells. (c) Analysis of total numbers of Ly5.2+/CD8+ T cell populations showed that memory ACT resulted in a significant recruitment of endogenously-derived CD8+ T cells that persisted on day 14; despite using half the number of Tmem, combinatorial ACT also resulted in durable infiltration of endogenously-derived CD8+ T cells. This experiment was repeated twice with similar results, 4–5 mice per group. (* p < 0.05 compared with control condition; † p < 0.05 compared with day 4)