Fig 1: Anti-tumor effects of IL7-Fc in non-lymphopenic and lymphopenic conditions. (A) C57BL/6 mice were subcutaneously implanted with 2 × 105 B16-F10 melanoma cells in their backs. Mice were i.p. injected with the indicated dose of CTX to induce prior lymphodepletion on day 3. Activated pmel-1 Thy1.1+CD8+ T cells were prepared by isolating CD8+ T cells from Thy1.1+pmel-1 Tg mice and stimulating them with 5 µg/mL of human gp100 peptide in the presence of 5% CD8-depleted splenocytes for 2 days, and transferred into mice on day 5 via the i.v. route. All mice received 25,000 IU of rhIL-2 daily for 6 days. Human IgG (hIgG) or IL7-Fc was also injected daily into mice for 6 days. (B) The growth rate of B16-F10 melanoma. (C) Flow cytometric analysis of tumor-draining lymph nodes (TDLNs) and tumor tissues. Single cell suspensions were prepared from inguinal TDLNs and tumor tissues on days 13 and 19, and stained with anti-CD8-PE-Cy5 and anti-Thy1.1-FITC. All samples were further stained with propidium iodide (PI) and subsequently analyzed using FACSCalbur (BD Bioscience). Live cells were gated and plotted as the indicated markers. (D) Absolute numbers of TDLN cells were calculated using ADAM-MC2 (Nanoentek, Seoul, Korea). Absolute numbers of Thy1.1+CD8+ T cells were calculated from TDLN cell numbers and the percentages of Thy1.1+CD8+ T cells. Percentages of transferred pmel-1 Thy1.1+CD8+ T cells and endogenous Thy1.1-CD8+ T cells in tumor tissues were calculated from (C). CTX; cyclophosphamide, mpk; mg per Kg. Data are from three (B) or two (C,D) independent experiments with 5 (B) or 3 (C,D) mice per experiment. Student’s t-test was performed in D, and the results are expressed as mean ± SD (* p < 0.05; ** p < 0.01; *** p < 0.005).