IL-15 enhances the in vivo antitumor activity of tumor-reactive CD8+ T cells - PubMed (original) (raw)

. 2004 Feb 17;101(7):1969-74.

doi: 10.1073/pnas.0307298101. Epub 2004 Feb 4.

Steven E Finkelstein, Deborah R Surman, Michael K Lichtman, Luca Gattinoni, Marc R Theoret, Navrose Grewal, Paul J Spiess, Paul A Antony, Douglas C Palmer, Yutaka Tagaya, Steven A Rosenberg, Thomas A Waldmann, Nicholas P Restifo

Affiliations

IL-15 enhances the in vivo antitumor activity of tumor-reactive CD8+ T cells

Christopher A Klebanoff et al. Proc Natl Acad Sci U S A. 2004.

Abstract

IL-15 and IL-2 possess similar properties, including the ability to induce T cell proliferation. However, whereas IL-2 can promote apoptosis and limit CD8(+) memory T cell survival and proliferation, IL-15 helps maintain a memory CD8(+) T cell population and can inhibit apoptosis. We sought to determine whether IL-15 could enhance the in vivo function of tumor/self-reactive CD8(+) T cells by using a T cell receptor transgenic mouse (pmel-1) whose CD8(+) T cells recognize an epitope derived from the self/melanoma antigen gp100. By removing endogenous IL-15 by using tumor-bearing IL-15 knockout hosts or supplementing IL-15 by means of exogenous administration, as a component of culture media or as a transgene expressed by adoptively transferred T cells, we demonstrate that IL-15 can improve the in vivo antitumor activity of adoptively transferred CD8(+) T cells. These results provide several avenues for improving adoptive immunotherapy of cancer in patients.

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Figures

Fig. 1.

Fig. 1.

Exogenous IL-15 enhances the in vivo antitumor activity of tumor-reactive CD8+ T cells. WT mice bearing 13-d established s.c. B16 tumors were sublethally irradiated and left untreated as controls (⋄) or received adoptive transfer of 1 × 106 pmelIL2 cells and rFPhgp100 vaccination (▴). In addition to cells and vaccine, indicated groups also received exogenous administration of either rhIL-2 (○) or rhIL-15 (▪) at doses of 12 μg (A) 36 μg (B), or 108 μg (C). Data shown are representative of four independent experiments.

Fig. 2.

Fig. 2.

Endogenous IL-15, but not IL-2, enhances the in vivo antitumor activity of adoptively transferred CD8+ T cells. WT, IL-15–/–, and IL-2–/– mice bearing 14-d s.c. B16 tumors received sublethal irradiation and were left untreated as controls or given a triple regimen of 6 × 106 pmelIL2 cells, rFPhgp100 vaccine, and exogenous IL-2 (36 μg per dose). Tumors grew similarly in untreated WT (⋄), IL-15–/– (□), and IL-2–/– (▵) controls. (A) The treatment effect of the combined immunotherapy regimen is impaired in IL-15–/– hosts (▪) relative to WT controls (○). (B) Treatment in IL-2–/– hosts (▴) is similar to that of WT controls (•). Data shown are representative of two independent experiments.

Fig. 3.

Fig. 3.

pmel-1 splenocytes differentially polarize either to a TEM-orTCM-like population when cultured in IL-2 or IL-15, respectively. Splenocytes from a pmel-1 Tg mouse were primed with 1 μM hgp10025–33 peptide and cultured in culture media containing 10 ng/ml rhIL-2 or 10 ng/ml rhIL-15. On d 7, FACS analysis for surface expression of the activation markers CD25, CD44, and CD69 and the lymph node homing markers CD62L and CCR7 was performed. Naïve pmel-1 cells were obtained from splenocytes of an age-matched littermate. Results from a representative experiment are shown after gating on propidium iodide-negative and CD8+ T cells.

Fig. 4.

Fig. 4.

Tumor/self-reactive CD8+ T cells cultured in IL-15 or IL-2 polarize to two functionally distinct populations with unique in vitro and in vivo functions. IFN-γ (A), TNF-α (B), IL-10 (C), and IL-2 (D) production by CD8-enriched pmel-1 splenocytes (▴), pmelIL2 (○), and pmelIL15 (▪) cells cocultured for 24 h with EL-4 pulsed with titrated doses of hgp10025–33 peptide. Data shown are representative of at least two independent coculture experiments. (E) Quantitative RT-PCR for IL-2 mRNA in CD8-enriched pmel-1 splenocytes (gray bar), pmelIL2 (open bar), and pmelIL15 cells (black bar) after a 6-h coculture with EL-4 targets pulsed with 1 × 10–7 M hgp10025–33. Data shown are representative of three independent experiments. (F) pmelIL15 cells at d 8 are less cytolytic than pmelIL2 cells directed against hgp10025–33 pulsed MCA-205 targets. Data shown are representative of three independent cytolytic assays. (G) Absolute number of adoptively transferred cells on d 6 in the blood of tumor-bearing, sublethally irradiated WT mice from groups treated with rFPhgp100, IL-2 (36 μg per dose), and 1 × 106 pmelIL2 cells (open bar) or pmelIL15 cells (filled bar). Data shown are mean ± SEM of three mice per group and represent the global maximum in cell number for groups receiving pmelIL2 and pmelIL15 cells. Similar results were also observed in the spleens of treated animals (data not shown). This experiment was performed twice with similar results.

Fig. 5.

Fig. 5.

IL-15-cultured tumor-reactive CD8+ T cells treat established B16 melanoma with enhanced efficacy compared with IL-2-cultured cells. WT mice bearing 14-d established s.c. B16 tumors were sublethally irradiated and either were left untreated as controls (⋄) or received adoptive transfer of 1 × 106 pmel-1 cells cultured in 10 ng/ml rhIL-2 (•) or 10 ng/ml rhIL-15 (▪), rFPhgp100 vaccination, and exogenous IL-2 (36 μg per dose). Tumor area (A) and survival (B) in mice receiving pmelIL2 or pmelIL15 cells, rFPhgp100 vaccination, and exogenous IL-2 compared with untreated controls. Data shown are representative of three independent experiments.

Fig. 6.

Fig. 6.

Forced expression of IL-15 by adoptively transferred CD8+ T cells enhances their in vivo antitumor function. (A) FACS analysis for surface expression of CD122 (IL-2 and IL-15Rβ) and CD44 on CD8+ T cells derived from a pmel-IL-15 double Tg mouse or an age-matched pmel-1 single Tg littermate. Percentages shown represent the percentage of gated cells within the respective quadrant. Results from one representative experiment are shown after gating on propidium iodide-negative and CD8+ T cells. (B) WT mice were inoculated with s.c. B16 melanoma, and 14 d later they received adoptive transfer of 5 × 106 pmel-1 or pmel-IL-15 splenocytes, rFPhgp100 vaccination, and exogenous IL-2 (36 μg per dose) or were left untreated as controls. In addition to tumor size, groups that received pmel-IL-15 splenocytes, rFPhgp100, and IL-2 survived significantly longer (P = 0.0016) compared with groups that received pmel-1 splenocytes, rFPhgp100, and IL-2 (data not shown). Data shown are representative of four independent experiments.

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