Sustained activation and tumor targeting of NKT cells using a CD1d–anti-HER2–scFv fusion protein induce antitumor effects in mice
Kathrin Stirnemann, … , H. Robson MacDonald, Alena Donda
Kathrin Stirnemann, … , H. Robson MacDonald, Alena Donda
Published February 7, 2008
Citation Information: J Clin Invest. 2008;118(3):994-1005. https://doi.org/10.1172/JCI33249.
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Sustained activation and tumor targeting of NKT cells using a CD1d–anti-HER2–scFv fusion protein induce antitumor effects in mice

Abstract

Invariant NKT (iNKT) cells are potent activators of DCs, NK cells, and T cells, and their antitumor activity has been well demonstrated. A single injection of the high-affinity CD1d ligand α-galactosylceramide (αGalCer) leads to short-lived iNKT cell activation followed, however, by long-term anergy, limiting its therapeutic use. In contrast, we demonstrated here that when αGalCer was loaded on a recombinant soluble CD1d molecule (αGalCer/sCD1d), repeated injections led to sustained iNKT and NK cell activation associated with IFN-γ secretion as well as DC maturation in mice. Most importantly, when αGalCer/sCD1d was fused to a HER2-specific scFv antibody fragment, potent inhibition of experimental lung metastasis and established s.c. tumors was obtained when systemic treatment was started 2–7 days after the injection of HER2-expressing B16 melanoma cells. In contrast, administration of free αGalCer at this time had no effect. The antitumor activity of the CD1d–anti-HER2 fusion protein was associated with HER2-specific tumor localization and accumulation of iNKT, NK, and T cells at the tumor site. Targeting iNKT cells to the tumor site thus may activate a combined innate and adaptive immune response that may prove to be effective in cancer immunotherapy.

Authors

Kathrin Stirnemann, Jackeline F. Romero, Lucia Baldi, Bruno Robert, Valérie Cesson, Gurdyal S. Besra, Maurice Zauderer, Florian Wurm, Giampietro Corradin, Jean-Pierre Mach, H. Robson MacDonald, Alena Donda

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Figure 6

Activated iNKT cells retain their capacity to transactivate NK cells and promote DC maturation.

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Activated iNKT cells retain their capacity to transactivate NK cells and...
Production of IFNγ by NK cells in the same mice analyzed in Figure 5, ex vivo 20 min after an i.v. injection (A) or after in vitro rechallenge (B). NK population was gated on NK1.1 single positive cells. (A) Results are expressed as percent of IFNγ-producing NK cells. (B) Same legend as in Figure 5B. *P < 0.05; **P < 0.0006. (C) The antitumor activity is in great part lost after NK cell depletion. Three groups of mice were grafted s.c. with 700,000 B16-HER2 cells, and 2 groups were treated with the αGalCer/sCD1d–anti-HER2 fusion 7 days later when tumors were palpable. For NK cell depletion, 1 of these groups was repeatedly i.p. injected with anti-asialo–GM1 antibodies during the whole treatment with the αGalCer/sCD1d–anti-HER2 protein. Results represent the kinetic of s.c. tumor growth (in mm3) as the mean ± SD of 4 mice per group. (D) Induction of DC maturation by αGalCer/sCD1d-activated iNKT cells. Splenocytes were isolated 16 hours after the third i.v. injection of PBS (control), equimolar amounts of αGalCer (0.4 μg), or αGalCer-loaded sCD1d (25 μg). DCs were sorted with anti-CD11c magnetic beads and stained with anti-CD11c–FITC and either biotinylated with anti-CD80, anti-CD86, or anti-CD40 antibodies followed by Streptavidin-PE. Results show the 3 activation markers on gated CD11c-positive cells, and numbers indicate the percent of cells with upregulated marker.