Melanoma immunotherapy by targeted IL-2 depends on CD4+ T-cell help mediated by CD40/CD40L interaction
Holger N. Lode, Rong Xiang, Ursula Pertl, Elisabeth Förster, Stephen P. Schoenberger, Stephen D. Gillies, Ralph A. Reisfeld
Holger N. Lode, Rong Xiang, Ursula Pertl, Elisabeth Förster, Stephen P. Schoenberger, Stephen D. Gillies, Ralph A. Reisfeld
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Melanoma immunotherapy by targeted IL-2 depends on CD4+ T-cell help mediated by CD40/CD40L interaction

Abstract

The induction of tumor-protective immunity against malignancies remains a major challenge in cancer immunotherapy. A novel, humanized anti-ganglioside-GD2–IL-2 immunocytokine (hu14.18–IL-2) induced CD8+ T cells to eradicate established pulmonary metastases of B78-D14 murine melanoma, in a process that required help by CD4+ T cells and was mediated by the CD40/CD40 ligand (CD40L) interaction. The anti-tumor effect was diminished in mice deficient in CD4+ T-cells. Three lines of evidence show that CD4+ T-cell help was mediated by CD40/CD40L interaction but not by endogenous IL-2 production. First, the hu14.18–IL-2–induced anti-tumor response is partially abrogated in C57BL/6J CD40L knockout (KO) mice in contrast to C57BL/6J IL-2 KO animals, in which the immunocytokine was completely effective. Second, partial abrogation of the anti-tumor effect is induced with anti-CD40L antibodies to the same extent as with CD4+ T-cell depletion. Third, a complete anti-tumor response induced by hu14.18–IL-2 can be reconstituted in C57BL/6J CD40L KO mice by simultaneous stimulation with an anti-CD40 mAb. These results suggest that help provided by CD4+ T cells via CD40/CD40L interactions in our tumor model is crucial for effective immunotherapy with an IL-2 immunocytokine.

Authors

Holger N. Lode, Rong Xiang, Ursula Pertl, Elisabeth Förster, Stephen P. Schoenberger, Stephen D. Gillies, Ralph A. Reisfeld

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T-cell activation after hu14.18–IL-2 and anti-CD40 therapy of establishe...
T-cell activation after hu14.18–IL-2 and anti-CD40 therapy of established pulmonary melanoma metastases. Increase in the proportion of CD8+ T cells characterized by elevated CD69 and CD25 expression was investigated in mice bearing established pulmonary metastases (resulting from 1.25 × 106 B78-D14 2.34 cells injected intravenously) after therapy with hu14.18–IL-2 and anti-CD40. Treatment was initiated 4 days after tumor-cell inoculation by daily intravenous administration of either 20 μg hu14.18–IL-2 or PBS for 5 days, or a single intraperitoneal injection with 200 μg anti-CD40 mAb. Depletion of CD4+ T cells was accomplished as described in Methods. One group of six mice was not injected with B78-D14 2.34 cells (naive control). Four days after completion of the treatment, mice were euthanized, and splenocytes were subjected to FACS® analysis for CD69/CD8 and CD25/CD8 double-positive T cells. Bars represent mean and SD of five mice per group. Findings between experimental groups and all control groups were statistically significant (AP < 0.05, BP < 0.01, CP < 0.001).