Enhancement of vaccine-mediated antitumor immunity in cancer patients after depletion of regulatory T cells.
In this study, we investigated whether elimination of CD4+/CD25+ Tregs using the recombinant IL-2 diphtheria toxin conjugate DAB(389)IL-2 (also known as denileukin diftitox and ONTAK) is capable of enhancing the immunostimulatory efficacy of tumor RNA-transfected DC vaccines. We show that DAB(389)IL-2 is capable of selectively eliminating CD25-expressing Tregs from the PBMCs of cancer patients without inducing toxicity on other cellular subsets with intermediate or low expression of CD25. DAB(389)IL-2-mediated Treg depletion resulted in enhanced stimulation of proliferative and cytotoxic T cell responses in vitro but only when DAB(389)IL-2 was omitted during T cell priming. DAB(389)IL-2 significantly reduced the number of Tregs present in the peripheral blood of metastatic renal cell carcinoma (RCC) patients and abrogated Treg-mediated immunosuppressive activity in vivo. Moreover, DAB(389)IL-2-mediated elimination of Tregs followed by vaccination with RNA-transfected DCs significantly improved the stimulation of tumor-specific T cell responses in RCC patients when compared with vaccination alone. Our findings may have implications in the design of immune-based strategies that may incorporate the Treg depletion strategy to achieve potent antitumor immunity with therapeutic impact.
Duke Scholars
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Related Subject Headings
- Transfection
- Time Factors
- T-Lymphocytes, Regulatory
- T-Lymphocytes
- Reverse Transcriptase Polymerase Chain Reaction
- Receptors, Interleukin-2
- RNA, Neoplasm
- RNA
- Neoplasms
- Neoplasm Metastasis
Citation
Published In
DOI
ISSN
Publication Date
Volume
Issue
Start / End Page
Location
Related Subject Headings
- Transfection
- Time Factors
- T-Lymphocytes, Regulatory
- T-Lymphocytes
- Reverse Transcriptase Polymerase Chain Reaction
- Receptors, Interleukin-2
- RNA, Neoplasm
- RNA
- Neoplasms
- Neoplasm Metastasis