Mage-3 and Influenza-Matrix Peptide-Specific Cytotoxic T Cells Are Inducible in Terminal Stage HLA-A2.1+ Melanoma Patients by Mature Monocyte-Derived Dendritic Cells

143

104

Dendritic cells produce IL-12 both in response to microbial stimuli and to T cells, and can thus skew T cell reactivity toward a Th1 pattern. We investigated the capacity of dendritic cells to elaborate IL-12 with special regard to their state of maturation, different maturation stimuli, and its regulation by Th1/Th2-influencing cytokines. Monocyte-derived dendritic cells were generated with GM-CSF and IL-4 for 7 days, followed by another 3 days ± monocyte-conditioned media, yielding mature (CD83+/dendritic cell-lysosome-associated membrane glycoprotein+) and immature (CD83−/dendritic cell-lysosome-associated membrane glycoprotein−) dendritic cells. These dendritic cells were stimulated for another 48 h, and IL-12 p70 was measured by ELISA. We found the following: 1) Immature dendritic cells stimulated with CD154/CD40 ligand or bacteria (both of which concurrently also induced maturation) secreted always more IL-12 than already mature dendritic cells. Mature CD154-stimulated dendritic cells still made significant levels (up to 4 ng/ml). 2) Terminally mature skin-derived dendritic cells did not make any IL-12 in response to these stimuli. 3) Appropriate maturation stimuli are required for IL-12 production: CD40 ligation and bacteria are sufficient; monocyte-conditioned media are not. 4) Unexpectedly, IL-4 markedly increased the amount of IL-12 produced by both immature and mature dendritic cells, when present during stimulation. 5) IL-10 inhibited the production of IL-12. Our results, employing a cell culture system that is now being widely used in immunotherapy, extend prior data that IL-12 is produced most abundantly by dendritic cells that are beginning to respond to maturation stimuli. Surprisingly, IL-12 is only elicited by select maturation stimuli, but can be markedly enhanced by the addition of the Th2 cytokine, IL-4.

Section: Augmenting Effects Of Il-4: Relevancesupporting

confidence: 69%

Production of IL-12 by Human Monocyte-Derived Dendritic Cells Is Optimal When the Stimulus Is Given at the Onset of Maturation, and Is Further Enhanced by IL-4

Ebner¹,

Ratzinger²,

Krösbacher³

et al. 2001

143

104

“…With increased understanding of the requirements for initiating immunity, dendritic cells (DCs) 3 have become attractive vectors for immunotherapy of this and other cancers (2)(3)(4)(5)(6)(7)(8)(9). DCs are proving to be effective in initiating and expanding immune responses in humans (10,11), providing a rationale for their use as adjuvants for active immunization against melanoma (12)(13)(14)(15)(16). Different strategies have been developed to load DCs with tumor Ags, including MHC-restricted synthetic peptides derived from the Ag (12)(13)(14)(15)(16)(17), tumor RNA (18,19), tumor lysates (20), tumor-derived exosomes (21), and dying tumor cells (22)(23)(24)(25)(26); these have been assessed in preclinical models and, in some cases, clinical trials (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)…”

mentioning

confidence: 99%

“…DCs are proving to be effective in initiating and expanding immune responses in humans (10,11), providing a rationale for their use as adjuvants for active immunization against melanoma (12)(13)(14)(15)(16). Different strategies have been developed to load DCs with tumor Ags, including MHC-restricted synthetic peptides derived from the Ag (12)(13)(14)(15)(16)(17), tumor RNA (18,19), tumor lysates (20), tumor-derived exosomes (21), and dying tumor cells (22)(23)(24)(25)(26); these have been assessed in preclinical models and, in some cases, clinical trials (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26). Tumor cells (dying cells or Ab-coated tumor cells) are of interest as an antigenic source, because the DCs would have the potential to present a broad range of tumor-associated Ags and on both MHC class I and II products regardless of the MHC haplotype of the patient (27)(28)(29)(30).…”

mentioning

confidence: 99%

Dendritic Cells Charged with Apoptotic Tumor Cells Induce Long-Lived Protective CD4+ and CD8+ T Cell Immunity against B16 Melanoma

Goldszmid

Idoyaga

Bravo³

et al. 2003

177

143

Dendritic cells (DCs) are potent APCs and attractive vectors for cancer immunotherapy. Using the B16 melanoma, a poorly immunogenic experimental tumor that expresses low levels of MHC class I products, we investigated whether DCs loaded ex vivo with apoptotic tumor cells could elicit combined CD4+ and CD8+ T cell dependent, long term immunity following injection into mice. The bone marrow-derived DCs underwent maturation during overnight coculture with apoptotic melanoma cells. Following injection, DCs migrated to the draining lymph nodes comparably to control DCs at a level corresponding to ∼0.5% of the injected inoculum. Mice vaccinated with tumor-loaded DCs were protected against an intracutaneous challenge with B16, with 80% of the mice remaining tumor-free 12 wk after challenge. CD4+ and CD8+ T cells were efficiently primed in vaccinated animals, as evidenced by IFN-γ secretion after in vitro stimulation with DCs loaded with apoptotic B16 or DCs pulsed with the naturally expressed melanoma Ag, tyrosinase-related protein 2. In addition, B16 melanoma cells were recognized by immune CD8+ T cells in vitro, and cytolytic activity against tyrosinase-related protein 2180–188-pulsed target cells was observed in vivo. When either CD4+ or CD8+ T cells were depleted at the time of challenge, the protection was completely abrogated. Mice receiving a tumor challenge 10 wk after vaccination were also protected, consistent with the induction of tumor-specific memory. Therefore, DCs loaded with cells undergoing apoptotic death can prime melanoma-specific helper and CTLs and provide long term protection against a poorly immunogenic tumor in mice.

“…Because of the demonstrable host immune response to melanoma and the current understanding of tumor immunology, vaccine therapy is being investigated as a therapeutic strategy for melanoma (7)(8)(9)(10)(11)(12)(13). Dendritic cells (DCs) 3 are the most potent APCs, highly specialized to prime T cell-dependent Ag-specific immune responses (14 -17).…”

mentioning

confidence: 99%

Host Absence of CCR5 Potentiates Dendritic Cell Vaccination

Ng-Cashin

Kuhns

Burkett

et al. 2003

Previous work has shown that dendritic cells (DCs) express specific chemokine receptors that allow for coordinated movement in vivo. To test the in vivo relevance of this, we used a murine melanoma system and knockout mice to investigate the function of the chemokine receptor CCR5 and its ligands, CCR ligand (CCL)3 and CCL5. We found that the lack of CCR5 in the host mouse resulted in delayed tumor growth, but this effect was overcome at a higher tumor load. With the administration of tumor charged DCs, CCR5−/− mice that had previously been injected with tumor were completely protected from tumor. This effect was dependent on the dose of tumor cells and the expression of CCR5 on the DC and its absence in the host. In contrast, the loss of the CCR5 ligand, CCL3, led to an early delay in tumor growth that did not persist, while the absence of the CCR5 ligand, CCL5, had no effect. Blocking the activity of CCR5 in the host may represent a new strategy for enhancing the activity of a therapeutic melanoma DC vaccine.