Intradermal CpG-B activates both plasmacytoid and myeloid dendritic cells in the sentinel lymph node of melanoma patients.

Purpose: A decrease in the frequency and activation state of dendritic cells in the sentinel lymph node (SLN) has been observed in early stages of melanoma development. This may hinder the generation of effective antitumor T-cell responses and increase the likelihood of metastatic spread. Immunopotentiation of the melanoma SLN may therefore be a valuable adjuvant treatment option.

Leukemia-specific T-cell reactivity induced by leukemic dendritic cells is augmented by 4-1BB targeting.

Purpose: Acute myelogenous leukemia (AML) blasts are able to differentiate into leukemia-derived dendritic cells (AML-DC), thereby enabling efficient presentation of known and unknown leukemic antigens. Advances in culture techniques and AML-DC characterization justify clinical application. However, additional measures are likely needed to potentiate vaccines and overcome the intrinsic tolerant state of the patients' immune system.

A CD34(+) human cell line model of myeloid dendritic cell differentiation: evidence for a CD14(+)CD11b(+) Langerhans cell precursor.

The study of early events in dendritic cell (DC) differentiation is hampered by the lack of homogeneous primary cell systems that allow the study of cytokine-driven, transitional DC differentiation steps. The CD34(+) acute myeloid leukemia cell line MUTZ-3 displays a unique ability to differentiate into interstitial DC (IDC) and Langerhans cells (LC) in a cytokine-dependent manner. Phenotypic characterization revealed MUTZ-3 to consist of three distinct subpopulations.

Immunomodulation of the melanoma sentinel lymph node: a novel adjuvant therapeutic option.

Cutaneous melanoma is the most aggressive type of skin cancer. Paradoxically, melanoma is also the most immunogenic tumour identified to date: tumour-reactive T cells are detectable both in the blood and in tumour-draining lymph nodes (TDLN) of melanoma patients and their frequency can be increased by specific vaccination. However, early melanoma development is accompanied by impaired immune effector functions in the initial TDLN, the sentinel lymph node (SLN).

Intradermal delivery of adenoviral type-35 vectors leads to high efficiency transduction of mature, CD8+ T cell-stimulating skin-emigrated dendritic cells.

Recombinant adenovirus (Ad) type 35 (rAd35) shows great promise as vaccine carrier with the advantage of low pre-existing immunity in human populations, in contrast to the more commonly used rAd5 vector. The rAd35 vector uses CD46 as a high-affinity receptor, which, unlike the rAd5 receptor, is expressed on human dendritic cells (DC), the most powerful APCs identified to date. In this study, we show that in contrast to rAd5, rAd35 infects migrated and mature CD83+ cutaneous DC with high efficiency (up to 80%), when delivered intradermally in an established human skin explant model.

A postmigrational switch among skin-derived dendritic cells to a macrophage-like phenotype is predetermined by the intracutaneous cytokine balance.

Migration of dendritic cells (DC) to secondary lymphoid organs under proinflammatory conditions coincides with their maturation and acquisition of T cell stimulatory abilities. In contrast, impaired activation of DC, e.g.

Tumor-specific CD8+ T cell reactivity in the sentinel lymph node of GM-CSF-treated stage I melanoma patients is associated with high myeloid dendritic cell content.

Purpose: Impaired immune functions in the sentinel lymph node (SLN) may facilitate early metastatic events during melanoma development. Local potentiation of tumor-specific T cell reactivity may be a valuable adjuvant treatment option.

Experimental Design: We examined the effect of locally administered granulocyte/macrophage-colony stimulating factor (GM-CSF) on the frequency of tumor-specific CD8+ T cells in the SLN and blood of patients with stage I melanoma.

Dendritic cells require multidrug resistance protein 1 (ABCC1) transporter activity for differentiation.

Dendritic cells (DC) express the ATP-binding cassette (ABC) transporters P-glycoprotein (ABCB1) and multidrug resistance protein 1 (MRP1; ABCC1). Functionally, both these transporters have been described to be required for efficient DC and T cell migration. In this study, we report that MRP1 activity is also crucial for differentiation of DC.

Constitutively active STAT5b induces cytokine-independent growth of the acute myeloid leukemia-derived MUTZ-3 cell line and accelerates its differentiation into mature dendritic cells.

The CD34(+) human acute myeloid leukemia-derived cell line MUTZ-3 is dependent on hematopoietic growth factors for its proliferation and is able to differentiate into dendritic cells (DCs) in response to the combination of granulocyte-macrophage colony-stimulating factor, interleukin-4, and tumor necrosis factor-alpha. This cell line carries human leukocyte antigen (HLA)-A2.1, HLA-A3, and HLA-B44, which cover most of the caucasian population, and it could therefore be used as an off-the-shelf allogeneic DC-based vaccine.

In vitro priming of tumor-specific cytotoxic T lymphocytes using allogeneic dendritic cells derived from the human MUTZ-3 cell line.

The adoptive transfer of in vitro-induced and expanded tumor-specific cytotoxic T lymphocytes (CTL) presents a promising immunotherapeutic approach for the treatment of cancer. The in vitro induction of tumor-reactive CTL requires repeated stimulation of CTL precursors with dendritic cells (DC). To circumvent problems like scarcity of blood DC precursors and donor variability, it would be attractive to use DC from a non-autologous, unlimited source.

Matched skin and sentinel lymph node samples of melanoma patients reveal exclusive migration of mature dendritic cells.

Mature and immature myeloid dendritic cells (DCs) are thought to differentially modulate T-cell responses in secondary lymphoid tissues. Although mature DCs are believed to induce T-cell activation under proinflammatory conditions, immature DCs are believed to maintain a state of T-cell tolerance under steady state conditions. However, little is known about the actual activation state of human DCs under these different conditions.

A single-component CD40-targeted adenovirus vector displays highly efficient transduction and activation of dendritic cells in a human skin substrate system.

Dendritic cell (DC) based tumor vaccination usually involves the administration of ex vivo generated autologous DC. Transduction of DC by viral vectors in vivo has been proposed as a more standardized and easily clinically applicable approach. Previously, we have reported that an Ad5 vector targeted to CD40 via genetic capsid incorporation of CD40L achieves selective transduction of DC in vitro.

High efficiency transduction of dendritic cells by adenoviral vectors targeted to DC-SIGN.

Dendritic cells (DCs) are a central element in the development of antigen-specific immune responses. The lack of a specific and efficient technique for the in vivo delivery of antigens to DCs remains a major obstacle limiting a vaccine's ability to induce an effective immune response. The efficacy of adenoviral (Ad) vectors in this regard can be enhanced through alterations in vector tropism such that DC-targeted transduction is achieved.

Circulating Valpha24+Vbeta11+ NKT cell numbers and dendritic cell CD1d expression in hepatitis C virus infected patients.

CD1d-restricted natural killer T (NKT) cells are involved in the regulation of various immune responses, and have been shown to inhibit viral replication in animal hepatitis models when activated by the glycolipid alpha-galactosylceramide (alpha-GalCer, KRN7000). Previous studies have indicated that alpha-GalCer-induced activation of the immune system requires both CD1d expression by antigen-presenting cells as well as (normal) numbers of NKT cells. Discrepancies exist over circulating numbers of human invariant Valpha24+Vbeta11+ NKT cells during hepatitis C virus (HCV) infection.

Local administration of granulocyte/macrophage colony-stimulating factor increases the number and activation state of dendritic cells in the sentinel lymph node of early-stage melanoma.

The initial tumor-draining lymph node, the sentinel lymph node, not only constitutes the first expected site of micrometastasis but also the first point of contact between tumor-associated antigens and the adaptive immune system. A tumor-induced decrease in the frequency and activation state of sentinel lymph node dendritic cells will impair the generation of effective antitumor T-cell responses and increase the likelihood of metastatic spread. Here, we demonstrate that intradermal administration of granulocyte macrophage-colony stimulating factor around the excision site of stage I primary melanoma tumors increases the number and activation state of dendritic cells in the paracortical areas of the sentinel lymph node and enhances their binding to T cells.

CD40-targeted adenoviral gene transfer to dendritic cells through the use of a novel bispecific single-chain Fv antibody enhances cytotoxic T cell activation.

Adenoviral (Ad) transduction of dendritic cells (DC) is a promising vaccination strategy. However, clinical applicability of Ad vectors is hampered by the necessity to use high titers of infectious Ad particles for efficient DC transduction. Here, we report on the production of a bacterially expressed bispecific conjugate, consisting of a fusion of recombinant single-chain (sc) mAb Fv fragments, which bind and neutralize the Ad fiber knob (through the S11 mAb scFv) and retarget Ad to CD40 on the DC surface (through the G28-5 mAb scFv).

Serum-free generation of antigen presenting cells from acute myeloid leukaemic blasts for active specific immunisation.

Purpose: Immunotherapy holds promise as a new strategy for the eradication of residual cells in acute myeloid leukaemia (AML). Leukaemic antigen presenting cells (APCs) combining optimal antigen presentation and tumour antigenicity could be used as potent T cell activators. For clinical purposes it is desirable to culture APCs under serum-free conditions.

Prolonged maturation and enhanced transduction of dendritic cells migrated from human skin explants after in situ delivery of CD40-targeted adenoviral vectors.

Therapeutic tumor vaccination with viral vectors or naked DNA, carrying the genetic code for tumor-associated Ags, critically depends on the in vivo transduction of dendritic cells (DC). Transfection of predominantly nonprofessional APC and only small numbers of DC may hamper proper T cell activation. Aim of this study was, therefore, the targeted, selective, and enhanced in situ transduction of DC.

Expansion of dendritic cell precursors from human CD34(+) progenitor cells isolated from healthy donor blood; growth factor combination determines proliferation rate and functional outcome.

CD34(+) haematopoietic progenitor cells, which circulate at extremely low frequencies in peripheral blood, are used to generate dendritic cells (DC) in vitro. Here, we describe a method to grow large numbers of DC precursors from these low frequent cells. Different combinations of early acting haematopoietic growth factors supported expansion of CD34(+) cells.

Sampling tumor-draining lymph nodes for phenotypic and functional analysis of dendritic cells and T cells.

Immune responses against tumor antigens will initially occur in the first tumor-draining lymph node, the sentinel node (SN). Because of extensive diagnostic procedures, obtaining a piece of SN to isolate viable immune cells for functional analyses is often impossible. For this reason an alternative method to obtain viable cells from a lymph node (LN) was investigated, ie, scraping LNs with a surgical blade, and compared with dissociation of total LNs.

MUTZ-3, a human cell line model for the cytokine-induced differentiation of dendritic cells from CD34+ precursors.

Many human myeloid leukemia-derived cell lines possess the ability to acquire a dendritic cell (DC) phenotype. However, cytokine responsiveness is generally poor, requiring direct manipulation of intracellular signaling mechanisms for differentiation. In contrast, the CD34+ human acute myeloid leukemia cell line MUTZ-3 responds to granulocyte macrophage- colony-stimulating factor (GM-CSF), interleukin 4 (IL-4), and tumor necrosis factor alpha (TNFalpha), cytokines known to be pivotal both in vivo and in vitro for DC generation from monocytes and CD34+ stem cells.

Prostanoids play a major role in the primary tumor-induced inhibition of dendritic cell differentiation.

Production of immunosuppressive factors is one of the mechanisms by which tumors evade immunosurveillance. Soluble factors hampering dendritic cell (DC) development have recently been identified in culture supernatants derived from tumor cell lines. In this study, we investigated the presence of such factors in 24-h culture supernatants from freshly excised solid human tumors (colon, breast, renal cell carcinoma, and melanoma).

Immunologic and biologic properties of the primary tumor during prolonged neoadjuvant chemoimmunotherapy.

Patients with locally advanced cancers have a poor prognosis when treated with radiotherapy and/or surgery alone. The appearance of distant metastases shortly after removal of the primary tumor indicates that micrometastases are already present at the time of diagnosis. We observed a favorable outcome in patients with locally advanced breast cancer treated with a prolonged regimen of neoadjuvant chemotherapy plus granulocyte-macrophage colony-stimulating factor (GM-CSF[Leukine]) compared with patients receiving fewer chemotherapy cycles prior to surgery and radiotherapy.

Up-regulation of drug resistance-related vaults during dendritic cell development.

P-glycoprotein (Pgp) and vaults are associated with multidrug resistance in tumor cells, but their physiological functions are not yet clear. Pgp, the prototypical transmembrane transporter molecule, may also facilitate the migration of skin dendritic cells (DC). Vaults--ribonucleoprotein cell organelles, frequently overexpressed in Pgp-negative drug-resistant tumor cells--have also been associated with intracellular transport processes.

Human papillomavirus type 16 E2-specific T-helper lymphocyte responses in patients with cervical intraepithelial neoplasia.

T-cell-mediated immune responses against mucosal oncogenic types of human papillomaviruses (HPV) are thought to play a role in the control of the virus infection and its associated cervical lesions. The in vitro production of interleukin-2 by T-helper (Th) cells in response to the C-terminal and N-terminal domains of the HPV-16 E2 protein was determined in 74 women with cytological evidence of premalignant cervical epithelial neoplasia who participated in a non-intervention follow-up (FU) study. Cross-sectional analysis at the end of FU showed that Th cell responses against the C-terminal domain were associated with evidence of previous or present HPV-16 infection as compared to patients with no evidence of any HPV infection (18.