Characterization of monocyte-derived IFNalpha-generated dendritic cells

Identification of CD56dim subpopulation marked with high expression of GZMB/PRF1/PI-9 in CD56+ interferon-α-induced dendritic cells

As the sentinels of innate and adaptive immune system, dendritic cells (DCs) have been considered to hold a great promise for medical application. Among the diverse types of DCs, monocyte-derived DCs (mo-DCs) generated in vitro have been most commonly employed. We have been improving the culture protocol and devised a protocol to produce mature interferon-α-induced DCs (IFN-DCs), hereinafter called (mat)IFN-DCs. While exploring the relationship between the expression of CD56 and the cytotoxic activity of (mat)IFN-DCs, we unexpectedly found that sorting of (mat)IFN-DCs with CD56 antibody-coated microbeads (MB) resulted in fractionating cells with tumoricidal activity into the flow-through (FT) but not MB-bound fraction. We uncovered that the FT fraction contains cells expressing low but substantial level of CD56. Moreover, those cells express granzyme B (GrB), perforin (PFN), and serpin B9 at high levels. By employing a specific inhibitor of PFN, we confirmed that direct tumoricidal activity relies on the GrB/PFN pathway. We designated subpopulation in FT fraction as CD56^dim and that in CD56 positively sorted fraction as CD56^bright , respectively. This is the first time, to our knowledge, to identify subpopulations of CD56-positive IFN-DCs with distinct tumoricidal activity which is ascribed to high expression of the components of GrB/PFN pathway.

Maturation inside and outside bone marrow dendritic cells (BMDCs) modulated by interferon-α (IFN-α)

Interferons are made by cells in response to appropriate stimuli such as viruses, bacteria, parasites or tumor cells and are released into the surrounding medium. They then bind to receptors on target cells to allow for communication between cells to trigger the protective defenses of the immune system that eradicate pathogens or tumors. IFN-α is produced by leukocytes and is mainly involved in innate immune response against viral or bacterial infections and for tumor control. The aim of this work is to explore the detailed modulation of IFN-α on phenotypic and functional maturation inside and outside murine bone marrow derived dendritic cells (BMDCs). The maturity of BMDCs post treatment with IFN-α was evaluated with conventional light microscope and transmission electron microscopy (TEM) for morphology changes; flow cytometry (FCM) for changes of surface molecules on BMDCs; cytochemistry, acid phosphatase activity (ACP) test, and FITC-dextran bio-assay for biochemistry analysis and enzyme-linked immunosorbent assay (ELISA) for cytokine production by BMDCs. We have shown that IFN-α 1) up-regulates the expression of MHC II, CD40, CD83, CD80 and CD86 molecules on BMDCs; 2) down-regulates the rates of pinocytosis and phagocytosis by BMDCs as evidenced by the results of decreased ACP, and FITC-dextran bio-assay; 3) enhances the ability of BMDCs to drive T cell function; and 4) induces higher levels of IL-12 and TNF-α secreted by BMDCs. Therefore, we conclude that IFN-α can efficiently promote the maturation of BMDCs through detailed modulation inside and outside BMDCs. Our study has provided more detailed data on changes of BMDCs modulated by IFN-α, and rationale on future application of IFN-α for enhancing host immunity and potent adjuvant administration in the design of DC-based vaccines.

Advances in cellular therapy for the treatment of thyroid cancer

Up to now, there are no curative therapies available for the subset of metastasized undifferentiated/anaplastic thyroid carcinomas. This review describes the possible use of immunocompetent cells which may help to restore the antitumor immune recognition for treating an existing tumor or preventing its recurrence. The most prominent experimental strategy is the use of dendritic cells (DCs) which are highly potent in presenting tumor antigens. Activated DCs subsequently migrate to draining lymph nodes where they present antigens to naïve lymphocytes and induce cytotoxic T cells (CTL). Alternatively to DC therapy, adoptive cell transfer may be performed by either using natural killer cells or ex vivo maturated CTLs. Within this review article we will focus on recent advances in the understanding of anti-tumor immune responses, for example, in thyroid carcinomas including the advances which have been made for the identification of potential tumor antigens in thyroid malignancies.

Dendritic cell immunotherapy for HIV infection: from theory to reality

Knowledge concerning the immunology of dendritic cells (DCs) accumulated over the last few decades and the development of methodologies to generate and manipulate these cells in vitro has made their therapeutic application a reality. Currently, clinical protocols for DC-based therapeutic vaccine in HIV-infected individuals show that it is a safe and promising approach. Concomitantly, important advances continue to be made in the development of methodologies to optimize DC acquisition, as well as the selection of safe, immunogenic HIV antigens and the evaluation of immune response in treated individuals.

Survival and migration of human dendritic cells are regulated by an IFN-alpha-inducible Axl/Gas6 pathway

Axl, a prototypic member of the transmembrane tyrosine kinase receptor family, is known to regulate innate immunity. In this study, we show that Axl expression is induced by IFN-alpha during human dendritic cell (DC) differentiation from monocytes (IFN/DC) and that constitutively Axl-negative, IL-4-differentiated DC (IL-4/DC) can be induced to up-regulate Axl by IFN-alpha. This effect is inhibited by TLR-dependent maturation stimuli such as LPS, poly(I:C), TLR7/8 ligand, and CD40L. LPS-induced Axl down-regulation on the surface of human IFN-alpha-treated DC correlates with an increased proteolytic cleavage of Axl and with elevated levels of its soluble form. GM6001 and TAPI-1, general inhibitors of MMP and ADAM family proteases, restored Axl expression on the DC surface and diminished Axl shedding. Furthermore, stimulation of Axl by its ligand, Gas6, induced chemotaxis of human DC and rescued them from growth factor deprivation-induced apoptosis. Our study provides the first evidence that Gas6/Axl-mediated signaling regulates human DC activities, and identifies Gas6/Axl as a new DC chemotaxis pathway. This encourages one to explore whether dysregulation of this novel pathway in human DC biology is involved in autoimmunity characterized by high levels of IFN-alpha.