Murine epidermal Langerhans cells mature into potent immunostimulatory dendritic cells in vitro

Schuler, G., and Steinman, R.M. Murine epidermal Langerhans cells mature into potent immunostimulatory dendritic cells in vitro. J. Exp. Med. 161: 526-546, 1985https://digitalcommons.rockefeller.edu/historical-scientific-reports/1016/thumbnail.jp

Immunologic properties of purified epidermal Langerhans cells: Distinct requirements for stimulation of unprimed and sensitized T lymphocytes

Inaba, K., Schuler, G., Witmer, M., Valinsky, J., Atassi, B., and Steinman, R.M. Immunologic properties of purified epidermal Langerhans cells: Distinct requirements for stimulation of unprimed and sensitized T lymphocytes. J. Exp. Med. 164: 605-613, 1986.https://digitalcommons.rockefeller.edu/historical-scientific-reports/1019/thumbnail.jp

Immunologic properties of purified epidermal langerhans cells: Distinct requirements for stimulation of unprimed and sensitized T lymphocytes

[No abstract available

Immediate Pigment Darkening Phenomenon. A Reevaluation of Its Mechanisms

Proposed mechanisms of immediate pigment darkening (IPD) are controversial. They include photooxidation of “premelanin,” changes in the distribution pattern of microfilaments and microtubules, movement of melanosomes to melanocyte dendrites, increased transfer of melanosomes to keratinocytes, and changes in the melanosome distribution pattern in keratinocytes. We investigated the following aspects of IPD: (1) production of IPD by UVA under physiologic and nonphysiologic conditions in full-thickness skin and epidermal sheets; (2) reversibility of IPD in vitro after in vivo and in vitro production; (3) blocking of IPD by disruption of the microfibrillar or microtubular system in vitro; (4) alterations of the cytoskeleton of melanocytes; (5) the melanosome distribution pattern in melanocytes and keratinocytes.The results were as follows: IPD could be elicited in vitro in full-thickness skin and in epidermal sheets. Its production was temperature independent (0°-37°) and was not inhibited by repeated freezing and thawing, or by formalin fixation. IPD was reversible in vitro under tissue culture conditions but only in viable skin. IPD could not be blocked by substances that disrupt the microfibrillar or microtubular system (cytochalasin B, colcemid, vincristine). As shown with a monoclonal antivimentin antibody, IPD-producing UBA doses did not induce changes in the cytoskeleton of melanocytes. No changes in number and distribution patter of melanosomes were observed electron-microscopically and by morphometric analysis of EM micrographs. Productions of IPD does not depend on the structural and functional integrity of themelanocyte cytoskeletal apparatus and is not confined to viable skin, whereas its reversibility is. The fact that no increased melanosome transfer occurs may explain the lack of a UV protective action

Induction of Interleukin 10–Producing, Nonproliferating Cd4+ T Cells with Regulatory Properties by Repetitive Stimulation with Allogeneic Immature Human Dendritic Cells

The functional properties of dendritic cells (DCs) are strictly dependent on their maturational state. To analyze the influence of the maturational state of DCs on priming and differentiation of T cells, immature CD83− and mature CD83+ human DCs were used for stimulation of naive, allogeneic CD4+ T cells. Repetitive stimulation with mature DCs resulted in a strong expansion of alloreactive T cells and the exclusive development of T helper type 1 (Th1) cells. In contrast, after repetitive stimulation with immature DCs the alloreactive T cells showed an irreversibly inhibited proliferation that could not be restored by restimulation with mature DCs or peripheral blood mononuclear cells, or by the addition of interleukin (IL)-2. Only stimulation of T cells with mature DCs resulted in an upregulation of CD154, CD69, and CD70, whereas T cells activated with immature DCs showed an early upregulation of the negative regulator cytotoxic T lymphocyte–associated molecule 4 (CTLA-4). These T cells lost their ability to produce interferon γ, IL-2, or IL-4 after several stimulations with immature DCs and differentiated into nonproliferating, IL-10–producing T cells. Furthermore, in coculture experiments these T cells inhibited the antigen-driven proliferation of Th1 cells in a contact- and dose-dependent, but antigen-nonspecific manner. These data show that immature and mature DCs induce different types of T cell responses: inflammatory Th1 cells are induced by mature DCs, and IL-10–producing T cell regulatory 1–like cells by immature DCs

The future of affordable cancer immunotherapy

The treatment of cancer was revolutionized within the last two decades by utilizing the mechanism of the immune system against malignant tissue in so-called cancer immunotherapy. Two main developments boosted cancer immunotherapy: 1) the use of checkpoint inhibitors, which are characterized by a relatively high response rate mainly in solid tumors; however, at the cost of serious side effects, and 2) the use of chimeric antigen receptor (CAR)-T cells, which were shown to be very efficient in the treatment of hematologic malignancies, but failed to show high clinical effectiveness in solid tumors until now. In addition, active immunization against individual tumors is emerging, and the first products have reached clinical approval. These new treatment options are very cost-intensive and are not financially compensated by health insurance in many countries. Hence, strategies must be developed to make cancer immunotherapy affordable and to improve the cost-benefit ratio. In this review, we discuss the following strategies: 1) to leverage the antigenicity of “cold tumors” with affordable reagents, 2) to use microbiome-based products as markers or therapeutics, 3) to apply measures that make adoptive cell therapy (ACT) cheaper, e.g., the use of off-the-shelf products, 4) to use immunotherapies that offer cheaper platforms, such as RNA- or peptide-based vaccines and vaccines that use shared or common antigens instead of highly personal antigens, 5) to use a small set of predictive biomarkers instead of the “sequence everything” approach, and 6) to explore affordable immunohistochemistry markers that may direct individual therapies

Human CD4+CD25+ Regulatory, Contact-dependent T Cells Induce Interleukin 10–producing, Contact-independent Type 1-like Regulatory T Cells

It has been recently demonstrated that regulatory CD4+CD25+ CD45RO+ T cells are present in the peripheral blood of healthy adults and exert regulatory function similar to their rodent counterparts. It remains difficult to understand how the small fraction of these T cells that regulate via direct cell-to-cell contact and not via secretion of immunosuppressive cytokines could mediate strong immune suppression. Here we show that human CD4+CD25+ T cells induce long-lasting anergy and production of interleukin (IL)-10 in CD4+CD25− T cells. These anergized CD4+CD25− T cells then suppress proliferation of syngenic CD4+ T cells via IL-10 but independent of direct cell contact, similar to the so-called type 1 regulatory T (Tr1) cells. This ‘catalytic’ function of CD4+CD25+ T cells to induce Tr1-like cells helps to explain their central role for the maintenance of immune homeostasis

Human Cutaneous Dendritic Cells Migrate Through Dermal Lymphatic Vessels in a Skin Organ Culture Model

The capacity to migrate from peripheral tissues, where antigen is encountered, to lymphoid organs, where the primary immune response is initiated, is crucial to the immunogenic function of dendritic cells (DC). The skin is a suitable tissue to study migration. DC were observed to gather in distinct nonrandom arrays (“cords”) in the dermis upon culture of murine whole skin explants. It is assumed that cords represent lymphatic vessels. Using a similar organ culture model with human split-thickness skin explants, we investigated migration pathways in human skin.We made the following observations. 1) Spontaneous emigration of Langerhans cells took place in skin cultured for 1–3 d. Nonrandom distribution patterns of strongly major histocompatibility complex class II-expressing DC (cords) occurred in cultured dermis. A variable, yet high (>50%) percentage of these DC coexpressed the Birbeck granule-associated antigen “Lag” Ultrastructurally, the cells corresponded to mature DC. 2) Electron microscopy proved that the dermal structures harboring the accumulations of DC (i.e., cords) were typical lymph vessels. Moreover, markers for blood endothelia (monoclonal antibody PAL-E, Factor VIII-related antigen) and markers for cords (strong major histocompatibility complex class II expression on nonrandomly arranged, hairy-appearing cells) were expressed in a mutually exclusive pattern. 3) On epidermal sheets we failed to detect gross changes in the levels of expression of adhesion molecules (CD44, CD54/ICAM-1, E-cadherin) on keratinocytes in the course of the culture period.The reactivity of a part of the DC in the dermal cords with Birbeck granule-specific monoclonal antibody “Lag” suggests that the migratory population is composed of both epidermal Langerhans cells and dermal DC. We conclude that this organ culture model may prove helpful in resolving pathways and mechanisms of DC migration

Preclinical evaluation of NF-kappa B-triggered dendritic cells expressing the viral oncogenic driver of Merkel cell carcinoma for therapeutic vaccination

Background: Merkel cell carcinoma (MCC) is a rare but very aggressive skin tumor that develops after integration of a truncated form of the large T-antigen (truncLT) of the Merkel cell polyomavirus (MCV) into the host’s genome. Therapeutic vaccination with dendritic cells (DCs) loaded with tumor antigens is an active form of immunotherapy, which intends to direct the immune system towards tumors which express the respective vaccination antigens. Methods: Cytokine-matured monocyte-derived DCs of healthy donors and MCC patients were electroporated with mRNA encoding the truncLT. To permit major histocompatibility complex (MHC) class II next to class I presentation, we used an RNA construct in which the antigen was fused to a DCLamp sequence in addition to the unmodified antigen. To further improve their immunogenicity, the DCs were additionally activated by co-transfection with the constitutively active nuclear factor (NF)-κB activator caIKK. These DCs were used to stimulate autologous CD8 + T-cells or a mixture of CD4 + and CD8 + T-cells. Then the percentage of T-cells, specific for the truncLT, was quantified by interferon (IFN)γ ELISpot assays. Results: Both the truncLT and its DCLamp-fusion were detected within the DCs by flow cytometry, albeit the latter required blocking of the proteasome. The transfection with caIKK upregulated maturation markers and induced cytokine production. After 2–3 rounds of stimulation, the T-cells from 11 out of 13 healthy donors recognized the antigen. DCs without caIKK appeared in comparison less potent in inducing such responses. When using cells derived from MCC patients, we could induce responses for 3 out of 5 patients; however, here the caIKK-transfected DCs did not display their superiority. Conclusion: These results show that optimized DCs are able to induce MCV-antigen-specific T-cell responses. Therapeutic vaccination with such transfected DCs could direct the immune system against MCC