Langerhans Cells Differentiation Research Articles

Sequential BMP7/TGF-β1 signaling and microbiota instruct mucosal Langerhans cell differentiation.

Mucosal Langerhans cells (LCs) originate from pre-dendritic cells and monocytes. However, the mechanisms involved in their in situ development remain unclear. Here, we demonstrate that the differentiation of murine mucosal LCs is a two-step process. In the lamina propria, signaling via BMP7-ALK3 promotes translocation of LC precursors to the epithelium. Within the epithelium, TGF-β1 finalizes LC differentiation, and ALK5 is crucial to this process. Moreover, the local microbiota has a major impact on the development of mucosal LCs, whereas LCs in turn maintain mucosal homeostasis and prevent tissue destruction. These results reveal the differential and sequential role of TGF-β1 and BMP7 in LC differentiation and highlight the intimate interplay of LCs with the microbiota.

Cbfβ2 deficiency preserves Langerhans cell precursors by lack of selective TGFβ receptor signaling.

The mouse Langerhans cell (LC) network is established through the differentiation of embryonic LC precursors. BMP7 and TGFβ1 initiate cellular signaling that is essential for inducing LC differentiation and preserving LCs in a quiescent state, respectively. Here we show that loss of Cbfβ2, one of two RNA splice variants of the Cbfb gene, results in long-term persistence of embryonic LC precursors after their developmental arrest at the transition into the EpCAM+ stage. This phenotype is caused by selective loss of BMP7-mediated signaling essential for LC differentiation, whereas TGFβR signaling is intact, maintaining cells in a quiescent state. Transgenic Cbfβ2 expression at the neonatal stage, but not at the adult stage, restored differentiation from Cbfβ2-deficient LC precursors. Loss of developmental potential in skin-residential precursor cells was accompanied by diminished BMP7-BMPR1A signaling. Collectively, our results reveal an essential requirement for the Cbfβ2 variant in LC differentiation and provide novel insight into how the establishment and homeostasis of the LC network is regulated.

Research Techniques Made Simple: Experimental Methodology for Single-Cell Mass Cytometry

Growing recognition of the complexity of interactions within cellular systems has fueled the development ofmass cytometry. The precision of time-of-flight mass spectrometry combined with the labeling of specificligands with mass tags enables detection and quantification of more than 40 markers at a single-cell resolution. The 135 available detection channels allow simultaneous study of additional characteristics of complex biological systems across millions of cells. Cutting-edge mass cytometry by time-of-flight (CyTOF) can profoundly affect our knowledge of cell population heterogeneity and hierarchy, cellular state, multiplexed signaling pathways, proteolysis products, and mRNA transcripts. Although CyTOF is currently scarcely used within the field of investigative dermatology, we aim to highlight CyTOF's utility and demystify the technique. CyTOF may, for example, uncover the immunological heterogeneity and differentiation of Langerhans cells, delineate the signaling pathways responsible for each phase of the hair cycle, or elucidate which proteolysis products from keratinocytes promote skin inflammation. However, the success of mass cytometry experiments depends on fully understanding the methods and how to control for variations when making comparisons between samples. Here, we review key experimental methods for CyTOF that enable accurate data acquisition by optimizing signal detection and minimizing background noise and sample-to-sample variation.

Effects of calcitonin gene-related peptide on functions of Langerhans cells

The regulatory effects of neuropeptides on skin immune cells in the neuroimmunomodulation process have gained more and more attention in chronic inflammatory skin diseases. Under psychentonia, stress and pressure, nerve fibers in local skin produce calcitonin gene-related peptide (CGRP)to regulate Langerhans cells, which are professional antigen-presenting cells in the epidermis. Recent studies have found that CGRP can affect not only the proliferation and differentiation of Langerhans cells, but also their antigen-presenting capacity. Moreover, CGRP can influence Langerhans cell-induced immune reactions by inhibiting the activation of nuclear factor kappa B (NF-κB)signaling pathway and expression of costimulatory molecules. Key words: Langerhans cells; Calcitonin gene-related peptide; Neuroimmunomodulation; Neuropeptides; NF-kappa B

TNF-alfa and IL-17 differently affects Langerhans cell distribution and differentiation in an innovative three dimensional model of normal human skin

TNF-alfa and IL-17 differently affects Langerhans cell distribution and differentiation in an innovative three dimensional model of normal human skin

Human blood BDCA-1 dendritic cells differentiate into Langerhans-like cells with thymic stromal lymphopoietin and TGF-β

AbstractThe ontogeny of human Langerhans cells (LCs) remains poorly characterized, in particular the nature of LC precursors and the factors that may drive LC differentiation. Here we report that thymic stromal lymphopoietin (TSLP), a keratinocyte-derived cytokine involved in epithelial inflammation, cooperates with transforming growth factor (TGF)-β for the generation of LCs. We show that primary human blood BDCA-1+, but not BDCA-3+, dendritic cells (DCs) stimulated with TSLP and TGF-β harbor a typical CD1a+Langerin+ LC phenotype. Electron microscopy established the presence of Birbeck granules, an intracellular organelle specific to LCs. LC differentiation was not observed from tonsil BDCA-1+ and BDCA-3+ subsets. TSLP + TGF-β LCs had a mature phenotype with high surface levels of CD80, CD86, and CD40. They induced a potent CD4+ T-helper (Th) cell expansion and differentiation into Th2 cells with increased production of tumor necrosis factor-α and interleukin-6 compared with CD34-derived LCs. Our findings establish a novel LC differentiation pathway from BDCA-1+ blood DCs with potential implications in epithelial inflammation. Therapeutic targeting of TSLP may interfere with tissue LC repopulation from circulating precursors.

Langerhans cells are generated by two distinct PU.1-dependent transcriptional networks

Langerhans cells (LCs) are the unique dendritic cells found in the epidermis. While a great deal of attention has focused on defining the developmental origins of LCs, reports addressing the transcriptional network ruling their differentiation remain sparse. We addressed the function of a group of key DC transcription factors-PU.1, ID2, IRF4, and IRF8-in the establishment of the LC network. We show that although steady-state LC homeostasis depends on PU.1 and ID2, the latter is dispensable for bone marrow-derived LCs. PU.1 controls LC differentiation by regulating the expression of the critical TGF-β responsive transcription factor RUNX3. PU.1 directly binds to the Runx3 regulatory elements in a TGF-β-dependent manner, whereas ectopic expression of RUNX3 rescued LC differentiation in the absence of PU.1 and promoted LC differentiation from PU.1-sufficient progenitors. These findings highlight the dual molecular network underlying LC differentiation, and show the central role of PU.1 in these processes.

Ex Vivo Generation Of Functional Plasmacytoid and Myeloid Dendritic Cells Is Strongly Promoted By The Aryl Hydrocarbon Receptor Antagonist Stemregenin 1

The prominent role of dendritic cells (DCs) in T cell activation is the rational for DC-based immunotherapy of cancer and infectious diseases. In cancer, DC therapy aims to induce tumor-specific effector T cell responses that can reduce or eliminate the tumor, and to develop immunological memory to control tumor relapse. So far, the vast majority of DC vaccination studies have been performed with DCs differentiated from monocytes (Mo-DCs) that are loaded with tumor-associated antigens (TAAs) or minor histocompatibility antigens (MiHA). This strategy has been reported to induce the expansion of antigen-specific CD4+ and/or CD8+ T cells in the majority of patients, however only a fraction of the patients develop clinical responses. Strategies to improve the potency of DC-based vaccines are to increase the stimulatory and migratory capacity of Mo-DCs, or to use alternative DC subtypes, such as naturally circulating plasmacytoid DCs (pDCs), BDCA1+ myeloid DCs (mDCs) or BDCA3+ mDCs. These DC subsets are potent inducers of antigen-specific T cell responses, and are therefore attractive cells to exploit for DC-based therapy. However, since their frequency in blood is very low, it is a challenge to obtain high enough numbers for immunotherapy. It would be advantageous if DCs, which are phenotypically and functionally similar to blood pDCs and mDCs, could be generated from CD34+ hematopoietic progenitor cells (HPCs). Interestingly, recent findings have indicated that the aryl hydrocarbon receptor (AhR) not only regulates toxic effects of environmental contaminants, but also plays a role in modulating hematopoiesis and the immune system. For instance, it has been reported that StemRegenin 1 (SR1), a small molecule inhibitor of AhR, promotes the ex vivo expansion of human CD34+ HPCs that are able to effectively engraft immunodeficient mice. Furthermore, differentiation of Langerhans cells and monocytes in vitro from HPCs can be inhibited by the addition of the AhR agonist VAF347. In light of these data, we investigated if we could generate DC subsets from CD34+ HPCs by supplementing SR1. Therefore, we cultured CD34+ HPCs in medium containing SCF, Flt3L, IL-6, TPO supplemented with 1 μM SR1 or DMSO as control. Interestingly, addition of SR1 explicitly promoted the emergence of pDCs (CD11c-HLA-DR+CD123hiBDCA2+BDCA4+ cells), BDCA1+ mDCs (Lin1-HLA-DR+BDCA1+BDCA3- cells) and BDCA3+ mDCs (Lin1-HLA-DR+BDCA1-BDCA3+ cells). After three weeks of culture, the frequency of these DC subsets was significantly higher in cultures with SR1 compared to control conditions; 2.9% vs. 0.04% for pDCs, 4.6% vs. 0.5% for BDCA1+ mDCs and 1.1% vs. 0.1% for BDCA3+ mDCs (n=3-5 donors). The average yield after three weeks of culture with SR1 starting from 105 CD34+ UCB cells was 3.8x106 pDCs, 5.3x106 BDCA1+ mDCs and 1.2x106 BDCA3+ mDCs (n=3-5 donors). Furthermore, SR1 also promoted the differentiation of DC subsets from CD34+ cells obtained from peripheral blood of G-CSF-mobilized donors. The average frequency of DCs in these SR1-cultures was 4.7%, 3.8% and 0.9% for pDCs, BDCA1+ and BDCA3+ mDCs, respectively (n=3 donors), which is comparable to the frequency obtained from UCB CD34+ cells. But the expansion potential of G-CSF-mobilized blood CD34+ HPCs was lower than that of UCB CD34+ cells, resulting in average DC yields of 0.6x106, 0.5x106 and 0.1x106 from 105 CD34+ cells (n=3). Flow cytometry analysis demonstrated that the SR1-induced pDCs and mDCs are phenotypically comparable to their naturally occurring counterpart in blood. Furthermore, the ex vivo-generated pDCs potently responded to stimulation with TLR7 and TLR9 ligands by secreting high amounts of IFN-α and upregulating CD83, CD80, CD86 and CCR7. The HPC-mDC subsets also upregulate CD80 and CD83 upon TLR3, TLR4 or TLR7/8 ligation. Finally, both the ex vivo-generated pDCs and mDCs induced potent allogeneic T cell responses and activated CD8+ effector T cells against hematopoietic-restricted MiHA. These findings demonstrate that our SR1 culture system not only allows detailed study of DC differentiation and molecular regulations in vitro, but it also offers the opportunity to evaluate the in vivo efficacy of cultured DC subsets upon vaccination into patients with cancer and viral infections. Disclosures:Spanholtz:Glycostem Therapeutics: Employment.

Identification of bone morphogenetic protein 7 (BMP7) as an instructive factor for human epidermal Langerhans cell differentiation

Human Langerhans cell (LC) precursors populate the epidermis early during prenatal development and thereafter undergo massive proliferation. The prototypic antiproliferative cytokine TGF-β1 is required for LC differentiation from human CD34(+) hematopoietic progenitor cells and blood monocytes in vitro. Similarly, TGF-β1 deficiency results in LC loss in vivo. However, immunohistology studies revealed that human LC niches in early prenatal epidermis and adult basal (germinal) keratinocyte layers lack detectable TGF-β1. Here we demonstrated that these LC niches express high levels of bone morphogenetic protein 7 (BMP7) and that Bmp7-deficient mice exhibit substantially diminished LC numbers, with the remaining cells appearing less dendritic. BMP7 induces LC differentiation and proliferation by activating the BMP type-I receptor ALK3 in the absence of canonical TGF-β1-ALK5 signaling. Conversely, TGF-β1-induced in vitro LC differentiation is mediated via ALK3; however, co-induction of ALK5 diminished TGF-β1-driven LC generation. Therefore, selective ALK3 signaling by BMP7 promotes high LC yields. Within epidermis, BMP7 shows an inverse expression pattern relative to TGF-β1, the latter induced in suprabasal layers and up-regulated in outer layers. We observed that TGF-β1 inhibits microbial activation of BMP7-generated LCs. Therefore, TGF-β1 in suprabasal/outer epidermal layers might inhibit LC activation, resulting in LC network maintenance.

Rosiglitazone promotes the differentiation of Langerhans cells and inhibits that of other dendritic cell types from CD133 positive hematopoietic precursors.

Dendritic cells and their precursors express PPAR-gamma, whose stimulation has inhibitory effects on the maturation and function of dendritic cells in vivo. Dendritic cells can differentiate in vitro from CD133+ progenitors; the influence of PPAR-gamma stimulation on this process is unknown. We have addressed the effect of PPAR-gamma agonist rosiglitazone, at a concentration as used in clinics, on the differentiation of dendritic cells from human CD133+ progenitors. Cells were harvested from cord blood by density gradient and immunomagnetic separation, and cultured for 18 days with fetal calf serum, cytokines and 1 μmol/L rosiglitazone. Analyses included flow cytometry, electron microscopy and mixed lymphocyte reaction. As expected, control cells generated without rosiglitazone were dendritic, expressed MHC-II, CD80, CD83 and CD86 and stimulated mixed reaction potently. A minority of cells expressed the Langerhans cell marker CD207/langerin, but none contained Birbeck granules. With rosiglitazone much fewer cells were generated; they were all dendritic, expressed differentiation and maturation-related antigens in higher percentage and were better stimulators of lymphocytes than those generated without the drug. The vast majority of cells expressed CD207/langerin and many contained Birbeck granules, i.e. were full-fledged Langerhans cells. We conclude that stimulation of PPAR-gamma, while negatively affecting the number of generated cells, promotes the maturation of human cord blood CD133 positive precursors into efficient, immunostimulating dendritic cells with a Langerhans cell phenotype.

β-Catenin Promotes the Differentiation of Epidermal Langerhans Dendritic Cells

The epithelial signaling protein and transcriptional regulator β-catenin has recently been implicated in hematopoietic dendritic cell (DC) differentiation as well as in DC-mediated tolerance. We here observed that epidermal Langerhans cells (LCs) but not interstitial/dermal DCs express detectable β-catenin. LCs are unique among the DC family members in that LC networks critically depend on epithelial adhesion molecules as well as on the cytokine transforming growth factor-β1 (TGF-β1). However, despite the important functions of LCs in the immune system, the molecular mechanisms governing LC differentiation and maintenance remain poorly defined. We found that TGF-β1 induces β-catenin in progenitor cells undergoing LC differentiation and that β-catenin promotes LC differentiation. Vitamin D, another epidermal signal, enhanced TGF-β1-mediated β-catenin induction and promoted the expression of multiple epithelial genes by LCs. Moreover, full-length vitamin D receptor (VDR) promoted, whereas a truncated VDR diminished, the positive effects of ectopic β-catenin on LC differentiation. Therefore, we here identified β-catenin as a positive regulator of LC differentiation in response to TGF-β1 and identified a functional interaction between β-catenin and VDR in these cells.

肺好酸球性肉芽腫症の 1 例

We here report a case of Pulmonary Langerhans cell histiocytosis (PLCH) diagnosed by imprint cytology obtained from thoracoscopic biopsy. Intraoperative tumor imprint smears showed Langerhans cells in a background with eosonophils, macrophage, and lymphocytes. Langerhans cell having noched nuclei and abundant cytoplasm with pseudopodia-like projections. The differentiation of Langerhans cells are epithelioid cells or the cells derive from epithelioid hemangioendothelioma. Langerhans cell can diagnose through the above remarks. In our case since the diagnosis of PLCH was made based upon characteristic cytological findings, cytology was useful in diagnosing PLCH.

Activin A Inhibits Antigen-Induced Allergy in Murine Epicutaneous Sensitization

Activin A, a member of the TGFβ superfamily, is involved in physiological processes such as cell differentiation, tissue homeostasis, wound healing, reproduction, and in pathological conditions, such as fibrosis, cancer, and asthma. Activin enhances mast cell maturation, as well as regulatory T-cell and Langerhans cell differentiation. In this study we investigated the potential role of activin in epicutaneous sensitization with ovalbumin (OVA), notably with respect to its effect on known Th2-polarization. For this purpose, transgenic mice overexpressing activin in keratinocytes and their wild-type (WT) controls were sensitized epicutaneously with OVA. Skin biopsies were analyzed with regard to histopathological features and mRNA expression of pro-inflammatory and Th1/Th2 cytokines, and Ig levels were measured in the serum. Unexpectedly, activin overexpressing animals were protected from Th2-cytokine expression and induction of OVA-specific IgE levels compared to WT animals. On the other hand, transgenic mice were more susceptible to inflammation compared to WT littermates after tape-stripping and saline (vehicle) or OVA application, as shown by increased pro-inflammatory cytokine mRNA levels and neutrophil accumulation at the site of the treatment. We conclude that activin protects from antigen-induced cutaneous Th2-polarization through modulation of the immune response. These findings highlight the role of activin in cutaneous sensitization, allergy, and in skin homeostasis.

Requirement of E-cadherin Interactions for Langerhans Cell Differentiation

Requirement of E-cadherin Interactions for Langerhans Cell Differentiation

E‐cadherin: From epithelial glue to immunological regulator

E-cadherin is best known as a central molecule in adherens junctions, joining adjacent epithelial cells together, thereby safeguarding epithelial barrier function. However, recent findings have uncovered an immunological role for this adhesion molecule, linked to its expression in dendritic cells (DCs) and alternatively activated macrophages (MPHs) and its impact on intracellular signaling pathways. In this respect, E-cadherin has been shown to influence the immunogenicity/tolerogenicity of DCs through the regulation of β-catenin functionality. For Langerhans cells (LCs), the DC type found in the skin epidermis, E-cadherin is known to mediate interactions with keratinocytes (KCs), thereby immobilizing immature LCs in the epidermis and preventing their maturation. In this issue of the European Journal of Immunology, a study by Mayumi et al. [Eur. J. Immunol. 2013. 43: 270-280] now describes a role for E-cadherin in the final steps of LC differentiation from human peripheral blood monocytes. Although TGF-β induces LC-like cells, these intermediates still express the dermal DC marker DC-SIGN along with Langerin; E-cadherin ligation is sufficient to induce the full LC phenotype in these cells. Here, we place these findings in the context of current knowledge and propose new avenues for future research.

E‐cadherin interactions are required for Langerhans cell differentiation

Human skin contains the following two distinct DC subsets: (i) Langerhans cells (LCs), expressing Langerin but not DC-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN), are predominantly localized in the epidermis; and (ii) dermal DCs, expressing DC-SIGN but not Langerin, are observed mainly in the dermis. It is not known whether localization in the epidermis provides cues for LC differentiation. Here, we show that E-cadherin expressed by epidermal keratinocytes (KCs) is crucial for differentiation of LCs. Monocytes differentiated into LC-like cells in presence of IL-4, GM-CSF, and TGF-β1. However, these LC-like cells expressed not only Langerin but also DC-SIGN. Notably, co-culturing of these LC-like cells with KCs expressing E-cadherin or recombinant E-cadherin strongly decreased expression of DC-SIGN and further induced a phenotype similar to purified epidermal LCs. Moreover, pretreatment of LC-like cells with anti-E-cadherin-specific antibody completely abolished their Langerin expression, indicating the requirement of E-cadherin–E-cadherin interactions for the differentiation into Langerin+ cells. These findings suggest that E-cadherin expressed by KCs provide environmental cues that induce differentiation of LCs in the epidermis.

Identification of Axl as a downstream effector of TGF-β1 during Langerhans cell differentiation and epidermal homeostasis

Transforming growth factor-β1 (TGF-β1) is a fundamental regulator of immune cell development and function. In this study, we investigated the effects of TGF-β1 on the differentiation of human Langerhans cells (LCs) and identified Axl as a key TGF-β1 effector. Axl belongs to the TAM (Tyro3, Axl, and Mer) receptor tyrosine kinase family, whose members function as inhibitors of innate inflammatory responses in dendritic cells and are essential to the prevention of lupus-like autoimmunity. We found that Axl expression is induced by TGF-β1 during LC differentiation and that LC precursors acquire Axl early during differentiation. We also describe prominent steady-state expression as well as inflammation-induced activation of Axl in human epidermal keratinocytes and LCs. TGF-β1-induced Axl enhances apoptotic cell (AC) uptake and blocks proinflammatory cytokine production. The antiinflammatory role of Axl in the skin is reflected in a marked impairment of the LC network preceding spontaneous skin inflammation in mutant mice that lack all three TAM receptors. Our findings highlight the importance of constitutive Axl expression to tolerogenic barrier immunity in the epidermis and define a mechanism by which TGF-β1 enables silent homeostatic clearing of ACs to maintain long-term self-tolerance.

Clonal relationship between langerhans cell histiocytosis and myeloid sarcoma

Langerhans cells (LCs) represent the main antigen capturing, processing and presenting dentritic cells (DCs) resident in epithelial surfaces including the skin or the oral mucosa, thus leading to either the induction of immune responses or tolerance. They are classically considered as myeloid-derived DCs sharing initial steps of their differentiation with monocytes. LC histiocytosis (LCH) and the more aggressive variant LC sarcoma (LCS) are considered as the neoplastic counterparts of this DC cell type. The immunoreactivity for macrophage-associated antigens in conjunction with CD1a, S-100 protein and langerin (CD207) represents a useful tool to establish the diagnosis of LCH in paraffin-embedded material.1 Rare cases of neoplasms with LC differentiation features developing in patients previously diagnosed with follicular lymphoma or acute lymphoblastic lymphoma/leukaemia (ALL) of T- and B-cell lineage have been reported. In these cases, identical clonal IgH- or TCRγ-gene rearrangements were detected in the H/DC neoplasms and the lymphomas consistent with a common clonal origin.2, 3, 4, 5 The development of the histiocytic dentritic/cell (H/DC) neoplasm was associated with progressive disease in most of these cases. Thus, it has been suggested that these tumours may represent a part of the clonal evolution of the underlying lymphomas.4 The development of a LCS in a patient with an acute B-ALL in complete remission for 9 years has been attributed to a transcription factor-induced transdifferentiation.5 Both neoplasms showed an identical IgH rearrangement, but different expressions of PAX5 and ID2.5

Glioblastoma-Induced Inhibition of Langerhans Cell Differentiation from CD34 + Precursors is Mediated by IL-6 but Unaffected by JAK2/STAT3 cinhibition

Langerhans cell (LC) infiltration has been observed in glioblastoma, but the glioblastoma microenvironment may be conditioned to resist antitumor immune responses. As little is known about how glioblastoma may affect dendritic cell differentiation, here we set out to delineate the effects of glioblastoma-derived soluble factors on LC differentiation. CD34(+) precursor cells of the human myeloid cell line MUTZ-3 were differentiated into LC in the presence of conditioned media of the human glioblastoma cell lines U251 or U373 and phenotypically and functionally characterized. Glioblastoma-conditioned media inhibited LC differentiation, resulting in functional impairment, as determined by allogeneic mixed leukocyte reactivity, and induction of STAT3 activation. IL-6 blockade completely abrogated these glioblastoma-induced immunosuppressive effects and reduced STAT3 phosphorylation. However, neither addition of JSI-124 (cucurbitacin-I; a JAK2/STAT3 inhibitor), nor of GW5074 (a Raf-1 inhibitor), both of which interfere with signaling pathways reported to act downstream of the IL-6 receptor, prevented the observed inhibitory effects on LC differentiation. Glioblastoma-derived IL-6 is responsible for the observed suppression of LC differentiation from CD34(+) precursors but appears to exert this effect in a STAT3 and Raf-1 independent fashion.

Preferential Langerhans cell differentiation from CD34+ precursors upon introduction of ABCG2 (BCRP)

Epidermal Langerhans cells (LC) and dermal interstitial dendritic cells (IDC) were found to express the ATP-binding cassette (ABC) transporter breast cancer resistance protein (BCRP; ABCG2). Also, low BCRP expression was present on CD34(+) blood DC precursors and expression was increased upon their differentiation to LC. The CD34(+) acute myeloid leukemia-derived DC cell line MUTZ3 can be cultured into LC or IDC, depending on the cytokine cocktail used. Introduction of functional BCRP in MUTZ3 progenitor cells through retroviral transduction resulted in the emergence of typical LC-characteristics in IDC cultures; the majority of cells remained negative for the IDC-specific C-type lectin DC-SIGN, but rather displayed enhanced expression of the LC-specific C-type lectin Langerin and characteristic high expression levels of CD1a. BCRP-induced skewing toward LC-like differentiation coincided with early RelB expression in 'IDC', derived from MUTZ3-BCRP, and depended on endogenous transforming growth factor beta (TGF-β) production. Intriguingly, cellular BCRP localization differed between skin LC and IDC, and a more cytoplasmic BCRP localization, as observed in primary skin LC, seemed to relate to LC-like differentiation in IDC cultures upon BCRP introduction in MUTZ3 progenitors. Together these data support a role for BCRP in preferential LC differentiation from CD34(+) myeloid DC progenitors.