Coexpression of CD1a, langerin and Birbeck's granules in Langerhans cell histiocytoses (LCH) in children: ultrastructural and immunocytochemical studies

Langerhans cell histiocytoses (LCH) represent rare diseases of unclear etiology and pathogenesis. Most of the cases include children, 1 to 15 years of age, and various organs are involved (bones, skin, liver, lymph nodes, bone marrow and other). The diagnosis of LCH used to be established by biopsy of the inflamed tissue and demonstration of expression of markers specific for Langerhans cells: CD1a and langerin. The diagnosis can be ultimately confirmed by demonstration of Birbeck's granules in the electron microscopy. The present study was aimed at immunocytochemical demonstration, in the examined LCH material (skin, bones, lymph nodes), of the specific antigen expression and at comparing it with the presence of Birbeck's granules. In the examined 11 cases co-expression of CD1a with langerin and with the presence of Birbeck's granules was noted. Also in all examined biopsies the expression of S-100 protein on inflammatory cells was found. The results corroborate the usefulness of immunocytochemical studies on CD 1 a and langerin expression in diagnosis of LCH.     

Polymorphisms in human langerin affect stability and sugar binding activity

Langerhans cells are specialized skin dendritic cells that take up and degrade antigens for presentation to the immune system. Langerin, a cell surface C-type lectin of Langerhans cells, can be internalized and accumulates in Birbeck granules, subdomains of the endosomal recycling compartment that are specific to Langerhans cells. Langerin binds and mediates uptake and degradation of glycoconjugates containing mannose and related sugars. Analysis of the human genome has identified three single nucleotide polymorphisms that result in amino acid changes in the carbohydrate-recognition domain of langerin. The effects of the amino acid changes on the activity of langerin were examined by expressing each of the polymorphic forms. Expression of full-length versions of the four common langerin haplotypes in fibroblasts revealed that all of these forms can mediate endocytosis of neoglycoprotein ligands. However, sugar binding assays and differential scanning calorimetry performed on fragments from the extracellular domain showed that two of the amino acid changes reduce the affinity of the carbohydrate-recognition domain for mannose and decrease the stability of the extracellular domain. In addition, analysis of sugar binding by langerin containing the rare W264R mutation, previously identified in an individual lacking Birbeck granules, shows that this mutation abolishes sugar binding activity. These findings suggest that certain langerin haplotypes may differ in their binding to pathogens and thus might be associated with susceptibility to infection.     

CD207+ Langerhans cells constitute a minor population of skin-derived antigen-presenting cells in the draining lymph node following exposure to Schistosoma mansoni

Infectious cercariae of Schistosoma mansoni gain entry to the mammalian host through the skin where they induce a transient inflammatory influx of mononuclear cells. Some of these cells have antigen-presenting cell function (MHCII+) and have been reported to migrate to the skin-draining lymph nodes (sdLN) where they have the potential to prime CD4+ cells of the acquired immune response. Here, in mice exposed to vaccinating radiation-attenuated schistosome larvae, which induce high levels of protective immunity to challenge infection, we describe the parasite-induced migration of Langerhans cells (LCs) from the epidermal site of immunisation to the sdLN using a specific monoclonal antibody that recognises langerin (CD207). CD207+ cells with dendritic morphology were abundant in the epidermis at all times and their migration into the dermis was detected soon after vaccination. All CD207+ LCs were MHCII+ but not all MHCII+ cells in the skin were CD207+. LCs migrated from the dermis in enhanced numbers after vaccination, as detected in dermal exudate populations recovered after in vitro culture of skin biopsies. Elevated numbers of CD207+ LCs were also detected in the sdLN from 24h to 4 days after vaccination. However, compared with other dermal-derived antigen-presenting cells that were CD207-MHCII+ or CD207-CD11c+, the relative numbers of CD207+ cells in the dermal exudate population and in the sdLN were very small. Furthermore, the migration of CD207+ cells after exposure to 'protective' radiation-attenuated, compared with 'non-protective' normal cercariae, was similar in terms of numbers and kinetics. Together, these studies suggest that CD207+ LCs are only a minor component of the antigen-presenting cell population that migrates from the epidermis and they are unlikely to be important in the priming of protective CD4+ cells in the sdLN.     

Evidence that Langerhans cells in adult pulmonary Langerhans cell histiocytosis are mature dendritic cells: importance of the cytokine microenvironment.

Because Langerhans cells (LC) in peripheral tissues are generally "immature" cells with poor lymphostimulatory activity, the contribution of immune responses initiated by LC to the pathogenesis of pulmonary LC histiocytosis (LCH) has been uncertain. In this study we demonstrate that LC accumulating in LCH granulomas are phenotypically similar to mature lymphostimulatory dendritic cells present in lymphoid organs. LC in LCH granulomas intensely expressed B7-1 and B7-2 molecules, whereas normal pulmonary LC and LC accumulating in other pathologic lung disorders did not express these costimulatory molecules. The presence of B7+ LC in LCH granulomas was associated with the expression in these lesions, but not at other sites in the lung, of a unique profile of cytokines (presence of GM-CSF, TNF-alpha, and IL-1beta and the absence of IL-10) that is known to promote the in vitro differentiation of LC into cells expressing a lymphostimulatory phenotype. Finally, LCH granulomas were the only site where CD154-positive T cells could be identified in close contact with LC intensely expressing CD40 Ags. Taken together, these results strongly support the idea that an abnormal immune response initiated by LC may participate in the pathogenesis of pulmonary LCH, and suggest that therapeutic strategies aimed at modifying the lymphostimulatory phenotype of LC may be useful in the treatment of this disorder.     

Langerin+ dermal dendritic cells are critical for CD8+ T cell activation and IgH γ-1 class switching in response to gene gun vaccines

The C-type lectin langerin/CD207 was originally discovered as a specific marker for epidermal Langerhans cells (LC). Recently, additional and distinct subsets of langerin(+) dendritic cells (DC) have been identified in lymph nodes and peripheral tissues of mice. Although the role of LC for immune activation or modulation is now being discussed controversially, other langerin(+) DC appear crucial for protective immunity in a growing set of infection and vaccination models. In knock-in mice that express the human diphtheria toxin receptor under control of the langerin promoter, injection of diphtheria toxin ablates LC for several weeks whereas other langerin(+) DC subsets are replenished within just a few days. Thus, by careful timing of diphtheria toxin injections selective states of deficiency in either LC only or all langerin(+) cells can be established. Taking advantage of this system, we found that, unlike selective LC deficiency, ablation of all langerin(+) DC abrogated the activation of IFN-γ-producing and cytolytic CD8(+) T cells after gene gun vaccination. Moreover, we identified migratory langerin(+) dermal DC as the subset that directly activated CD8(+) T cells in lymph nodes. Langerin(+) DC were also critical for IgG1 but not IgG2a Ab induction, suggesting differential polarization of CD4(+) T helper cells by langerin(+) or langerin-negative DC, respectively. In contrast, protein vaccines administered with various adjuvants induced IgG1 independently of langerin(+) DC. Taken together, these findings reflect a highly specialized division of labor between different DC subsets both with respect to Ag encounter as well as downstream processes of immune activation.     

Immunohistochemical detection of Langerhans cells in dental granulomas and radicular cysts

Objective Dental granulomas (DGs) and radicular cysts (RCs) are chronic periapical lesions frequently involving the jaws. Langerhans cells (LCs) are dendritic cells responsible for the presentation of antigens to T lymphocytes. This study examined the expression of LCs in DG and RCs by immunohistochemical staining. Study Design Eighteen cases of DGs and 26 cases of RCs were analyzed using anti-CD1a marker. Results CD1a-labeled LCs were observed in 11.1% of DGs and in 69.2% of RCs, showing a significant correlation (P < 0.0001; Fisher’s test). In DGs, LCs were only observed in granulation tissue, showing discrete immunostaining density. In RCs, LCs exhibited both a round and a dendritic shape in all epithelial layers. Although a correlation was observed between immunostaining density and epithelial thickness, as well as between immunostaining and inflammatory intensity, the differences were not significant in radicular cysts. Conclusion Langerhans cells provide important insight into the immunopathogenesis of chronic periapical lesions.     

Disruption of the langerin/CD207 gene abolishes Birbeck granules without a marked loss of Langerhans cell function

Langerin is a C-type lectin expressed by a subset of dendritic leukocytes, the Langerhans cells (LC). Langerin is a cell surface receptor that induces the formation of an LC-specific organelle, the Birbeck granule (BG). We generated a langerin(-/-) mouse on a C57BL/6 background which did not display any macroscopic aberrant development. In the absence of langerin, LC were detected in normal numbers in the epidermis but the cells lacked BG. LC of langerin(-/-) mice did not present other phenotypic alterations compared to wild-type littermates. Functionally, the langerin(-/-) LC were able to capture antigen, to migrate towards skin draining lymph nodes, and to undergo phenotypic maturation. In addition, langerin(-/-) mice were not impaired in their capacity to process native OVA protein for I-A(b)-restricted presentation to CD4(+) T lymphocytes or for H-2K(b)-restricted cross-presentation to CD8(+) T lymphocytes. langerin(-/-) mice inoculated with mannosylated or skin-tropic microorganisms did not display an altered pathogen susceptibility. Finally, chemical mutagenesis resulted in a similar rate of skin tumor development in langerin(-/-) and wild-type mice. Overall, our data indicate that langerin and BG are dispensable for a number of LC functions. The langerin(-/-) C57BL/6 mouse should be a valuable model for further functional exploration of langerin and the role of BG.     

Experimental paracoccidioidomycosis in the Syrian hamster

Male hamsters (105) received intratesticular injection of suspension of a live yeast phase culture ofParacoccidioides brasiliensis and were sacrificed weekly during 20 weeks. Humoral immunity was studied by the agar-gel immunodiffusion (ID) and indirect immunofluorescence (IF) tests. Cell-mediated immunity was determined by the macrophage migration inhibition test in the presence of phytohemagglutinin (PHA) andParacoccidioides brasiliensis soluble antigen (PbAg). The morphology of the lesions was studied in the inoculation site, lymph nodes, lung, liver, spleen and kidneys.Disseminated paracoccidioidomycosis was observed in 100% of the animals after the first week. The lesions were initially made up of fungi surrounded by polymorphonuclear neutrophils and macrophages. Up to the 10th week the majority of the lesions appeared as compact confluent ephitelioid granulomas containing rare large fungi, some showing signs of degeneration. At this time, the specific antibody titers and the cellular immune response to PHA and PbAg were highest.From the 11th week on the granulomas became less compact, edematous with the epithelioid cells loosely arranged. This change was accompanied by an increase in the number of fungi showing reproductive activity and was associated with renal amyloidosis and progressive decline of cellular immune response both to PHA and PbAg. Contrariwise the titers of circulating antibodies were maintained.In the present model, disseminated paracoccidioidomycosis of the hamster was associated with depression of cellular immunity, change in the pattern of the granuloma, intense fungi proliferation and amyloidosis.     

Carbohydrate-Dependent Binding of Langerin to SodC,a Cell Wall Glycoprotein of Mycobacterium leprae

Langerhans cells participate in the immune response in leprosy by their ability to activate T cells that recognize the pathogen, Mycobacterium leprae, in a langerin-dependent manner. We hypothesized that langerin, the distinguishing C-type lectin of Langerhans cells, would recognize the highly mannosylated structures in pathogenic Mycobacterium spp. The coding region for the extracellular and neck domain of human langerin was cloned and expressed to produce a recombinant active trimeric form of human langerin (r-langerin). Binding assays performed in microtiter plates, by two-dimensional (2D) Western blotting, and by surface plasmon resonance demonstrated that r-langerin possessed carbohydrate-dependent affinity to glycoproteins in the cell wall of M. leprae. This lectin, however, yielded less binding to mannose-capped lipoarabinomannan (ManLAM) and even lower levels of binding to phosphatidylinositol mannosides. However, the superoxide dismutase C (SodC) protein of the M. leprae cell wall was identified as a langerin-reactive ligand. Tandem mass spectrometry verified the glycosylation of a recombinant form of M. leprae SodC (rSodC) produced in Mycobacterium smegmatis. Analysis of r-langerin affinity by surface plasmon resonance revealed a carbohydrate-dependent affinity of rSodC (equilibrium dissociation constant [K_D] = 0.862 μM) that was 20-fold greater than for M. leprae ManLAM (K_D = 18.69 μM). These data strongly suggest that a subset of the presumptively mannosylated M. leprae glycoproteins act as ligands for langerin and may facilitate the interaction of M. leprae with Langerhans cells.     

Characterization of carbohydrate recognition by langerin,a C-type lectin of Langerhans cells

Langerin is a type II transmembrane cell surface receptor found on Langerhans cells. The extracellular domain of langerin consists of a neck region containing a series of heptad repeats and a C-terminal C-type carbohydrate-recognition domain (CRD). A role for langerin in processing of glycoprotein antigens has been proposed, but until now there has been little study of the langerin protein. In this study, analytical ultracentrifugation and circular dichroism spectroscopy of recombinant soluble fragments of human langerin have been used to show that the extracellular region of this receptor exists as a stable trimer held together by a coiled coil of alpha-helices formed by the neck region. The langerin CRD shows specificity for mannose, GlcNAc, and fucose, but only the trimeric extracellular domain fragment binds to glycoprotein ligands. Langerin extracellular domain binds mammalian high mannose oligosaccharides, as well mannose-containing structures on yeast invertase but does not bind complex glycan structures. Full-length langerin stably expressed in rat fibroblast transfectants mediates efficient uptake and degradation of a mannosylated neoglycoprotein ligand. pH-dependent ligand release appears to involve interactions between the CRDs or between the CRDs and the neck region in the trimer. The results are consistent with a role for langerin in internalization of both self and nonself glycoprotein antigens.     

Targeting of epidermal Langerhans cells with antigenic proteins: attempts to harness their properties for immunotherapy

Langerhans cells, a subset of skin dendritic cells in the epidermis, survey peripheral tissue for invading pathogens. In recent functional studies it was proven that Langerhans cells can present exogenous antigen not merely on major histocompatibility complexes (MHC)-class II molecules to CD4⁺ T cells, but also on MHC-class I molecules to CD8⁺ T cells. Immune responses against topically applied antigen could be measured in skin-draining lymph nodes. Skin barrier disruption or co-application of adjuvants was required for maximal induction of T cell responses. Cytotoxic T cells induced by topically applied antigen inhibited tumor growth in vivo, thus underlining the potential of Langerhans cells for immunotherapy. Here we review recent work and report novel observations relating to the potential use of Langerhans cells for immunotherapy. We investigated the potential of epicutaneous immunization strategies in which resident skin dendritic cells are loaded with tumor antigen in situ. This contrasts with current clinical approaches, where dendritic cells generated from progenitors in blood are loaded with tumor antigen ex vivo before injection into cancer patients. In the current study, we applied either fluorescently labeled protein antigen or targeting antibodies against DEC-205/CD205 and langerin/CD207 topically onto barrier-disrupted skin and examined antigen capture and transport by Langerhans cells. Protein antigen could be detected in Langerhans cells in situ, and they were the main skin dendritic cell subset transporting antigen during emigration from skin explants. Potent in vivo proliferative responses of CD4⁺ and CD8⁺ T cells were measured after epicutaneous immunization with low amounts of protein antigen. Targeting antibodies were mainly transported by langerin⁺ migratory dendritic cells of which the majority represented migratory Langerhans cells and a smaller subset the new langerin⁺ dermal dendritic cell population located in the upper dermis. The preferential capture of topically applied antigen by Langerhans cells and their ability to induce potent CD4⁺ and CD8⁺ T cell responses emphasizes their potential for epicutaneous immunization strategies. This article is a symposium paper from the conference “Immunotherapy—From Basic Research to Clinical Applications,” Symposium of the Collaborative Research Center (SFB) 685, held in Tübingen, Germany, 6–7 March 2008.     

Oxytocin-producing and vasopressin-producing eosinophils in the mouse spleen: immunohistochemical,immuno-electron-microscopic and in situ hybridization studies

The localization of an endogenous 14-kDa -galactoside-binding lectin (galectin) and its pattern of gene expression were examined in normal human skin by light- and electron microscopy. Under the light microscope, immunostaining of 14-kDa galectin was observed in the cell membrane of cells in the basal and spinous layers of the epidermis. Galectin was also found in the Langerhans cells, as shown by double labeling using anti-14-kDa galectin and anti-CD1a antibodies. In the dermis, immunostaining for the 14-kDa galectin was positive in the extracellular matrix and fibroblasts. At the electron-microscopic level of resolution, galectin was located primarily along the plasma membrane of keratinocytes, and in both the cytoplasm and nucleus of Langerhans cells in the epidermis, whereas in the dermis it was detected in the extracellular matrix and in both the nucleus and cytoplasm of fibroblasts. The gene expression of 14-kDa galectin was visualized by the HRP-staining method following in situ hybridization techniques. The expression was detected in the cytoplasm of cells in the basal and spinous layers of the epidermis; whereas, in the dermis, it was detected in the cytoplasm of fibroblasts. Moreover, SDS-polyacrylamide gel electrophoresis and lectin-blot analysis revealed that this galectin bound to glycoproteins of approximately 17, 62, and 72 kDa in the epidermis and to those of 29, 54, and 220 kDa in the dermis. The present study indicates that 1) normal human skin produces the -galactoside-binding 14-kDa galectin, and 2) this galectin is located in both the epidermis, particularly in the keratinocytes and Langerhans cells, and in the dermis. These results suggest that galectin is important for cell-cell contact and/or adhesion in the epidermis and for cell-extracellular matrix interaction in the dermis.     

Ketoconazole in the treatment of experimental murine paracoccidioidomycosis

In a murine model of chronic disseminated paracoccidioidomycosis (strain 18; intravenous route), Ketoconazole (200 mg/kg in 0.2% agar) was given daily by gavage in three different schedules. Continuous treatment from an early stage of infection (day 3) up to week 20 was the most effective protocol, leading to remission of histopathological lesions and of both humoral and cellular anti-P. brasiliensis immune response, and clearance of the fungus in lungs; only 1 treated animal at week 20 showed pulmonary granulomas, although less extensive than control mice. Continuous treatment from early stage up to week 8, followed by a 16 week-period of drug discontinuity, caused remission of lesions in all but 3 treated mice which showed active pulmonary paracoccidioidomycosis similar to controls (14.2% of unresponsiveness to treatment). The continuous Ketoconazole protocol since a late stage of infection (week 4) up to week 20 produced a slower remission of lesions and immune response when compared with the first drug schedule. In this model of paracoccidioidomycosis, Ketoconazole showed no detectable side-effects and was a very effective drug especially in a prolonged administration protocol from an early stage of infection.     

Spatial discontinuities in human immunodeficiency virus type 1 quasispecies derived from epidermal Langerhans cells of a patient with AIDS and evidence for double infection.

A nonhomogeneous spatial distribution of human immunodeficiency virus type 1 quasispecies was observed for epidermal Langerhans cells purified from skin patches taken from a patient with AIDS soon after death. Each patch presented a unique collection of sequences, distinct from those of juxtaposed patches or those derived from the other leg. Infection of Langerhans cells by virus from underlying T cells in the dermis might explain this partition. The analysis revealed the presence of two distinct cocirculating viral strains, indicating double infection.     

Langerhans's cell histiocytosis in old subjects: two rare case reports and review of the literature

doi: 10.1111/j.1741‐2358.2012.00629.x Langerhans’s cell histiocytosis in old subjects: two rare case reports and review of the literature Background: Langerhans cell histiocytosis (LCH) is a proliferative disease of histiocyte‐like cells that generally affects children; LCH onset is rare in adults; immunohistochemistry is essential to obtain the correct diagnosis, and treatment protocols are controversial. Objective: To describe two new cases of adult onset oral LCH. Case reports: Case 1: a 71‐year‐old woman, complaining of diffuse oral pain, presented with erythematous mucosal lesions; the panoramic radiograph and CT scan showed multiple mandible radiolucent areas. Immunohistochemical assay for S‐100, CD1a and langerin test was essential in reaching the correct diagnosis. Case 2: a 77‐year‐old female patient presented with a non‐painful, non‐bleeding, slightly elevated erythematous palatal lesion of 6 months duration, together with a genital vulvar lesion of uncertain nature. The pathology confirmed the diagnosis of LCH. Many therapies (etoposid, radiotherapy) could induce only a clinical partial remission; Cladribine induced a complete recovery. Conclusion: The first case was difficult to diagnose: the clinical presentation and course of the disease (LCH) in the elderly are multiple and unpredictable. An immunohistochemistry study is often essential to obtain the correct diagnosis. The second case required several therapeutic interventions: even though some cases regress spontaneously, others require systemic chemotherapy.     

Cutting edge: CD1a+ antigen-presenting cells in human dermis respond rapidly to CCR7 ligands

Recent data from murine models have confirmed that Langerhans cells are not the only population of APCs in the skin involved in initiating immune responses. In healthy human skin, we identify CD1a(+) dermal APCs located close to the lymphatic vessels in the upper layers of the dermis that are unequivocally distinct from migrating Langerhans cells but exhibit both potent allostimulatory capacity and a chemotactic response to CCR7 ligands. In contrast, CD14(+) dermal APCs are distributed throughout the dermis and lack a chemotactic response to CCR7 ligands. CD1a(+) dermal APCs therefore represent an APC population distinct from Langerhans cells that are capable of migrating to lymph nodes and stimulating naive T cells. In humans, CD1a(+) dermal APCs may fulfill some of the roles previously ascribed to Langerhans cells.     

Dermal and intravascular Langerhans cells at sites of passively induced allergic contact sensitivity.

In order to further define the role of Langerhans cells in contact allergic reactions, passive transfer studies were done in guinea pigs using 2,4-dinitro-1-chlorobenzene (DNCB)-sensitive donor cells. Langerhans cells were found in the lumen of dermal vessels resembling lymphatics at 2, 3, 15, and 48 hr after DNCB challenge. In contrast to the previously reported findings in actively sensitized guinea pigs, the changes involving Langerhans cells in passively sensitized guinea pigs were mainly noted in the dermis. These consisted of increased numbers of Langerhans cells and of mononuclear cells apposed to Langerhans cells 3 or more hours after challenge with DNCB. The increased Langerhans cell population in the dermis and the presence of Langerhans cells in dermal vessels in specifically challenged sites in adoptive immune reactions furnishes further support for a significant role of Langerhans cells in the interaction between antigen and sensitized cells.     

Significant virus replication in Langerhans cells following application of HIV to abraded skin: relevance to occupational transmission of HIV

The cellular events that occur following occupational percutaneous exposure to HIV have not been defined. In this study, we studied relevant host cellular and molecular targets used for acquisition of HIV infection using split-thickness human skin explants. Blockade of CD4 or CCR5 before R5 HIV application to the epithelial surface of skin explants completely blocked subsequent HIV transmission from skin emigrants to allogeneic T cells, whereas preincubation with C-type lectin receptor inhibitors did not. Immunomagnetic bead depletion studies demonstrated that epithelial Langerhans cells (LC) accounted for >95% of HIV dissemination. When skin explants were exposed to HIV variants engineered to express GFP during productive infection, GFP+ T cells were found adjacent to GFP+ LC. In three distinct dendritic cell (DC) subsets identified among skin emigrants (CD1a+langerin+DC-specific intercellular adhesion molecule grabbing non-integrin (SIGN)- LC, CD1a+langerin-DC-SIGN- dermal DC, and CD1a-langerin-DC-SIGN+ dermal macrophages), HIV infection was detected only in LC. These results suggest that productive HIV infection of LC plays a critical role in virus dissemination from epithelium to cells located within subepithelial tissue. Thus, initiation of antiretroviral drugs soon after percutaneous HIV exposure may not prevent infection of LC, which is likely to occur rapidly, but may prevent or limit subsequent LC-mediated infection of T cells.     

Exploiting the role of endogenous lymphoid-resident dendritic cells in the priming of NKT cells and CD8+ T cells to dendritic cell-based vaccines

Transfer of antigen between antigen-presenting cells (APCs) is potentially a physiologically relevant mechanism to spread antigen to cells with specialized stimulatory functions. Here we show that specific CD8+ T cell responses induced in response to intravenous administration of antigen-loaded bone marrow-derived dendritic cells (BM-DCs), were ablated in mice selectively depleted of endogenous lymphoid-resident langerin+ CD8α+ dendritic cells (DCs), suggesting that the antigen is transferred from the injected cells to resident APCs. In contrast, antigen-specific CD4+ T cells were primed predominantly by the injected BM-DCs, with only very weak contribution of resident APCs. Crucially, resident langerin+ CD8α+ DCs only contributed to the priming of CD8+ T cells in the presence of maturation stimuli such as intravenous injection of TLR ligands, or by loading the BM-DCs with the glycolipid α-galactosylceramide (α-GalCer) to recruit the adjuvant activity of activated invariant natural killer-like T (iNKT) cells. In fact, injection of α-GalCer-loaded CD1d-/- BM-DCs resulted in potent iNKT cell activation, suggesting that this glycolipid antigen can also be transferred to resident CD1d+ APCs. While iNKT cell activation per se was independent of langerin+ CD8α+ DCs, some iNKT cell-mediated activities were reduced, notably release of IL-12p70 and transactivation of NK cells. We conclude that both protein and glycolipid antigens can be exchanged between distinct DC species. These data suggest that the efficacy of DC-based vaccination strategies may be improved by the incorporation of a systemic maturation signal aimed to engage resident APCs in CD8+ T cell priming, and α-GalCer may be particularly well suited to this purpose.     

Chronic pulmonary paracoccidioidomycosis in the state of Rio Grande do Sul,Brazil

Since 1942, when paracoccidioidomycosis was first identified in the state of Rio Grande do Sul, paracoccidioidal pulmonary lesions became a great concern to physicians. The present study focuses on 53 patients diagnosed over a seven-year period who presented paracoccidioidal lesions circumscribed to the lungs. These patients presented clinical and radiological features that simulated several pulmonary infectious and non-infectious conditions. Four unusual cases are briefly discussed. A sequence of laboratorial tests should be established for the diagnosis of pulmonary paracoccidioidomycosis. This revised version was published online in June 2006 with corrections to the Cover Date.