Search Results (55)

Background: Dendritic cells (DCs) are heterogeneous antigen-presenting cells that bridge innate and adaptive immunity. Recent classifications of hematolymphoid neoplasms highlight the complex origins of DC-related neoplasms. DCs have also been associated with the progression of multiple myeloma (MM). This report presents the case of a patient with MM in whom bone marrow analysis revealed an unusual additional clonal population of immature cells, in addition to plasmacytoid DCs, that later evolved into plasmacytoid dendritic cell proliferation associated with acute myeloid leukemia (pDC-AML). Methods: The bone marrow of a 69-year-old man with neutropenia and thrombocytopenia was examined by morphology, immunohistochemistry, flow cytometry, cytogenetics, fluorescence in situ hybridization (FISH), and next-generation sequencing (NGS). Serial assessments were performed before and during treatment with bortezomib and dexamethasone for MM, and later with daunorubicin/cytarabine for AML. Results: Initial bone marrow analysis revealed coexisting clonal plasma cells with t(11;14) and a population of CD34+/CD123+/CD45RA+ cells lacking lineage markers, in addition to pDCs, suggestive of precursor DCs rather than acute undifferentiated leukemia. Cytogenetic analysis identified a small clone with isolated del(20q), which corresponded in size to the clone of undifferentiated cells and to the clone with pathogenic variants detected by NGS in the BCOR, RUNX1, and SRSF2 genes. Myeloma therapy decreased both MM and undifferentiated cells; however, within four months, pDC-AML evolved with del(20q) and higher variant allele frequencies of the previously detected gene variants. Remission was achieved with standard AML chemotherapy. Conclusions: This case supports evidence that MM-associated immune dysfunction and bone marrow niche alterations may promote secondary myeloid malignancies independently of cytotoxic therapy. It demonstrates the earliest events in pDC-AML evolution. Furthermore, the immature immunophenotype raises the question of appropriate treatment, since a diagnosis of acute undifferentiated leukemia can be established. Full article

Background/Objectives: Cutaneous lupus erythematosus (CLE) is a complex autoimmune skin disease driven by genetic predisposition, environmental triggers, and immune dysregulation. Environmental factors such as ultraviolet radiation, smoking, and certain drugs can initiate disease onset by inducing keratinocyte apoptosis. The subsequent release of nucleic acids and danger-associated molecular patterns activates pattern recognition receptors (PRRs) on keratinocytes and immune cells, leading to the production of type I and type III interferons (IFNs) and pro-inflammatory cytokines. The objective of this review is to summarize recent advances in understanding the immunopathogenesis of CLE, with particular attention to emerging cellular players and their therapeutic implications. Methods: A narrative review of the recent literature was performed, including experimental, translational, and clinical studies investigating the cellular and molecular mechanisms underlying CLE and novel targeted treatments derived from these findings. Results: Although plasmacytoid dendritic cells (pDCs) have traditionally been considered the major producers of IFN-I, recent data indicate that pDCs in CLE are functionally impaired and are not the primary source. Other cells, such as keratinocytes have emerged as key producers of IFN-I, contributing to a prelesional, IFN-rich microenvironment. This promotes the recruitment and activation of dendritic cells and other inflammatory myeloid subsets, which are now recognized as central players in amplifying local inflammation. Concurrently, T cells infiltrate the skin, where cytotoxic CD8⁺ T cells attack keratinocytes and CD4⁺ T cells further propagate inflammation via cytokine production. B cells and plasma cells produce autoantibodies, forming immune complexes that perpetuate inflammation. Neutrophils release neutrophil extracellular traps (NETs), exposing autoantigens and further stimulating IFN pathways. Macrophages contribute by presenting autoantigens, producing pro-inflammatory mediators, and failing to effectively clear apoptotic cells and immune complexes. Conclusions: The dynamic interplay between the innate and adaptive immune systems sustains the chronic inflammatory state characteristic of CLE. Based on the pathogenetic novelties, new therapeutic agents targeting specific molecules have been developed, which may improve the treatment of this complex disease in the future. Full article

Background: Endometrial cancer is one of the most common female genital cancers and poses a significant clinical problem due to its increasing incidence and variable prognosis depending on the stage of the disease. The development of EC is largely dependent on interactions with the immune system, including immune checkpoints (ICPs) such as PD-1, PD-L1, and PD-L2. The aim of our study was to evaluate the PD-1/PD-L1/PD-L2 pathway in EC and its clinical significance. Methods: The analysis was performed by flow cytometry on myeloid and plasmacytoid dendritic cells and monocytes (MO) in peripheral blood (PB). The concentration of sPD-1, sPD-L1, and sPD-L2 in plasma was determined by ELISA. Additionally, PD-L1 and PD-L2 gene expression levels in tumor tissue (TT) were assessed using real-time polymerase chain reaction (qPCR). The obtained results were correlated with clinical data of EC patients. Results: Patients with EC had lower percentages of PD-L1-positive MO and pDCs, as well as PD-L2-positive MO and mDCs, compared with the control group. We observed accumulation of sPD-1 and lower levels of sPD-L1 and sPD-L2 in EC patients compared to the control group, with sPD-L2 correlating with PD-L2 gene expression level in the TT. Conclusions: The study results indicate a difference in the distribution of mDCs, pDCs, and MO with PD-L1/PD-L2 expression in EC patients. Reduced percentages of MO and DCs expressing PD-L1 and PD-L2, altered concentrations of soluble forms of these IPCs, and correlations with gene expression in TT suggest that dysregulation of this pathway may influence disease progression. Furthermore, the relationships between immunological parameters and clinical features such as BMI and FIGO stages suggest the potential use of these factors as diagnostic and prognostic biomarkers and the possibility of incorporating them into future therapeutic strategies. However, further studies are necessary to validate this hypothesis. Full article

Background: Plasma cell myeloma is an incurable malignancy of clonal plasma cells. Recent success in immunotherapeutic strategies has altered the landscape of myeloma treatment. Daratumumab is an anti-CD38 IgG kappa monoclonal antibody that has shown great efficacy in the treatment of myeloma. However, Daratumumab brought with it new challenges in post-therapeutic laboratory assessment, including therapeutic antibody interference with serum protein electrophoresis and serum immunofixation electrophoresis assays. In this study, we highlight the interference identified in post-therapeutic flow cytometry analysis related to bound Daratumumab on normal hematopoietic cells. We also highlight the methods of detection of residual plasma cell neoplasm, post-Daratumumab therapy.: A total of 28 patients with refractory plasma cell myeloma who received Daratumumab (2016–2018) were included in this study. Flow cytometry was performed using 4- or 10-color antibody panels (BD FASC Canto) and analyzed by cluster analysis (Cytopaint Classic software) using four tube panels including VS38c for measurable residual disease (MRD) testing. Pretreatment and post-Daratumumab follow-up bone marrow flow cytometry samples were analyzed. In addition, 10 multiple myeloma patient samples were reflexed to multi-epitope CD38 analysis by flow cytometric analysis of post-Daratumumab residual disease. When discussing CD38 expression, we will refer to CD38 as being detected by conventional reagents. Results: All post-Daratumumab-treated cases (100%) showed negative staining for CD38 using conventional reagents on all plasma cells in the specimens. MRD testing successfully identified small clonal plasma cell populations using VS38C and multi-epitope CD38 (meCD38) antibodies, despite the absence of demonstrable CD38 expression. Additionally, all cases exhibited weak kappa light chain staining on hematogones, attributed to the binding of Daratumumab kappa monoclonal antibody. This interaction can create the appearance of a CD10+ monotypic B-cell population. We also noted diminished CD38 staining on myeloblasts, resulting in an atypical CD34/CD38 staining pattern. This alteration could potentially be misinterpreted as indicative of a myelodysplastic neoplasm (MDS). Furthermore, decreased staining of CD38 was noted on T cells, natural killer (NK) cells, basophils, monocytes, and plasmacytoid dendritic cells. Conclusions: With the emergence of successfully targeted immunotherapies, such as anti-CD38 antibodies, it is important to understand and correctly interpret variations in flow cytometry that may arise from the therapy. Hematogones exhibit high-intensity levels of CD38 expression; thus, Daratumumab binds to them, creating the appearance of kappa expression on all hematogones. Stage I/early stage II hematogones normally lack surface immunoglobulin light chain expression, but in the presence of Daratumumab, they appear to be a CD10(+) monotypic population of B cells. The misinterpretation of these normal cells as a CD10(+) B-cell clone can lead to inaccurate assessment, unnecessary bone marrow immunohistochemical evaluation, and unwarranted anxiety. Additionally, artefacts on various other hematopoietic cells can result in inaccurate assessments of immunophenotypic aberrancy due to binding of the drug. This may lead to the false interpretation of a secondary/therapy-related myeloid neoplasm. This study highlights in detail the interferences that must be considered when assessing residual disease in the era of targeted drug therapies. Full article

Metastatic cancer poses significant clinical challenges, necessitating effective immunotherapies with minimal systemic toxicity. Building on prior research demonstrating the rWTC-MBTA vaccine’s ability to inhibit tumor metastasis and growth, this study focuses on its clinical translation by optimizing vaccine composition, dosing regimens, and freezing techniques. The vaccine formula components included three TLR ligands (LTA, Poly I:C, and Resiquimod) and an anti-CD40 antibody, which were tested in melanoma and triple-negative breast cancer (TNBC) models. The formulations were categorized as rWTC-MBT (Mannan-BAM with LTA, Poly I:C, Resiquimod), rWTC-MBL (LTA), rWTC-MBP (Mannan-BAM with Poly I:C), and rWTC-MBR (Resiquimod). In the melanoma models, all the formulations exhibited efficacy that was comparable to that of the full vaccine, while in the “colder” TNBC models, the formulations with multiple TLR ligands or Resiquimod alone performed the best. Vaccine-induced activation of dendritic cell (DC) subsets, including conventional DCs (cDCs), myeloid DCs (mDCs), and plasmacytoid DCs (pDCs), was accompanied by significant CD80+CD86+ population induction, suggesting robust innate immune stimulation. An initial three-dose schedule followed by booster doses (3-1-1-1 or 3-3-3-3) reduced the metastatic burden effectively. Gradual freezing (DMSO-based preservation) maintained vaccine efficacy, underscoring the importance of intact cell structure. These findings highlight the potential of simplified formulations, optimized dosing, and freezing techniques in developing practical, scalable immunotherapies for metastatic cancers. Full article

Dendritic cells (DCs) play a crucial role in controlling viral infections. Little is known about the changes in frequencies of the DC subsets in patients with chronic hepatitis C (CHC), particularly in the era of interferon-free regimens. We aimed to evaluate the impact of sofosbuvir/daclatasvir on the frequency of different peripheral DC subsets, the expression of the inhibitory CD200R and its ligand CD200 on DC, and their relation to the treatment outcome. A total of 1000 patients with CHC were enrolled and treated with a fixed oral dose of 400 mg of sofosbuvir and 60 mg of daclatasvir for 12 weeks. A total of 940 patients achieved sustained virologic response (SVR), and only 60 patients were non-responders (NRs). The frequencies of the peripheral plasmacytoid (pDC) and myeloid (mDCs) subsets and their surface expressions of CD200R and CD200 molecules were analyzed using flow cytometry. This analysis included 60 non-responders (NR group), 60 randomly selected sustained virologic responders (SVR group) at baseline, and at the end of treatment, and 60 healthy controls. HCV infection was associated with a down-regulation in the frequency of mDC, compared to healthy controls. In addition, mDC in HCV-infected patients showed lower levels of CD200R. However, neither the pDC frequency nor their CD200R expression was significantly altered. Interestingly, by the end of therapy, the frequencies of circulating mDCs and CD200R⁺mDC increased significantly in the SVR group and were even comparable to healthy controls. The levels of these cells were not normalized in the NR group. Percentages of mDCs and CD200R⁺mDC subsets showed good prognostic accuracy for predicting virologic response to therapy. Our results showed that HCV infection was associated with modulation of the mDC frequency and their surface expression of CD200R. Successful daclatasvir and sofosbuvir combined therapy was associated with the normalization of the percentages of mDC and CD200R⁺mDC. Full article

Plasmacytoid dendritic cells (pDCs) express Toll-like receptor 7 (TLR7) in the endosomes, recognize viral single-stranded RNA (ssRNA), and produce significant amounts of interferon (IFN)-α. Bovine lactoferrin (LF) enhances the response of IFN regulatory factors followed by the activation of IFN-sensitive response elements located in the promoter regions of the IFN-α gene and IFN-stimulated genes in the TLR7 reporter THP-1 cells in the presence of R-848, a TLR7 agonist. In ex vivo experiments using human peripheral blood mononuclear cells, LF enhances IFN-α levels in the supernatant in the presence of R-848. Additionally, it increases the expression of IFN-α, human leukocyte antigen (HLA)-DR, and CD86 in pDCs; HLA-DR and CD86 in myeloid dendritic cells; CD69 in CD56 dim natural killer and T killer cells; and IFN-γ in T helper type 1 and B cells in the presence of R-848. The inhibition of phagocytosis or neutralization of nucleolin, a receptor of LF, suppresses LF incorporation into pDCs. These results suggest that pDCs incorporate LF through phagocytosis or nucleolin-mediated endocytosis, and LF enhances TLR7 response in the endosome and subsequent IFN signaling pathway and activates innate and adaptive immune cells. We anticipate that LF modulates antiviral immunity against environmental ssRNA viruses and contributes to homeostasis. Full article

Dendritic cells (DCs) are professional antigen-presenting cells that are traditionally divided into two distinct subsets: myeloid DCs (mDCs) and plasmacytoid DCs (pDCs). pDCs are known for their ability to secrete large amounts of cytokine type I interferons (IFN- α). In our previous work, we have demonstrated that pDC infiltration promotes glioblastoma (GBM) tumor immunosuppression through decreased IFN-α secretion via TLR-9 signaling and increased suppressive function of regulatory T cells (Tregs) via increased IL-10 secretion, resulting in poor overall outcomes in mouse models of GBM. Further dissecting the overall mechanism of pDC-mediated GBM immunosuppression, in this study, we identified CCL21 as highly upregulated by multiple GBM cell lines, which recruit pDCs to tumor sites via CCL21-CCR7 signaling. Furthermore, pDCs are activated by CCL21 in the GBM microenvironment through intracellular signaling of β-arrestin and CIITA. Finally, we found that CCL21-treated pDCs directly suppress CD8+ T cell proliferation without affecting regulatory T cells (Tregs) differentiation, which is considered the canonical pathway of immunotolerant regulation. Taken together, our results show that pDCs play a multifaced role in GBM immunosuppression, and CCL21 could be a novel therapeutic target in GBM to overcome pDC-mediated immunosuppression. Full article

The onset of malaria causes the induction of various inflammatory markers in the host’s body, which in turn affect the body’s homeostasis and create several cerebral complications. Polarization of myeloid-derived suppressor cells (MDSCs) from the classically activated M1 to alternatively activated M2 phenotype increases the secretion of pro-inflammatory molecules. Treatment with recombinant IL-33 (rIL-33) not only alters this MDSC’s polarization but also targets the glycolysis pathway of the metabolism in MDSCs, rendering them less immunosuppressive. Along with that, the Helper T-cells subset 17 (Th17)/T regulatory cells (Tregs) ratio is skewed towards Th17, which increases inflammation by producing more IL-17. However, treating with rIL-33 also helps to restore this ratio, which brings back homeostasis. During malaria infection, there is an upregulation of IL-12 production from dendritic cells along with a distorted myeloid dendritic cells (mDC)/plasmacytoid dendritic cells (pDC) ratio towards mDCs promoting inflammation. Administering rIL-33 will also subvert this IL-12 production and increase the population of pDC in the host’s immune system during malaria infection, thus restoring mDC/pDC to homeostasis. Therefore, treatment with rIL-33 to reduce the pro-inflammatory signatures and maintenance of immune homeostasis along with the increase in survivability could be a potential therapeutic approach for cerebral malaria. Full article

In this review, we aim to provide a summary of the diverse immunophenotypic presentations of distinct entities associated with plasmacytoid dendritic cell (pDC) proliferation. These entities include the following: (1) blastic plasmacytoid dendritic cell neoplasm (BPDCN); (2) mature pDC proliferation (MPDCP), most commonly seen in chronic myelomonocytic leukemia (CMML); and (3) myeloid neoplasms with pDC differentiation, in which pDCs show a spectrum of maturation from early immature pDCs to mature forms, most commonly seen in acute myeloid leukemia (pDC-AML). Our aim is to provide a flow cytometry diagnostic approach to these distinct and sometimes challenging entities and to clarify the immunophenotypic spectrum of neoplastic pDCs in different disease presentations. In this review, we also cover the strategies in the evaluation of residual disease, as well as the challenges and pitfalls we face in the setting of immune and targeted therapy. The differential diagnosis will also be discussed, as blasts in some AML cases can have a pDC-like immunophenotype, mimicking pDCs. Full article

Spontaneous remissions (SRs) in blastic plasmacytoid dendritic cell neoplasms (BPDCNs) are infrequent, poorly documented, and transient. We report a 40-year-old man presenting with bycitopenia and soft tissue infection. The bone marrow exhibited 3% abnormal cells. Immunophenotyping of these cells revealed the antigens CD45+ (dim), CD34+, CD117+, CD123+ (bright), HLA-DR+ (bimodal), CD56+ (bright), CD33+, CD13+, CD2+, and CD22+ (dim) and the partial expression of the CD10+, CD36+, and CD7+ antigens. All other myeloid, monocytic, and lymphoid antigens were negative. Genetic studies showed a complex karyotype and mutations in the TP53^R337C and KRAS^G12D genes. On hospital admission, the patient showed a subcutaneous nodule on the right hand and left lower limb. Flow cytometry multiparameter (FCM) analysis showed the presence of 29% abnormal cells with the previously described immunophenotype. The patient was diagnosed with BPDCN. The patient was treated with broad-spectrum antibiotics for soft tissue infection, which delayed therapy for BPDCN. No steroids or chemotherapeutic or hypomethylating agents were administered. His blood cell counts improved and skin lesions disappeared, until the patient relapsed five months after achieving spontaneous remission. About 60% of abnormal cells were identified. No changes in immunophenotype or the results of genetic studies were observed. The patient underwent a HyperCVAD chemotherapy regimen for six cycles. Consolidation therapy was performed via allogeneic bone marrow transplantation with an HLA-unrelated donor. One year after the bone marrow transplant, the patient died due to the progression of his underlying disease, coinciding with a respiratory infection caused by SARS-CoV-2. In the available literature, SRs are often linked to infections or other stimulators of the immune system, suggesting that powerful immune activation could play a role in controlling the leukemic clone. Nevertheless, the underlying mechanism of this phenomenon is not clearly understood. We hypothesize that the immune system would force the leukemic stem cell (LSC) to undergo a state of quiescence. This loss of replication causes the LSC progeny to die off, resulting in the SR of BPDCN. Full article

Homeobox genes encode developmental transcription factors regulating tissue-specific differentiation processes and drive cancerogenesis when deregulated. Dendritic cells (DCs) are myeloid immune cells occurring as two types, either conventional or plasmacytoid DCs. Recently, we showed that the expression of NKL-subclass homeobox gene VENTX is restricted to conventional DCs, regulating developmental genes. Here, we identified and investigated homeobox genes specifically expressed in plasmacytoid DCs (pDCs) and derived blastic plasmacytoid dendritic cell neoplasm (BPDCN). We analyzed gene expression data, performed RQ-PCR, protein analyses by Western blot and immuno-cytology, siRNA-mediated knockdown assays and subsequent RNA-sequencing and live-cell imaging. Screening of public gene expression data revealed restricted activity of the CUT-class homeobox gene CUX2 in pDCs. An extended analysis of this homeobox gene class in myelopoiesis showed that additional CUX2 activity was restricted to myeloid progenitors, while BPDCN patients aberrantly expressed ONECUT2, which remained silent in the complete myeloid compartment. ONECUT2 expressing BPDCN cell line CAL-1 served as a model to investigate its regulation and oncogenic activity. The ONECUT2 locus at 18q21 was duplicated and activated by IRF4, AUTS2 and TNF-signaling and repressed by BMP4-, TGFb- and IL13-signalling. Functional analyses of ONECUT2 revealed the inhibition of pDC differentiation and of CDKN1C and CASP1 expression, while SMAD3 and EPAS1 were activated. EPAS1 in turn enhanced survival under hypoxic conditions which thus may support dendritic tumor cells residing in hypoxic skin lesions. Collectively, we revealed physiological and aberrant activities of CUT-class homeobox genes in myelopoiesis including pDCs and in BPDCN, respectively. Our data may aid in the diagnosis of BPDCN patients and reveal novel therapeutic targets for this fatal malignancy. Full article

Resistance and toxicity associated with current treatments for human cytomegalovirus (HCMV) infection highlight the need for alternatives and immunotherapy has emerged as a promising strategy. This study examined the in vitro immunological effects of co-administration of Thymosin-alpha-1 (Tα1) and polyanionic carbosilane dendrimers (PCDs) on peripheral blood mononuclear cells (PBMCs) during HCMV infection. The biocompatibility of PCDs was assessed via MTT and LDH assays. PBMCs were pre-treated with the co-administered compounds and then exposed to HCMV for 48 h. Morphological alterations in PBMCs were observed using optical microscopy and total dendritic cells (tDCs), myeloid dendritic cells (mDCs), and plasmacytoid dendritic cells (pDCs), along with CD4+/CD8+ T cells and regulatory T cells (Treg), and were characterized using multiparametric flow cytometry. The findings revealed that Tα1 + PCDs treatments increased DC activation and maturation. Furthermore, increased co-receptor expression, intracellular IFNγ production in T cells and elevated Treg functionality and reduced senescence were evident with Tα1 + G2-S24P treatment. Conversely, reduced co-receptor expression, intracellular cytokine production in T cells, lower functionality and higher senescence in Treg were observed with Tα1 + G2S16 treatment. In summary, Tα1 + PCDs treatments demonstrate synergistic effects during early HCMV infection, suggesting their use as an alternative therapeutic for preventing virus infection. Full article

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare, aggressive hematologic malignancy with poor outcomes. The World Health Organization (WHO) redefined BDCN as a distinct disease entity in 2016. BPDCN arises from plasmacytoid dendritic cells, manifesting primarily in the skin, bone marrow, and lymph nodes, occasionally involving the central nervous system (CNS). This presents challenges in diagnosis and treatment, with CNS involvement often overlooked in standard diagnostic workups due to BPDCN’s rarity and patients often being neurologically asymptomatic at diagnosis. CNS involvement typically emerges during relapse, yet clinical trials often exclude such cases, limiting our understanding of its development and treatment. Treatment options for CNS involvement include intrathecal (IT) chemotherapies like methotrexate and cytarabine, often in combination with systemic agents. Tagraxofusp and traditional regimens for acute myeloid leukemia show limited success at preventing CNS relapse, prompting exploration of combined therapies like hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone (HyperCVAD) with venetoclax and adding IT chemotherapy to other backbones. Ongoing clinical trials investigating emerging therapies offer hope despite limited focus on CNS implications. Trials incorporating CNS-involved patients aim to pioneer novel treatment approaches, potentially reshaping BPDCN management. Understanding CNS involvement’s complexities in BPDCN remains crucial for tailored treatments and better patient outcomes. Full article

Chemerin is an atypical chemokine first described as a chemoattractant agent for monocytes, natural killer cells, plasmacytoid and myeloid dendritic cells, through interaction with its main receptor, the G protein-coupled receptor chemokine-like receptor 1 (CMKLR1). Chemerin has been studied in various lung disease models, showing both pro- and anti-inflammatory properties. Given the incidence and burden of inflammatory lung diseases from diverse origins (infectious, autoimmune, age-related, etc.), chemerin has emerged as an interesting therapeutical target due to its immunomodulatory role. However, as highlighted by this review, further research efforts to elucidate the mechanisms governing chemerin’s dual pro- and anti-inflammatory characteristics are urgently needed. Moreover, although a growing body of evidence suggests chemerin as a potential biomarker for the diagnosis and/or prognosis of inflammatory lung diseases, this review underscores the necessity for standardizing both sampling types and measurement techniques before drawing definitive conclusions. Full article