Showing papers on "Myeloid published in 2009"
TL;DR: Experimental data demonstrating the role of the microenvironment in metastasis is described, areas for future research are identified and possible new therapeutic avenues are suggested.
Abstract: Metastasis is a multistage process that requires cancer cells to escape from the primary tumour, survive in the circulation, seed at distant sites and grow. Each of these processes involves rate-limiting steps that are influenced by non-malignant cells of the tumour microenvironment. Many of these cells are derived from the bone marrow, particularly the myeloid lineage, and are recruited by cancer cells to enhance their survival, growth, invasion and dissemination. This Review describes experimental data demonstrating the role of the microenvironment in metastasis, identifies areas for future research and suggests possible new therapeutic avenues.
3,332 citations
TL;DR: Somatic mutations in TET2 occur in about 15% of patients with various myeloid cancers and were present in hematopoietic stem cells and preceded the JAK2 V617F mutation in the five samples from patients with myeloproliferative disorders that were analyzed.
Abstract: Background The myelodysplastic syndromes and myeloproliferative disorders are associated with deregulated production of myeloid cells. The mechanisms underlying these disorders are not well defined. We initially identified deletions or mutations in TET2 in three patients with myelo- dysplastic syndromes, in three of five patients with myeloproliferative disorders, in two patients with primary AML, and in one patient with secondary AML. We selected the six patients with myelodysplastic syndromes or AML because they carried acquired rearrangements on chromosome 4q24; we selected the five patients with myelopro- liferative disorders because they carried a dominant clone in hematopoietic progeni- tor cells that was positive for the V617F mutation in the Janus kinase 2 (JAK2) gene. TET2 defects were observed in 15 of 81 patients with myelodysplastic syndromes (19%), in 24 of 198 patients with myeloproliferative disorders (12%) (with or with- out the JAK2 V617F mutation), in 5 of 21 patients with secondary AML (24%), and in 2 of 9 patients with chronic myelomonocytic leukemia (22%). TET2 defects were present in hematopoietic stem cells and preceded the JAK2 V617F mutation in the five samples from patients with myeloproliferative disorders that we analyzed. Conclusions Somatic mutations in TET2 occur in about 15% of patients with various myeloid cancers.
1,612 citations
TL;DR: It is found that increased CD47 expression is an independent, poor prognostic factor that can be targeted on human AML stem cells with blocking monoclonal antibodies capable of enabling phagocytosis of LSC.
1,372 citations
TL;DR: It is concluded that CD47 upregulation is an important mechanism that provides protection to normal HSCs during inflammation-mediated mobilization, and that leukemic progenitors co-opt this ability in order to evade macrophage killing.
1,197 citations
TL;DR: How advanced cancer cells usurp components of the host innate immune system, including bone-marrow-derived myeloid progenitors, to generate an inflammatory microenvironment hospitable for metastatic growth is explained.
Abstract: Metastatic progression depends on genetic alterations intrinsic to cancer cells as well as the inflammatory microenvironment of advanced tumours. To understand how cancer cells affect the inflammatory microenvironment, we conducted a biochemical screen for macrophage-activating factors secreted by metastatic carcinomas. Here we show that, among the cell lines screened, Lewis lung carcinoma (LLC) were the most potent macrophage activators leading to production of interleukin-6 (IL-6) and tumour-necrosis factor-alpha (TNF-alpha) through activation of the Toll-like receptor (TLR) family members TLR2 and TLR6. Both TNF-alpha and TLR2 were found to be required for LLC metastasis. Biochemical purification of LLC-conditioned medium (LCM) led to identification of the extracellular matrix proteoglycan versican, which is upregulated in many human tumours including lung cancer, as a macrophage activator that acts through TLR2 and its co-receptors TLR6 and CD14. By activating TLR2:TLR6 complexes and inducing TNF-alpha secretion by myeloid cells, versican strongly enhances LLC metastatic growth. These results explain how advanced cancer cells usurp components of the host innate immune system, including bone-marrow-derived myeloid progenitors, to generate an inflammatory microenvironment hospitable for metastatic growth.
1,008 citations
TL;DR: In this paper, the mutational status of TET1, TET2, and TET3 in myeloproliferative neoplasms (MPNs), chronic myelomonocytic leukemia (CMML), and acute myeloid leukemia (AML) was evaluated.
677 citations
TL;DR: Recent studies indicate that those miRNAs that are selectively and/or highly expressed in immune cells have a ‘permissive’ function in the maturation, proliferation and differentiation of myeloid and lymphoid cells.
623 citations
TL;DR: The results show that ASXL1 might play the role of a tumour suppressor in myeloid malignancies, a disease classified as MDS/Myeloproliferative disorder.
Abstract: The myelodysplastic syndromes (MDSs) are a heterogeneous group of clonal haematological diseases characterized by ineffective haematopoiesis and predisposition to acute myeloid leukaemia (AML). The pathophysiology of MDSs remains unclear. A definition of the molecular biology of MDSs may lead to a better classification, new prognosis indicators and new treatments. We studied a series of 40 MDS/AML samples by high-density array-comparative genome hybridization (aCGH). The genome of MDSs displayed a few alterations that can point to candidate genes, which potentially regulate histone modifications and WNT pathways (e.g. ASXL1, ASXL2, UTX, CXXC4, CXXC5, TET2, TET3). To validate some of these candidates we studied the sequence of ASXL1. We found mutations in the ASXL1 gene in four out of 35 MDS patients (11%). To extend these results we searched for mutations of ASXL1 in a series of chronic myelomonocytic leukaemias, a disease classified as MDS/Myeloproliferative disorder, and found mutations in 17 out of 39 patients (43%). These results show that ASXL1 might play the role of a tumour suppressor in myeloid malignancies.
555 citations
TL;DR: In vitro assays unveil a hierarchy of immunoregulatory activity among MDSC subsets that is controlled by tumor‐released GM‐CSF, and Gene silencing experiments indicated that GM‐ CSF was necessary to induce preferential expansion of both CD11b+/Gr‐1int and CD11B+/ Gr‐1low subsets in the spleen of tumor‐bearing mice and mediate tumor‐induced tolerance.
Abstract: CD11b+/Gr-1+ myeloid-derived suppressor cells (MDSC) contribute to tumor immune evasion by restraining the activity of CD8+ T-cells. Two major MDSC subsets were recently shown to play an equal role in MDSC-induced immune dysfunctions: monocytic- and granulocytic-like. We isolated three fractions of MDSC, i.e. CD11b+/Gr-1high, CD11b+/Gr-1int, and CD11b+/Gr-1low populations that were characterized morphologically, phenotypically and functionally in different tumor models. In vitro assays showed that CD11b+/Gr-1int cell subset, mainly comprising monocytes and myeloid precursors, was always capable to suppress CD8+ T-cell activation, while CD11b+/Gr-1high cells, mostly granulocytes, exerted appreciable suppression only in some tumor models and when present in high numbers. The CD11b+/Gr-1int but not CD11b+/Gr-1high cells were also immunosuppressive in vivo following adoptive transfer. CD11b+/Gr-1low cells retained the immunosuppressive potential in most tumor models. Gene silencing experiments indicated that GM-CSF was necessary to induce preferential expansion of both CD11b+/Gr-1int and CD11b+/Gr-1low subsets in the spleen of tumor-bearing mice and mediate tumor-induced tolerance whereas G-CSF, which preferentially expanded CD11b+/Gr-1high cells, did not create such immunosuppressive environment. GM-CSF also acted on granulocyte-macrophage progenitors in the bone marrow inducing local expansion of CD11b+/Gr-1low cells. These data unveil a hierarchy of immunoregulatory activity among MDSC subsets that is controlled by tumor-released GM-CSF.
529 citations
TL;DR: Results provide clear validation for therapeutic monoclonal antibody targeting of AML-LSCs and for translation of in vivo preclinical research findings toward a clinical application.
522 citations
TL;DR: It is demonstrated that in vivo studies demonstrated that AMD3465 induced mobilization of AML cells and progenitor cells into circulation and enhanced antileukemic effects of chemotherapy and sorafenib, resulting in markedly reduced leukemia burden and prolonged survival of the animals.
TL;DR: It is concluded that, at least in the models examined, G-CSF expression by tumor or stromal cells is a determinant of refractoriness to anti-VEGF-A treatment.
Abstract: Recent studies suggest that tumor-associated CD11b+Gr1+ myeloid cells contribute to refractoriness to antiangiogenic therapy with an anti-VEGF-A antibody. However, the mechanisms of peripheral mobilization and tumor-homing of CD11b+Gr1+ cells are unclear. Here, we show that, compared with other cytokines [granulocyte-macrophage colony stimulating factor (GM-CSF), stromal derived factor 1α, and placenta growth factor], G-CSF and the G-CSF-induced Bv8 protein have preferential expression in refractory tumors. Treatment of refractory tumors with the combination of anti-VEGF and anti-G-CSF (or anti-Bv8) reduced tumor growth compared with anti-VEGF-A monotherapy. Anti-G-CSF treatment dramatically suppressed circulating or tumor-associated CD11b+Gr1+ cells, reduced Bv8 levels, and affected the tumor vasculature. Conversely, G-CSF delivery to animals bearing anti-VEGF sensitive tumors resulted in reduced responsiveness to anti-VEGF-A treatment through induction of Bv8-dependent angiogenesis. We conclude that, at least in the models examined, G-CSF expression by tumor or stromal cells is a determinant of refractoriness to anti-VEGF-A treatment.
TL;DR: The emerging evidence supporting the importance of the bone marrow microenvironment in LSC survival is discussed and the physiologic interactions of HSCs and the niche that inform the understanding of microenvironment support of LSCs are considered.
TL;DR: The data support a tumor suppressor role for miR-29 and provide a rationale for the use of synthetic mi R-29b oligonucleotides as a novel strategy to improve treatment response in AML.
TL;DR: It is difficult to assign a specific role in the pathogenesis or progression of myeloproliferative neoplasms to mutant TET2, and it is suggested that a role for TET1 in disease progression is suggested.
Abstract: To the Editor: The finding of Delhommeau and colleagues that TET2 mutations occur in myeloid cancers (May 28 issue)1 has been confirmed by others.2-5 The presence of single-copy and doublecopy TET2 defects and the frequent occurrence of frameshift, nonsense, or deletion mutations are consistent with the notion that TET2 is a tumor suppressor. Delhommeau et al. suggest a role for TET2 in disease progression. We looked into this possibility by studying stored, serial bone marrow samples from eight patients with myeloproliferative neoplasms. Mutant TET2 was not detected in any of the follow-up samples, even though leukemic or fibrotic transformation occurred in three of these patients. These results are consistent with observations of similar frequencies of TET2 mutations in chronic and advanced-phase myeloproliferative neoplasms.3 We therefore believe that it is difficult to assign a specific role in the pathogenesis or progression of myeloproliferative neoplasms to mutant TET2.
TL;DR: It is demonstrated that CD11b(+)CD62L(+)Ly6C(hi) monocytes with colony-forming potential are mobilized into the bloodstream by a granulocyte-macrophage colony-stimulating factor-dependent pathway immediately before EAE relapses, suggesting a novel pathway for therapeutic targeting.
TL;DR: CX3CR1 deficiency selectively impairs the recruitment of blood Gr1+ monocytes in the spleen after transfer and during acute Listeria monocytogenes infection but does not affect the development of monocytes, cDCs, and PDCs.
Abstract: CX3CR1 expression is associated with the commitment of CSF-1R+ myeloid precursors to the macrophage/dendritic cell (DC) lineage. However, the relationship of the CSF-1R+ CX3CR1+ macrophage/DC precursor (MDP) with other DC precursors and the role of CX3CR1 in macrophage and DC development remain unclear. We show that MDPs give rise to conventional DCs (cDCs), plasmacytoid DCs (PDCs), and monocytes, including Gr1+ inflammatory monocytes that differentiate into TipDCs during infection. CX3CR1 deficiency selectively impairs the recruitment of blood Gr1+ monocytes in the spleen after transfer and during acute Listeria monocytogenes infection but does not affect the development of monocytes, cDCs, and PDCs.
TL;DR: In this paper, gain-of-function mutations of the C-CBL (also known as CBL) tumour suppressor are tightly associated with acquired uniparental disomy (aUPD) in myeloid neoplasms showing myeloproliferative features.
Abstract: Acquired uniparental disomy (aUPD) is a common feature of cancer genomes, leading to loss of heterozygosity. aUPD is associated not only with loss-of-function mutations of tumour suppressor genes, but also with gain-of-function mutations of proto-oncogenes. Here we show unique gain-of-function mutations of the C-CBL (also known as CBL) tumour suppressor that are tightly associated with aUPD of the 11q arm in myeloid neoplasms showing myeloproliferative features. The C-CBL proto-oncogene, a cellular homologue of v-Cbl, encodes an E3 ubiquitin ligase and negatively regulates signal transduction of tyrosine kinases. Homozygous C-CBL mutations were found in most 11q-aUPD-positive myeloid malignancies. Although the C-CBL mutations were oncogenic in NIH3T3 cells, c-Cbl was shown to functionally and genetically act as a tumour suppressor. C-CBL mutants did not have E3 ubiquitin ligase activity, but inhibited that of wild-type C-CBL and CBL-B (also known as CBLB), leading to prolonged activation of tyrosine kinases after cytokine stimulation. c-Cbl(-/-) haematopoietic stem/progenitor cells (HSPCs) showed enhanced sensitivity to a variety of cytokines compared to c-Cbl(+/+) HSPCs, and transduction of C-CBL mutants into c-Cbl(-/-) HSPCs further augmented their sensitivities to a broader spectrum of cytokines, including stem-cell factor (SCF, also known as KITLG), thrombopoietin (TPO, also known as THPO), IL3 and FLT3 ligand (FLT3LG), indicating the presence of a gain-of-function that could not be attributed to a simple loss-of-function. The gain-of-function effects of C-CBL mutants on cytokine sensitivity of HSPCs largely disappeared in a c-Cbl(+/+) background or by co-transduction of wild-type C-CBL, which suggests the pathogenic importance of loss of wild-type C-CBL alleles found in most cases of C-CBL-mutated myeloid neoplasms. Our findings provide a new insight into a role of gain-of-function mutations of a tumour suppressor associated with aUPD in the pathogenesis of some myeloid cancer subsets.
TL;DR: In this paper, the authors show that myeloid dermal dendritic cells (DCs) accumulate in chronically inflamed tissues such as psoriasis and produce inflammatory cytokines.
TL;DR: After transplantation of haploidentical hematopoietic stem cells and infusion of donor T cells, leukemic cells can escape from the donor's antileukemic T cells through the loss of the mismatched HLA haplotype, which leads to relapse.
Abstract: BACKGROUND Transplantation of hematopoietic stem cells from partially matched family donors is a promising therapy for patients who have a hematologic cancer and are at high risk for relapse. The donor T-cell infusions associated with such transplantation can promote post-transplantation immune reconstitution and control residual disease. METHODS We identified 43 patients who underwent haploidentical transplantation and infusion of donor T cells for acute myeloid leukemia or myelodysplastic syndrome and conducted post-transplantation studies that included morphologic examination of bone marrow, assessment of hematopoietic chimerism with the use of short-tandem-repeat amplification, and HLA typing. The genomic rearrangements in mutant variants of leukemia were studied with the use of genomic HLA typing, microsatellite mapping, and single-nucleotide-polymorphism arrays. The post-transplantation immune responses against the original cells and the mutated leukemic cells were analyzed with the use of mixed lymphocyte cultures. RESULTS In 5 of 17 patients with leukemia relapse after haploidentical transplantation and infusion of donor T cells, we identified mutant variants of the original leukemic cells. In the mutant leukemic cells, the HLA haplotype that differed from the donor's haplotype had been lost because of acquired uniparental disomy of chromosome 6p. T cells from the donor and the patient after transplantation did not recognize the mutant leukemic cells, whereas the original leukemic cells taken at the time of diagnosis were efficiently recognized and killed. CONCLUSIONS After transplantation of haploidentical hematopoietic stem cells and infusion of donor T cells, leukemic cells can escape from the donor's antileukemic T cells through the loss of the mismatched HLA haplotype. This event leads to relapse.
TL;DR: The importance of the PD-1/PD-L1 pathway in immune evasion by a hematologic malignancy by hematopoietic cancers, such as acute myeloid leukemia, is suggested, providing a rationale for clinical trials targeting this pathway in leukemia patients.
TL;DR: In situ analysis of the cellular infiltrate from sequential biopsies of HSV-2 lesions from patients on and off antiviral therapy found the persistence and enrichment of HIV receptor–positive inflammatory cells in the genitalia help explain the inability of anti–HSV- 2 therapy to reduce HIV acquisition.
Abstract: Infection with HSV-2 increases the likelihood of HIV acquisition, but suppression of HSV-2 reactivation with antiviral drugs does not seem to reduce the acquisition of HIV. Laurence Corey and colleagues provide a potential mechanism underlying this observation, showing that even after acyclovir treatment for the HSV-2 infection, many inflammatory and immune cells possessing the receptors required for HIV infection persist in the mucosa, making the initial 'spark' of infection more likely. To explore the mechanism by which herpes simplex virus (HSV)-2 infection is related to HIV-1 acquisition, we conducted in situ analysis of the cellular infiltrate from sequential biopsies of HSV-2 lesions from patients on and off antiviral therapy. CD4+ and CD8+ T cells and a mixed population of plasmacytoid and myeloid dendritic cells (DCs), including cells expressing the C-type lectin receptor DC-SIGN, persisted at sites of HSV-2 reactivation for months after healing, even with daily antiviral therapy. The CD4+ T cells that persisted reacted to HSV-2 antigen, were enriched for expression of the chemokine receptor CCR5, and were contiguous to DCs expressing the interleukin-3 receptor CD123 or DC-SIGN. Ex vivo infection with a CCR5-tropic strain of HIV-1 revealed greater concentrations of integrated HIV-1 DNA in cells derived from healed genital lesion biopsies than in cells from control skin biopsies. The persistence and enrichment of HIV receptor–positive inflammatory cells in the genitalia help explain the inability of anti–HSV-2 therapy to reduce HIV acquisition.
TL;DR: In this article, a single wave of Langerhans cells was recruited in the epidermis of mice around embryonic day 18 and acquired a dendritic morphology, major histocompatibility complex II, CD11c, and langerin expression immediately after birth.
Abstract: Most tissues develop from stem cells and precursors that undergo differentiation as their proliferative potential decreases. Mature differentiated cells rarely proliferate and are replaced at the end of their life by new cells derived from precursors. Langerhans cells (LCs) of the epidermis, although of myeloid origin, were shown to renew in tissues independently from the bone marrow, suggesting the existence of a dermal or epidermal progenitor. We investigated the mechanisms involved in LC development and homeostasis. We observed that a single wave of LC precursors was recruited in the epidermis of mice around embryonic day 18 and acquired a dendritic morphology, major histocompatibility complex II, CD11c, and langerin expression immediately after birth. Langerin+ cells then undergo a massive burst of proliferation between postnatal day 2 (P2) and P7, expanding their numbers by 10–20-fold. After the first week of life, we observed low-level proliferation of langerin+ cells within the epidermis. However, in a mouse model of atopic dermatitis (AD), a keratinocyte signal triggered increased epidermal LC proliferation. Similar findings were observed in epidermis from human patients with AD. Therefore, proliferation of differentiated resident cells represents an alternative pathway for development in the newborn, homeostasis, and expansion in adults of selected myeloid cell populations such as LCs. This mechanism may be relevant in locations where leukocyte trafficking is limited.
TL;DR: It is shown here that direct injection of protamine-protected mRNA is feasible and safe and the significant influence of the treatment on the frequency of immunosuppressive cells, the increase of vaccine-directed T cells upon treatment in a subset of patients together with the demonstration of a complete clinical response encourage further clinical investigation of the protamines-mRNA vaccine.
Abstract: In mice, injection of messenger RNA (mRNA) coding for tumor-associated antigens can induce antitumor immune responses and therefore offers a broadly applicable immunotherapy approach We injected intradermally protamine-stabilized mRNAs coding for Melan-A, Tyrosinase, gp100, Mage-A1, Mage-A3, and Survivin in 21 metastatic melanoma patients In 10 patients keyhole limpet hemocyanin (KLH) was added to the vaccine Granulocyte macrophage colony-stimulating factor was applied as an adjuvant Endpoints were toxicity and immune responses No adverse events more than grade II have been observed During treatment the frequency of Foxp3+/CD4+ regulatory T cells was significantly decreased upon mRNA vaccination in peripheral blood of the patients in the KLH arm, whereas myeloid suppressor cells (CD11b+HLA-DR lo monocytes) were reduced in the patients not receiving KLH A reproducible increase of vaccine-directed T cells was observed in 2 of 4 immunologically evaluable patients One of 7 patients with measurable disease showed a complete response In conclusion, we show here that direct injection of protamine-protected mRNA is feasible and safe The significant influence of the treatment on the frequency of immunosuppressive cells, the increase of vaccine-directed T cells upon treatment in a subset of patients together with the demonstration of a complete clinical response encourage further clinical investigation of the protamine-mRNA vaccine
TL;DR: Designing miR-155 based therapies will require a better understanding of the molecular basis of its action as well as of how mi R-155 levels are regulated in a cell-specific manner.
Abstract: MicroRNAs are short non-coding RNAs that posttranscriptionally modulate the expression of multiple target genes and are thus implicated in a wide array of cellular and developmental processes. miR-155 is processed from BIC, a non-coding transcript highly expressed in both activated B and T cells and in monocytes/macrophages. miR-155 levels change dynamically during both hematopoietic lineage differentiation and the course of the immune response. Different mouse models developed recently indicate that miR-155 plays a critical role during hematopoiesis and regulates lymphocyte homeostasis and tolerance. A moderate increase of miR-155 levels is observed in many types of malignancies of B cell or myeloid origin, and transgenic over-expression of miR-155 in mice results in cancer. While the high levels of miR-155 reached transiently during the course of the immune response remain unharmful for the organism, the reason why a moderate up-regulation of miR-155 can lead to cancer remains obscure. As prolonged expo...
TL;DR: Findings suggest that HOTAIRM1 plays a role in the myelopoiesis through modulation of gene expression in the HOXA cluster.
TL;DR: It is demonstrated that HOXA9 depletion in 17 human AML/ALL cell lines induces proliferation arrest and apoptosis specifically in MLL-rearranged cells, and mice transplanted with HOX a9-depleted t(4;11) SEMK2 cells revealed a significantly lower leukemia burden, thus identifying a role for HOX
TL;DR: It is shown that gene expression profiling allows accurate prediction of certain acute myeloid leukemia subtypes, e.g. those characterized by expression of chimeric transcription factors, however, detection of mutations affecting signaling molecules and numerical abnormalities still requires alternative molecular methods.
Abstract: We examined the gene expression profiles of two independent cohorts of patients with acute myeloid leukemia [n=247 and n=214 (younger than or equal to 60 years)] to study the applicability of gene expression profiling as a single assay in prediction of acute myeloid leukemia-specific molecular subtypes. The favorable cytogenetic acute myeloid leukemia subtypes, i.e., acute myeloid leukemia with t(8;21), t(15;17) or inv(16), were predicted with maximum accuracy (positive and negative predictive value: 100%). Mutations in NPM1 and CEBPA were predicted less accurately (positive predictive value: 66% and 100%, and negative predictive value: 99% and 97% respectively). Various other characteristic molecular acute myeloid leukemia subtypes, i.e., mutant FLT3 and RAS, abnormalities involving 11q23, -5/5q-, -7/7q-, abnormalities involving 3q (abn3q) and t(9;22), could not be correctly predicted using gene expression profiling. In conclusion, gene expression profiling allows accurate prediction of certain acute myeloid leukemia subtypes, e.g. those characterized by expression of chimeric transcription factors. However, detection of mutations affecting signaling molecules and numerical abnormalities still requires alternative molecular methods.
TL;DR: Older and younger patients with AML show modest differences in their risk profiles and equally no dose response to intensified chemotherapy under harmonized conditions, but their observed fundamental difference in outcome across all subgroups remains unexplained.
Abstract: Purpose The purpose of the study was to assess the contribution of age and disease variables to the outcome of untreated patients with acute myeloid leukemia (AML) receiving varying intensive induction chemotherapy. Patients and Methods Patients 16 to 85 years of age with primary AML, known karyotype, and uniform postremission chemotherapy enrolled onto two consecutive trials were eligible and were randomly assigned to induction either with a standard-dose (cytarabine, daunorubicin, and 6-thioguanine) and a high-dose (cytarabine and mitoxantrone) combination, or with two courses of the high-dose combination. Subgroups were defined by karyotype, nucleophosmin and FLT3 mutation, WBC count, serum lactate dehydrogenase, and residual blasts. Results In 1,284 patients, the overall survival at 4 years in those younger and older than 60 years was 37% versus 16% (P < .001) and the ongoing remission duration was 46% versus 22% (P < .001). Similar age-related differences in outcome were found for all defined subgrou...
TL;DR: It is shown that myeloid cells with immunosuppressive properties accumulate both in mononuclear and polymorphonuclear fractions of circulating blood leukocytes of patients with colon cancer and melanoma, thus unveiling a generalized alteration in the homeostasis of the myeloids compartment.
Abstract: Myeloid-derived suppressor cells (MDSC) contribute to immune dysfunctions induced by tumors both in experimental models and patients. In mice, MDSC are phenotypically heterogeneous cells that vary in their surface markers, likely depending on soluble factors produced by different tumors. We recently described a subset of inflammatory monocytes with immunosuppressive properties that can be found within the tumor mass, blood, and lymphoid organs of tumor-bearing mice. These cells expressed the α-chain of the receptor for IL-4 (IL4Rα) that was critical for their negative activity on CD8 + T cells. In cancer patients, the nature of MDSC is still poorly defined because evidence exists for both monocytic and granulocytic features. We show in this study that myeloid cells with immunosuppressive properties accumulate both in mononuclear and polymorphonuclear fractions of circulating blood leukocytes of patients with colon cancer and melanoma, thus unveiling a generalized alteration in the homeostasis of the myeloid compartment. Similarly to mouse MDSC, IL4Rα is up-regulated in both myeloid populations but its presence correlates with an immunosuppressive phenotype only when mononuclear cells, but not granulocytes, of tumor-bearing patients are considered.