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INTRODUCTION: Platelet Monocyte Complexes (PMCs) are commonly expressed in coronary artery disease but their pathologic significance in ST elevation myocardial infarction (STEMI) is unclear. This study evaluates the relationship between locally activated PMCs and intracoronary inflammation in stable and unstable coronary disease. MATERIAL AND METHODS: Micro catheter aspirated blood samples of 15 STEMI and 7 stable angina patients are collected from the coronary artery (CA), aorta (AO) and right atrium (RA). Samples are labelled with monoclonal antibodies and prepared for flow cytometry. CD 14 and CD 61 double positive cells are identified as PMC. P-selectin expression is identified by additional CD62P positivity and TF expression by additional CD142 positivity. Plasma TNF-alpha and IL-6 are measured using ELISA and CRP is measured in plasma using a high sensitivity automated microparticle enhanced latex turbidimetric immunoassay. RESULTS: No site-specific difference is seen in overall PMC expression in STEMI or stable angina. Surface P-selectin expression in STEMI [median (IQR)] is significantly higher in CA [35.01 (23.15-56.99)] compared with AO [15.99 (10.3-18.85)] or RA [14.02 (10.42-26.08)] (p = 0.003). Intracoronary PMC correlates significantly with intracoronary TNFalpha (r = 0.87, p = 0.001) and intracoronary IL-6 (r = 0.76, p = 0.03). Bound monocytes within P-selectin positive and tissue factor positive complexes correlate positively with intracoronary TNF-alpha (r = 0.81, p = 0.008 & r = 0.80, p = 0.009 respectively) and IL-6 (r = 0.54, p = 0.16 & r = 0.71, p = 0.05 respectively). No such correlation is observed in the peripheral circulation of STEMI and stable angina patients. CONCLUSION: Inflammation is not attributable to PMC formation per se. However, increased intracoronary P-selectin expression by activated platelets and tissue factor expression by activated monocytes within the complexes are determinants of local intracoronary inflammatory burden in STEMI. [ABSTRACT FROM AUTHOR]

Pre-clinical studies of allogeneic stem cell transplantation suggest that depletion of naive T cells from donor lymphocytes will reduce the risk of GvHD but preserve immunity to infectious pathogens. In this study, we have established a clinical-grade protocol under good manufacturing practice conditions for purging CD62L+ naive T cells from steady-state leukapheresis products using the CliniMACS system. The efficacy of immunomagnetic CD62L depletion was assessed by analysis of cell composition and functional immune responses. A median 2.9 log CD62L depletion was achieved with no evidence of CD62L shedding during the procedure and a mean T-cell yield of 47%. CD62L− cells comprised an equal mix of CD4+ and CD8+ T cells, with elimination of B cells but maintenance of regulatory T cells and natural killer cell populations. CD62L-depleted T cells were predominantly CD45RA− and CD45RA+ effector memory (>90%) and contained the bulk of pentamer-staining antivirus-specific T cells. Functional assessment of CD62L− cells revealed the maintenance of antiviral T-cell reactivity and a reduction in the alloreactive immune response compared with unmanipulated cells. Clinical-grade depletion of naive T cells using immunomagnetic CD62L beads from steady-state leukapheresis products is highly efficient and generates cells suitable for adoptive transfer in the context of clinical trials. [ABSTRACT FROM AUTHOR]

Background:Biobanking is the process of storing high quality human biospecimens alongside linked clinical data, for research purposes. The aim is to identify novel biomarkers with prognostic or diagnostic significance. However, the challenges implicit in the collection and storage of human tissue for research have curtailed the impact of this technique to date.Aim:This paper aims to summarise the challenges faced by biobanking within the ENT specialty in the UK, and to present protocols used for the routine collection, freezing and storage of tissue specimens at the Royal National Throat, Nose and Ear Hospital. These protocols could be used to guide other ENT departments (in the UK and worldwide) wishing to initiate the routine collection and storage of tissue samples. Their publication could also help to establish basic standards and ensure consistency in ENT tissue storage.Methods:Interviews conducted with industry experts, and a literature review of ‘best practice’ in biobanking.Conclusion:The ENT specialty must stay abreast of progress in human tissue research in order to ensure the best possible management of its patients. Our protocol for the routine banking of ENT tissue at the Royal National Throat, Nose and Ear Hospital could be used as a template for other ENT departments (in the UK and worldwide) to encourage widespread implementation of high quality tissue banking. [ABSTRACT FROM PUBLISHER]

Background/Aims: Hepatocyte progenitors have frequently been cultured from rodents but reports from human liver are rare. Methods: Non-parenchymal cell fraction isolated from 19 explant livers (removed at orthotopic liver transplantation for acute or chronic liver disease) and histologically normal human liver was cultured. Results: Proliferating epithelioid colonies were identifiable after 2–3 weeks culture as a very rare event (<1 per million cells plated) expressing mRNAs and protein antigens of mixed hepatocytic/biliary phenotype. Colony survival could be prolonged by transduction of the catalytic sub-unit of telomerase. Hepatocyte growth factor, epidermal growth factor and oncostatin M did not further enhance hepatocytic differentiation. The expression of markers associated with hepatocyte precursor status was investigated by flow cytometry. Cells expressing the stem cell-associated markers CD133 and CD117 were identified at low frequency. The proportion of cells expressing the integrin CD49f was higher in diseased liver than in normal liver, but the proportion expressing the hepatocyte growth factor receptor c-met was lower. Successful enrichment of plated populations for progenitors was not achieved. Conclusion: Although there is clear histological evidence of hepatocyte precursors in human explant livers, predictable culture of such cells with differentiation toward mature hepatocyte phenotype remains elusive. Copyright © 2007 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

We show that at least half of patients with common variable immunodeficiency (CVID) have circulating CD8+ T cells specific for epitopes derived from cytomegalovirus (CMV) and/or the Epstein–Barr virus (EBV). Compared to healthy age-matched subjects, more CD8+ T cells in CVID patients were committed to CMV. Despite previous reports of defects in antigen presentation and cellular immunity in CVID, specific CD4+ and CD8+ T cells produced interferon (IFN)-γ after stimulation with CMV peptides, and peripheral blood mononuclear cells secreted perforin in response to these antigens. In CVID patients we found an association between a high percentage of circulating CD8+ CD57+ T cells containing perforin, CMV infection and a low CD4/CD8 ratio, suggesting that CMV may have a major role in the T cell abnormalities described previously in this disease. We also show preliminary evidence that CMV contributes to the previously unexplained severe enteropathy that occurs in about 5% of patients. [ABSTRACT FROM AUTHOR]

We have studied the in vitro actions of the sesquiterpene lactone parthenolide (PTL) on cells isolated from patients with chronic lymphocytic leukemia (CLL). Dye reduction viability assays showed that the median LD50 for PTL was 6.2 μM (n=78). Fifteen of these isolates were relatively resistant to the conventional agent chlorambucil but retained sensitivity to PTL. Brief exposures to PTL (1–3 h) were sufficient to induce caspase activation and commitment to cell death. Chronic lymphocytic leukemia cells were more sensitive towards PTL than were normal T lymphocytes or CD34+ haematopoietic progenitor cells. The mechanism of cell killing was via PTL-induced generation of reactive oxygen species, resulting in turn in a proapoptotic Bax conformational change, release of mitochondrial cytochrome c and caspase activation. Parthenolide also decreased nuclear levels of the antiapoptotic transcription factor nuclear factor-kappa B and diminished phosphorylation of its negative regulator IκB. Killing of CLL cells by PTL was apparently independent of p53 induction. This is the first report showing the relative selectivity of PTL towards CLL cells. The data here warrant further investigation of this class of natural product as potential therapeutic agents for CLL.Leukemia (2006) 20, 1073–1079. doi:10.1038/sj.leu.2404230; published online 20 April 2006 [ABSTRACT FROM AUTHOR]

Immunocompetent donor T cells in Allogeneic Haematopoietic Stem Cell grafts mediate acute Graft versus Host Disease (GvHD), still a major cause of recipient morbidity and mortality post transplant. Despite the advent of high resolution HLA-typing and matching at HLA loci, acute GvHD remains a significant problem, even in HLA matched siblings, due primarily to minor histocompatability antigen mismatches. Treatment of GvHD remains ineffective and highly immunosuppressive and the challenge to find effective methods of prevention continues. Non selective removal of donor T cells from the graft has been proven to be effective in preventing GvHD but the beneficial effects of donor T cells, namely effective immune reconstitution and anti tumour activity, are lost. This review considers mechanisms by which acute GvHD may be prevented in the context of the current model of GvHD immunopathogenesis, with a special emphasis on the recent techniques of selective removal or destruction of donor allogeneic T cells that have been described. [ABSTRACT FROM AUTHOR]

Natural killer cells represent the predominant lymphoid cell in the peripheral blood for many months after allogeneic or autologous stem cell transplant and their role in immunity to pathogens during this period is established. However, following the largely unsuccessful trials of NK and IL-2 activated NK cells for the treatment of haematological malignancies in the 1980's and 90’s, their role in tumour immunology was discredited. Over the past ten years we have come to understand some of the complex regulatory pathways involved in NK cell activation and we are now in a position to capitalise upon this knowledge. This review presents our current state of understanding of NK cell regulation and highlights the role of these cells in engraftment, graft-versus-host disease, anti-leukaemia activity and post-transplant infection. [ABSTRACT FROM AUTHOR]

The advent of the Code of Practice for Tissue Banks has led to the requirement for quality systems to be established in all laboratories involved in the production or processing of all cellular tissues to be used therapeutically. The quality system is all-encompassing from process validations and quality assurance to the standard of facilities and staff training. This seems self-evident to those working within the transfusion field but is a relatively novel concept to many hospital laboratories preparing transplant products such as bone marrow or peripheral blood derived haematopoietic stem cells. This review places the current guidelines in an historical context and explains many of the central tenets and requirements of the Code of Practice while outlining a process to facilitate preparation for accreditation. [ABSTRACT FROM AUTHOR]

Evidence of an immune mediated graft-versus-leukaemia effect has led to the belief that T and NK cell based adoptive immunotherapy can constitute effective treatment for relapsed leukaemias. However, work on solid tumours has shown this strategy may be hampered, by an immune escape mechanism in which tumour secreted immunosuppressive factors compromise T and NK cell function. Indeed, acute myeloid leukaemia (AML) cells secrete immunosuppressive factors that block the synthesis of Th1 type cytokines in T cells. We demonstrate here that this immunosuppression, mediated by both HL60 AML cell line and primary AML blasts, inhibits T and NK cell proliferation but not cytolytic activity. Supernatants from HL60 cell line and primary AML blasts inhibited T cell proliferation to mitogenic and alloantigen stimulation but had no effect on cytolytic function. Similarly, the proliferation of NK cells to IL-2 and IL-15 stimulation was inhibited whilst their cytolytic function, shown by lysis of AML blasts, K562 and Daudi cells remained unaffected. The failure of T and NK cells to proliferate was not due to effector cell apoptosis. Indeed, removal of lymphocytes from the immunosuppressive environment partially restored their capacity to respond to mitogenic stimulation. T cells exposed to immunosuppressive supernatants did not increase expression of mitotic inhibitory proteins that arrest cell division, thereby ruling this out as a mechanism of operation for this immunosuppression. T cell expansion requires antigen stimulation, usually provided in the form of AML blasts, therefore our data suggest that NK cells may be more practical for the immunotherapy of AML. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editor discusses various reports within the issue on topics including graft versus host disease, hematopoietic stem cells transplantation, and complications on bone marrow transplantation.

One of the main goals in allogeneic bone marrow transplantation is the abrogation of graft-versus-host disease with the preservation of antileukaemia and antiviral activity. We have established a novel system for the selective removal of alloreactive lymphocytes from donor grafts while retaining an effective allogeneic response to third-party stimulator cells. Initial feasibility studies were done with unrelated HLA-mismatched pairs and then extended into the matched setting. Mononuclear cells from HLA-matched donors were cocultured with irradiated recipient cells prestimulated with cytokines (γ-IFN and TNF-α) in a modified mixed lymphocyte culture (MLC). Alloreactive donor lymphocytes were identified by expression of CD69, an early activation marker and selectively removed by paramagnetic bead sorting. The remaining ‘non-alloreactive’ lymphocytes were tested in proliferative assays against the original matched recipient and to a third-party donor. A mean depletion of proliferative capacity to 11.5 ± 9.9% of the original matched recipient response was achieved while the residual third-party response was largely preserved at 77.8 ± 20.9% which should translate into improved immune reconstitution and preservation of antiviral activity. The non-alloreactive lymphocytes could also possess functional antileukaemia activity. Moreover, the alloreactive cells are easily recoverable in this selective T cell depletion strategy for cryopreservation and ready for immediate access as therapeutic donor lymphocyte infusions in cases of frank relapse post transplant. [ABSTRACT FROM AUTHOR]

The prophylactic use of T cell depletion (TCD) strategies for the prevention of graft-versus-host disease (GVHD) following allogeneic stem cell transplantation remains widespread. Initial reports of high incidence of graft rejection after TCD BMT led to a move away from this approach but improved conditioning regimens have reduced this risk substantially. The use of TCD has also been associated with higher relapse risk post-BMT although the success of donor leukocyte infusion (DLI) as treatment for relapse has reduced this problem, especially in chronic myeloid leukaemia (CML). Currently the use of TCD BMT is increasing particularly due to the relative increase in BMT from non-related donors for whom TCD is the optimal GVHD prophylaxis. However, doubts remain over the long-term effect on the reconstituted immune system of recipients of TCD BMT, particularly in adult recipients. In this study we have undertaken a detailed sequential analysis in 23 patients who received allo-grafts from HLA-identical sibling donors after high-dose chemo/radiotherapy for acute or chronic leukaemia. Of these patients, 11 received non-manipulated grafts, five received ‘partially TCD’ (PTCD) and a further seven received ‘fully TCD’ (FTCD) bone marrow. T cell depletion was performed ex vivo by Campath-1M plus autologous serum as a source of complement. Partial TCD describes grafts with a T cell reduction of 1–2 log. Full TCD refers to grafts with a reduction of >2.5 log. The decision regarding the optimal degree of TCD was clinical and was based upon the perceived relative risk of relapse based upon the disease and remission status. All patients were monitored for up to 12 months post-BMT with regard to reconstitution of T and NK cell subsets. T cell depletion at either level was associated with a slower recovery of CD4 cells. This was most marked in the FTCD recipients and lasted throughout the period of study. CD8 cell recovery was also slower in... [ABSTRACT FROM AUTHOR]

Anti-leukaemia activity after allogeneic bone marrow transplantation has been studied extensively but its antigen specificity and effector cell phenotype remain unknown. Here we report a study in three recipients of autologous bone marrow transplantation done as part of the treatment for acute leukaemia, in whom we were able to detect innate specific anti-leukaemia activity post-transplant. One patient maintained selective cell-mediated cytolytic activity against her autologous leukaemic cells in the absence of cytolysis of her normal bone marrow mononuclear cells (BMMC). She remains in complete remission 3 years after ABMT for acute myeloid leukaemia (M5). A second patient was transplanted for acute lymphoblastic leukaemia and had detectable anti-leukaemia activity up to 20 weeks post-ABMT. At this point anti-leukaemia activity could no longer be demonstrated and the patient suffered a relapse 2 weeks later. A third patient was transplanted for AML (M4 Eo) and lacked detectable leukaemia- specific immune reactivity at 1, 3 and 6 months post-ABMT. She relapsed 6 months after her ABMT and returned to complete remission after further chemotherapy. She commenced treatment with alpha interferon and regained NK function. Furthermore, she developed high level cytolytic activity against her autologous leukaemic cells in the absence of activity against her remission bone marrow samples. She remains in complete remission 17 months after her initial relapse. This is the first report of an apparent association between in vitro leukaemia-specific cytolytic activity in individual patients after ABMT and clinical outcome. It encourages the theory that autologous immuno- modulation may be useful in the future treatment of leukaemia. [ABSTRACT FROM AUTHOR]

Low expression of CD45RB on CD45RO+ T lymphocytes defines a subset of highly differentiated T lymphocytes that accumulate in vivo within the affected joints of patients with rheumatoid arthritis (RA). Although it is known that CD45RO+ T lymphocytes migrate to sites of inflammation m vivo, it is not clear whether within this subset the CD45RBlo cells are selectively recruited or develop in situ within the joint. Using a transwell system we show that a small proportion of resting T lymphocytes migrated across unactivated human umbilical vein endothelial cells (HUVEC). These migrating cells were CD45RO+ and enriched for low CD45RB expression. In addition, both the CD45RO+ CD45RBlo subset and migrating cells expressed increased levels of β1 and β2 integrins and CD44. The percentage of CD45RO+ CD45RBlo T lymphocytes was increased in the circulation of patients with acute Epstein-Barr virus (EBV) infection. These in vim activated cells also expressed increased levels βl and β2 integrins and CD44, and showed an enhanced rate of transmigration compared with resting T lymphocytes. Transmigration of T lymphocytes was increased using the chemokines RANTES and lymphotactin and the cytokine interleukin-15 (IL-15). In addition, infection of the HUVEC with cytomegalovirus (CMV) led to an enhanced movement of T lymphocytes. In all of these cases the selective migration of the CD45RBlo subset was maintained. Thus although the rate of T-lymphocyte transmigration could be influenced by a number factors, the CD45RO+ CD45RBlo subset has a migratory advantage suggesting that more differentiated CD45RO+ CD45RBlo T lymphocytes are selectively recruited to sites of inflammation. [ABSTRACT FROM AUTHOR]

HLA-B27 has an unpaired cysteine on or near its serologically defined spondylitis associated epitope, and it has been argued that its sulphydryl side chain may be chemically reactive. In a previous study it was shown that chemical treatment of HLA-B27 cells with the sulphydryl binding agent p-chloromercuriphenylsulphonic acid (pCMPSA) specifically reduced binding of antibodies to HLA-B27 by up to 80%, as measured in a cellular enzyme linked immunosorbent assay (CELISA). The effect of sulphydryl blockade on intact B27 cells was investigated using flow cytometry. Compared with the CELISA, inhibition required higher concentrations of pCMPSA, and the degree of inhibition produced by a greater than or equal to 30 microM solution of pCMPSA as measured by flow cytometry (median 28.9%) was significantly lower than that measured by CELISA (median 73.6%; p = 1.6 x 10(-6)). Analysis of unfixed, cell surface HLA-B27 by flow cytometry suggests that on most B27 molecules the unpaired sulphydryl site is not available. On the basis of this evidence for modification after translation, a new 'altered self' hypothesis is proposed for the part which HLA-B27 plays in inflammatory disease. [ABSTRACT FROM PUBLISHER]

Defects of humoral immunity are well documented after bone marrow transplantation (BMT). Immunoglobulin recovery can be impaired and selective deficiencies of IgG subclasses have been reported. The nature of these deficiencies may reflect patterns of infection in the post-BMT period. We studied immunoglobulin and IgG subclass recovery in 20 long term ( > 100 days) survivors of T depicted allogeneic BMT, Although there was no fall in mean levels of IgG. IgM or IgA for the patient group, 14 patients (70%) developed a deficiency of one or more immunoglobulin isotype at some stage post-BMT. Eight patients (40%s) had deficiency of IgG, IgA and IgM and six had selective deficiencies. When IgG subclasses were measured it was seen that mean levels of IgG2 and IgG4 fell post-BMT with trough levels occurring at around 120 days post-transplant. Sixty per cent of patients developed IgG2 subclass deficiency and of these patients 78% had an associated IgG4 deficiency. Deficiencies of IgG1 and IgG3 were less common and less prolonged than those of IgG2 and IgG4; in addition, mean levels of IgG1 and IgG3 showed a rise early post-BMT. In conclusion, a majority of our patients developed immunoparesis following BMT, usually at around 120 days after transplantation. IgG2 subclass deficiency, often in association with IgG4 deficiency, is common and may occur despite normal total IgG levels. Deficiencies of immunoglobulin and IgG subclasses may persist for longer than 1 year post-BMT, Differing profiles of immunoglobulin and IgG subclass recovery may help dictate patterns of infection in long-term survivors of BMT. [ABSTRACT FROM AUTHOR]

Female CBA/H (H-2k, Misb) mice alloimmunized prior to and during syngeneic pregnancy with DBA/2 (H-2d, Misa) splenocytes gave rise to offspring which resisted graft-versus-host disease (GVHD) following neonatal intraperitoneal inoculation of high doses of DBA/2 spleen cells. Lymphocytes from GVHD-resistant mice tested after 6 weeks of age were unresponsive to DBA/2 stimulator cells in 72 h mixed lymphocyte cultures. Isotope uptake measured 24 h after culture, however, indicated that a considerable early response was made to DBA/2 which later declined. Proliferative responses to BALB/c were also depressed but no early response to this strain was detected, FACS analysis of T-lymphocyte profiles of the GVHD-resistant CBA/H mice revealed a 100% increase in the Lyt-2+ subpopulation compared to normal CBA/H mice. Significant increases in Lyt-2+ cells were also noted in in vitro cultures of CBA/H lymphocytes responding to GVHD-resistant CBA/H stimulators. Lymphocytes from GVHD-resistant mice suppressed the proliferative responses of normal CBA/H lymphocytes to alloantigenic but not mitogenic stimulation. Suppression of alloantigenic responses were shown to be specific to DBA/2 and did not affect the response to BALB/c stimulator cells, indicating that both anergy and specific suppressor cells were operative in inducing unresponsiveness. [ABSTRACT FROM AUTHOR]

Alterations of lymphocyte subsets have been recently reported in pre-type 1 diabetes but the relation with other immunological markers, in particular islet cell antibodies (ICA), is still unknown. In the present study, we have investigated prospectively changes of lymphocyte subsets in 86 first-degree relatives of patients affected by type 1 diabetes and correlated such modifications with ICA titres. Among individuals with persistent ICA, 8 had ICA titres of more than 20 JDF units, 14 had ICA titres between 5 and 20 JDF units and 64 had ICA titres between 0 and 5 JDF units. First-degree relatives with ICA titres of more than 20 JDF units had significantly decreased proportions of CD3 cells. This reduction was predominantly in the CD4 subset, giving rise to a decreased CD4/CD8 lymphocyte ratio. Those with ICA titres between 5 and 20 JDF units showed abnormalities in both CD3 and CD4 lymphocytes, but not in CD4/CD8 lymphocyte ratio. Further characterization of the CD4 cell subset was performed using three other monoclonal antibodies, CD45RO (UCHL1), CD45RA and CD29, phenotyping memory T-cells, the inducer cells of suppressor function and helper-inducer cells, respectively. The proportions of total CD45RO and CD45RA were not significantly different among first-degree relative with distinct ICA titres in a cross-sectional studt, whereas a trend towards a reduced proportion of CD4/ CD45RA cells was observed. The longitudinal study demonstrated that individuals potentially susceptible to the development of type 1 diabetes and who possess high titres of ICA have impairment of CD4/CD8 lymphocyte ratio, mainly due to a reduction in the CD4 subset. This alteration may contribute to the initial generation of the autoimmune response towards beta cells. All the calculations were made using minimum median and maximum value analyses. [ABSTRACT FROM AUTHOR]

Natural killer (NK) cells are increasingly used in clinical studies in order to treat patients with various malignancies. The following review summarizes platform lectures and 2013–2015 consortium meetings on manufacturing and clinical use of NK cells in Europe and United States. A broad overview of recent pre-clinical and clinical results in NK cell therapies is provided based on unstimulated, cytokine-activated, as well as genetically engineered NK cells using chimeric antigen receptors (CAR). Differences in donor selection, manufacturing and quality control of NK cells for cancer immunotherapies are described and basic recommendations are outlined for harmonization in future NK cell studies. [ABSTRACT FROM AUTHOR]

Comments on the evolution of stem cells and immunotherapy. Development of a method to protect mice against radiation-induced bone marow failure; Quantification of stem cells using clonogenic assays; Concept of stem cell plasticity.

The spondylitis associated HLA-B27 epitope includes a characteristic unpaired cysteine at amino acid position 67. On some B27 molecules the thiol (-SH) side chain of this residue seems to be available for chemical interactions. The possibility that free radicals produced during inflammation might specifically affect this group was investigated in this work. Cells bearing HLA-B27 were exposed to free radicals generated by ultraviolet irradiation or hydrogen peroxide, and HLA antigens were then measured by flow cytometry. Binding of monoclonal antibodies to B27 was not affected. These results do not support a specific susceptibility of HLA-B27 to damage by free radicals, despite its apparently vulnerable structure. [ABSTRACT FROM PUBLISHER]

Background We have previously described an aberrant innate immune response in Huntington's disease (HD) in which proinflammatory cytokines are increased in HD patient brain striatum, plasma and CSF, and mutant htt expressing myeloid cells produce increased interleukin 6 in response to lipopolysaccharide (LPS). This suggests that altered myeloid cell function may be a key correlate of HD pathogenesis. Moreover, alterations in central nervous system immune cell function appear to be mimicked by those in the periphery, suggesting that monitoring peripheral myeloid cells may provide insights into the potentially pathogenic actions of myeloid cells in the brain. Aims To examine peripheral myeloid cell function in the R6/2 and Hdh150Q mouse models of HD. Methods Cytokine production by LPS stimulated myeloid cells was analysed by multiplex ELISA. Myeloid cell function was assessed using specific assays for cell adhesion, differentiation, migration and phagocytosis. Results Cytokine production by LPS stimulated blood monocytes isolated from 22 month Hdh150Q mice showed a significant increase in the production of proinflammatory cytokines compared with controls. To further characterise these mice, we examined subsets of different Hdh150Q myeloid cell types. Interestingly, the spleens of both 22 month Hdh150Q and 12 week R6/2 mice contain more resting monocytes and fewer MHC II-high cells compared with controls. Further work to characterise the function of peripheral myeloid cell types in terms of adhesion, differentiation, migration and phagocytosis, and to correlate these functional read-outs with those of microglia, the resident myeloid cell of the CNS, is ongoing and will be presented. Conclusions We demonstrate that peripheral myeloid cells are aberrant in mouse models of HD in a manner similar to that observed in patients. Such studies will provide further insights into the role of myeloid cells and innate immune system dysregulation in HD pathogenesis. [ABSTRACT FROM PUBLISHER]

Background In previous work, we described an altered innate immune response in Huntington's disease (HD), demonstrating that proinflammatory cytokines such as interleukin (IL)-6 were significantly increased in the striatum and plasma of HD patients. We also reported altered peripheral and CNS myeloid cell function with elevated IL6 production in mutant htt expressing cells in both HD patients and mouse models of HD, suggesting that altered myeloid cell function may be relevant to HD pathogenesis. Furthermore, alterations in innate immune cell function in the CNS appear to mimic those in the periphery, suggesting that monitoring peripheral myeloid cells may provide insights into the potentially pathogenic actions of myeloid cells in the brain. Aims To analyse expression of other proinflammatory cytokines in mutant htt expressing myeloid cells and to examine signalling pathways involved in their production. Methods Cytokine production was measured using the MesoScale multiplex ELISA platform. NF-κB and JAK-STAT signalling were assessed by specific activity assays and Phospho-Flow FACS analysis, respectively. Results Lipopolysaccharide stimulated monocytes from HD patients showed a significant increase in production of proinflammatory cytokines such as IL6, IL8 and IL1β in symptomatic and pre-manifest HD patients. We then examined activation of the NF-κB and JAK/STAT signalling pathways, demonstrating that symptomatic HD patients showed increased NF-κB activation compared with controls and that basal STAT5 levels appear to increase with disease progression. STAT5 is known to interact with the NF-κB pathway in the production of IL6, and alterations in these pathways could contribute to the increase in proinflammatory cytokines produced by monocytes from HD patients. Conclusions Ongoing work involves the further characterisation of these signalling pathways in myeloid cells in HD. To date, however, our data suggest altered intracellular signalling in HD may underlie the overproduction of proinflammatory cytokines by HD monocytes. [ABSTRACT FROM PUBLISHER]