Interleukin-2 Receptor Expression Research Articles

Herbal Compound "Jiedu Huayu" Reduces Liver Injury in Rats via Regulation of IL-2, TLR4, and PCNA Expression Levels.

Aim of the Study. To investigate the preventative effects of Jiedu Huayu (JDHY) on D-galactosamine (D-GalN) and lipopolysaccharide-induced acute liver failure (ALF) and to evaluate the possible mechanisms of action. Materials and Methods. ALF was induced in Wistar rats by administrating D-GalN (900 mg/kg) and lipopolysaccharide (10 μg/kg). After treatment with JDHY granules, the levels of blood alanine aminotransferase, aspartate aminotransferase, total bilirubin, and prothrombin time were determined. Proliferating cell nuclear antigen was detected by immunohistochemistry staining. The expression of interleukin-2 (IL-2) and toll-like receptor 4 (TLR4) was examined by fluorescence quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blot. Results. JDHY treatment dramatically improved liver function and increased survival rates in an ALF model in rats. We observed a decrease in IL-2 and TLR4 expression following treatment with JDHY in liver cells from ALF rats using qRT-PCR and Western blot analysis. Conclusion. We hypothesize that the therapeutic potential of JDHY for treating ALF is due to its modulatory effect on the suppression of inflammation and by promoting hepatocyte regeneration. Our results contribute towards validation of the traditional use of JDHY in the treatment of liver disease.

Human Articular Chondrocytes Induce Interleukin-2 Nonresponsiveness to Allogeneic Lymphocytes.

Introduction We previously showed that articular chondrocytes (ACs) have immune privilege and immunomodulatory functions like those of mesenchymal stem cells. To elucidate these mechanisms, we focused on interleukin-2 (IL-2), which plays critical roles in lymphocyte mitogenic activity. The purpose of this study was to explore whether ACs affect the role of IL-2 underlying immunomodulatory functions. Material and Methods Irradiated human ACs from osteoarthritis donors were used. Third-party ACs were added to the mixed lymphocyte reaction (MLR) with or without recombinant human IL-2 (rhIL-2), and the levels of IL-2 and the soluble form of the IL-2 receptor α (sIL-2Rα) protein in supernatant were measured by enzyme-linked immunosorbent assay. Recombinant human IL-2 (rhIL-2) was also added to the MLR. To detect the expression of IL-2 receptor α (CD25) on lymphocytes in the MLR, flow cytometric analysis was performed. Last, ACs and allogeneic activated CD4+ T cell were co-cultured, and the expression of CD25 on activated T cells was examined by flow cytometry. Results Third-party ACs significantly inhibited the MLR and reduced the level of sIL-2Rα in a dose-dependent manner, but did not affect the concentration of IL-2. Exogenous rhIL-2 accelerated MLR but did not rescue the inhibitory effect of ACs. ACs inhibited the expression of CD25 on activated CD4+ T cells. Discussion Our results showed that third-party ACs inhibited the proliferation of allogeneic activated lymphocytes, thereby inhibiting production sIL-2Rα, although ACs did not affect IL-2 secretion from lymphocytes. Also, ACs inhibited CD25 expression on activated CD4+ T cells. Thus, ACs inhibited the immune response of allogeneic lymphocytes by inducing IL-2 nonresponsiveness.

Cardiomyocytes Derived from MHC-Homozygous Induced Pluripotent Stem Cells Exhibit Reduced Allogeneic Immunogenicity in MHC-Matched Non-human Primates.

SummaryInduced pluripotent stem cells (iPSCs) can serve as a source of cardiomyocytes (CMs) to treat end-stage heart failure; however, transplantation of genetically dissimilar iPSCs even within species (allogeneic) can induce immune rejection. We hypothesized that this might be limited by matching the major histocompatibility complex (MHC) antigens between the donor and the recipient. We therefore transplanted fluorescence-labeled (GFP) iPSC-CMs donated from a macaque with homozygous MHC haplotypes into the subcutaneous tissue and hearts of macaques having heterozygous MHC haplotypes (MHC-matched; group I) or without identical MHC alleles (group II) in conjunction with immune suppression. Group I displayed a higher GFP intensity and less immune-cell infiltration in the graft than group II. However, MHC-matched transplantation with single or no immune-suppressive drugs still induced a substantial host immune response to the graft. Thus, the immunogenicity of allogeneic iPSC-CMs was reduced by MHC-matched transplantation although a requirement for appropriate immune suppression was retained for successful engraftment.

Methylated SFRP1,2 and CD25 Expression in Acute Myeloid Leukemia Play an Important Role in the Pathogenesis of the Disease and in Turn in its Treatment

Objectives: Recently, hyperactivation of the Wnt signaling pathway has been implicated in leukomogenesis, so we studied the epigenetic dysfunction of SFRP1,2 and expression of interleukin2 receptor α chain (IL2Rα, also known as CD25) and its prognostic impact in acute myeloblastic leukemia (AML). Methods: We studied the methylation profile of SFRP1,2 in AML cells by methylation-specific polymerase chain reaction (MSP) and the hyper expression of IL2Rα (CD25) by flowcytometry. Results: We analyzed the methylation profile of SFRP1,2 in 40 de novo AML patients. The percentage of hypermethylation in the patient samples were 37.5% for SFRP1, 12.5% for SFRP2. CD25 was positive in 12(30%) of 40 patients AML. We found that in patients whom 60 years and younger with intermediate risk cytogenetics in de novo AML, hypermethylation of SFRP1 and CD25 were accompanied with relapse (P=0.024). Conclusion: Our data indicates that in a subgroup of AML patients, hypermethylation of SFRP1 and high expression of CD25 predict relapse

Prognostic Impact of Hypermethylated SFRP1, SFRP2 and Over Expression of CD25 in Acutemyeloid Leukemia

Objective: To study the epigenetic dysfunction of SFRP1, SFRP2 and expression of interleukin-2 receptor α chain (IL2Rα, also known as CD25) in acute myeloblastic leukaemia (AML). Methods: We study the methylation profile of SFRP1, SFRP2 in AML cells by methylation-specii¬c polymerase chain reaction (MSP) and the hyperexpression of IL2Rα (CD25) by flow-cytometry. Results: We analysed the methylation profile of SFRP1, SFRP 2 in 40 de novo AML patients. The percentage of hypermethylation in the patient samples were 37.5% for SFRP1 and 12.5% for SFRP2. CD25 was positive in 12 (30%) of 40 patients AML. In patients whom 60 years and younger with intermediate risk cytogenetics in de novo AML, hypermethylation of SFRP1 and CD25 were accompanied with relapse (P=0.024). Conclusion: Our data indicates that in a subgroup of AML patients, hypermethylation of SFRP1 and high expression of CD25 predict relapse.

New Molecular and Cellular Mechanisms of Tolerance: Tolerogenic Actions of IL-2.

Interleukin-2 (IL-2) is an old molecule with brand new functions. Indeed, IL-2 has been first described as a T-cell growth factor but recent data pointed out that its main function in vivo is the maintenance of immune tolerance. Mechanistically, IL-2 is essential for the development and function of CD4(+) Foxp3(+) regulatory T cells (Treg cells) that are essential players in the control of immune responded to self, tumors, microbes and grafts. Treg cells are exquisitely sensitive to IL-2 due to their constitutive expression of the high affinity IL-2 receptor (IL-2R) and the new paradigm suggests that low-doses of IL-2 could selectively boost Treg cells in vivo. Consequently, a growing body of clinical research is aiming at using IL-2 at low doses as a tolerogenic drug to boost endogenous Treg cells in patients suffering from autoimmune or inflammatory conditions. In this manuscript, we briefly review IL-2/IL-2R biology and the role of IL-2 in the development, maintenance, and function of Treg cells; and also its effects on other immune cell populations such as CD4(+) T helper cells and CD8(+) memory T cells. Then, focusing on type 1 diabetes, we review the preclinical studies and clinical trials supporting the use of low-doses IL-2 as a tolerogenic immunotherapy. Finally, we discuss the limitations and future directions for IL-2 based immunotherapy.

The Immunomodulation of Mangiferin on the Proliferation and Interleukin-2 Receptors Expression of in Vitro Culture of T lymphocytes Derived from Mammary Tumor Bearing Mice

The development of a tumor has a strong relationship with cellular immunity mediated by T lymphocytes. Some research showed that mangiferin can increase host immunity but its scientific base was still unclear. The purpose of this study was to explain the role of mangiferin as an immunostimulator on in vitro T lymphocytes culture of mammary tumor bearing mice. T lymphocytes were isolated from the spleen of mice after two weeks of mammary tumor transplantation. The isolation was performed by using sterile nylon net and passed through nylon wool. Isolated T lymphocytes were cultured in vitro on RPMI 1640 medium. The culture of T lymphocytes was divided into three groups containing 5, 25 and 50 mg/L of mangiferin, and a control group (RPMI medium). The proportion of T lymphocytes and IL-2Rα (CD25) expressed T cells were evaluated using immunoflouorescens techniques after one and three days of lymphocytes cultures. Our study showed that 5, 25 and 50 mg/L mangiferin was effective to enhance IL-2Rα (CD25) on T lymphocytes culture and T lymphocytes prolifferation.

Piperine blocks interleukin-2-driven cell cycle progression in CTLL-2 T lymphocytes by inhibiting multiple signal transduction pathways

Piperine, a pungent alkaloid found in the fruits of black pepper plants, has diverse physiological effects, including the ability to inhibit immune cell-mediated inflammation. Since the cytokine interleukin-2 (IL-2) is essential for the clonal expansion and differentiation of T lymphocytes, we investigated the effect of piperine on IL-2 signaling in IL-2-dependent mouse CTLL-2 T lymphocytes. Tritiated-thymidine incorporation assays and flow cytometric analysis of Oregon Green 488-stained cells showed that piperine inhibited IL-2-driven T lymphocyte proliferation; however, piperine did not cause T lymphocytes to die or decrease their expression of the high affinity IL-2 receptor, as determined by flow cytometry. Western blot analysis showed that piperine blocked the IL-2-induced phosphorylation of signal transducer and activator of transcription (STAT) 3 and STAT5 without affecting the upstream phosphorylation of Janus kinase (JAK) 1 and JAK3. In addition, piperine inhibited the IL-2-induced phosphorylation of extracellular signal-regulated kinase 1/2 and Akt, which are signaling molecules that regulate cell cycle progression. Piperine also suppressed the expression of cyclin-dependent kinase (Cdk) 1, Cdk4, Cdk6, cyclin B, cyclin D2, and Cdc25c protein phosphatase by IL-2-stimulated T lymphocytes, indicating G0/G1 and G2/M cell cycle arrest. Piperine-mediated inhibition of IL-2 signaling and cell cycle progression in CTLL-2 T lymphocytes suggests that piperine should be further investigated in animal models as a possible natural source treatment for T lymphocyte-mediated transplant rejection and autoimmune disease.

Immunohistochemical expression of interleukin-2 receptor and interleukin-6 in patients with prostate cancer and benign prostatic hyperplasia: Association with asymptomatic inflammatory prostatitis NIH category IV

Objective. This study prospectively investigated the immunohistochemical expression of interleukin-2 receptor (IL-2R) and interleukin-6 (IL-6) in patients with prostate cancer and benign prostatic hyperplasia (BPH), and a possible association of these conditions with asymptomatic inflammatory prostatitis National Institutes of Health (NIH) category IV. Materials and methods. The study included 139 consecutive patients who underwent transurethral resection of the prostate and transvesical enucleation of the prostate (n = 82) or radical prostatectomy (n = 57). To characterize inflammatory changes the criteria proposed by Irani et al. [J Urol 1997;157:1301–3] were used. IL-2R and IL-6 expression was studied by a standard immunohistochemical method. Results were correlated with tumour, node, metastasis stage, Gleason scores, total prostate-specific antigen, International Prostate Symptom Score and body mass index. Results. IL-2R and IL-6 expression was significantly higher in neoplastic prostate cancer tissue than in normal tissue of prostate cancer patients (p < 0.001 and p < 0.04, respectively). Prostate cancer patients with prostatitis showed significantly higher IL-2R expression than those without inflammation (p < 0.03). In patients with BPH, expression of IL-2R as well as IL-6 was higher in patients with prostatitis than in those without (p < 0.01 and p < 0.02, respectively). Conclusions. IL-2R and IL-6 expression was significantly higher in prostate cancer tissue than in normal tissue. Patients with asymptomatic inflammatory prostatitis NIH category IV showed significantly greater activity.

CD8αα+ Innate-Type Lymphocytes in the Intestinal Epithelium Mediate Mucosal Immunity

Innate immune responses are critical for mucosal immunity. Here we describe an innate lymphocyte population, iCD8α cells, characterized by expression of CD8α homodimers. iCD8α cells exhibit innate functional characteristics such as the capacity to engulf and kill bacteria. Development of iCD8α cells depends on expression of interleukin-2 receptor γ chain (IL-2Rγc), IL-15, and the major histocompatibility complex (MHC) class Ib protein H2-T3, also known as the thymus leukemia antigen or TL. While lineage tracking experiments indicated that iCD8α cells have a lymphoid origin, their development was independent of the transcriptional suppressor Id2, suggesting that these cells do not belong to the family of innate lymphoid cells. Finally, we identified cells with a similar phenotype in humans, which were profoundly depleted in newborns with necrotizing enterocolitis. These findings suggest a critical role of iCD8α cells in immune responses associated with the intestinal epithelium.

Identification of a cytotoxic form of dimeric interleukin-2 in murine tissues.

Interleukin-2 (IL-2) is a multi-faceted cytokine, known for promoting proliferation, survival, and cell death depending on the cell type and state. For example, IL-2 facilitates cell death only in activated T cells when antigen and IL-2 are abundant. The availability of IL-2 clearly impacts this process. Our laboratory recently demonstrated that IL-2 is retained in blood vessels by heparan sulfate, and that biologically active IL-2 is released from vessel tissue by heparanase. We now demonstrate that heparanase digestion also releases a dimeric form of IL-2 that is highly cytotoxic to cells expressing the IL-2 receptor. These cells include “traditional” IL-2 receptor-bearing cells such as lymphocytes, as well as those less well known for IL-2 receptor expression, such as epithelial and smooth muscle cells. The morphologic changes and rapid cell death induced by dimeric IL-2 imply that cell death is mediated by disruption of membrane permeability and subsequent necrosis. These findings suggest that IL-2 has a direct and unexpectedly broad influence on cellular homeostatic mechanisms in both immune and non-immune systems.

Evaluation of the laser therapy clinical efficacy in chronic vulval dystrophic diseases

It has been found that copper vapour laser emission is a highly effective treatment of chronic degenerative diseases of the vulva (HDZV): squamous cell hyperplasia and sclerotic depriving vulva (SLV). Application of a copper vapor laser can reduce the clinical manifestations of these diseases and decrease the frequency of recurrences. The basis of pathogenesis-based treatment is normalization of hormonal status in patients with vulvar squamous cell hyperplasia (PRTs) and immunomodulatory effects, manifested by normalization of major subpopulations of immunocompetent cells relations, changes in the level of expression of receptors for interleukin-2 and transferrin on lymphocytes, increased levels of nonspecific resistance.

Immunosuppressive activity of an aqueous Viola tricolor herbal extract

Ethnopharmacological relevanceHeartsease (Viola tricolor L.), a member of the Violaceae family, has a long history as a medicinal plant and has been documented in the Pharmacopoeia of Europe. Due to its anti-inflammatory properties it is regarded as a traditional remedy against skin diseases, for example for the treatment of scabs, itching, ulcers, eczema or psoriasis, and it is also used in the treatment of inflammation of the lungs and chest such as bronchitis or asthma. Because T-cells play an important role in the pathological process of inflammatory diseases we investigated the effect of an aqueous Viola extract on lymphocyte functions and explored the ‘active’ principle of the extract using bioactivity-guided fractionation. Material and MethodsAn aqueous Viola extract was prepared by C18 solid-phase extraction. Effects on proliferation of activated lymphocytes (using the cell membrane permeable fluorescein dye CFSE), apoptosis and necrosis (using annexin V and propidium iodide staining), interleukin-2 (IL-2) receptor expression (using fluorochrome-conjugated antibodies) and IL-2 cytokine secretion (using an ELISA-based bead array system) were measured by flow cytometry. Influence on lymphocyte polyfunctionality was characterized by Viola extract-induced production of IFN-γ and TNF-α, as well as its influence on lymphocyte degranulation activity. Fractionation and phytochemical analysis of the extract were performed by RP-HPLC and mass spectrometry. ResultsThe aqueous Viola extract inhibited proliferation of activated lymphocytes by reducing IL-2 cytokine secretion without affecting IL-2 receptor expression. Similarly, effector functions were affected as indicated by the reduction of IFN-γ and TNF-α production; degranulation capacity of activated lymphocytes remained unaffected. Bioassay-guided fractionation and phytochemical analysis of the extract led to identification of circular plant peptides, so called cyclotides, as bioactive components. ConclusionAn aqueous Viola extract contains bioactive cyclotides, which inhibit proliferation of activated lymphocytes in an IL-2 dependent manner. The findings provide a rationale for use of herbal Viola preparations in the therapy of disorders related to an overactive immune system. However, further studies to evaluate its clinical potency and potential risks have to be performed.

Immune reactivity of renal transplant recipients receiving interleukin-2 receptor antagonists during the early posttransplant period

There is a need for methods that would enable monitoring of the effects of immunosuppression on the recipient's immune system to avoid rejection, immunodeficiency-related complications and non-immune toxicities of the drugs used in therapy. This prospective trial included thirty patients who underwent renal transplantation in our center. All patients received an interleukin-2 receptor (IL-2R) antagonist in combination with mycophenolate, corticosteroid and calcineurin inhibitor. During the first 6 weeks after transplantation, the anti-CD3-stimulated proliferative response of peripheral blood T lymphocytes (PBTL) was studied by cell cycle analysis. The proportion of PBTL in different phases of the cell cycle and expression of IL-2R were determined by flow cytometry. As an effect of quadruple immunosuppressive therapy including IL-2R antagonists, cell cycle analysis showed an incremental decrease in the proliferative response of PBTL during the first 6 weeks after renal transplantation. A sudden drop in the proportion of IL-2R-positive cells was observed immediately after the first dose of the IL-2R antagonist and a significant antiproliferative effect on PBTL after the second dose. In vitro, IL-2R antagonists showed a dose-dependent inhibition of the anti-CD3-stimulated proliferation of PBTL of healthy blood donors. Cell cycle analysis of the immune reactivity of renal allograft recipients may represent a valuable tool for the immunological posttransplant follow-up and optimization of the immunosuppressive therapy.

All Subunits of the Interleukin-2 Receptor are Expressed by Canine Cutaneous Mast Cell Tumours

Cutaneous mast cell tumours (MCTs) are among the most important skin tumours in dogs. Apart from c-KIT mutations, which are present in <18% of MCTs, little is known of the mechanisms of MCT development and independent growth of tumour cells. Recently, the α-subunit (CD25) of the interleukin (IL)-2 receptor (IL-2R) has been found to be expressed by canine cutaneous MCTs and this expression is negatively correlated with tumour grade. We thus hypothesized that the other two subunits of the IL-2R and the ligand IL-2 are also expressed and that IL-2-dependent pathways may have an impact on MCT development and independent tumour cell growth. Messenger RNA and protein expression levels of the IL-2R β-subunit (CD122), the IL-2R γ-subunit (CD132) and IL-2 were analyzed in canine cutaneous MCTs and compared with tumour grade and c-KIT mutation status. Eighty-six percent of the tumours expressed both subunits of the IL-2R and 64% expressed IL-2. In addition, neoplastic mast cells seem able to bind IL-2. IL-2Rγ and IL-2 protein expression levels were significantly decreased in higher grade tumours and IL-2 expression was significantly decreased in c-KIT mutated tumours. Thus, expression of the complete IL-2R and its ligand by canine cutaneous MCTs indicates a potential impact of IL-2R signalling in MCT development and tumour cell proliferation. The decrease in IL-2R expression with increasing histological evidence of malignancy suggests that the IL-2R may be more relevant for early MCT development and well-differentiated tumours.

Glycodelin-A interferes with IL-2/IL-2R signalling to induce cell growth arrest, loss of effector functions and apoptosis in T-lymphocytes

The progesterone-regulated glycoprotein glycodelin-A (GdA), secreted by the decidualized endometrium at high concentrations in primates, inhibits the maternal immune response against fetal antigens and thereby contributes to the tolerance of the semi-allogenic fetus during a normal pregnancy. Our earlier studies demonstrated the ability of GdA to induce an intrinsic apoptotic cascade in CD4(+) T-lymphocytes and suppress the cytolytic effector function of CD8(+) T-lymphocytes. In this report, we investigated further into the mechanism of action of GdA controlling perforin and granzyme B expression in CD8(+) T-lymphocytes and the mechanism of action of GdA leading to lymphocyte death. Flow cytometry analysis was performed to check for the surface expression of interleukin-2 receptor α (IL-2Rα) and intracellular eomesodermin (Eomes) in activated T-lymphocytes, whereas quantitative RT-PCR analysis was used to find out their mRNA profile upon GdA treatment. Western analysis was carried out to confirm the protein level of Bax and Bcl-2. GdA reduces the surface expression of the high-affinity IL-2R complex by down-regulating the synthesis of IL-2Rα (CD25). This disturbs the optimal IL-2 signalling and decreases the Eomes expression, which along with IL-2 directly regulates perforin and granzymes expression. Consequently, the CD8(+) T-lymphocytes undergo growth arrest and are unable to mature into competent cytotoxic T-lymphocytes. In the CD4(+) T-lymphocytes, growth factor IL-2 deprivation leads to proliferation inhibition, decreased Bcl-2/enhanced Bax expression, culminating in mitochondrial stress and cell death. GdA spurs cell cycle arrest, loss of effector functions and apoptosis in different T-cell subsets by making T-lymphocytes unable to respond to IL-2.

Toward a molecular understanding of adaptive immunity: a chronology – part II

By 1980 it was obvious that to more fully understand adaptive immunity, one needed to somehow reduce the tremendous complexity of antigen recognition by T cell populations. Thus, there were two developments that resulted in a paradigm shift in immunology, one being the generation of monoclonal antibodies (MoAbs), and the other the development of monoclonal functional antigen-specific T cell lines. For the first time, the cellular reagents became available to ask new questions as to how individual cells comprising the complex cell populations recognize and respond to changes in their molecular environments. The first successful generation of monoclonal T cells depended upon the understanding that antigen renders cells responsive to the antigen non-specific T cell growth factor that came to be termed interleukin-2 (IL-2), which could then be used in propagating large numbers of the progeny of single cells, which in turn could then be used for molecular analyses. Monoclonal functional human T cells were used to immunize mice to generate clone-specific (clonotypic) MoAbs, which then permitted the first biochemical characterizations of the antigen recognition elements of the T cell antigen receptor (TCR) complex. Moreover, the use of monoclonal cytolytic and helper/inducer human T cell clones essentially proved that the T cell-specific molecules T4 (CD4) and T8 (CD8) functioned as accessory molecules in antigen recognition by defining MHC class II or class I restriction respectively. As well, the expression of the T3 (CD3) molecules, found to be common to all T cells, were shown further to be obligatory for functional antigen-specific T cell signaling. The monoclonal IL-2-dependent T cells were also instrumental in the isolation and purification of the IL-2 molecule to homogeneity, the first interleukin molecule to be identified and characterized. These advances then led to the generation of pure radiolabeled IL-2 molecules that were used to identify the first interleukin cellular receptors, and as well the generation of the first MoAbs reactive with both IL-2 and IL-2 receptors. All of these advances led subsequently to the isolation of the first cDNA clones recognizing one of the two chains comprising the T cell antigen recognition elements (β-chain), as well cDNA clones encoding IL-2. Accordingly, armed with all of these unique cellular and molecular reagents, it was possible to determine that antigen triggering of the TCR complex initiates IL-2 production and IL-2 receptor expression, which in turn initiate the T cell clonal proliferative expansion, envisioned by Burnet in his formulation of the clonal selection theory. Thus, adaptive immunity receives antigen-specific activation signals from the environment and turns them into antigen non-specific endogenous action signals.

Intermediate-affinity interleukin-2 receptor expression predicts CD56bright natural killer cell expansion after daclizumab treatment in the CHOICE study of patients with multiple sclerosis

Objective: The objective of this study was to evaluate whether interleukin-2 (IL-2) receptor expression on CD56bright natural killer (NK) cells predicted CD56bright NK cell expansion and therapeutic response to daclizumab (DAC) in multiple sclerosis (MS). Methods: DAC exposure, CD56bright NK cell counts, IL-2 receptor alpha (CD25) and beta (CD122) subunits, and new or enlarged lesions on brain MRI were measured in 64 subjects in a pharmacokinetic/pharmacodynamic substudy of the phase 2 CHOICE trial at multiple time points. Peripheral blood mononuclear cell (PBMC) samples were obtained from healthy subjects to assess the relationship among DAC treatment, intermediate affinity IL-2 signaling, and CD56bright NK cell expansion. Results: Increased CD56bright NK cell counts in DAC/interferon beta (IFNβ)-treated subjects were observed by day 14, the first post-dosing time point (mean [SD] ln{CD56bright NK cell count}: DAC high/IFNβ, 2.01 [1.25]; DAC low/IFNβ, 2.29 [1.06]; placebo/IFNβ, 1.01 [1.03]; adjusted p = 0.003), and persisted throughout the treatment period. Higher DAC dose predicted a faster rate of CD56bright NK cell expansion (p < 0.001), but individual subjects’ increases in CD56bright NK cells from baseline levels were only weakly correlated with DAC exposure (r2 = 0.167). Higher expression of the intermediate-affinity IL-2 receptor subunit (CD122) on CD56bright NK cells at baseline predicted fewer new gadolinium-enhanced (Gd+) lesions during the treatment period (1.77 vs. 0.62 adjusted mean new Gd+ lesions during weeks 8–24, lowest vs. highest quartile of percentage CD122+ CD56bright NK cells; p = 0.033) and a greater increase in CD56bright NK cell counts at the end of DAC dosing (p = 0.029). Conclusion: CD56bright NK cell expansion after DAC treatment appears to reflect individual differences in the capacity for intermediate-affinity IL-2 signaling and could provide a basis for predicting clinical response to DAC in MS.

Murine hepatic stellate cells veto CD8 T cell activation by a CD54-dependent mechanism

The liver has a role in T cell tolerance induction, which is mainly achieved through the functions of tolerogenic hepatic antigen-presenting cells (APCs) and regulatory T cells. Hepatic stellate cells (HSCs) are known to have various immune functions, which range from immunogenic antigen presentation to the induction of T cell apoptosis. Here we report a novel role for stellate cells in vetoing the priming of naive CD8 T cells. Murine and human HSCs and stromal cells (but not hepatocytes) prevented the activation of naive T cells by dendritic cells, artificial APCs, and phorbol 12-myristate 13-acetate/ionomycin by a cell contact-dependent mechanism. The veto function for inhibiting T cell activation was directly correlated with the activation state of HSCs and was most pronounced in HSCs from fibrotic livers. Mechanistically, high expression levels of CD54 simultaneously restricted the expression of interleukin-2 (IL-2) receptor and IL-2 in T cells, and this was responsible for the inhibitory effect because exogenous IL-2 overcame the HSC veto function. Our results demonstrate a novel function of HSCs in the local skewing of immune responses in the liver through the prevention of local stimulation of naive T cells. These results not only indicate a beneficial role in hepatic fibrosis, for which increased CD54 expression on HSCs could attenuate further T cell activation, but also identify IL-2 as a key cytokine in mediating local T cell immunity to overcome hepatic tolerance.

Early infiltration of arterial intima by activated dendritic γ/δ T-cells in ligated human arteries: An ultrastructural and immunocytochemical study

To clarify the role of immune mechanisms in the vascular response to injury in humans, the sequence, subset and activation status of lymphocytes infiltrating acutely ischemic arteries were studied. Thirty-five branches of mesenteric arteries removed from 8 men during surgery—22 of which were ligated for 0.5–4 hours—were examined ultrastructurally and immunocytochemically. The ligated arteries showed early intimal infiltration by activated T-cells, the predominant subset of which was dendritic, γ/δ T-cell receptor (TCR)-bearing and phenotyped CD3+, CD4-, and CD8-. Their activated status is shown by strong HLA-DR positivity, expression of interleukin-2 receptors, increased expression of lymphocyte function antigen-1, and frequent lymphocyte-macrophage interactions. Intimal macrophage infiltration consisted of single cells in the earlier biopsy specimens and clusters of cells in the later ones. These findings suggest that an early immune mechanism initiated by activated γ/δ dendritic T-cells, and amplified later by macrophages, may play a pivotal role in the inflammatory response after acute arterial injury.