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Idiopathic pulmonary fibrosis (IPF) is a lethal, medically refractory syndrome characterized by intrapulmonary accumulations of extracellular matrix (ECM) proteins produced by fibroblasts. Activation, clonal expansion, and differentiation of lymphocytes are also frequently present in IPF. Activated T cells are known to exert several effects that promote ECM production, but opposing homeostatic actions, wherein T cells can inhibit fibrosis, are less well understood. We found that CD27, a TNF receptor ubiquitously expressed on naive T cells, is downregulated on CD4 T cells of patients with IPF and that CD70, the sole ligand for CD27, is present on human pulmonary fibroblasts. We hypothesized that cognate engagements between lymphocyte CD27 and fibroblast CD70 could have functional consequences. Accordingly, a series of subsequent studies were conducted to examine the possible role of CD27-CD70 interactions in the regulation of fibrogenesis. Using IB, flow cytometry, RT-PCR, and kinomic assays, we found that fibroblast CD70 expression was inversely correlated with cell density and upregulated by TGF-b1 (transforming growth factor-b1). CD70 agonists, including T-cell-derived soluble CD27, markedly diminished fibroblast collagen and fibronectin synthesis, and these effects were potent enough to also inhibit profibrotic actions of TGF-b1 on ECM production in vitro and in two distinct ex vivo human skin models. CD70 activation was mediated by AKT (protein kinase B) and complex interconnected signaling pathways, and itwas abated by prior CD70 knockdown. These results show that the CD70-CD27 axis modulates T-cell-fibroblast interactions and may be an important regulator of fibrosis and wound healing. Fibroblast CD70 could also be a novel target for specific mechanistically based antifibrosis treatments. [ABSTRACT FROM AUTHOR]

After antigen stimulation cognate naïve CD8+ T cells undergo rapid proliferation and ultimately their progeny differentiates into short-lived effectors and longer-lived memory T cells. Although the expansion of individual cells is very heterogeneous, the kinetics are reproducible at the level of the total population of cognate cells. After the expansion phase, the population contracts, and if antigen is cleared, a population of memory T cells remains behind. Different markers like CD62L, CD27, and KLRG1 have been used to define several T cell subsets (or cell fates) developing from individual naïve CD8+ T cells during the expansion phase. Growing evidence from high-throughput experiments, like single cell RNA sequencing, epigenetic profiling, and lineage tracing, highlights the need to model this differentiation process at the level of single cells. We model CD8+ T cell proliferation and differentiation as a competitive process between the division and death probabilities of individual cells (like in the Cyton model). We use an extended form of the Cyton model in which daughter cells inherit the division and death times from their mother cell in a stochastic manner (using lognormal distributions). We show that this stochastic model reproduces the dynamics of CD8+ T cells both at the population and at the single cell level. Modeling the expression of the CD62L, CD27, and KLRG1 markers of each individual cell, we find agreement with the changing phenotypic distributions of these markers in single cell RNA sequencing data. Retrospectively re-defining conventional T-cell subsets by "gating" on these markers, we find agreement with published population data, without having to assume that these subsets have different properties, i.e., correspond to different fates. [ABSTRACT FROM AUTHOR]

Background and purpose: Cytomegalovirus (CMV) infection has recently been associated with a lower multiple sclerosis (MS) susceptibility, although it remains controversial whether it has a protective role or is merely an epiphenomenon related to westernization and early‐life viral infections. We aimed to evaluate whether CMV serostatus may differ in patients with early MS as compared with patients with non‐early MS, analyzing the putative association of this virus with MS clinical course and humoral immune responses against other herpesviruses. Methods: Multicentric analysis was undertaken of 310 patients with MS (early MS, disease duration ≤5 years, n = 127) and controls (n = 155), evaluating specific humoral responses to CMV, Epstein–Barr virus and human herpesvirus‐6, as well as T‐cell and natural killer (NK)‐cell immunophenotypes. Results: Cytomegalovirus seroprevalence in early MS was lower than in non‐early MS or controls (P < 0.01), being independently associated with disease duration (odds ratio, 1.04; 95% confidence interval, 1.01–1.08, P < 0.05). CMV+ patients with MS displayed increased proportions of differentiated T‐cells (CD27−CD28−, CD57+, LILRB1+) and NKG2C+ NK‐cells, which were associated with a lower disability in early MS (P < 0.05). CMV+ patients with early MS had an age‐related decline in serum anti‐EBNA‐1 antibodies (P < 0.01), but no CMV‐related differences in anti‐human herpesvirus‐6 humoral responses. Conclusions: Low CMV seroprevalence was observed in patients with early MS. Modification of MS risk attributed to CMV might be related to the induction of differentiated T‐cell and NK‐cell subsets and/or modulation of Epstein–Barr virus‐specific immune responses at early stages of the disease. [ABSTRACT FROM AUTHOR]

The immunological outcome of infections and vaccinations is largely determined during the initial first days in which antigen-presenting cells instruct T cells to expand and differentiate into effector and memory cells. Besides the essential stimulation of the T-cell receptor complex a plethora of co-stimulatory signals not only ensures a proper T-cell activation but also instils phenotypic and functional characteristics in the T cells appropriate to fight off the invading pathogen. The tumour necrosis factor receptor/ligand pair CD27/CD70 gained a lot of attention because of its key role in regulating T-cell activation, survival, differentiation and maintenance, especially in the course of viral infections and cancer. We sought to investigate the role of CD70 co-stimulation for immune responses induced by the vaccine vector modified vaccinia virus Ankara-Bavarian Nordic® (MVA-BN®). Short-term blockade of CD70 diminished systemic CD8 T-cell effector and memory responses in mice. The dependence on CD70 became even more apparent in the lungs of MHC class II-deficient mice. Importantly, genetically encoded CD70 in MVA-BN® not only increased CD8 T-cell responses in wild-type mice but also substituted for CD4 T-cell help. MHC class II-deficient mice that were immunized with recombinant MVA-CD70 were fully protected against a lethal virus infection, whereas MVA-BN®-immunized mice failed to control the virus. These data are in line with CD70 playing an important role for vaccine-induced CD8 T-cell responses and prove the potency of integrating co-stimulatory molecules into the MVA-BN® backbone. [ABSTRACT FROM AUTHOR]

Natural antibodies, particularly natural IgM, are proved to play indispensable roles in the immune defenses against common infections. More recently, the protective roles of these natural IgM were also recognized in autoimmune diseases. They are mainly produced by B-1 and innate-like B cells (ILBs). Human CD19+CD27+IgD+ B cells, also termed as un-switched memory B cells, were proposed to be a kind of ILBs. However, functional features and characteristics of these cells in rheumatoid arthritis (RA) remained poorly understood. In this study, we found that human CD27+IgD+ B cells could produce natural antibody-like IgM. Under RA circumstance, the frequencies of these cells were significantly decreased. Moreover, the IgM-producing capacities of these cells were also dampened. Interestingly, the BCR repertoire of these cells was altered in RA, demonstrating decreased diversity with preferential usage alteration from VH3-23D to VH1-8. Single cell sequencing further revealed the proinflammatory biased features of these cells in RA. These CD27+IgD+ B cells were negatively correlated with RA patient disease activities and clinical manifestations. After effective therapy with disease remission in RA, these cells could be recovered. Taken together, these results have revealed that CD27+IgD+ B cells were impaired in RA with dysfunctional features, which might contribute to the disease perpetuation. [ABSTRACT FROM AUTHOR]

Introduction: Huntington’s disease (HD) is a neurodegenerative disorder, but evidence also suggests neuroinflammation in the pathogenesis. The immune mechanisms involved and the timing of their activation need further clarification. Methods: A clinically well-characterized HD cohort and gene negative controls were enrolled. YKL-40 reflecting innate immunity and sCD27, a marker of adaptive immunity, were measured across disease stages. Comparisons were made with markers of neurodegeneration: neurofilament light (NFL), total-tau (T-tau), and phospho-tau (P-tau). Results: 52 cross-sectional cerebrospinal fluid samples and 23 follow-up samples were analyzed. sCD27 was elevated in manifest HD and premanifest gene expansion carriers, whereas controls mostly had undetectable levels. YKL-40 showed a trend toward increase in manifest HD. sCD27 correlated with YKL-40 which in turn was closely associated to all included markers of neurodegeneration. YKL-40, NFL, and both forms of tau could all independently predict HD symptoms, but only NFL levels differed between groups after age-adjustment. Conclusion: Increased sCD27 in premanifest HD is a sign of T cell-mediated neuroinflammation. This finding is novel since other reports almost exclusively have found early involvement of innate immunity. Validation of sCD27 in a larger HD cohort is needed. The role of adaptive immunity in HD needs further clarification, as it may hasten disease progression. [ABSTRACT FROM AUTHOR]

In recent years, monoclonal antibodies (mAbs) able to reinvigorate antitumor T-cell immunity have heralded a paradigm shift in cancer treatment. The most high profile of these mAbs block the inhibitory checkpoint receptors PD-1 and CTLA-4 and have improved life expectancy for patients across a range of tumor types. However, it is becoming increasingly clear that failure of some patients to respond to checkpoint inhibition is attributable to inadequate T-cell priming. For full T-cell activation, 2 signals must be received, and ligands providing the second of these signals, termed costimulation, are often lacking in tumors. Members of the TNF receptor superfamily (TNFRSF) are key costimulators of T cells during infection, and there has been an increasing interest in harnessing these receptors to augment tumor immunity. We here review the immunobiology of 2 particularly promising TNFRSF target receptors, CD27 and OX40, and their respective ligands, CD70 and OX40L, focusing on their role within a tumor setting. We describe the influence of CD27 and OX40 on human T cells based on in vitro studies and on the phenotypes of several recently described individuals exhibiting natural deficiencies in CD27/CD70 and OX40. Finally, we review key literature describing progress in elucidating the efficacy and mode of action of OX40- and CD27-targeting mAbs in preclinical models and provide an overview of current clinical trials targeting these promising receptor/ligand pairings in cancer. [ABSTRACT FROM AUTHOR]

The CD27--CD70 pathway is known to provide a costimulatory signal, with CD70 expressed on APCs and CD27 functions on T cells. Although CD70 is also expressed on activated T cells, it remains unclear how T cell--derived CD70 affects T cell function. Therefore, we have assessed the role of T cell--derived CD70 using adoptive-transfer models, including autoimmune inflammatory bowel disease and allogeneic graft-versus-host disease. Surprisingly, compared with wild-type T cells, CD70-/- T cells caused more severe inflammatory bowel disease and graft-versus-host disease and produced higher levels of inflammatory cytokines. Mechanistic analyses reveal that IFN-γ induces CD70 expression in T cells, and CD70 limits T cell expansion via a regulatory T cell--independent mechanism that involves caspase-dependent T cell apoptosis and upregulation of inhibitory immune checkpoint molecules. Notably, T cell--intrinsic CD70 signaling contributes, as least in part, to the inhibitory checkpoint function. Overall, our findings demonstrate for the first time, to our knowledge, that T cell--derived CD70 plays a novel immune checkpoint role in inhibiting inflammatory T cell responses. This study suggests that T cell--derived CD70 performs a critical negative feedback function to downregulate inflammatory T cell responses. [ABSTRACT FROM AUTHOR]

Hashimoto thyroiditis (HT) may occur isolated or associated with other non-endocrine autoimmune disorders (NEAD). No data are available about Breg cells in these disorders and this represented the aim of the study. Th17 and Breg cells subset were characterized on peripheral blood mononuclear cells isolated from 18 healthy donors (HD), 19 patients with isolated HT and 26 patients with HT + NEAD. Th17 were higher in patients with isolated HT than in HD but no further changes were seen in patients with HT + NEAD. CD24 hi CD38 hi unstimulated Breg cells were similar in HT patients and in HD, but significantly higher in patients with HT + NEAD than in both HT and in HD. CD19 + CD24 hi CD27 + Breg memory phenotype was similar in HD and in HT patients, but decreased in patients with HT + NEAD (23.4%vs38.5%). Upon CpG-stimulation, CD24 hi CD38 hi IL-10 + Breg cells were higher in HT patients than in HD (3.9%vs1.8%) but similar in patients with HT + NEAD (2.4%). [ABSTRACT FROM AUTHOR]

The mechanisms involved in sequential immunoglobulin G (IgG) class switching are still largely unknown. Sequential IG class switching is linked to higher levels of somatic hypermutation (SHM) in vivo, but it remains unclear if these are generated temporally during an immune response or upon activation in a secondary response. We here aimed to uncouple these processes and to distinguish memory B cells from primary and secondary immune responses. SHM levels and IgG subclasses were studied with 454 pyrosequencing on blood mononuclear cells from young children and adults as models for primary and secondary immunological memory. Additional sequencing and detailed immunophenotyping with IgG subclass-specific antibodies was performed on purified IgG+ memory B-cell subsets. In both children and adults, SHM levels were higher in transcripts involving more downstream-located IGHG genes (esp. IGHG2 and IGHG4). In adults, SHM levels were significantly higher than in children, and downstream IGHG genes were more frequently utilized. This was associated with increased frequencies of CD27+IgG+ memory B cells, which contained higher levels of SHM, more IGHG2 usage, and higher expression levels of activation markers than CD27−IgG+ memory B cells. We conclude that secondary immunological memory accumulates with age and these memory B cells express CD27, high levels of activation markers, and carry high SHM levels and frequent usage of IGHG2. These new insights contribute to our understanding of sequential IgG subclass switching and show a potential relevance of using serum IgG2 levels or numbers of IgG2-expressing B cells as markers for efficient generation of memory responses. [ABSTRACT FROM AUTHOR]

Background: The use of TNF-inhibitors and/or the IL-6 receptor antagonist, tocilizumab, in rheumatoid arthritis (RA) have pleiotropic effects that also involve circulating B-cells. The main goal of this study was to assess the effect of TNF-inhibitors and tocilizumab on B-cell phenotype and gene expression in RA. Methods: Blood samples were collected from untreated early RA (ERA) patients, established RA patients under methotrexate treatment, established RA patients before and after treatment with TNF-inhibitors and tocilizumab, and healthy donors. B-cell subpopulations were characterized by flow cytometry and B-cell gene expression was analyzed by real-time PCR on isolated B-cells. Serum levels of BAFF, CXCL13 and sCD23 were determined by ELISA. Results: The frequency of total CD19+ B cells in circulation was similar between controls and all RA groups, irrespective of treatment, but double negative (DN) IgD-CD27- memory B cells were significantly increased in ERA and established RA when compared to controls. Treatment with TNF-inhibitors and tocilizumab restored the frequency of IgD-CD27- B-cells to normal levels, but did not affect other B cell subpopulations. TACI, CD95, CD5, HLA-DR and TLR9 expression on B-cells significantly increased after treatment with either TNF-inhibitors and/ or tocilizumab, but no significant changes were observed in BAFF-R, BCMA, CD69, CD86, CXCR5, CD23, CD38 and IgM expression on B-cells when comparing baseline with post-treatment follow-ups. Alterations in B-cell gene expression of BAFF-R, TACI, TLR9, FcγRIIB, BCL-2, BLIMP-1 and β2M were found in ERA and established RA patients, but no significant differences were observed after TNF-inhibitors and tocilizumab treatment when comparing baseline and follow-ups. Serum levels of CXCL13, sCD23 and BAFF were not significantly affected by treatment with TNF-inhibitors and tocilizumab. Conclusions: In RA patients, the use of TNF-inhibitors and/ or tocilizumab treatment affects B-cell phenotype and IgD-CD27- memory B cells in circulation, but not B-cell gene expression levels. [ABSTRACT FROM AUTHOR]

Hepatitis C virus (HCV) infection is associated with B cell abnormality; however the phenotypic profiles of immunoglobulin (Ig)M+B cell subsets in patients with HCV infection remain unclear. In the current study, the effect of HCV infection on IgM+B cell subsets was evaluated. The percentages, as well as the differentiation and activation features of peripheral IgM+B naive subsets [cluster of differentiation (CD)27-IgM+B cells] and IgM+B memory subsets (CD27+IgM+B cells) were assessed using flow cytometry in 27 patients with chronic hepatitis C (CHC) and 20 healthy controls (HCs). The frequency of CD27+IgM+B memory subsets detected in patients with CHC was significantly higher than that in HCs (P<0.05). Although the frequency of CD27-IgM+B naive subsets was similar in both groups, there was a significantly higher proportion of CD5+B cells detected in the CD27-IgM+B subsets of patients with CHC compared with HCs (P<0.05). Among CD27-IgM+B subsets, abnormal differentiation was associated with HCV infection, with significantly increased percentages of IgD+B cells and CD38+B cells in patients with CHC compared with HCs (P<0.05). In CD27+IgM+B memory subsets, the abnormality of cell differentiation was associated with a significantly increased percentage of CD38+B cells in patients with CHC compared with HCs (P<0.05). In addition, the percentage of activated CD27+IgM+B subsets in patients with CHC were significantly higher than those observed in HCs (P<0.05). The number of CD27-IgD+IgM+B, CD27-CD38+IgM+B and CD27+CD38+IgM+B cells were negatively correlated with HCV RNA in patients with CHC. These results suggest that HCV infection contributes to abnormalities in the percentage, differentiation and activation of IgM+B cell subsets and may disrupt the immune response mediated by IgM+B cells. [ABSTRACT FROM AUTHOR]

B cells play a crucial role in the pathogenesis of autoimmune diseases, such as systemic lupus erythematosus (SLE). However, the relevance of the metabolic pathway in the differentiation of human B cell subsets remains unknown. In this article, we show that the combination of CpG/TLR9 and IFN-α markedly induced the differentiation of CD27+IgD+ unswitched memory B cells into CD27hi CD38hi plasmablasts. The response was accompanied by mammalian target of rapamycin complex 1 (mTORC1) activation and increased lactate production, indicating a shift to glycolysis. However, CpG alone induced the differentiation of unswitched memory B cells into CD27-IgD-memory B cells with high cytokine production, but such differentiation was suppressed by IFN-a. AMP-activated protein kinase activation enhanced the differentiation to CD27+IgD+ B cells, but it attenuated mTORC1 activation and differentiation into plasmablasts. High mTORC1 activation was noted in CD19+ B cells of patients with SLE and correlated with plasmablast differentiation and disease activity. Taken together, differential metabolic reprogramming commits the differentiation of human unswitched memory B cells into plasmablasts (the combination of CpG and IFN-α amplifies mTORC1-glycolysis pathways) or CD27-IgD- memory B cells (CpG alone amplifies the AMP-activated protein kinase pathway). The former metabolic pathway may play a pivotal role in SLE. [ABSTRACT FROM AUTHOR]

Hashimoto's thyroiditis (HT) is characterized by dysregulated immune responses and is commonly associated with insulin resistance. However, the mechanism of insulin resistance in HT remains to be fully elucidated. The aim of the present study was to investigate the correlation between the percentage of B regulatory lymphocytes (Bregs) and insulin resistance in patients with HT but with normal thyroid function (type I). A total of 59 patients with type I HT and 38 healthy volunteers were enrolled in the study. An oral glucose tolerance test was performed to measure insulin secretion and assess β‑cell functions. Flow cytometry was performed to examine the percentages of lymphocyte populations. The patients with HT exhibited normal fasting and postprandial glucose and fasting insulin secretion, but increased secretion of early‑phase and total insulin. The patients with HT also had insufficient β‑cell compensation for insulin resistance, indicated by a reduced disposition index, in the fasting state. An elevation in the percentage of CD19+CD24+CD27+ Bregs was also observed, which correlated positively with insulin secretion and insulin resistance in the fasting state. The patients with type I HT had postprandial insulin resistance and insufficient β‑cell compensation for fasting insulin resistance. Therefore, the increase in CD19+CD24+CD27+ Bregs was closely associated with fasting insulin secretion. These results provide novel insight into the mechanism of insulin resistance in HT. [ABSTRACT FROM AUTHOR]

Background: Accumulating evidence suggests that regulatory B cells (Bregs) play an important role in modulating the immune response to tumours. Our previous study indicated that a small percentage of peripheral CD19+CD24hCD27+ Breg cells slowed gastric cancer progression in XELOX-treated patients. Here, we further investigated the relationship between dynamic changes in circulating Breg cells and the clinical course in XELOX-treated gastric cancer patients. Methods: A total of 52 patients with advanced gastric cancer were enrolled in this study. The frequencies of CD19+CD24hCD27+ cells in peripheral blood were tested before (as a baseline) and 9 weeks after administration of oxaliplatin and capecitabine (XELOX). The primary endpoint of the study was progression-free survival time (PFS) of the patients. The overall survival (OS) and adverse events of chemotherapy were also recorded. Results: The median PFS of patients was 6 months (95% CI, 5.27-6.73) with effective rate of 46.2%. The percentage of CD19+CD24hCD27+ cells in lymphocytes ranged from 0.007% to 1.94%, with a median value of 0.45%. The median percentage of CD19+CD24hCD27+ lymphocytes was 0.59% (0.01%-6.02%) 9 weeks after treatment. There were no significant differences for this index. However, the patients with decreased Breg frequencies after XELOX treatment had a longer PFS time (7.0 months vs. 5.0 months, p=0.01) than those with increased Breg frequencies. Conclusion: Patients with downtrend of CD19+CD24hCD27+ B lymphocytes during early stages of chemotherapy relative to their initial values had longer PFS times, and this could be used to predict the efficacy of chemotherapy and help physicians adjust treatments accordingly. [ABSTRACT FROM AUTHOR]

CD27 is a T-cell and B-cell co-stimulatory glycoprotein of the tumor necrosis factor (TNF) receptor superfamily that is dependent on the availability of the TNF-like ligand CD70. Therapeutic approaches to treating autoimmune diseases and cancers with antagonistic and agonistic anti-CD27 monoclonal antibodies (mAbs), respectively, have recently been developed. Mouse anti-human CD27 mAb 2177 shows potency in neutralizing CD70-induced signaling; however, it does not block the binding of soluble CD70. To provide insight into the mechanism of action of the mAb, the crystal structure of the CD27 extracellular domain in complex with the Fab fragment of mAb 2177 was determined at 1.8 Å resolution. CD27 exhibits the assembly of cysteine-rich domains characteristic of the TNF receptor superfamily. The structure reveals a unique binding site of mAb 2177 at the edge of the receptor molecule, which allows the mAb to sterically block the cell-bound form of CD70 from reaching CD27 while leaving the ligand epitope clear. This mode of action suggests a potential dual use of mAb 2177 either as an antagonist or as an agonist. [ABSTRACT FROM AUTHOR]

The capacity of the immune system to recognize and respond to tumors has been appreciated for over 100 years. However, clinical success has largely depended on the elucidation of the positive and negative regulators of effector cells after their activation via the antigen cell receptor. On the one hand, effector cells upregulate checkpoint molecules that are thought to play a role in limiting immunopathology. On the other, second and third waves of costimulation are often required to promote the expansion, survival and differentiation of effector cells. While it is clear that the immune system can be unleashed by blocking checkpoint molecules, this approach is most effective when pre-existing responses exist in patients’ tumors. Thus, coordinating checkpoint blockade with costimulation could potentially expand the patient population that receives benefit from cancer immunotherapy. This review will discuss how the costimulatory molecule CD27 sculpts immunity and preclinical/clinical data indicating its potential for cancer immunotherapy and its clinical translation. [ABSTRACT FROM AUTHOR]

CD27 is a T and B cell co-stimulatory protein of the TNF receptor superfamily dependent on the availability of the TNF-like ligand CD70. Two anti-CD27 neutralizing monoclonal antibodies were obtained from mouse hybridoma and subsequently humanized and optimized for binding the target. The two antibodies are similar in terms of their CD27-binding affinity and ability to block NF-κB signaling, however their clearance rates in monkeys are very different. The pharmacokinetics profiles could be epitope dependent. To identify the epitopes, we determined the crystal structure of the ternary complex between CD27 and the Fab fragments of these non-competing antibodies. The structure reveals the binding modes of the antibodies suggesting that their mechanisms of action are distinctly different and provides a possible explanation of the in vivo data. [ABSTRACT FROM AUTHOR]

Immune aging occurs in the elderly and in autoimmune diseases. Recently, IgD-CD27- (double negative, DN) and CD21-CD11c+ (CD21low) B cells were described as age-associated B cells with proinflammatory characteristics. This study investigated the prevalence and functional characteristics of DN and CD21low B cells in multiple sclerosis (MS) patients. Using flow cytometry, we demonstrated a higher proportion of MS patients younger than 60 y with peripheral expansions of DN (8/41) and CD21low (9/41) B cells compared with age-matched healthy donors (1/33 and 2/33, respectively), which indicates an increase in age-associated B cells in MS patients. The majority of DN B cells had an IgG+ memory phenotype, whereas CD21low B cells consisted of a mixed population of CD272 naive, CD27+ memory, IgG+, and IgM+ cells. DN B cells showed similar (MS patients) or increased (healthy donors) MHCII expression as class-switched memory B cells and intermediate costimulatory molecule expression between naive and class-switched memory B cells, indicating their potential to induce (proinflammatory) T cell responses. Further, DN B cells produced proinflammatory and cytotoxic cytokines following ex vivo stimulation. Increased frequencies of DN and CD21low B cells were found in the cerebrospinal fluid of MS patients compared with paired peripheral blood. In conclusion, a proportion of MS patients showed increased peripheral expansions of age-associated B cells. DN and CD21low B cell frequencies were further increased in MS cerebrospinal fluid. These cells could contribute to inflammation by induction of T cell responses and the production of proinflammatory cytokines. [ABSTRACT FROM AUTHOR]

NK cells represent a critical first-line of immune defense against a bevy of viral pathogens, and infection can provoke them to mediate supportive and suppressive effects on virus-specific adaptive immunity. In mice expressing MHC class I Dk (Dk), a major murine CMV (MCMV) resistance factor and self-ligand of the inhibitory Ly49G2 (G2) receptor, licensed G2+ NK cells provide essential host resistance against MCMV infection. Additionally G2+ NK cell responses to MCMV increase the rate and extent of dendritic cell (DC) recovery, as well as early priming of CD8+ T cell effectors in response to MCMV. However, relatively little is known about the NK cell effect on costimulatory ligand patterns displayed by DCs or on ensuing effector and memory T cell responses. In this study, we found that CD27-dependent CD8+ T cell priming and differentiation are shaped by the efficiency of NK responses to virus infection. Surprisingly, differences in specific NK responses to MCMV in Dk-disparate mice failed to distinguish early DC costimulatory patterns. Nonetheless, although CD27 deficiency did not impede licensed NK-mediated resistance, CD70 and CD27 were required to efficiently prime and regulate effector CD8+ T cell differentiation in response to MCMV, which eventually resulted in biased memory T cell precursor formation in Dk mice. In contrast, CD8+ T cells accrued more slowly in non-Dk mice and eventually differentiated into terminal effector cells regardless of CD27 stimulation. Disparity in this requirement for CD27 signaling indicates that specific virus control mediated by NK cells can shape DC costimulatory signals needed to prime CD8+ T cells and eventual T cell fate decisions. [ABSTRACT FROM AUTHOR]

Objective and design: Here, we evaluated the distribution and functional profile of circulating CD27 and CD27 γδ T-cell subsets in systemic sclerosis (SSc) patients to assess their potential role in this disorder. Materials and methods: Peripheral blood from 39 SSc patients and 20 healthy individuals was used in this study. The TCR-γδ repertoire, cytokine production and cytotoxic signatures of circulating γδ T-cell subsets were assessed by flow cytometry. Gene expression of EOMES, NKG2D and GZMA was evaluated by quantitative RT-PCR in both purified γδ T-cell subsets. Results: Absolute numbers of γδ T-cell subsets were significantly decreased in SSc groups, likely reflecting their mobilization to the inflamed skin. Both γδ T-cell subsets preserved their relative proportions and Th1-type cytokine responses. However, cytotoxic properties showed significant disease-associated and subset-specific changes. SSc patients exhibited increased percentages of CD27 γδ T cells expressing granzyme B or perforin and upregulated GZMA expression in diffuse cutaneous SSc. Conversely, EOMES and NKG2D were downregulated in both SSc γδ T-cell subsets vs. normal controls. Interestingly, patients with pulmonary fibrosis showed a biased TCR repertoire, with a selected expansion of effector Vγ9 γδ T cells associated with increased frequency of cells expressing granzyme B, but decreased IFN-γ production. Conclusions: Significant alterations on circulating γδ T-cell subsets suggest a deregulated (increased) cytotoxic activity and thus enhanced pathogenic potential of CD27 γδ T cells in SSc. [ABSTRACT FROM AUTHOR]

In addition to the majority of T cells which carry the αβ T cell receptor (TCR) for antigen, a distinct subset of about 1–5% of human peripheral blood T cells expressing the γδ TCR contributes to immune responses to infection, tissue damage and cancer. T cells with the Vδ2 + TCR, usually paired with Vγ9, constitute the majority of these γδ T cells. Analogous to αβ T cells, they can be sorted into naive (CD27 + CD45RA + ), central memory (CD27 + CD45RA − ), effector memory (CD27 − CD45RA − ), and terminally-differentiated effector memory (CD27 − CD45RA + ) phenotypes. Here, we found that CD27 − CD45RA + γδ T cells can be further divided into two populations based on the level of expression of CD45RA: CD27 − CD45RA int and CD27 − CD45RA hi . Those with the CD27 − CD45RA hi phenotype lack extensive proliferative capacity, while those with the CD27 − CD45RA int phenotype can be easily expanded by culture with zoledronate and IL-2. These CD27 - CD45RA hi potentially exhausted γδ T cells were found predominantly in cancer patients but also in healthy subjects. We conclude that γδ T cells can be divided into at least 5 subsets enabling discrimination of γδ T cells with poor proliferative capacity. It was one of our goals to predict the feasibility of γδ T cell expansion to sufficient amounts for adoptive immunotherapy without the necessity for conducting small-scale culture tests. Fulfilling the ≥1.5% criterion for γδ T cells with phenotypes other than CD27 − CD45RA hi , may help avoid small-scale culture testing and shorten the preparation period for adoptive γδ T cells by 10 days, which may be beneficial for patients with advanced cancer. [ABSTRACT FROM AUTHOR]

NK cells participate in the development of human multiple sclerosis (MS) and mouse experimental autoimmune encephalomyelitis (EAE), but the roles of different NK cell subsets in disease onset remain poorly understood. In this study, murine NK cells were divided into CD27high and CD27low/− subsets. The CD27high subset was decreased and the CD27low/− subset was increased in lymphoid organs during the pre-onset stage of EAE. Compared with the counterpart in naïve mice, the CD27high subset showed lower expression of Ly49D, Ly49H and NKG2D, and less production of IFN-γ, whereas the CD27low/− subset showed similar expression of the above mentioned surface receptors but higher cytotoxic activity in EAE mice. Compared with the CD27high subset, the CD27low/− subset exhibited increased promotion of DC maturation and no significant inhibition of T cells proliferation and Th17 cells differentiation in vitro. Additionally, adoptive transfer of the CD27low/− subset, but not the CD27high subset, exacerbated the severity of EAE. Collectively, our data suggest the CD27 NK cell subsets play different roles in controlling EAE onset, which provide a new understanding for the regulation of NK cell subsets in early autoimmune disease. [ABSTRACT FROM AUTHOR]

The transcription factors GATA-3, T-bet and Eomesodermin play important roles in T-cell development, differentiation and memory formation. However, their expression has not been studied in great detail in porcine T cells. We report on protein expression at the single cell-level of these transcription factors in thymocytes and mature αβ T cells. GATA-3 expression was found in γδ − thymocytes, with decreasing expression from the CD4 − CD8α − stage towards single-positive stages. Extra-thymic CD4 + T cells but not CD8β + T cells expressed low levels of GATA-3, which decreased with age. CD4 + and CD8β + T-bet + cells mainly displayed a CD8α + CD27 − and perforin + CD27 dim/− phenotype, respectively and had the capacity for IFN-γ production; indicative of an effector/effector memory phenotype. Eomesodermin + αβ T cells had mixed phenotypes in regard to CD8α, CD27 and perforin expression. In conclusion, our data so far support the hitherto reported roles for GATA-3 in T-cell development and T-bet for Th1 effector-differentiation, but question the role of Eomesodermin for memory formation of porcine T-cells. [ABSTRACT FROM AUTHOR]

B cells play a pivotal role in the pathogenesis of autoimmune diseases. In patients with systemic lupus erythematosus (SLE), the percentages of plasmablasts and IgD-CD27- doublenegative memory B cells in peripheral blood are significantly increased, while IgD+CD27+ IgM memory B cells are significantly decreased compared to healthy donors. The phenotypic change is significantly associated with disease activity and concentration of autoantibodies. Treatment of B-cell depletion using rituximab results in the reconstitution of peripheral B cells in SLE patients with subsequent improvement in disease activity. Numerous studies have described abnormalities in B-cell receptor (BCR)-mediated signaling in B cells of SLE patients. Since differences in BCR signaling are considered to dictate the survival or death of naïve and memory B cells, aberrant BCR signal can lead to abnormality of B-cell subsets in SLE patients. Although Syk and Btk function as key molecules in BCR signaling, their pathological role in SLE remains unclear. We found that Syk and Btk do not only transduce activation signal through BCR, but also mediate crosstalk between BCR and Toll-like receptor (TLR) as well as BCR and JAK-STAT pathways in human B cells in vitro. In addition, pronounced Syk and Btk phosphorylation was observed in B cells of patients with active SLE compared to those of healthy individuals. The results suggest the involvement of Syk and Btk activation in abnormalities of BCR-mediated signaling and B-cell phenotypes during the pathological process of SLE and that Syk, Btk and JAK are potential therapeutic targets in SLE. [ABSTRACT FROM AUTHOR]

Background Psychosocial stress is thought to play a key role in the acceleration of immunological aging. This study investigated the relationship between lifetime and past-year history of post-traumatic stress disorder (PTSD) and the distribution of T cell phenotypes thought to be characteristic of immunological aging. Methods Data were from 85 individuals who participated in the community-based Detroit Neighborhood Health Study. Immune markers assessed included the CD4:CD8 ratio, the ratio of late-differentiated effector (CCR7-CD45RA+CD27-CD28-) to naïve (CCR7+CD45RA+CD27+CD28+) T cells, the percentage of KLRG1-expressing cells, and the percentage of CD57-expressing cells. Results In models adjusted for age, gender, race/ethnicity, education, smoking status, and medication use, we found that past-year PTSD was associated with statistically significant differences in the CD8+ T cell population, including a higher ratio of late-differentiated effector to naïve T cells, a higher percentage of KLRG1+ cells, and a higher percentage of CD57+ cells. The percentage of CD57+ cells in the CD4 subset was also significantly higher and the CD4:CD8 ratio significantly lower among individuals who had experienced past-year PTSD. Lifetime PTSD was also associated with differences in several parameters of immune aging. Conclusions PTSD is associated with an aged immune phenotype and should be evaluated as a potential catalyzer of accelerated immunological aging in future studies. [ABSTRACT FROM AUTHOR]

γδ T lymphocytes are programmed into distinct IFN-γ-producing CD27+ (γδ27+) and IL-17-producing CD27- (γδ27-) subsets that play key roles in protective or pathogenic immune responses. Although the signature cytokines are shared with their αβ Th1 (for γδ27+) and Th17 (for γδ27-) cell counterparts, we dissect in this study similarities and differences in the transcriptional requirements of murine effector γδ27+, γδ27-CCR6-, and γδ27-CCR6+ γδ T cell subsets and αβ T cells. We found they share dependence on the master transcription factors T-bet and RORγt for IFN-γ and IL-17 production, respectively. However, Eomes is fully dispensable for IFN-γ production by γδ T cells. Furthermore, the Th17 cell auxiliary transcription factors RORα and BATF are not required for IL-17 production by γδ27- cell subsets. We also show that γδ27- (but not γδ27+) cells become polyfunctional upon IL-1β plus IL-23 stimulation, cosecreting IL-17A, IL-17F, IL-22, GM-CSF, and IFN-γ. Collectively, our in vitro and in vivo data firmly establish the molecular segregation between γδ27+ and γδ27- T cell subsets and provide novel insight on the nonoverlapping transcriptional networks that control the differentiation of effector γδ versus αβ T cell subsets. [ABSTRACT FROM AUTHOR]

Background: The immune responses to pneumococcal conjugate vaccine (PCV) are low in immunocompromised hosts. The effect of memory B cells on the immune response to PCV remains elusive.Methods: In this prospective study, 53 children who received 7-valent PCV were enrolled. Antipneumococcal immunoglobulin G (IgG) levels and opsonization index (OI) titers, along with lymphocyte subsets, were investigated in immunocompromised and immunocompetent hosts. Immunocompromised patients comprised 8 hematopoietic stem cell transplant recipients (group A) and 9 immunosuppressive therapy recipients (group B), and controls consisted of 14 children aged >1 year (group C) and 22 infants (group D).Results: Serotype-specific IgG concentrations and OIs in group A were lower than those in group C. These did not differ among groups B, C, and D. The rates of achieving immunity (defined as an IgG level of 1.0 µg/mL and an OI of 8) in group A were also lower than in group C. Despite the sustained numbers of total T cells and B cells, CD27(+) B-cell and CD4(+) T-cell counts in group A were lower than those in group C. In group B, the immunoglobulin D-expressing CD27(-) B-cell count was only lower than that in group C.Conclusions: Circulating numbers of CD27(+) B cells, rather than CD4(+) T cells, may predict the effective PCV responses in immunocompromised children. [ABSTRACT FROM AUTHOR]

The CD27+IgD+ B cell population, known as IgM memory, reduces with age. It is thought that this population is responsible for pneumococcal polysaccharide T-independent responses, and that the age-related reduction might be partially responsible for the increased susceptibility of older people to bacterial pathogens. There are other IgM+ B cell populations that do not express IgD. We compared the different IgM populations using high-throughput sequencing of the immunoglobulin (Ig) gene repertoire and multidimensional cell phenotyping and found that the different populations of IgM cells, defined by CD27 and IgD expression, have repertoire differences. Some of these differences are likely indicative of different selection pressures in an immune response, although the older individuals were found to have a changed repertoire in naive B cells, which may contribute to some of the changes seen in memory cells. In addition, even within the CD27+IgD+ IgM memory population there are multiple cell types. We show that the level of IgM expression varies substantially and hypothesize that this distinguishes between T-dependent and T-independent types of IgM memory cells. Significant age-related changes in the relative proportions of these populations may exacerbate the reduction in T-independent responders in old age. [ABSTRACT FROM AUTHOR]

Maturation and differentiation of B-cells are driven by T-cells' help through IL-21/STAT3 axis in GC centers or through extrafollicular pathways, in a T-independent manner. B-cell differentiation is defective in common variable immunodeficiency disease (CVID) patients. We investigated if IL-21/STAT3 axis alterations could influence B-cell fate. We activated purified CVID B-cells with surrogate T-dependent (anti-CD40), T-independent (TLR-9 ligand) stimuli or through B-cell receptor engagement (anti-IgM) with or without IL-21. IL-21 mediated STAT3 activation was greater on CD27 − than CD27 + B-cells depending on the stimulus. IL-21 alone induced STAT3 phosphorylation (pSTAT3) only on CD27 − B-cells and IL-21 induced higher pSTAT3 levels on CD27 − than CD27 + B-cells after anti-IgM or anti-CD40 activation. CVID CD27 + B-cells showed selective STAT3 hyperphosphorylation after activation with anti-IgM or anti-CD40 alone and anti-IgM, anti-CD40 or ODN combined with IL-21. Increased STAT3 activation during immune responses could result in B-cell differentiation defects in CVID. [ABSTRACT FROM AUTHOR]

Background: Clinical targeting of TNFR family of receptors (CD40, CD134 and CD137) with immunostimulatory monoclonal antibodies has been successful in cancer immunotherapy. However, targeting of CD27 with a mAb is a relatively new approach to provide costimulation of immune cells undergoing activation. Thus, activation of human CD27 (TNFRSF7) with a monoclonal antibody (varlilumab) has previously been demonstrated to result in T cell activation and anti-tumor activity in preclinical models, and is currently in early phase clinical trials in patients with advanced malignancies. In this study we used an in vitro system using human peripheral blood T cells to characterize the varlilumab-mediated costimulatory effects in combination with TCR stimulation in terms of phenotypic, transcriptional and functionality changes. Methods: T cells were isolated from normal volunteer PBMCs using magnetic bead isolation kits and stimulated in vitro with plate bound anti-CD3 Ab (OKT3) and varlilumab or control Ab for 72 h. Activation profiles were monitored by ELISA or Luminex-based testing cytokine/chemokine releases, cell surface phenotyping for costimulatory and coinhibitory markers and CFSE dye dilution by proliferating T cells and Tregs. Changes in gene expression and transcriptome analysis of varlilumab-stimulated T cells was carried on Agilent Human whole genome microarray datasets using a suite of statistical and bioinformatic software tools. Results: Costimulation of T cells with varlilumab required continuous TCR signaling as pre-activated T cells were unable to produce cytokines with CD27 signaling alone. Analysis of T cell subsets further revealed that memory CD4+ and CD8+ T cells were specifically activated with a bias toward CD8+ T lymphocyte proliferation. Activation was accompanied by upregulated cell surface expression of costimulatory [4-1BB, OX40, GITR and ICOS] and coinhibitory [PD-1] molecules. Importantly, varlilumab costimulation did not activate purified Tregs as measured by cytokine production, proliferation and suppression of dividing non-Treg T cells. Analysis of changes in gene expression during varlilumab stimulation of T cells revealed modulation of pro-inflammatory signatures consistent with cellular activation and proliferation, with the IL-2 pathway showing the highest frequency of gene modulation. Conclusions: Altogether, the data reveal the requirements and T cell subtype-specific effects of CD27 costimulation, and helps select relevant biomarkers for studying the effects of varlilumab in patients. [ABSTRACT FROM AUTHOR]

Identification and isolation of hematopoietic stem cells (HSCs) in mice is most commonly based on the expression of surface molecules Kit and Sca-1 and the absence of markers of mature lineages. However, Sca-1 is absent or weakly expressed in hematopoietic progenitors in many strains, including nonobese diabetic (NOD), BALB/c, C3H, and CBA mice. In addition, both Kit and Sca-1 levels are modulated following bone marrow injury. In these cases, other markers and dye exclusion methods have been employed to identify HSCs, yet there is no antibody-based stain that enables identification of HSCs and early progenitors when Kit and Sca-1 are inadequate. CD201 is a marker that is highly restricted to HSCs and progenitors, and CD27 is expressed at moderate-to-high levels on HSCs. We show here that combining CD201 and CD27 enables highly efficient isolation of long-term HSCs in NOD mice as well as in other strains, including SJL, FVB, AKR, BALB/c, C3H, and CBA. We also find that HSCs appear to maintain expression of CD201 and CD27 after hematopoietic injury when Kit expression is downregulated. These results suggest a widely applicable yet simple alternative for HSC isolation in settings where Kit and Sca-1 expression are insufficient. [ABSTRACT FROM AUTHOR]

The severity and intensity of autoimmune disease in immune dysregulation, polyendocrinopathy, enteropathy, X-linked ( IPEX) patients and in scurfy mice emphasize the critical role played by thymus-derived regulatory T cells ( tTregs) in maintaining peripheral immune tolerance. However, although tTregs are critical to prevent lethal autoimmunity and excessive inflammatory responses, their suppressive mechanism remains elusive. Here, we demonstrate that tTregs selectively inhibit CD27/ CD70-dependent Th1 priming, while leaving the IL-12-dependent pathway unaffected. Immunized mice depleted of tTregs showed an increased response of IFN-γ-secreting CD4+ T cells that was strictly reliant on a functional CD27/ CD70 pathway. In vitro studies revealed that tTregs downregulate CD70 from the plasma membrane of dendritic cells ( DCs) in a CD27-dependent manner. CD70 downregulation required contact between Tregs and DCs and resulted in endocytosis of CD27 and CD70 into the DC. These findings reveal a novel mechanism by which tTregs can maintain tolerance or prevent excessive, proinflammatory Th1 responses. [ABSTRACT FROM AUTHOR]

Surface markers have been used to identify distinct cell subpopulations and to delineate various stages of maturation or activation of lymphocytes. In particular CD27 is used for delineation of naïve and memory B cell populations, and is readily detected by flow cytometry. We here used flow cytometry to examine the expression of CD27 on lymphocytes isolated from various tissues of rhesus macaques, and found its expression was consistently low to absent on intestinal cell suspensions. However, immunohistochemistry revealed abundant CD27+ cells in intestinal tissue sections. Further investigation showed the marked loss of CD27 expression on processed intestinal cells was due to collagenase digestion of intestinal tissues, yet CD27 expression was recoverable within hours of cell isolation. By combining confocal microscopy, we confirmed that only a fraction of B cells express CD27, in contrast to expression on all T cells from tissues examined including the gut. Taken together, our results suggest that CD27 may be a memory marker for B cells, but not for T cells, since essentially all CD3 T cells expressed CD27. In summary, it is important to consider the influence of isolation procedures on cell surface expression of phenotypic markers, especially when examining tissue-resident lymphocytes by flow cytometry. [ABSTRACT FROM AUTHOR]

Introduction: Current clinical trials utilize mesenchymal stromal cells (MSCs) expanded in culture, however these interventions carry considerable costs and concerns pertaining to culture-induced losses of potency. This study assessed the feasibility of new clinical-grade technology to obtain uncultured MSC isolates from three human intra-osseous tissue sources based on immunomagnetic selection for CD271-positive cells. Materials and Methods: MSCs were isolated from bone marrow (BM) aspirates or surgical waste materials; enzymatically digested femoral heads (FHs) and reamer irrigator aspirator (RIA) waste fluids. Flow cytometry for the CD45−/lowCD73+CD271+ phenotype was used to evaluate uncultured MSCs before and after selection, and to measure MSC enrichment in parallel to colony forming-unit fibroblast assay. Trilineage differentiation assays and quantitative polymerase chain-reaction for key transcripts involved in bone regeneration was used to assess the functional utility of isolated cells for bone repair. Results: Uncultured CD45−/lowCD271+ MSCs uniformly expressed CD73, CD90 and CD105 but showed variable expression of MSCA-1 and SUSD2 (BM>RIA>FH). MSCs were enriched over 150-fold from BM aspirates and RIA fluids, whereas the highest MSC purities were obtained from FH digests. Enriched fractions expressed increased levels of BMP-2, COL1A2, VEGFC, SPARC and CXCL12 transcripts (BM>RIA>FH), with the highest up-regulation detected for CXCL12 in BM (>1300-fold). Following culture expansion, CD271-selected MSCS were tri-potential and phenotypically identical to plastic adherence-selected MSCs. Discussion: A CD271-based GMP-compliant immunomagnetic selection resulted in a substantial increase in MSC purity and elevated expression of transcripts involved in bone formation, vascularisation and chemo-attraction. Although this technology, particularly from RIA fluids, can be immediately applied by orthopaedic surgeons as autologous therapy, further improvements in MSC purities and pre-clinical testing of product safety would be required to develop this process for allogeneic applications. [ABSTRACT FROM AUTHOR]

Memory B cells (MBCs) have a long lifespan compared with naive B cells (NBCs), remaining viable for years. This could predispose them to suffer misbalances in the gene expression pattern in the long term, which might be involved in the development of age-related B-cell disorders. In order to identify genes whose expression might change during life, we analysed the gene expression patterns of CD27- NBCs versus CD27+ MBCs in young and old subjects. Using microarray assays we observed that the expression pattern of CD27- NBCs versus CD27+ MBCs is significantly different. Furthermore, to evaluate the age effect, we compared the gene expression pattern of young versus aged subjects in both cell populations. Interestingly, we did not find significant differences in the CD27- NBC population between young and aged individuals, whereas we found 925 genes differentially expressed in CD27+ MBCs. Among these genes, 193 were also differentially expressed in CD27+ MBCs compared with CD27- NBCs, most of them involved in cell survival, cell growth and proliferation, cellular development and gene expression. We conclude that gene expression profiles of CD27- NBCs and CD27+ MBCs are different. Moreover, whereas the gene expression pattern of CD27+ MBCs varies with age, the same does not happen in CD27- NBCs. This suggests that MBCs undergo time-dependent changes, which could underlie a higher susceptibility to dysfunction with age. [ABSTRACT FROM AUTHOR]

Hypogammaglobulinemia (serum IgG lower than 2 SD below the age-matched mean) and clinical symptoms such as increased susceptibility to infection, autoimmune manifestations, granulomatous disease, and unexplained polyclonal lymphoproliferation are considered to be diagnostic hallmarks in patients with common variable immunodeficiency (CVID), the most frequent clinically severe primary immunodeficiency syndrome. In the present study, we investigated patients with hypogammaglobulinemia and no clinical or immunological signs of defective cell-mediated immunity and differentiated two groups on the basis of their IgG antibody formation capacity against a variety of different antigens (bacterial toxins, polysaccharide antigens, viral antigens). Patients with hypogammaglobulinemia and intact antibody production (HIAP) displayed no or only mild susceptibility to infections, while CVID patients showed marked susceptibility to bacterial infections that normalized following initiation of IVIG or subcutaneous immunoglobulin replacement therapy. There was a substantial overlap in IgG serum levels between the asymptomatic HIAP group and the CVID patients examined before immunoglobulin treatment. HIAP patients showed normal levels of switched B-memory cells (CD19+CD27+IgD-), while both decreased and normal levels of switched B-memory cells could be found in CVID patients. IgG antibody response to a primary antigen, tick-borne encephalitis virus (TBEV), was defective in CVID patients, thus confirming their substantial defect in IgG antibody production. Defective IgG antibody production against multiple antigens could also be demonstrated in an adult patient with recurrent infections but normal IgG levels. To facilitate early treatment before recurrent infections may lead to organ damage, the antibody formation capacity should be examined in hypogammaglobulinemic patients and the decision to treat should be based on the finding of impaired IgG antibody production. [ABSTRACT FROM AUTHOR]

Collagenases are widely used for tissue digestion in experiments due to their potent hydrolysis of connective tissue. CD27, also known as tumor necrosis factor receptor superfamily 7 (TNFRSF7), is limited to be expressed on the cells of the lymphoid lineage. In our preliminary research, we found that CD27 on NK cells was almost disappeared with the digestion of type I collagenase for 90 min. This phenomenon suggests that the process of tissue digestion may affect the density of CD27 on cells. In order to verify this, the lungs of mice were digested with types I and IV collagenase or grinded, respectively. The percentage of CD27 + cells and the density of CD27 on cells were assayed by flow cytometry. The data presented that the percentage of CD27 + cells and the density of CD27 on lymphocytes gradually decreased with the time of digestion with type I or IV collagenase. We also detected that the density of CD11b on NK cells was not affected by collagenase digestion. Collectively, the findings of the present study suggest that the collagenase digestion has a selective effect on the density of molecules on cells. [ABSTRACT FROM AUTHOR]

The effects of heightened microbial translocation on B cells during HIV infection are unknown. We examined the in vitro effects of HIV and lipopolysaccharide (LPS) on apoptosis of CD27+ IgD- memory B (mB) cells from healthy controls. In vivo analysis was conducted on a cohort of 82 HIV+ donors and 60 healthy controls. In vitro exposure of peripheral blood mononuclear cells (PBMCs) to LPS and HIV led to mB cell death via the Fas/Fas ligand (FasL) pathway. Plasmacytoid dendritic cells (pDCs) produced FasL in response to HIV via binding to CD4 and chemokine coreceptors. HIV and LPS increased Fas expression on mB cells in PBMCs, which was dependent on the presence of pDCs and monocytes. Furthermore, mB cells purified from PBMCs and pretreated with both HIV and LPS were more sensitive to apoptosis when cocultured with HIV-treated pDCs. Blocking the interferon receptor (IFNR) prevented HIV-stimulated FasL production in pDCs, HIV-plus-LPS-induced Fas expression, and apoptosis of mB cells. In vivo or ex vivo, HIV+ donors have higher levels of plasma LPS, Fas expression on mB cells, and mB cell apoptosis than controls. Correspondingly, in HIV+ donors, but not in controls, a positive correlation was found between plasma FasL and HIV RNA levels and between Fas expression on mB cells and plasma LPS levels. This work reveals a novel mechanism of mB cell apoptosis mediated by LPS and HIV through the Fas/FasL pathway, with key involvement of pDCs and type I IFN, suggesting a role for microbial translocation in HIV pathogenesis. [ABSTRACT FROM AUTHOR]

Background: Chronic hepatitis B virus (HBV) infection includes a set of heterogeneous clinical patterns, and core-protein-specific T cell response is important for virus control and disease progression, yet is not well elucidated. Objectives: To analyze the phenotypic and functional profiles of HBV-core-protein-specific CD8+ T cells in different clinical patterns of chronic HBV infection. Study design: A total of 46 HBV patients were recruited and classified according to their clinical status. CD8+ T cell responses in different patterns of chronic HBV infections were tested with flow cytometry using overlapping 15-mer peptides covering HBV core protein. Meanwhile, the CCR7/CD27 phenotypes of these CD8+ T cells were also determined. Results: Frequencies of gamma interferon (IFN-γ) positive CD8+ T cells in inactive HBV surface antigen (HBsAg) carriers in response to the core protein peptide pools were generally stronger than those of chronic HBV carriers and resolved individuals, especially with regards to peptide pool C13-C24. Moreover, phenotypic studies further highlighted the group of CD8+ CCR7-CD27+ T memory cells, which showed significantly higher levels of IFN-γ secretion in inactive HBsAg carriers than those in chronic hepatitis B patients, chronic HBV carriers and resolved individuals. Conclusions: Core-protein-specific T cell response plays an important role in chronic HBV infection. Inactive HBsAg carriers showed a much stronger core-protein-specific cytotoxic T cell response than other types of chronically infected patients. CD8+ CCR7-CD27+ T memory lymphocytes may be crucial in the immune pathogenesis of chronic HBV infection. [ABSTRACT FROM AUTHOR]

The impairment of humoral immune response in elderly humans has been extensively demonstrated. We have reported the increase of memory B cells (IgG+IgD−CD27−, double negative, DN) population in the elderly, in which there is also a typical inflammatory micro-environment. In order to evaluate whether this pro-inflammatory status could influence the trafficking phenotype of naïve/memory B cells, we have assessed the expression of CCR7, CCR6, CXCR3, CXCR4, CXCR5 and CD62L on naïve/memory B cell subpopulations in young and elderly subjects. Moreover, the combination of pro-inflammatory interleukin-21 (IL-21) and B cell receptor (BCR) stimulation enables B cells to produce and secrete granzyme B (GrB), which plays a critical role in early anti-viral immune responses, in the regulation of autoimmune mechanisms and in cancer immunosurveillance. Our data demonstrate that in the elderly, naïve/memory B cell populations present a different expression of the studied receptors that could be discussed in terms of “inflamm-aging”. In particular IgG+IgD−CD27− DN B cells show a tissue trafficking phenotype and they can be stimulated to produce GrB. [ABSTRACT FROM AUTHOR]

The mechanisms that contribute to the maintenance of serological memory are still unclear. Rotavirus (RV) memory B cells (mBc) are enriched in IgM+ and CD27- subpopulations, which are associated with autoimmune diseases pathogenesis. In patients with autoimmune diseases treated with Rituximab (RTX), some autoantibodies (auto-Abs) decrease after treatment, but other auto-Abs and pathogen-specific IgG Abs remain unchanged. Thus, maintenance of autoimmune and pathogen-specific serological memory may depend on the type of antigen and/or Ab isotype evaluated. Antigen-specific mBc and antigen-specific Abs of different isotypes have not been simultaneously assessed in patients after RTX treatment. To study the relationship between mBc subpopulations and serological memory we characterized total, RV- and tetanus toxoid (TT)-specific mBc by flow cytometry in patients with autoimmune diseases before and after treatment with RTX. We also measured total, RV- and TT-Abs, and some auto-Abs by kinetic nephelometry, ELISA, and EliA tests, respectively. Minor differences were observed between the relative frequencies of RV-mBc in healthy controls and patients with autoimmune disease. After RTX treatment, naïve Bc and total, RV- and TT-specific mBc [IgM+, switched (IgA+/IgG+), IgM+ only, IgD+ only, and CD27- (IgA+/IgG+/IgM+)] were significantly diminished. An important decrease in total plasma IgM and minor decreases in total IgG and IgA levels were also observed. IgM rheumatoid factor, IgG anti-CCP, and IgG anti-dsDNA were significantly diminished. In contrast, RV-IgA, RV-IgG and RV-IgG1, and TT-IgG titers remained stable. In conclusion, in patients with autoimmunity, serological memory against RV and TT seem to be maintained by long-lived plasma cells, unaffected by RTX, and an important proportion of total IgM and serological memory against some auto-antigens seem to be maintained by short-lived plasma cells, dependent on mBc precursors depleted by RTX. [ABSTRACT FROM AUTHOR]

Human natural killer ( NK) cells have distinct functions as NKtolerant, NKcytotoxic and NKregulatory cells and can be divided into different subsets based on the relative expression of the surface markers CD27 and CD11b. CD27+ NK cells, which are abundant cytokine producers, are numerically in the minority in human peripheral blood but constitute the large population of NK cells in cord blood, spleen, tonsil and decidua tissues. Recent data suggest that these NK cells may have immunoregulatory properties under certain conditions. In this review, we will focus on these new NK cell subsets and discuss how regulatory NK cells may serve as rheostats or sentinels in controlling inflammation and maintaining immune homeostasis in various organs. [ABSTRACT FROM AUTHOR]

Plasma cells (PCs) are essentially characterized by the co-expression of CD138 and CD38, which allows their identification in flowcytometry in bone marrow(BM), peripheral blood, or cell suspensions from tissues. These terminally differentiated B-cells may lose the expression of surface CD19 and that of CD20 while retaining CD27. When malignant, they can gain a number of other markers such as CD28, CD33, CD56, or CD117 and lose CD27. Moreover, since each PC is only able to produce a single type of immunoglobulins (Igs), they display isotypic restriction and clonal malignant PCs can be further characterized by their homogeneous expression of either kappa or lambda light chains. In multiple myeloma (MM), such PC clones produce the Ig identified in plasma as an abnormal peak. In the BM where they essentially accumulate, these PCs may however display various immunophenotypes. The latter were explored in a two-way approach. Firstly, the various subsets delineated by the selective or common expression of CD19 together with combined CD56/CD28 were explored in normal and MM BM. Then, other aberrant markers' expression was investigated, i.e., CD20, CD27, CD33, CD56, CD117. These data were compared to literature information. They underline the vast heterogeneity of MM PCs possibly accounting for the various answers to therapy of MM patients. [ABSTRACT FROM AUTHOR]

Highlights: [•] Rhesus macaque mucosal memory B-cells, unlike those of PBMC, lack CD27+ cells. [•] Duodenal/rectal explants of SIV/SHIV-infected macaques contain IgA secreting cells. [•] Mucosal explant culture supernatants yield significant levels of viral-specific IgA. [Copyright &y& Elsevier]

Problem The function of IL-10 producing regulatory B cells (Breg) during gestation is unknown. Here, we aimed to understand their participation in early pregnancy. Method CD19+ CD24hi CD27+B cell frequency, measured by flow cytometry, increased with pregnancy onset but not in the case of spontaneous abortions. Results B cells from non-pregnant women cultured with serum from normal pregnant women produced higher IL-10 levels than those cultured with serum from spontaneous abortion patients or autologous serum. CD19+-activated B cells from pregnant women strongly suppressed TNF-a production by CD4+T cells when cocultured. We identified hCG as an important factor regulating the number and function of Breg during pregnancy. Conclusions Breg emerge as important players in pregnancy; they suppress undesired immune responses from maternal T cells and are therefore important for tolerance acquisition. [ABSTRACT FROM AUTHOR]

HIV-mediated immune dysfunction may influence CD4+ T cell recovery during suppressive antiretroviral therapy (ART). We analyzed cellular biomarkers of immunological inflammation, maturation, and senescence in HIV-infected subjects on early suppressive ART. We performed longitudinal analyses of peripheral immunological biomarkers of subjects on suppressive ART (n = 24) from early treatment (median 6.4 months, interquartile range [IQR] 4.8–13.9 months) to 1–2 years of follow-up (median 19.8 months, IQR 18.3–24.6 months). We performed multivariate regression to determine which biomarkers were associated with and/or predictive of CD4+ T cell recovery. After adjusting for the pre-ART CD4+ T cell count, age, proximal CD4+ T cell count, and length of ART medication, the percentage of CD27+CD8+ T cells remained significantly associated with the CD4+ T cell recovery rate (β = 0.092 cells/ul/month, P = 0.028). In HIV-infected subjects starting suppressive ART, patients with the highest percentage of CD8+ T cells expressing CD27 had the greatest rate of CD4+ T cell recovery. [ABSTRACT FROM AUTHOR]

The CD70/CD27 pathway plays a significant role in the control of immunity and tolerance, and previous studies demonstrated that targeting murine CD27 (mCD27) with agonist mAbs can mediate antitumor efficacy. We sought to exploit the potential of this pathway for immunotherapy by developing 1F5, a fully human IgG1 mAb to human CD27 (hCD27) with agonist activity. We developed transgenic mice expressing hCD27 under control of its native promoter for in vivo testing of the Ab. The expression and regulation of hCD27 in hCD27-transgenic (hCD27-Tg) mice were consistent with the understood biology of CD27 in humans. In vitro, 1F5 effectively induced proliferation and cytokine production from hCD27-Tg-derived T cells when combined with TCR stimulation. Administration of 1F5 to hCD27-Tg mice enhanced Ag-specific CD8+ T cell responses to protein vaccination comparably to an agonist anti-mCD27 mAb. In syngeneic mouse tumor models, 1F5 showed potent antitumor efficacy and induction of protective immunity, which was dependent on CD4+ and CD8+ T cells. The requirement of FcR engagement for the agonistic and antitumor activities of 1F5 was demonstrated using an aglycosylated version of the 1F5 mAb. These data with regard to the targeting of hCD27 are consistent with previous reports on targeting mCD27 and provide a rationale for the clinical development of the 1F5 mAb, for which studies in advanced cancer patients have been initiated under the name CDX-1127. [ABSTRACT FROM AUTHOR]

Various cell types can produce the chemokine CXCL10 in response to IFN-γ stimulation. CXCL10 is generally viewed as a proinflammatory chemokine that promotes recruitment of CD8+ and Th1-type CD4+ effector T cells to infected or inflamed nonlymphoid tissues. We show that CXCL10 plays a role during CD8+ T cell priming in the mouse. Genome-wide expression profiling revealed the Cxcl10 gene as a target of CD27/CD70 costimulation in newly activated CD8+ T cells. CD27/CD70 costimulation is known to promote activated T cell survival, but CXCL10 did not affect survival or proliferation of primed CD8+ T cells in vitro. Accordingly, CXCL10 could not fully rescue CD27 deficiency in mice infected with influenza virus. Rather, CXCL10 acted as chemoattractant for other activated CD8+ T cells. It signaled downstream of CD27 in a paracrine fashion to promote generation of the CD8+ effector T cell pool in the Ag-draining lymph nodes. Consistently, CD8+ T cells required expression of the CXCL10 receptor CXCR3 for their clonal expansion in a CD27/CD70-dependent peptide-immunization model. Our findings indicate that CXCL10, produced by primed CD8+ T cells in response to CD27/CD70 costimulation, signals to other primed CD8+ T cells in the lymph node microenvironment to facilitate their participation in the CD8+ effector T cell pool. [ABSTRACT FROM AUTHOR]