The two-signal model of lymphocyte activation twenty-one years later

Selenoproteins as regulators of T cell proliferation, differentiation, and metabolism

Selenium (Se) is an essential micronutrient that plays a key role in regulating the immune system. T cells are of particular interest due to their important role in promoting adaptive immunity against pathogens and cancer as well as regulating tolerance, all of which are influenced by dietary Se levels. The biological effects of Se are mainly exerted through the actions of the proteins into which it is inserted, i.e. selenoproteins. Thus, the roles that selenoproteins play in regulating T cell biology and molecular mechanisms involved have emerged as important areas of research for understanding how selenium affects immunity. Members of this diverse family of proteins exhibit a wide variety of functions within T cells that include regulating calcium flux induced by T cell receptor (TCR) engagement, shaping the redox tone of T cells before, during, and after activation, and linking TCR-induced activation to metabolic reprogramming required for T cell proliferation and differentiation. This review summarizes recent insights into the roles that selenoproteins play in these processes and their implications in understanding how Se may influence immunity.

L’immunologie : les bases pour comprendre les traitements actuels et à venir

Le système immunitaire intègre un ensemble d’acteurs essentiellement présents dans les organes lymphoides et les tissus qui analysent les modifications avec notre interface essentiellement extérieure. Les acteurs sont aussi bien cellulaires : les cellules de l’immunité acquise lymphocytes T et B qu’innée et de type innée associé à des facteurs diffusibles qu’il s’agisse de cytokines et d’anticorps. Ce système présente des différences de fonctionnement dans les différents tissus et sous l’influence des agressions. Le cancer étant en l’espèce, un type particulier d’agression. L’immunologie est une science en mouvement qui évolue en continu. Les espoirs portés par elle sont justifiés mais les bases fondamentales encore en construction. Les nouvelles thérapies qui ont fait leurs preuves dans les dix années passées le démontrent. Les premières vagues portent sur la cosignalisation, les cellules de type CAR-T et les anticorps bispécifiques. Nous allons essayer de nous projeter sur les étapes suivantes avec les attentes portant sur la cytokine, la vaccination, les modifications du micro-environnement tumoral et les cellules innées et de type innée.

© 2020 SPLF. Publié par Elsevier Masson SAS. Tous droits réservés.

Immune checkpoint inhibitors: a narrative review of considerations for the anaesthesiologist

Immunotherapy has revolutionised the treatment of oncologic malignancies. Immune checkpoint inhibitors represent a new class of immunotherapy drugs. Although these drugs show promise, they are associated with immune-related adverse reactions. An increasing number of patients who undergo surgery will have had treatment with immune checkpoint inhibitors. In this narrative review article, we discuss their mechanism of action, therapeutic effects, pertinent toxicities, and address specific perioperative considerations for patients treated with immune checkpoint inhibitors.

Toward Small-Molecule Inhibition of Protein-Protein Interactions: General Aspects and Recent Progress in Targeting Costimulatory and Coinhibitory (Immune Checkpoint) Interactions

Protein-Protein Interactions (PPIs) that are part of the costimulatory and coinhibitory (immune checkpoint) signaling are critical for adequate T cell response and are important therapeutic targets for immunomodulation. Biologics targeting them have already achieved considerable clinical success in the treatment of autoimmune diseases or transplant recipients (e.g., abatacept, belatacept, and belimumab) as well as cancer (e.g., ipilimumab, nivolumab, pembrolizumab, atezolizumab, durvalumab, and avelumab). In view of such progress, there have been only relatively limited efforts toward developing small-molecule PPI inhibitors (SMPPIIs) targeting these cosignaling interactions, possibly because they, as all other PPIs, are difficult to target by small molecules and were not considered druggable. Nevertheless, substantial progress has been achieved during the last decade. SMPPIIs proving the feasibility of such approaches have been identified through various strategies for a number of cosignaling interactions including CD40-CD40L, OX40-OX40L, BAFFR-BAFF, CD80-CD28, and PD-1-PD-L1s. Here, after an overview of the general aspects and challenges of SMPPII-focused drug discovery, we review them briefly together with relevant structural, immune-signaling, physicochemical, and medicinal chemistry aspects. While so far only a few of these SMPPIIs have shown activity in animal models (DRI-C21045 for CD40-D40L, KR33426 for BAFFR-BAFF) or reached clinical development (RhuDex for CD80-CD28, CA-170 for PD-1-PD-L1), there is proof-of-principle evidence for the feasibility of such approaches in immunomodulation. They can result in products that are easier to develop/ manufacture and are less likely to be immunogenic or encounter postmarket safety events than corresponding biologics, and, contrary to them, can even become orally bioavailable.

CRISPR knock out CTLA-4 enhances the anti-tumor activity of cytotoxic T lymphocytes

T cell-mediated anti-tumor immunity plays a pivotal role in cancer immune surveillance. Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) is a protein receptor mainly expressed in activated T cells and regulatory T cells. CTLA-4 competes with CD28 for ligand binding and generates inhibitory signals to attenuate T cell activation. The blockade of CTLA-4 mediated immune inhibitory checkpoint has been associated with enhanced anti-tumor immunity. In this study, we use CRISPR-Cas9 system to knock out (KO) CTLA-4 from cytotoxic T lymphocytes (CTLs) and evaluate its effect on the anti-tumor activity of the CTLs. CTLA-4 KO CTLs robustly enhanced tumor cell death by 40% compared to the control and facilitated apoptosis and caspase activities in tumor cells. The knockout of CTLA-4 also increased TNF-α and IFN-γ secretion of the CTLs by approximately 2-fold. The effectiveness of CTLA-4 KO in enhancing anti-tumor activity of the CTLs was verified in vivo using mouse xenograft model. The xenografted mice treated with CTLA-4 KO CTLs demonstrated repressed tumor growth and prolonged survival compared to the control group. Our data suggest that CRISPR targeting CTLA-4 immune checkpoint could significantly improve the anti-tumor activity of CTLs.

Antigenic GM3 Lactone Mimetic Molecule Integrated Mannosylated Glycopeptide Nanofibers for the Activation and Maturation of Dendritic Cells

The ability of dendritic cells to coordinate innate and adaptive immune responses makes them essential targets for vaccination strategies. Presentation of specific antigens by dendritic cells is required for the activation of the immune system against many pathogens and tumors, and nanoscale materials can be functionalized for active targeting of dendritic cells. In this work, we integrated an immunogenic, carbohydrate melanoma-associated antigen-mimetic GM3-lactone molecule into mannosylated peptide amphiphile nanofibers to target dendritic cells through DC-SIGN receptor. Based on morphological and functional analyses, when dendritic cells were treated with peptide nanofiber carriers, they showed significant increase in antigen internalization and a corresponding increase in the surface expression of the activation and maturation markers CD86, CD83 and HLA-DR, in addition to exhibiting a general morphology consistent with dendritic cell maturation. These results indicate that mannosylated peptide amphiphile nanofiber carriers are promising candidates to target dendritic cells for antigen delivery.

Overlooked Mechanisms in Type 1 Diabetes Etiology: How Unique Costimulatory Molecules Contribute to Diabetogenesis

Type 1 Diabetes (T1D) develops when immune cells invade the pancreatic islets resulting in loss of insulin production in beta cells. T cells have been proven to be central players in that process. What is surprising, however, is that classic mechanisms of tolerance cannot explain diabetogenesis; alternate mechanisms must now be considered. T cell receptor (TCR) revision is the process whereby T cells in the periphery alter TCR expression, outside the safety-net of thymic selection pressures. This process results in an expanded T cell repertoire, capable of responding to a universe of pathogens, but limitations are that increased risk for autoimmune disease development occurs. Classic T cell costimulators including the CD28 family have long been thought to be the major drivers for full T cell activation. In actuality, CD28 and its family member counterparts, ICOS and CTLA-4, all drive regulatory responses. Inflammation is driven by CD40, not CD28. CD40 as a costimulus has been largely overlooked. When naïve T cells interact with antigen presenting cell CD154, the major ligand for CD40, is induced. This creates a milieu for T cell (CD40)-T cell (CD154) interaction, leading to inflammation. Finally, defined pathogenic effector cells including TH40 (CD4⁺CD40⁺) cells can express FOXP3 but are not Tregs. The cells loose FOXP3 to become pathogenic effector cells. Each of these mechanisms creates novel options to better understand diabetogenesis and create new therapeutic targets for T1D.

Mitogenicity of bacterial lipopolysaccharide on the T lymphocyte population bearing the γδT cell receptor

In vitro [3H]-thymidine (TdR) uptake in T lymphocyte populations, taken and purified from proteose peptone-induced peritoneal exudate cells (PEC), spleens and thymuses of C3H/HeN mice, were investigated by stimulation with bacterial lipopolysaccharide (LPS). The T cells taken from PEC (PEC-T) were purified by passing them through a nylon fiber column (Nfc) and a G-10 column. They were then treated with anti-lak, anti-Mac-1 and anti-LR-1 antibodies plus complement (C). The PEC-T cells showed an increased [ 3H]-TdR uptake in response to LPS, while the splenic T cells and thymic T cells that had been purified and treated by a similar procedure with minor modifications, poorly responded to LPS and did not respond to LPS, respectively. The response of PEC-T to LPS was abolished when the PEC-T were pretreated with anti-Thy-1 or anti-γδ antibody plus C, but not αβ, T cell receptor (TCR) antibody plus C. The thymic T cells did not show any increase of [ H]-TdR uptake in response to LPS or anti-αβ or γδTCR antibody. However, obvious uptake did occur when the cells were stimulated with LPS and anti-γδTCR antibody, but not with anti-αβTCR antibody. IL-1 did not substitute for LPS in the response. These results suggest that LPS has a mitogenic ability to respond to a T cell population bearing γδTCR in PEC, and to a γδTCR-stimulated cell population in thymic cells. The difference in response to LPS between PEC-γδT and thymic γδT cells was discussed.

[Immunological aspects of ovarian cancer: Therapeutic perspectives]

Ovarian cancer is recognized by the immunological system of its host. Initially, it is effective to destroy and eliminate the cancer. But gradually, resistant tumor cells more aggressive and those able to protect themselves by inducing immune tolerance will be selected. Immunotherapy to be effective should consider both components of immune response with an action on cytotoxic immune effectors and action on tolerance mechanisms. The manipulations of the immune system should be cautious, because the immune effects are not isolated. A theoretically efficient handling may simultaneously cause an adverse effect which was not envisaged and could neutralize the benefits of treatment. Knowledge of tolerance mechanisms set up by the tumor is for the clinician a prerequisite before they prescribe these treatments. For each cancer, the knowledge of its immunological status is a prerequisite to propose adapted immunological therapies.

Endoplasmic reticulum chaperones and their roles in the immunogenicity of cancer vaccines

The endoplasmic reticulum (ER) is a major site of passage for proteins en route to other organelles, to the cell surface, and to the extracellular space. It is also the transport route for peptides generated in the cytosol by the proteasome into the ER for loading onto major histocompatibility complex class I (MHC I) molecules for eventual antigen presentation at the cell surface. Chaperones within the ER are critical for many of these processes; however, outside the ER certain of those chaperones may play important and direct roles in immune responses. In some cases, particular ER chaperones have been utilized as vaccines against tumors or infectious disease pathogens when purified from tumor tissue or recombinantly generated and loaded with antigen. In other cases, the cell surface location of ER chaperones has implications for immune responses as well as possible tumor resistance. We have produced heat-shock protein/chaperone protein-based cancer vaccines called “chaperone-rich cell lysate” (CRCL) that are conglomerates of chaperones enriched from solid tumors by an isoelectric focusing technique. These preparations have been effective against numerous murine tumors, as well as in a canine with an advanced lung carcinoma treated with autologous CRCL. We also published extensive proteomic analyses of CRCL prepared from human surgically resected tumor samples. Of note, these preparations contained at least 10 ER chaperones and a number of other residents, along with many other chaperones/heat-shock proteins. Gene ontology and network analyses utilizing these proteins essentially recapitulate the antigen presentation pathways and interconnections. In conjunction with our current knowledge of cell surface/extracellular ER chaperones, these data collectively suggest that a systems-level view may provide insight into the potent immune stimulatory activities of CRCL with an emphasis on the roles of ER components in those processes.

Defining a new biomarker for the autoimmune component of Multiple Sclerosis: Th40 cells

Multiple Sclerosis (MS) is a chronic inflammatory, neurodegenerative disease. Diagnosis is very difficult requiring defined symptoms and multiple CNS imaging. A complicating issue is that almost all symptoms are not disease specific for MS. Autoimmunity is evident, yet the only immune-related diagnostic tool is cerebral-spinal fluid examination for oligoclonal bands. This study addresses the impact of Th40 cells, a pathogenic effector subset of helper T cells, in MS. MS patients including relapsing/remitting MS, secondary progressive MS and primary progressive MS were examined for Th40 cell levels in peripheral blood and, similar to our findings in autoimmune type 1 diabetes, the levels were significantly (p<0.0001) elevated compared to controls including healthy non-autoimmune subjects and another non-autoimmune chronic disease. Classically identified Tregs were at levels equivalent to non-autoimmune controls but the Th40/Treg ratio still predicted autoimmunity. The cohort displayed a wide range of HLA haplotypes including the GWAS identified predictive HLA-DRB1*1501 (DR2). However half the subjects did not carry DR2 and regardless of HLA haplotype, Th40 cells were expanded during disease. In RRMS Th40 cells demonstrated a limited TCR clonality. Mechanistically, Th40 cells demonstrated a wide array of response to CNS associated self-antigens that was dependent upon HLA haplotype. Th40 cells were predominantly memory phenotype producing IL-17 and IFNγ with a significant portion producing both inflammatory cytokines simultaneously suggesting an intermediary between Th1 and Th17 phenotypes.

Fine tuning and efficient T cell activation with stimulatory aCD3 nanoarrays

Anti-CD3 (aCD3) nanoarrays fabricated by self-assembled nanopatterning combined with site-directed protein immobilization techniques represent a novel T cell stimulatory platform that allows tight control over ligand orientation and surface density. Here, we show that activation of primary human CD4+ T cells, defined by CD69 upregulation, IL-2 production and cell proliferation, correlates with aCD3 density on nanoarrays. Immobilization of aCD3 through nanopatterning had two effects: cell activation was significantly higher on these surfaces than on aCD3-coated plastics and allowed unprecedented fine-tuning of T cell response.

Molecular mechanisms of retinal ganglion cell degeneration in glaucoma and future prospects for cell body and axonal protection

Glaucoma, which affects more than 70 million people worldwide, is a heterogeneous group of disorders with a resultant common denominator; optic neuropathy, eventually leading to irreversible blindness. The clinical manifestations of primary open-angle glaucoma (POAG), the most common subtype of glaucoma, include excavation of the optic disc and progressive loss of visual field. Axonal degeneration of retinal ganglion cells (RGCs) and apoptotic death of their cell bodies are observed in glaucoma, in which the reduction of intraocular pressure (IOP) is known to slow progression of the disease. A pattern of localized retinal nerve fiber layer (RNFL) defects in glaucoma patients indicates that axonal degeneration may precede RGC body death in this condition. The mechanisms of degeneration of neuronal cell bodies and their axons may differ. In this review, we addressed the molecular mechanisms of cell body death and axonal degeneration in glaucoma and proposed axonal protection in addition to cell body protection. The concept of axonal protection may become a new therapeutic strategy to prevent further axonal degeneration or revive dying axons in patients with preperimetric glaucoma. Further study will be needed to clarify whether the combination therapy of axonal protection and cell body protection will have greater protective effects in early or progressive glaucomatous optic neuropathy (GON).

[Immunological analogies between ovarian cancer and pregnancy]

During pregnancy an environment allowing installation of tolerance toward the fetus is set up locally at the materno-fetal interface. Numerous effectors of immunity are involved in this tolerance (NK cell, T cell, Macrophages, dendritic cell). Specific mechanisms during pregnancy attract locally these immunological cells. In the decidua, they are educated toward tolerance. These mechanisms evolve during the pregnancy because at the end of the pregnancy, tolerance is broken to prepare and activate the labor. Ovarian tumors, after having surmounted the immunosurveillance, like trophoblast, chair the installation of a tolerance of their host facilitating the development of the disease. The blocking of these mechanisms of tolerance coupled with activation of mechanisms of defenses offer new perspectives in the treatment of the ovarian cancer. The authors suggest showing the analogies of the tolerance observed during ovarian cancer and pregnancy. The knowledge of the orchestration of the physiological mechanisms observed during pregnancy will offer new therapeutic targets.

Antigen-specific blocking of CD4-specific immunological synapse formation using BPI and current therapies for autoimmune diseases

In this review, we discuss T-cell activation, etiology, and the current therapies of autoimmune diseases (i.e., MS, T1D, and RA). T-cells are activated upon interaction with antigen-presenting cells (APC) followed by a "bull's eye"-like formation of the immunological synapse (IS) at the T-cell-APC interface. Although the various disease-modifying therapies developed so far have been shown to modulate the IS and thus help in the management of these diseases, they are also known to present some undesirable side effects. In this study, we describe a novel and selective way to suppress autoimmunity by using a bifunctional peptide inhibitor (BPI). BPI uses an intercellular adhesion molecule-1 (ICAM-1)-binding peptide to target antigenic peptides (e.g., proteolipid peptide, glutamic acid decarboxylase, and type II collagen) to the APC and therefore modulate the immune response. The central hypothesis is that BPI blocks the IS formation by simultaneously binding to major histocompatibility complex-II and ICAM-1 on the APC and selectively alters the activation of T cells from T(H)1 to T(reg) and/or T(H)2 phenotypes, leading to tolerance.

Plasma sCD28, sCTLA-4 levels in neuromyelitis optica and multiple sclerosis during relapse

BACKGROUND

Soluble forms of CD28 (sCD28) and CTLA-4 (sCTLA-4) were associated with many autoimmune diseases like Sjögren's syndrome, systemic lupus erythematosus, asthma, and autoimmune myasthenia gravis. However, sCD28 and sCTLA-4 in neuromyelitis optica (NMO) and multiple sclerosis (MS) patients were less studied.

OBJECTIVE

To measure the plasma sCD28, sCTLA-4 in NMO and MS patients, and investigate whether sCD28 and sCTLA-4 possible use as sensitive biomarkers for diseases activity.

METHODS

Plasma concentrations of sCD28, sCTLA-4 were measured by an enzyme-linked immunosorbent assay (ELISA) in NMO (n=22), MS (n=21) patients and controls (n=18).

RESULTS

The concentration of sCD28 levels were higher in the inflammatory demyelinating diseases cohort compared with the controls (NMO, p=0.034; MS, p=0.026) and the levels of sCD28 were slightly higher in NMO compared with MS. The sCTLA-4 levels were lower in the MS subgroup compared with the controls (p=0.032). Both sCD28 and sCTLA-4 did not show any correlation with EDSS score in NMO and MS patients.

CONCLUSIONS

Our study revealed for the first time that the levels of increased plasma sCD28 and decreased plasma sCTLA-4 in NMO and MS patients, but had little correlation with clinical presentations.

Tumor antigen-dependent and tumor antigen-independent activation of antitumor activity in T cells by a bispecific antibody-modified tumor vaccine

New approaches of therapeutic cancer vaccination are needed to improve the antitumor activity of T cells from cancer patients. We studied over the last years the activation of human T cells for tumor attack. To this end, we combined the personalized therapeutic tumor vaccine ATV-NDV—which is obtained by isolation, short in vitro culture, irradiation, and infection of patient's tumor cells by Newcastle Disease Virus (NDV)—with bispecific antibodies (bsAbs) binding to this vaccine and introducing anti-CD3 (signal 1) and anti-CD28 (signal 2) antibody activities. This vaccine called ATV-NDV/bsAb showed the unique ability to reactivate a preexisting potentially anergized antitumor memory T cell repertoire. But it also activated naive T cells to have antitumor properties in vitro and in vivo. This innovative concept of direct activation of cancer patients' T cells via cognate and noncognate interactions provides potential for inducing strong antitumor activities aiming at overriding T cell anergy and tumor immune escape mechanisms.

Regulation of costimulatory signal in maternal-fetal immune tolerance

A pregnancy is associated with modifications in the immune status of the mother, but the mechanisms are not well understood. Several observations have indicated that CD28/CTLA-4 and B7-1/B7-2 are involved in the maternal-fetal immune regulation. This review aims to recapitulate our current knowledge concerning the role of CD28/CTLA-4 and B7-1/B7-2 in maternal-fetal immune regulation. Several studies suggest that up-regulation of B7-2 and/or CD28 and/or down-regulation of CTLA-4 are correlated with the occurrence of pregnancy loss. Therefore, an accurate expression of costimulatory molecules at the maternal-fetal interface may ensure that the decidual cells do not elicit a 'danger' signal to the maternal immune system, perhaps instead contributing to the establishment of immune tolerance in vivo. It is showed that costimulation blockade with anti-B7 mAbs results in altered allogeneic T-cell response and overcomes increased maternal rejection to the fetus, which improves fetus growth in the abortion-prone system. These findings suggest that the anti-B7-treated T cells not only function as potent suppresser cells but also exert immunoregulatory effect on the maternal T cells. This procedure might be potentially useful to immunotherapy for human recurrent spontaneous abortion.

Biological therapy of bone defects: the immunology of bone allo-transplantation

IMPORTANCE OF THE FIELD

Bone is one of the most transplanted tissues worldwide. Autograft is the ideal bone graft but is not widely used because of donor site morbidity and restricted availability. Allograft is easily accessible but can transmit infections and elicit an immune response.

AREAS COVERED IN THIS REVIEW

This review identifies all in vitro and in vivo evidence of immune responses following bone transplantation and highlights methods of improving host tolerance to bone allotransplantation.

WHAT THE READER WILL GAIN

In humans, the presence of anti-HLA specific antibodies against freeze-dried and fresh-frozen bone allografts has been demonstrated. Fresh-frozen bone allograft can still generate immune reactions whilst freeze-dried bone allografts present with less immunogenicity but have less structural integrity. This immune response can have an adverse effect on the graft's incorporation and increase the incidence of rejection. Decreasing the immune reaction against the allograft by lowering the immunogenic load of the graft or lowering the host immune response, would result in improved bone incorporation.

TAKE HOME MESSAGE

It is essential that the complex biological processes related to bone immunogenicity are understood, since this may allow the development of safer and more successful ways of controlling the outcome of bone allografting.

Costimulatory molecule programmed death-1 in the cytotoxic response during chronic hepatitis C

Hepatitis C virus (HCV)-specific CD8⁺ T cells play an important role in the resolution of HCV infection. Nevertheless, during chronic hepatitis C these cells lack their effector functions and fail to control the virus. HCV has developed several mechanisms to escape immune control. One of these strategies is the up-regulation of negative co-stimulatory molecules such us programmed death-1 (PD-1). This molecule is up-regulated on intrahepatic and peripheral HCV-specific cytotoxic T cells during acute and chronic phases of the disease, whereas PD-1 expression is low in resolved infection. PD-1 expressing HCV-specific CD8⁺ T cells are exhausted with impairment of several effector mechanisms, such as: type-1 cytokine production, expansion ability after antigen encounter and cytotoxic ability. However, PD-1 associated exhaustion can be restored by blocking the interaction between PD-1 and its ligand (PD-L1). After this blockade, HCV-specific CD8⁺ T cells reacquire their functionality. Nevertheless, functional restoration depends on PD-1 expression level. High PD-1-expressing intrahepatic HCV-specific CD8⁺ T cells do not restore their effector abilities after PD-1/PD-L1 blockade. The mechanisms by which HCV is able to induce PD-1 up-regulation to escape immune control are unknown. Persistent TCR stimulation by a high level of HCV antigens could favour early PD-1 induction, but the interaction between HCV core protein and gC1q receptor could also participate in this process. The PD-1/PD-L1 pathway modulation could be a therapeutic strategy, in conjunction with the regulation of others co-stimulatory pathways, in order to restore immune response against HCV to succeed in clearing the infection.

Anti-CD3 scFv-B7.1 fusion protein expressed on the surface of HeLa cells provokes potent T-lymphocyte activation and cytotoxicityThis paper is one of a selection of papers in this Special Issue, entitled International Symposium on Recent Advances in Molecular, Clinical, and Social Medicine, and has undergone the Journal's usual peer-review process

The targeting of tumor cells by cytotoxic T lymphocytes is a promising strategy for biotherapy, but T cells require 2 signals via the T-cell receptor – CD3 complex and CD28 molecules for activation. To bridge the gap between cytotoxic T lymphocytes and tumor cells, our objective in this study was to describe the construction and the cell surface-anchored expression of a fusion protein, anti-CD3 scFv-B7.1, derived from inserting a fusion gene encoding anti-CD3 scFv and the extra-cellular domain of B7.1 fused by the splicing by overlap extension method into a mammalian expression vector, pDisplay. Transfection of the recombinant vector by electroporation into HeLa cells resulted in the production of protein migrating at approximately 57 kDa under reducing conditions. The expressed fusion protein could bind to T lymphocytes and induce strong T-cell activation. Meanwhile, a potent cytotoxicity was induced in the mixed culture of T-cell-modified tumor cells in a 96 h methyl-thiazolyl-diphenyl tetrazolium bromide assay. Our results indicate that this bifunctional protein, through activating T lymphocytes to lyse homologous human carcinomas, may be of potential value for T-cell-based immunotherapeutical treatment protocols in vivo.

Autoimmune properties of nucleus pulposus: an experimental study in pigs

STUDY DESIGN

Assessment of activated T and B cells in a subcutaneous chamber filled with autologous nucleus pulposus using flow cytometry and immunohistochemistry.

OBJECTIVES

To examine if subcutaneously placed autologous nucleus pulposus may attract activated T and B cells in an animal model.

SUMMARY OF BACKGROUND DATA

Nucleus pulposus has been suggested to trigger an autoimmune response if exposed to the immune system, for example, in association with disc herniation. T-cell activation represents a hallmark in the generation of an autoimmune response, subsequently leading to the differentiation of B cells, but a causal association between the exposure of nucleus pulposus to the systemic circulation and T and B cell activation is still lacking.

METHODS

Autologous nucleus pulposus was harvested from the intervertebral disc of 9 pigs and placed subcutaneously in perforated titanium chambers. In order to control for the effect of the titanium chamber, an additional empty chamber was placed subcutaneously in each pig. After 7 days, the pigs were killed and the chambers were harvested. Flow cytometry and immunohistochemistry were used for analysis of T-helper cells (CD4+), cytotoxic T cells (CD8+), and B cells (Igkappa) in the chamber exudates and T cells (CD45RC) in the remaining blood clot tissue of the chamber.

RESULTS

As compared with the empty chambers, the proportion of activated T cells (CD4+ and CD8+) was significantly higher in the exudate of the nucleus pulposus filled chamber. The proportion of activated B cells expressing immunoglobulin kappa (Igkappa) was also significantly elevated in the exudate of the nucleus pulposus chambers. The analysis of the remaining chamber tissue revealed a significantly higher amount of T cells (CD45RC) in the nucleus pulposus chambers than in the empty chambers.

CONCLUSIONS

The present findings indicate that nucleus pulposus attracts activated T and B cells. However, since the cell population in the nucleus pulposus of young pigs may differ from that of adult humans, the obtained data may not be directly transferred to the human situation of a disc herniation. The observations in the present study may nevertheless explain some of the local tissue reactions occurring in association with disc herniation and nerve root involvement, thereby providing further insight into the pathophysiology of sciatica.

Adoptive Transfer of Paternal Antigen-Hyporesponsive T Cells Facilitates a Th2 Bias in Peripheral Lymphocytes and at Materno-Fetal Interface in Murine Abortion-prone Matings

PROBLEM

To investigate the Th1/Th2 cytokine changes in abortion-prone recipient mice adoptively transferred by the paternal antigen-hyporesponsive T cells.

METHOD OF STUDY

The paternal antigen-hyporesponsive T cells were generated by the anti-B7 monoclonal antibody (mAb) treatment and adoptively transferred into pregnant CBA/J mice of abortion-prone matings on day 4 of gestation. The intracellular expressions of Th1 cell-derived cytokine, tumor necrosis factor-alpha, gamma-interferon and interleukin-2 (IL-2) and Th2 cell-derived cytokine, IL-4 and IL-10 in the maternal spleen were analyzed by flow cytometry, and secretions of the Th1 and Th2 cytokines in supernatant of the feto-placental unit culture were analyzed by an enzyme-linked immunosorbent assay.

RESULTS

Our findings showed the increased secretion of Th1 cytokines and the decreased secretion of Th2 cytokines in abortion-prone matings. Treatment with anti-B7 mAbs on day 4 of gestation enhanced Th2 and reduced Th1 cytokine production in abortion-prone matings. Similarly, adoptive transfer of paternal antigen-hyporesponsive T cells induced maternal tolerance to the fetus and displayed a Th2 bias both in the peripheral lymphocytes and at the materno-fetal interface of the abortion-prone matings.

CONCLUSIONS

These findings indicate that the Th2 cytokine bias and an increase in fetal viability induced by the anti-B7 mAb treatment can be transferred to other pregnant mice of the abortion-prone matings.

On ‘Credo 2004’ as Viewed Under the ‘Development-Context’ Model of Colin Anderson

In analysing the Zinkernagel and Hengartner's 'Credo 2004,' Anderson introduces his 'development-context model' for the immunity-tolerance discrimination. He compares this model with the 'geographical model of Credo 2004' and our 'time-based two-signal model'. The discussion here deals with the advantages and limitations of the Anderson model considered largely at the level of principle. A meaningful discussion requires that we agree on the principle which separates the pathway of the effector output into two decision steps, the sorting of the repertoire and the regulation of effector class. The mechanism for the sorting of the repertoire is what might be referred to as the Self-Nonself discrimination. The black box approach, antigen-in, effector response-out, is what is referred to as the immunity-tolerance discrimination which includes the sorting of the repertoire. If this point of principle is accepted then we are left with a 'time-based two signal default model'.

PAS-1, a protein affinity purified from Ascaris suum worms, maintains the ability to modulate the immune response to a bystander antigen

Helminth infections and parasite components have potent immunomodulatory effects on a host's immune system. In the present study, we investigated the effect of PAS-1, a protein component of Ascaris suum adult worms recognized by a monoclonal antibody (MAIP-1), on humoral and cell-mediated responses to a bystander antigen (ovalbumin [OVA]). MAIP-1 recognized only one of the three polypeptide chains of PAS-1, but neutralized the suppressive effect of the whole worm extract on OVA-specific antibody production. PAS-1 inhibited antibody production against a T-cell-dependent, but not a T-cell-independent, antigen in a dose-dependent way. IgM, IgG1, IgG2b, and also IgE and anaphylactic IgG1 levels were downregulated. In addition, PAS-1 inhibited OVA-specific delayed type hypersensitivity reactions in the footpad of mice, showing a potent immunosuppressive activity on both Th1 and Th2 responses that seems to be mediated by the induction of large amounts of IL-10 and IL-4. Indeed, PAS-1-specific spleen cells secreted sevenfold more IL-10 and threefold more IL-4 than OVA-specific cells in response to in vitro restimulation with the respective antigens. In conclusion, we showed that PAS-1, a single protein component from A. suum, maintains all its immunosuppressive properties.

Plasma concentrations of soluble CTLA-4, CD28, CD80 and CD86 costimulatory molecules reflect disease severity of acute asthma in children

Recent studies have demonstrated an elevation of plasma soluble costimulatory molecules B7.1 (CD80) and B7.2 (CD86), and their T lymphocyte counter receptors cytotoxic T lymphocyte associated antigen-4 (CTLA-4) and CD28 in asthmatic patients. We hypothesized that these costimulatory molecules may reflect the severity of asthma and investigated the longitudinal changes of these soluble costimulatory molecules, and their clinical significance in children with an asthmatic exacerbation. Sixteen children hospitalized for asthmatic exacerbation were recruited and treated with systemic corticosteroid (CS) for 5 days. Plasma total Immunoglobulin E (IgE) and eosinophil cationic protein (ECP) concentrations were measured by microparticle immunoassay and fluorescence enzyme immunoassay, respectively. Soluble CTLA-4 (sCTLA-4), sCD28, sCD80, and sCD86 concentrations in plasma were measured by enzyme-linked immunosorbent assay, and their relationships with asthma severity, total IgE, ECP concentrations, and blood eosinophil count were analyzed. Plasma sCTLA-4, sCD28, sCD80, and sCD86 concentrations in patients were highest during the acute attack. They decreased significantly with a parallel increase of peak expiratory flow rate (PEFR) after CS treatment (all P < 0.05). Plasma sCTLA-4, sCD28, and sCD86 concentrations of patients at recruitment were inversely correlated with PEFR, whereas plasma sCD28 and sCD86 concentrations correlated positively with eosinophil count and plasma ECP concentration (all P < 0.05). Although there was no such correlation with IgE concentration, sCD28 was correlated very significantly with eosinophil count (r = 0.83, P < 0.0001). In conclusion, plasma sCTLA-4, sCD28, sCD86, and sCD80 concentrations may reflect the severity of acute asthma and more studies on larger cohorts are needed to assess whether these markers are useful for assessing asthmatic exacerbation in children.

Modification of accessory molecule signaling

The concept of costimulation, the requirement for an independent accessory cellular activation signal that supplements the signal delivered to a lymphocyte by antigen, has been a focal point of progress in understanding the regulation of the immune system. While considerable attention has been directed to new developments related to the activation of cells of the innate immune system through Toll-like receptors, resulting in the production of soluble mediators, augmented expression of cell surface costimulatory molecules on antigen-presenting cells is arguably the most significant early outcome of immune system activation. It is those cell surface molecules that provide the essential afferent costimulatory signals to T cells of the adaptive immune response. Once fully activated, T cells express their own cell surface accessory molecules that permit those T cells to instruct interacting B cells, macrophages, and dendritic cells to further implement an effective immune response. Significantly for patients with autoimmune diseases, the manipulation of costimulatory signals represents a rational and effective approach to modulating the chronic immune system activation that characterizes those diseases. Further elucidation of the complexities of members of the accessory molecule families and their functions should lead to an ever greater capacity for therapeutic modulation of the immune response in autoimmune and inflammatory diseases.

Role of inducible costimulator in the development of lupus in MRL/lpr mice

Inducible costimulator (ICOS) is a costimulatory molecule expressed in activated T cells and plays an important role in T-cell-dependent immune responses. We investigated the role of ICOS in the development of autoimmune diseases in MRL/Mpj-lpr/lpr (MRL/lpr) mice. ICOS was expressed on CD4(+) T cells from adult MRL/lpr mice. ICOS-deficient MRL/lpr mice showed mild lymphoadenopathy and a decreased memory type CD4(+) T cells in the spleen. The anti-dsDNA antibody levels were decreased. CD4(+) T cells from ICOS-deficient MRL/lpr mice showed less of a bias to Th1 and an enhanced production of IL-4 in response to anti-CD3 antibody in comparison to those from wild-type MRL/lpr mice. Although ICOS-deficiency abrogated renal vasculitis completely, the severity of glomerulonephritis was not altered. ICOS is considered to play a role in CD4(+) T cell activation, autoantibody production, and renal vasculitis. However, it is not essentially required in the development of glomerulonephritis.

Inhibitory effects of Triptolide on interferon-gamma-induced human leucocyte antigen-DR, intercellular adhesion molecule-1, CD40 expression on retro-ocular fibroblasts derived from patients with Graves' ophthalmopathy

PURPOSE

To explore the effects of Triptolide, the principal active diterpenoid from the Chinese Medicinal Herb Tripterygium Wilfordii Hook F that has immunosuppressive and anti-inflammatory properties, on cell proliferation, hyaluronic acid (HA) synthesis, and the expressions of human leucocyte antigen-DR (HLA-DR), intercellular adhesion molecule-1 (ICAM-1) and CD40 on cultured retro-ocular fibroblasts (RFs) from patients with Graves' ophthalmopathy.

METHODS

After two to five passages, cultured RFs were incubated for 48 h within a medium alone or in the presence of recombinant human interferon-gamma (IFN-gamma) and various concentrations of Triptolide. Cell viability was assessed by MTT (3-[4.5-dimethylahiazol-2-yl]-2,5-diphenyltetrazolium Bromide). RFs proliferation was assessed by [(3)H]-thymidine incorporation assay. Flow cytometry was used to investigate the amount of HLA-DR, ICAM-1 and CD40. HA synthesis was measured by radioimmunoassay.

RESULTS

Cell viability was not detrimentally affected when incubated with Triptolide from 0.01 microg/L to 10 microg/L for 48 h, and decreased with 20 microg/L Triptolide. The incorporation of [(3)H]-thymidine of RFs was 55 476 +/- 15 842 cpm incubated with medium alone or 18 352 +/- 3568 cpm with 10 microg/L Triptolide (t = 5.600, P < 0.01). Initially, the percentage of positive cells of HLA-DR, ICAM-1 and CD40 on RFs were 4.75 +/- 2.13%, 17.53 +/- 10.12% and 6.38 +/- 2.23%, respectively, and the synthesis of HA was 100 +/- 12%. Compared with basal values, 48-h incubation with IFN-gamma (100 U/mL) significantly enhanced the amount of HLA-DR, ICAM-1 and CD40, and HA synthesis. The values were 60.58 +/- 10.12% (t = 13.224, P < 0.01), 62.66 +/- 18.17% (t = 5.315, P < 0.01), 57.67 +/- 13.61% (t = 9.110, P < 0.01) and 164 +/- 22% (t = 9.238, P < 0.01), respectively. Triptolide 0.01 microg/L had little effect on IFN-gamma-induced HLA-DR, ICAM-1 and CD40 amounts, as well as HA synthesis. When the concentration ranged from 0.1 microg/L to 10 microg/L, Triptolide inhibited IFN-gamma-induced RFs activation in a dose-dependent manner. It was also found that Triptolide had the same inhibiting effects on IFN-gamma-induced RFs and skin fibroblasts from patients with normal individual conditions.

CONCLUSIONS

Triptolide could inhibit IFN-gamma-induced activation of RFs derived from patients with Graves' ophthalmopathy.

Use of recombinant lentivirus pseudotyped with vesicular stomatitis virus glycoprotein G for efficient generation of human anti-cancer chimeric T cells by transduction of human peripheral blood lymphocytes in vitro

BACKGROUND

Genetic redirection of lymphocytes that have been genetically engineered to recognize antigens other than those originally programmed in their germlines is a potentially powerful tool for immunotherapy of cancers and potentially also of persistent viral infections. The basis for this procedure is that both cancers and some viruses have developed strikingly similar mechanisms of evading attacks by host immune mechanisms. To redirect human peripheral blood lymphocytes (PBLs) with a chimeric T cell receptor (chTCR) so that they recognize a new target requires a high degree of transfection efficiency, a process that is regarded as technically demanding.

RESULTS

Infection with a retroviral vector carrying a chTCR cassette was shown to transduce 100% of rapidly dividing murine T cells but typically, only approximately 10% of PBLs could be infected with the same vector. In contrast with other retroviruses, lentiviruses integrate their genomes into non-dividing cells. To increase host cell range, vesicular stomatitis virus G protein was pseudotyped with a lentivirus vector, which resulted in approximately 100% PBL transduction efficiency. Signaling of PBLs bearing chimeric receptors was shown by specific proliferation on exposure to cells expressing cognate ligand. Further, T-bodies against CEA showed a startling ability to cause regression of malignant colon tumors in a nude mouse model of human cancer.

CONCLUSION

A lentivirus/VSV pseudotyped virus, which does not require replicating cells for integration of its genome, efficiently transduced a high proportion of human PBLs with chTCRs against CEA. PBLs transduced by infection with a lentivirus/VSV pseudotyped vector were able to proliferate specifically in vitro on exposure to CEA-expressing cells and further they had a startling therapeutic effect in a mouse model of human colon cancer.

Immune Modulation by Cadmium and Lead in the Acute Reporter Antigen–Popliteal Lymph Node Assay

Immune modulation by heavy metals may cause serious adverse health effects in humans, although the mechanisms involved are not well understood. Both cadmium and lead are important environmental and occupational toxins. Therefore, in the current study, the costimulatory/adjuvant effects and the T-cell-activating potential of these metals (i.e., CdCl2 and PbCl2), are examined. These immune-modulating properties are critical in the development of conditions such as allergy, hypersensitivity, and autoimmunity. Using the direct popliteal lymph node assay (PLNA) and reporter antigen-popliteal lymph node assay (RA-PLNA) both metals were examined individually for immunotoxicity. Mercury (i.e., HgCl2) was included for comparative purposes as its effects in the RA-PLNA are well documented. Seven days following a single footpad injection containing metal and/or RA (trinitrophenyl-ovalbumin [TNP-OVA] or TNP-Ficoll), BALB/c mice were sacrificed and the popliteal lymph nodes (PLNs) removed. PLN cellularity, TNP-specific antibody-secreting cells (ASCs), and lymphocyte subsets were assessed. All three metals strongly stimulated T- and B-cell proliferation and ASC production following coinjection with the RA TNP-OVA. In each case, ASC production was skewed towards the IgG1 isotype. In addition, all three metals induced IgG production to TNP-Ficoll (although relatively weakly in the case of Cd). These results show that each of these metals can provide adjuvant signals to promote lymphocyte proliferation and enhance adaptive immune responses to unrelated antigens. Skewing of immune responses towards T helper type 2 responses suggests that each of these metals can enhance allergic and hypersensitivity reactions to environmental antigens. Furthermore, the induction of IgG responses to TNP-Ficoll, a T-cell-independent antigen, indicates that each of these metals can activate neoantigen-specific T cells. T-cell activation by metals can lead to metal hypersensitivity and has been implicated in the development of autoimmunity. This is the first report of immune modulation by CdCl2 and PbCl2 in the RA-PLNA.

Evaluation of CD86 gene polymorphism at +1057 position in liver transplant recipients

BACKGROUND

Efficient T cell-APC interaction requires the participation of primary and co-stimulatory signals. The main co-stimulatory pathway involves the interaction of CD80 and CD86, expressed on the APCs, with their T cell counter-receptor, CD28 and CTLA-4. Recently, a G to A transition has been described at position +1057 of the CD86 gene, located in their cytoplasmic tail.

METHODS

CD86 polymorphism was analyzed by sequence based typing in DNA samples obtained from 205 liver transplant recipients. Acute rejection and chronic rejection were diagnosed based upon conventional clinical, biochemical and histological criteria.

RESULTS

The study of CD86 +1057 (G/A) polymorphism revealed that recipients bearing the A allele or the AA genotype have a reduced risk of acute rejection. In fact, the AA genotype was absent in the group of patients showing acute rejection episodes, whereas its frequency in those patients without acute rejection episodes was 8.8% (P=0.009, OR=0.07). This polymorphism did not reveal any association with the incidence of chronic rejection, but patients bearing the AA genotype showed a higher graft survival rate (83.3%) than those bearing the GA genotype (49.3%) or GG genotype (56.5%).

CONCLUSIONS

The results of the present report suggest that the CD86 AA genotype at +1057 position could be involved in liver transplant acceptance, given that its presence is related to a decrease of acute rejection frequency and to a graft survival increase.

Macrophages are involved in hexachlorobenzene-induced adverse immune effects

Hexachlorobenzene (HCB) is a persistent environmental pollutant that causes adverse immune effects in man and rat. The Brown Norway (BN) rat is very susceptible to HCB-induced immunopathology and oral exposure causes inflammatory skin and lung lesions, splenomegaly, lymph node (LN) enlargement, and increased serum levels of IgE and anti-ssDNA IgM. T cells play an important role but do not account for all adverse effects induced by HCB. Macrophages are probably also important and the relationship between macrophages and T cells was further investigated. To eliminate macrophages clodronate-liposomes were used. Furthermore, a kinetic study was performed to obtain insight in the early phase of the HCB-induced immune response. Also, experiments were performed to detect specific memory T cells. Therefore, an adoptive transfer study was performed. Our results indicate that macrophages are indeed involved in HCB-induced skin lesions, lung eosinophilia, and elevation of IgM against ssDNA. Kinetics showed that both skin and lung lesions appeared early after exposure. Moreover, immune effects could not be adaptively transferred. Thus, both macrophages and T cells are involved in HCB-induced immune effects but HCB exposure does not lead to specific T cell sensitization. Presumably, HCB exposure induces macrophage activation, thereby generating adjuvant signals that polyclonally stimulate T cells. Together, these events may lead to the observed immunopathology in BN rats.

Blockade of CD80 and CD86 at the time of implantation inhibits maternal rejection to the allogeneic fetus in abortion-prone matings

CD28/CTLA-4 interactions with their specific B7-ligands (CD80 and CD86) play a decisive role in antigenic and allogenic responses. Recently, experimental transplant studies demonstrated that donor-specific tolerance was achieved by blocking these interactions. However, the role of blockade of CD28/B7 costimulatory pathway in the maintenance of materno-fetal tolerance has received little attention. In the present study, abortion-prone CBA/J females mated with DBA/2 males were administered with anti-CD80 and anti-CD86 monoclonal antibodies (mAbs) on day 4 of gestation (time of murine implantation). We demonstrated that the combined use of anti-CD80 and anti-CD86 mAbs induced maternal tolerance to the fetus in the abortion-prone CBA/J mice, and displayed expansion of the maternal CD4(+)CD25+ regulatory T cell population and up-regulated expression of CTLA-4, suggesting an active mechanism of regulatory T cells in suppressing maternal rejection to the fetus. In addition, the anti-CD80/86 mAbs treatment enhanced Th2 and reduced Th1 cytokine production in mice, implying that the development of Th2 cells might contribute to maternal tolerance to her fetus. Together, these findings indicated that blocking CD80 and CD86 enhanced maternal tolerance to her fetus in mice by increasing regulatory T cell function and skewing toward a Th2 response. Our data might provide an enhanced understanding of the maternal-fetal immune relationship and be helpful in clinical trials for immunotherapy of recurrent spontaneous abortion.

Engagement of NKG2D by cognate ligand or antibody alone is insufficient to mediate costimulation of human and mouse CD8+ T cells

CD8+ T cells require a signal through a costimulatory receptor in addition to TCR engagement to become activated. The role of CD28 in costimulating T cell activation is well established. NKG2D, a receptor found on NK cells, CD8+ alphabeta-TCR+ T cells, and gammadelta-TCR+ T cells, has also been implicated in T cell costimulation. In this study we have evaluated the role of NKG2D in costimulating mouse and human naive and effector CD8+ T cells. Unexpectedly, in contrast to CD28, NKG2D engagement by ligand or mAb is not sufficient to costimulate naive or effector CD8+ T cell responses in conventional T cell populations. While NKG2D did not costimulate CD8+ T cells on its own, it was able to modify CD28-mediated costimulation of human CD8+ T cells under certain contitions. It is, therefore, likely that NKG2D acts as a costimulatory molecule only under restricted conditions or requires additional cofactors.

Elevation of plasma soluble T cell costimulatory molecules CTLA-4, CD28 and CD80 in children with allergic asthma

BACKGROUND

The surface expression of T cell costimulatory molecules CTLA-4 and CD28 and their counter-ligands, B7 molecules (CD80, CD86), is differentially induced for T cell activation and expansion in allergic asthma. However, the role of their soluble forms in plasma has not yet been elucidated. In this study, we investigated whether expression is altered and whether soluble costimulatory molecules are clinically relevant in asthmatic patients.

METHODS

Plasma concentrations of soluble CTLA-4 (sCTLA-4), CD28, CD80 and CD86 in 51 children with chronic allergic asthma with or without inhaled corticosteroid treatment, and 22 sex- and age-matched control subjects were measured by enzyme-linked immunosorbent assay. Plasma total IgE concentration was measured using a microparticle immunoassay.

RESULTS

Asthmatic patients had higher logarithmic plasma total IgE concentration (IgE(log)) than healthy subjects (p < 0.0001). In non-steroid-treated patients, plasma sCTLA-4, sCD28 and sCD80 but not sCD86 concentrations were significantly higher than those of control subjects (all p < 0.05). Plasma sCD80 and sCD86 but not sCTLA-4 and sCD28 concentrations correlated significantly with IgE(log) of all subjects (p < 0.05). There were also significant positive correlations between sCTLA-4 and sCD28 (p = 0.0007), and between sCD80 and sCD86 in all asthmatic patients (p = 0.001).

CONCLUSIONS

Plasma sCTLA-4, sCD28 and sCD80 concentrations are elevated in allergic asthma. The increased expression of these soluble proteins may reflect the dysregulation of T cell activation, contributing to the immunopathogenesis of allergic asthma.

Anti-tumour therapeutic efficacy of OX40L in murine tumour model

OX40 ligand (OX40L), a member of TNF superfamily, is a co-stimulatory molecule involved in T cell activation. Systemic administration of mOX40L fusion protein significantly inhibited the growth of experimental lung metastasis and subcutaneous (s.c.) established colon (CT26) and breast (4T1) carcinomas. Vaccination with OX40L was significantly enhanced by combination treatment with intra-tumour injection of a disabled infectious single cycle-herpes simplex virus (DISC-HSV) vector encoding murine granulocyte macrophage-colony stimulating factor (mGM-CSF). Tumour rejection in response to OX40L therapy required functional CD4+ and CD8+ T cells and correlated with splenocyte cytotoxic T lymphocytes (CTLs) activity against the AH-1 gp70 peptide of the tumour associated antigen expressed by CT26 cells. These results demonstrate the potential role of the OX40L in cancer immunotherapy.

Long time follow up of CD28- CD4+ T cells in living kidney transplant patients

We previously reported that the CD28(-) CD4(+) T cell subpopulation was expanded in the kidney allograft patients with long graft survival, although these T cells were rarely found in patients with graft survival <5 yr. To understand the CD28(-) CD4(+) T cells in the long-term acceptance of kidney allografts, we examined functions of this population and performed a 4 yr follow up study. Peripheral blood mononuclear cells (PBMC) were obtained from 47 long-term living related kidney allograft recipients. CD28(+) CD4(+) and CD28(-) CD4(+) T cells purified by cell sorting were analyzed for expression of V(beta) repertoire. Donor-specific response was examined in mixed lymphocyte reaction (MLR). A follow up study with long-term kidney allograft patients was performed for 4 yr about the rate of CD28(-) CD4(+) T cells. Eleven patients were examined by MLRs against donors and third party. Four patients with a marked increase of CD28(-) CD4(+) T cells showed the donor-specific responses appeared to be lower when compared with third party-specific responses. Freshly sorted CD28(-) CD4(+) T cells showed a restricted V(beta) repertoire, whereas the V(beta) usage of CD28(+) CD4(+) T cells from the same patients was much diversified. Such difference in V(beta) repertoire was not evident between the two populations from healthy control. A follow up study showed the ratio of CD28(-) CD4(+) T cells appeared to be lower in patients who were suspected of chronic rejection. These unusual CD4(+) T cells might be related to the long-term acceptance of human transplant allografts.

Adoptive Transfer of Paternal Antigen-Hyporesponsive T Cells Induces Maternal Tolerance to the Allogeneic Fetus in Abortion-Prone Matings

The embryo expresses paternal Ags foreign to the mother and therefore has been viewed as an allograft. It has been shown that anergic T cells generated by blocking of the CD28/B7 costimulatory pathway with anti B7-1 and anti B7-2 mAbs can be transferred as suppresser cells to prevent allograft rejection. Little is known, however, about the in vivo function of anti-B7-treated T cells after their transfer into abortion-prone mice in the maintenance of materno-fetal tolerance. In the present study, abortion-prone CBA/J females mated with DBA/2 males were administered anti-B7-1 and anti-B7-2 mAbs on day 4 of gestation (murine implantation window). The anti-B7-treated T cells subsequently were adoptively transferred into abortion-prone CBA/J mice. We demonstrated that costimulation blockade with anti-B7 mAbs at the time of implantation resulted in altered allogeneic T cell response and overcame increased maternal rejection to the fetus in the CBA/JxDBA/2 system. The transferred anti-B7-treated T cells appeared to be regulatory, decreasing responsiveness and generating clonal deviation in maternal recipient T cells. The transferred CFSE-labeled T cells were found to reside in the spleen and uterine draining lymph nodes, and a few were localized to the materno-fetal interface of the maternal recipient. Our findings suggest that the anti-B7-treated T cells not only function as potent suppresser cells, but also exert an immunoregulatory effect on the maternal recipient T cells, which cosuppresses maternal rejection to the fetus. This procedure might be considered potentially useful for fetal survival when used as an immunotherapy for human recurrent spontaneous abortion.

CD4-positive T cell-mediated neuroprotection requires dual compartment antigen presentation

Our laboratory discovered that CD4-positive (CD4+) T cells of the immune system convey transitory neuroprotection to injured mouse facial motoneurons (FMNs) (Serpe et al., 1999, 2000, 2003). A fundamental question in the mechanisms responsible for neuroprotection concerns the identity of the cell(s) that serves as the antigen-presenting cell (APC) to activate the CD4+ T cells. Here, we first establish that CD4+ T cells reactive to non-CNS antigen fail to support FMN survival and, second, demonstrate a two-compartment model of CD4+ T cell activation. Mouse bone marrow (BM) chimeras were developed that discriminate between resident antigen-presenting host cell and BM-derived antigen-presenting donor cell expression of major histocompatibility complex II within central and peripheral compartments, respectively. After facial nerve transection, neither compartment alone is sufficient to result in activated CD4+ T cell-mediated FMN survival. Rather, CD4+ T cell-mediated neuroprotection appears to depend on both resident microglial cells in the central compartment and a BM-derived APC in the peripheral compartment. This is the first in vivo report demonstrating a neuroprotective mechanism requiring APC functions by resident (i.e., parenchymal) microglial cells.

Inhibition of Activator Protein 1 by Barbiturates Is Mediated by Differential Effects on Mitogen-Activated Protein Kinases and the Small G Proteins Ras and Rac-1

Barbiturates are known to suppress protective immunity, and their therapeutic use is associated with nosocomial infections. Although barbiturates inhibit T cell proliferation, differentiation, and cytokine synthesis, only thiobarbiturates markedly reduce the activation of immune regulatory transcription factors such as nuclear factor-kappaB and nuclear factor of activated T cells. In this study, we investigated barbiturate-mediated effects on the regulation of the transcription factor activator protein 1 (AP-1) in primary T lymphocytes. We show that both thiobarbiturates and their oxy-analogs inhibit AP-1-dependent gene expression and AP-1 complex formation at clinically relevant doses. Furthermore, mitogen-activated protein (MAP) kinase activity, which transcriptionally and posttranslationally regulates AP-1 complex formation, is suppressed by most barbiturates. CD3/CD28- or phorbol 12-myristate 13-acetate (PMA)/ionomycin-induced p38 and extracellular signal-regulated kinase 1/2 phosphorylation or c-jun NH2-terminal kinase (JNK) 1/2 kinase activity was significantly diminished by pentobarbital, thiamylal, secobarbital, or methohexital treatment. These barbiturates also inhibited the initiators of the MAP kinase cascade, the small G proteins ras and rac-1, and prevented binding to their partners raf-1 and PAK, respectively. Thiopental, unlike the other barbiturates, only reduced ras and JNK activity upon direct CD3/CD28 receptor engagement. Contrarily, upon PMA/ionomycin stimulation, thiopental blocked AP-1-dependent gene expression independently of the small G protein ras and MAP kinases, thus suggesting an additional, unknown mechanism of AP-1 regulation. In conclusion, our results contribute to the explanation of a clinically manifested immune suppression in barbiturate-treated patients and support the idea of a MAP kinase-independent regulation of AP-1 by PKC and calcium in human T cells.

Cytotoxic Difference of T Cells Expanded with Anti-CD3 Monoclonal Antibody in the Presence and Absence of Anti-CD28 Monoclonal Antibody

Bulk T cells can be expanded by CD3 stimulation alone (CD3-Ts) or by CD3/CD28 dual stimulation (CD3/CD28-Ts) of peripheral blood mononuclear cells (PBMC). However, few reports have described the difference of features between CD3-Ts and CD3/CD28-Ts. PBMC were stimulated with anti-CD3 monoclonal antibody (mAb) alone or co-stimulated with anti-CD3/CD28 mAbs immobilized on plastic plates, in the presence of rhIL-2 for 4 days, subsequently cultured in the presence of rhIL-2 with no antibody then analyzed. The expansion rate was significantly lower for CD3-Ts (965 + 510-fold, n=5) than CD3/CD28-Ts (2263 + 856-fold, n=5) (p<0.05). The CD4/CD8 ratio, the percentage of CD28(+) cell, and the percentage of T cells with no ability to generate intracytoplasmic interleukin-4 (IL-4) or interferon-gamma (IFN-gamma) were all significantly higher, but, phenotypically, memory cells were lower in CD3/CD28-Ts than in CD3-Ts. The levels of activity of both natural killer (NK) and lymphocyte-activated killer (LAK) cells were lower in CD3/CD28-Ts than CD3-Ts. In comparison to CD3-Ts, CD3/CD28-Ts showed impaired migration toward RANTES. In conclusion, T cells expanded with anti-CD3 and anti-CD28 mAbs differ from those expanded with anti-CD3 alone with proliferation, cytotoxicity, chemotaxis, and phenotype. These differences may exert profound influences on the therapeutic potential of output cells.

The immunopathology of regression in benign lichenoid keratosis, keratoacanthoma and halo nevus

BACKGROUND

Regression is a phenomenon present in a variety of cutaneous lesions. It is likely that similar immunologic mechanisms explain the phenomenon of spontaneous regression occurring in the various lesions.

METHODS

Twenty-seven specimens, nine each of halo nevus, keratoacanthoma, and benign lichenoid keratosis, including three examples each of predominantly early, mid, and late regression were examined with antibodies to HLA-II, CD1a, CD3, CD4, CD8, CD20, CD34, CD56, and CD68.

RESULTS

Epidermotropism of inflammatory cells, including CD1a positive, CD68 positive, CD3 positive, and CD8 positive cells, was present in benign lichenoid keratosis and keratoacanthoma, but not in halo nevus. In halo nevus, the nests of halo nevus cells tended to be infiltrated by CD1a positive, CD68 positive, CD3 positive, and CD8 positive cells. The blood vessels exhibited endothelial cell swelling with luminal narrowing and disruption within the dermis of all lesions. The CD1a positive cells were increased in number in lesional epidermis except in keratoacanthoma lesions where the density of CD1a positive cells was increased in the epithelial lip, but decreased within the epithelial portion of the keratoacanthoma proper. Conversely, the CD8 positive cells were scarce in the dermis below the epithelial lip of the keratoacanthoma, but increased in the dermis of the neoplastic epithelium. CD1a positive cells were also seen throughout the dermal portion of the lesion, particularly at the lesion base. In halo nevus, the CD1a positive cells and CD68 positive cells within the lesions were larger than those in non-lesional skin, indicating activation. The composition of the inflammatory infiltrate varied within each lesion type according to stage of regression, but T-lymphocytes predominated.

CONCLUSION

Cytotoxic T-cells may be the final common denominator of regression in benign lichenoid keratosis, keratoacanthoma, and halo nevus. In halo nevus, cytotoxic T-cells may play the predominant role in regression. In keratoacanthoma and benign lichenoid keratosis, cytotoxic T-cells play a pivotal role, but additional mechanisms may also be involved in the phenomenon of regression. Benign lichenoid keratoses progress through stages of regression accompanied by varying proportions of inflammatory cells, including CD3, CD4, and CD8 positive T-lymphocytes, natural killer cells, macrophages and Langerhans cells.

Costimulatory molecules and T-cell-B-cell interactions

This article focuses on activating and inhibiting costimulatory signals that are delivered to the T cell from antigen-presenting cells, mediating and modulating T-cell clonal expansion and development of effector functions, as well as costimulatory signals that are delivered by activated T cells to interacting target cells. The coordinated expression and interaction of these molecules regulates responses to foreign antigens and avoidance of response to self-antigens. Knowledge of the structure and function of these costimulatory molecules can be used to manipulate immune function and inhibit autoimmunity and inflammation in the setting of disease.

The effects of chemotherapeutics on cellular metabolism and consequent immune recognition

Awidely held view is that oncolytic agents induce death of tumor cells directly. In this report we review and discuss the apoptosis-inducing effects of chemotherapeutics, the effects of chemotherapeutics on metabolic function, and the consequent effects of metabolic function on immune recognition. Finally, we propose that effective chemotherapeutic and/or apoptosis-inducing agents, at concentrations that can be achieved physiologically, do not kill tumor cells directly. Rather, we suggest that effective oncolytic agents sensitize immunologically altered tumor cells to immune recognition and immune-directed cell death.

IL-2-activated CD8+CD44high cells express both adaptive and innate immune system receptors and demonstrate specificity for syngeneic tumor cells

CD8(+) T cells depend on the alphabeta TCR for Ag recognition and function. However, Ag-activated CD8(+) T cells can also express receptors of the innate immune system. In this study, we examined the expression of NK receptors on a population of CD8(+) T cells expressing high levels of CD44 (CD8(+)CD44(high) cells) from normal mice. These cells are distinct from conventional memory CD8(+) T cells and they proliferate and become activated in response to IL 2 via a CD48/CD2-dependent mechanism. Before activation, they express low or undetectable levels of NK receptors but upon activation with IL-2 they expressed significant levels of activating NK receptors including 2B4 and NKG2D. Interestingly, the IL-2-activated cells demonstrate a preference in the killing of syngeneic tumor cells. This killing of syngeneic tumor cells was greatly enhanced by the expression of the NKG2D ligand Rae-1 on the target cell. In contrast to conventional CD8(+) T cells, IL-2-activated CD8(+)CD44(high) cells express DAP12, an adaptor molecule that is normally expressed in activated NK cells. These observations indicate that activated CD8(+)CD44(high) cells express receptors of both the adaptive and innate immune system and may play a unique role in the surveillance of host cells that have been altered by infection or transformation.

Distinctive response of naïve lymphocytes from cord blood to primary activation via TCR

Umbilical cord blood (UCB) is now being considered an alternative to bone marrow for restoring hematopoiesis after myeloablative therapy. The lower risk of acute and chronic graft-versus-host disease in patients who received UCB cells seems related to the nature of UCB-T cells. Phenotypically, UCB-CD3+ cells are mostly naive (CD45RA+) and represent a transitional population between thymocytes and adult T cells. We examined the immune reactivity of highly purified, negatively selected CD4+CD45RA+ cells by mimicking activation via T cell receptor (TCR). All experiments included the extensively characterized adult peripheral blood (APB) cells as reference. On the contrary to APB, naive UCB-CD4+ cells were able to proliferate with anti-CD3 stimulation alone. With addition of interleukin (IL)-2 or costimulatory signal, both populations reached similar proliferation. Forty-eight hours after anti-CD3 stimulation, CD4+CD45RA+ from UCB, but not APB, showed characteristic blastic morphology and significant expression of CD25 on the surface. A low concentration of IL-2 was detected at 24 h by anti-CD3-stimulated UCB CD4+CD45RA+, which rapidly disappeared. By 72 h after activation, CD4+CD45RA+ UCB cells showed extensive apoptosis, whereas CD4+CD45RA+ APB cells showed low levels of apoptosis. Using RNase protection assay, we observed that CD95L levels were significantly higher in naive CD4+ cells from UCB than from APB after activation. However, neutralizing Fas-Fc protein was unable to inhibit anti-CD3-induced apoptosis, suggesting that this was a CD95-independent mechanism. These results indicate that UCB-CD4+CD45RA+ cells are able to start proliferating as a result of early IL-2 production after TCR engagement alone, but probably, as a result of the consumption of this IL-2, they undergo cell death.