bluuebunny/crossref_metadata_2025 huggingface dataset:
Tolerization of Galα1,3Gal‐reactive B cells in pre‐sensitized α1,3‐galactosyltransferase‐deficient mice by nonmyeloablative induction of mixed chimerism
Authors: Ohdan Hideki , Swenson Kirsten G. , Kitamura Hiroshi , Yang Yong‐Guang , Sykes Megan
Published: March 2003

Abstract: Using a α1,3‐galactosyltransferase wild‐type (GalT+/+) to deficient (GalT–/–) mouse bone marrow transplantation model, we have previously demonstrated that a non‐myeloablative conditioning regimen is capable of permitting induction of allogeneic and xenogeneic mixed chimerism. Chimerism is associated with the rapid and lasting tolerization of anti‐Galα1,3Gal (Gal) natural antibody (Ab)‐producing B cells. However, one limitation of this model is that anti‐Gal natural Ab levels are lower in GalT–/– mice than in humans and other primates. To overcome this limitation, we have now investigated the possibility of inducing such tolerance in GalT–/– mice that produce much higher levels of anti‐Gal Abs due to presensitization with Gal‐bearing xenogeneic cells. B6 GalT–/– mice that were pre‐sensitized with rabbit red blood cells received non‐myeloablative conditioning with depleting anti‐CD4 and CD8 mAbs, 3Gy whole body and 7Gy thymic irradiation, and infusion of BALB/c GalT+/+ bone marrow cells (BMC). Although engraftment of standard marrow doses was inhibited by the presensitization, long‐lasting mixed chimerism could be induced in recipients of a high dose [160 × 106] of allogeneic wild‐type BMC. Achievement of persistent chimerism was associated with high levels of anti‐Gal IgG1 pretransplant, suggesting an inhibitory effect of non‐complement‐fixing IgG1 Ab on anti‐Gal‐mediated marrow rejection. Induction of mixed chimerism was associated with a rapid disappearance of serum anti‐Gal and tolerization of anti‐Gal Ab‐producing cells. B cells with anti‐Gal receptors became undetectable in mixed chimeras. Mixed chimeras accepted subsequently transplanted donor‐type GalT+/+ hearts (> 140 days), whereas rapid (within 2 days) rejection of GalT+/+ hearts occurred in conditioned control GalT–/– mice. In conclusion, when a high dose of GalT+/+ BMC was administered to pre‐sensitized GalT–/– mice, chimerism and tolerance were achieved. The absence of B cells with receptors recognizing Gal in mixed chimeras suggests a role for clonal deletion/receptor editing in the maintenance of B cell tolerance.
Rejection of porcine islet xenografts mediated by CD4+ T cells activated through the indirect antigen recognition pathway
Authors: Olack Barbara J. , Jaramillo Andrés , Benshoff Nicholas D. , Kaleem Zahid , Swanson Carol J. , Lowell Jeffrey A. , Mohanakumar T.
Published: March 2003

Olack BJ, Jaramillo A, Benshoff ND, Kaleem Z, Swanson CJ, Lowell JA, Mohanakumar T. Rejection of porcine islet xenografts mediated by CD4+ T cells activated through the indirect antigen recognition pathway. Xenotransplantation 2002; 9: 393–401. © Blackwell Munksgaard, 2002

We have previously demonstrated that human T cells responding to porcine islets are primarily CD4+ and recognized porcine major histocompatibility complex class I molecules through the indirect pathway of antigen presentation. To determine whether this mechanism is responsible for rejection of adult porcine islets xenografts, porcine islets from adult pigs were transplanted under the kidney capsule of streptozotocin‐treated CD4‐knockout (KO), CD8‐KO, Ig‐KO and normal C57BL/6 mice. Islet xenografts were acutely rejected with similar kinetics when transplanted into normal C57BL/6 (MST=17.6 ± 3.5 days) and Ig‐KO (MST=19.0 ± 1.7 days) mice. Interestingly, islet xenografts were rejected significantly earlier when transplanted into CD8‐KO mice as compared with normal C57BL/6 (MST=7.0 ± 0.01 days, P=2 × 10−4). Histopathological analysis revealed classical acute cellular rejection with severe diffuse interstitial cellular infiltrates in all rejected islet xenografts. In contrast, islet xenografts were not rejected when transplanted into CD4‐KO mice (MST ≥ 100 days, P=1 × 10−9). Histopathological analysis revealed no cellular infiltrates and intact islet xenografts. CD4+ T cells from both normal C57BL/6 and CD8‐KO xenograft recipients showed detectable proliferative responses to porcine islets in the presence but not in the absence of syngeneic antigen‐presenting cells. In addition, the anti‐islet proliferative responses observed in normal C57BL/6 mice were significantly lower than those observed in CD8‐KO mice. IgG anti‐porcine antibodies were readily detected in C57BL/6 and CD8‐KO xenograft recipients but not in Ig‐KO or CD4‐KO recipients. These results indicate that indirectly activated CD4+ T cells mediate acute rejection of adult porcine islet xenografts and that xenoreactive CD8+ T cells and antibodies are not necessary in this process.
Rapid, independent evolution of flightlessness in four species of Pacific Island rails (Rallidae): an analysis based on mitochondrial sequence data
Authors: Slikas Beth , Olson Storrs L. , Fleischer Robert C.
Published: March 2003

Flightless rails were once ubiquitous in the avifauna of Pacific oceanic islands. Most species have become extinct since human colonization of islands began about 2000 years ago. In this study, we use mitochondrial sequence data to estimate the phylogenetic relationships and ages of four species of flightless insular rails in the genus Porzana: palmeri, from Laysan Island in the Hawaiian archipelago; sandwichensis, from the island of Hawaii; monasa, from Kosrae Island in Micronesia; and atra, from Henderson Island in the Pitcairn group. Although all four species survived into historic times, all but atra are now extinct. The optimal trees show that palmeri is descended from Porzana pusilla, a volant crake distributed widely throughout the Old World. Porzana sandwichensis, P. monasa, and P. atra are each descended from the lineage leading to P.tabuensis, a volant rail widespread in northern and eastern Australia and on islands north to Micronesia and the Philippines and east through Polynesia. Loss of flight appears to have evolved rapidly in these insular rails, based on both sequence divergence values and data on the ages of the islands. In the case of the Laysan Rail (palmeri), divergences including loss of flight probably evolved in less than 125,000 years.
Variation in nest defense in ducks: methodological and biological insights
Authors: Gunness Michelle A. , Weatherhead Patrick J.
Published: March 2003

Studies of avian nest defense generally explain only a small proportion of the total variation in defense behavior. We explored two potential methodological sources of variation in nest defense in three species of ducks. One common method of quantifying nest defense rests on the assumption that different components of nest defense (e.g. flushing distance, distraction displays) are highly positively correlated. Defense behaviors we observed in this study were weakly related or unrelated to each other. Thus, the assumption of strong positive covariance between components of nest defense was not supported. We also considered the effect of repeated visits to the same nests on nest defense. Females of all three species took less risk defending their nests with repeated visits, and the effect of visit number on nest defense was greater than the effect of increasing value of nests associated with advancing incubation. Ducks appear to be different from other birds in the consistency with which they alter their nest defense in response to repeated nest visits. We propose that this could be a consequence of having nest predators that return to the vicinity of a nest if they were previously unsuccessful finding the nest, thus making repeated nest visits more dangerous to the ducks. By testing this or other hypotheses it should be possible to go beyond understanding the methodological implications of the effect of repeated visits on nest defense, and use this phenomenon to gain insight into the predator‐prey interactions that underlie nest defense.
Spatiotemporal expression of NGFR during pre‐natal human tooth development
Authors: Becktor KB , Hansen BF , Nolting D , Kjær I
Published: March 2003

Structured Abstract

Authors– Becktor KB, Hansen BF, Nolting D, Kjær I.

Objectives– The relation between nerve growth factor receptor (NGFR) in the human pre‐natal tooth buds and the dental follicle was investigated. In particular, we sought to determine if there is a specific pattern of p75NGFR expression in developing human tooth buds and their surrounding tissue.

Setting and Sample Population– The Department of Orthodontics at Copenhagen University, Denmark. Histological sections from 11 fetuses, aged 11–21 gestational weeks.

Method– The sections were studied by conventional immunohistochemistry.

Results– Specific spatiotemporal patterns of p75NGFR reactions were observed in the tooth buds and dental follicle: Before matrix production by the ameloblasts, the entire inner enamel epithelium and the entire dental follicle display p75NGFR immunoreactivity; after matrix production is initiated, the immunoreactivity of the matrix producing cells is lost, as is that of the dental follicle adjacent to these matrix‐producing cells.

Conclusion– A unique spatiotemporal distribution of NGFR in the pre‐eruptive human tooth bud was demonstrated.
The genomic context of natural killer receptor extended gene families
Authors: Trowsdale John , Barten Roland , Haude Anja , Stewart C. Andrew , Beck Stephan , Wilson Michael J.
Published: March 2003

Summary: The two sets of inhibitory and activating natural killer (NK) receptor genes belong either to the Ig or to the C‐type lectin superfamilies. Both are extensive and diverse, comprising genes of varying degrees of relatedness, indicative of a process of iterative duplication. We have constructed gene maps to help understand how and when NK receptor genes developed and the nature of their polymorphism. A cluster of over 15 C‐type lectin genes, the natural killer complex is located on human chromosome 12p13.1, syntenic with a region in mouse that borders multiple Ly49 loci. The equivalent locus in man is occupied by a single pseudogene, LY49L. The immunoglobulin superfamily of loci, the leukocyte receptor complex (LRC), on chromosome 19q13.4, contains many polymorphic killer cell immunoglobulin‐like receptor (KIR) genes as well as multiple related sequences. These include immunoglobulin‐like transcript (ILT) (or leukocyte immunoglobulin‐like receptor genes), leukocyte‐associated inhibitory receptor genes (LAIR), NKp46, FcαR and the platelet glycoprotein receptor VI locus, which encodes a collagen‐binding molecule. KIRs are expressed mostly on NK cells and some T cells. The other LRC loci are more widely expressed. Further centromeric of the LRC are sets of additional loci with weak sequence similarity to the KIRs, including the extensive CD66(CEA) and Siglec families. The LRC‐syntenic region in mice contains no orthologues of KIRs. Some of the KIR genes are highly polymorphic in terms of sequence as well as for presence/absence of genes on different haplotypes. Some anchor loci, such as KIR2DL4, are present on most haplotypes. A few ILT loci, such as ILT5 and ILT8, are polymorphic, but only ILT6 exhibits presence/absence variation. This knowledge of the genomic organisation of the extensive NK superfamilies underpins efforts to understand the functions of the encoded NK receptor molecules. It leads to the conclusion that the functional homology of human KIR and mouse Ly49 genes arose by convergent evolution. NK receptor immunogenetics has interesting parallels with the major histocompatibility complex (MHC) in which some of the polymorphic genes are ligands for NK molecules. There are hints of an ancient genetic relationship between NK receptor genes and MHC‐paralogous regions on chromosomes 1, 9 and 19. The picture that emerges from both complexes is of eternal evolutionary restlessness, presumably in response to resistance to disease.

This work was funded by the Wellcome Trust and the MRC
The UL16‐binding proteins, a novel family of MHC class I‐related ligands for NKG2D, activate natural killer cell functions
Authors: Sutherland Claire L. , Chalupny N. Jan , Cosman David
Published: March 2003

Summary: The UL16‐binding proteins (ULBPs) are a novel family of MHC class I‐related molecules (MICs) that were identified based on their ability to bind to the human cytomegalovirus (HCMV) glycoprotein UL16. UL16 also binds to a member of another family of MHC class I‐like molecules, MICB. The ULBPs and MICs are ligands for NKG2D/DAP10, an activating receptor expressed by natural killer (NK) cells and other immune effector cells, and this interaction can be blocked by UL16. Engagement of NKG2D/DAP10 by ULBPs or MICs expressed on a target cell can overcome an inhibitory signal generated by NK‐cell recognition of MHC class I molecules and trigger NK cytotoxicity. ULBPs elicit their effects on NK cells by activating the janus kinase 2, signal transducer and activator of transcription 5, extracellular‐signal‐regulated kinase mitogen‐activated protein kinase and Akt/protein kinase B signal transduction pathways. Although ULBPs alone activate multiple signaling pathways and induce modest cytokine production, ULBPs synergize strongly with interleukin‐12 for production of interferon‐γ by NK cells. This finding is consistent with reports in T cells that NKG2D/DAP10 can act as a co‐stimulatory receptor in a similar manner as CD28. The possible roles of ULBPs in mediating immune responses to viruses and tumors and the potential mechanisms by which UL16 may allow HCMV to evade immune detection are areas of active investigation.

We thank Gary Carlton for assistance with figures and Anne Aumell for editorial assistance.
Thymus and tolerance. Is regulation the major function of the thymus?
Authors: Durkin Helen G. , Waksman Byron H.
Published: March 2003

Summary: This paper will serve as a contribution to the current reassessment of the relative roles of clonal selection and regulation in specific immunologic tolerance. We review basic studies in the Waksman laboratory that first established the importance of the thymus in tolerance and the possible contribution of regulatory cells generated in the thymus to self‐tolerance. Experimental evidence is presented to suggest that there exists a wide range of immunoregulatory mechanisms, many of which deserve more intensive investigation in relation to the tolerance question. These include regulation based on idiotype‐specific recognition, multiple forms of immune deviation, two well‐described and quite distinct forms of T‐cell receptor αβ‘’suppressor cell”, and several regulatory systems involving multiple cells acting in concert. We do not comment on more recently described regulatory cells, such as certain γδ T‐cell subsets, natural killer T cells, CD4−CD8− T cells, and others. Basic studies in our laboratory and in other laboratories pointed to antigen‐presenting cells (APC) generated in the thymus as possible mediators of tolerance. Certain cytokines, first described in our laboratory, including lymphotoxin and the “inhibitor of DNA synthesis” produced by T cells and interleukin‐1 produced by macrophages, also may act as significant components of regulatory systems. The rapid entry of exogenous and self‐antigens into the thymus and the free migration of specific regulatory T cells and of APC in both directions between thymus and periphery are also stressed.
Suppressor T cells – they’re back and critical for regulation of autoimmunity!
Authors: Chatenoud Lucienne , Salomon Benoît , Bluestone Jeffrey A.
Published: March 2003

Summary: Regulation of the immune response to self‐antigens is a complex process that depends on maintaining self‐tolerance while retaining the capacity to mount a robust immune response to foreign antigens. Autoreactive T cells specific for these autoantigens are present in most normal individuals but are kept under control by multiple diverse peripheral tolerance mechanisms. In the last few years, there has been a re‐emergence of suppressor cells as among the most central of these regulatory mechanisms. These cells, which express CD4, CD25, and CD62L, develop in the thymus and survive in a CD28‐dependent manner in the periphery to maintain the homeostatic equilibrium of immunity and tolerance. In this review, we will summarize studies of these regulatory cells as they relate to autoimmune diseases and more specifically to type 1 diabetes and attempt to address some of the many outstanding questions. Finally, evidence is provided to support the ability of anti‐CD3 mAbs to stimulate the regulatory T cells and reset the rheostat of immune tolerance in an animal model of autoimmune diabetes, the NOD mouse.
Immune evasion strategies of the primate lentiviruses
Authors: Evans David T. , Desrosiers Ronald C.
Published: March 2003

Summary: Individuals infected with human immunodeficiency virus (HIV) and macaques infected with simian immunodeficiency virus (SIV) make vigorous virus‐specific antibody and cellular immune responses. Despite these responses, virus replication continues at all stages of infection and ultimately leads to immunological collapse, onset of opportunistic infections and death of infected hosts. Thus, the strategies by which HIV and SIV evade antiviral immune surveillance are fundamental to understanding lentiviral pathogenesis and crucial for our ability to develop effective strategies. It has become increasingly clear that the primate lentiviruses have evolved multiple and complementary mechanisms to circumvent host immune responses. Here we review these mechanisms of immune evasion considering contributions from both human and non‐human primate systems.
Non‐human primate models of multiple sclerosis
Authors: Brok Herbert P. M. , Bauer Jan , Jonker Margreet , Blezer Erwin , Amor Sandra , Bontrop Ronald E. , Laman Jon D. , ‘t Hart Bert A.
Published: March 2003

Summary: The phylogenetic proximity between non‐human primate species and humans is reflected by a high degree of immunological similarity. Non‐human primates therefore provide important experimental models for disorders in the human population that are caused by the immune system, such as autoimmune diseases. In this paper we describe non‐human primate models of multiple sclerosis, a chronic inflammatory and demyelinating disease of the human central nervous system. While reviewing data from the literature and our own research we will discuss the unique role of such models in the research of basic disease mechanisms and the development of new therapies.
Biochemical analysis of the lymphocyte cell surface – from alloantisera to the role of membrane proteins
Authors: Barclay A. Neil
Published: March 2003

Summary: The rat has been invaluable for many aspects of the molecular analysis of the lymphocyte cell surface. One advantage of the rat over mice is the ability to obtain cells in large numbers for biochemical analysis together with the availability of many disease models. This review outlines some of the key findings in this laboratory over the last 25 years together with the technological advances that may be of relevance in this new post‐genomic era where the goal is to understand the functions of the proteins coded by the multitude of genes now identified.
Perspective on antigen processing and presentation
Authors: Unanue Emil R.
Published: March 2003

Summary: The phenomenon of antigen processing and presentation and the concept that T cells recognize peptides resulting from the partial catabolism of proteins, are relatively new. These concepts were first recognized and developed at a time when lymphocyte immunity − the adaptive system – and cellular immunity, with its major component of activated macrophages, were not perceived as part of one integrated system. To me, it was the fundamental findings on the role of major histocompatibility (MHC) molecules that set the framework for understanding how phagocytes and the antigen presenting cell (APC) system interact with the adaptive cellular system, in a truly symbiotic relationship (1). In this chapter we make a historical review of the developments that, in my biased opinion, led to the understanding of antigen presentation as a central event. I emphasize my own work, placing it in my perspective of how I saw the field moving.
Reprogramming the immune system
Authors: Waldmann Herman
Published: March 2003

Summary:The immune system is organized so as to react to pathogens without risking damage to self. Harnessing those processes that prevent self‐reactivity will have enormous potential in clinical medicine. This review outlines the efforts of this laboratory over the last 25 years to exploit tolerance so as to reprogram the immune system for therapeutic purposes.
Cell adhesion and polarity during immune interactions
Authors: Montoya María C. , Sancho David , Vicente‐Manzanares Miguel , Sánchez‐Madrid Francisco
Published: March 2003

Summary: Intercellular interactions are critical for a coordinated function of different cell types involved in the immune response. Here we review the cellular and molecular events occurring during cell–cell immune contacts. Cognate naïve CD4+ T lymphocyte‐dendritic cell (DC) and primed T cell–antigen‐presenting B lymphocyte interactions are discussed. The engagement of cytotoxic T lymphocytes (CTL) or natural killer cells (NK) with their targets is analyzed and compared to the process of T cell–antigen‐presenting cell (APC) conjugate formation. The immunological synapse, a complex cluster of molecules organized at the contact area of cell conjugates, exhibits common features but shows some differences depending on cell types involved. Cellular interactions occur in sequential stages that involve dramatic changes in cell polarity and dynamic redistribution of cell membrane receptors. The role of membrane microdomains, adaptor molecules and the cytoskeleton in the regulation of the molecular reorganization at cell–cell contacts is also discussed.
Nature or nurture? Steady‐state lymphocyte formation in adults does not recapitulate ontogeny
Authors: Kincade Paul W. , Owen John J.T. , Igarashi Hideya , Kouro Taku , Yokota Takafumi , Rossi Maria Isabel D.
Published: March 2003

Summary:  Substantial progress has been made in determining developmental relationships between lymphocyte precursors and those corresponding to other blood cell lineages. Indeed, exploitation of RAG1/GFP knock‐in mice has recently made it possible to chart the entire sequence of lymphocyte differentiation events in adult bone marrow and thymus. However, the differentiation pathways proposed for fetal life are very different from this model. We review many examples where the results of gene targeting experiments are substantially dependent on developmental age. In mice, adult patterns of gene expression and corresponding properties of lymphocyte precursors are not fully established until several weeks after birth, and the same might be true for humans. Furthermore, examples are cited where fetal hematopoietic cells did not efficiently acquire those properties when transplanted to an adult environment. There are several important implications of these findings. Cognizance of developmental age‐related changes might resolve apparent conflicts in the literature. Hematopoietic stem cells and their lymphoid lineage progeny appear in waves, and a direct connection is yet to be established between fetal stem cells and ones that sustain adult blood cell formation. There is the possibility that adult stem cells derive from founders with an unknown origin.
Cytolytic T‐cell responses of cancer patients vaccinated with a MAGE antigen
Authors: Coulie Pierre G. , Karanikas Vaios , Lurquin Christophe , Colau Didier , Connerotte Thierry , Hanagiri Takeshi , Van Pel Aline , Lucas Sophie , Godelaine Danièle , Lonchay Christophe , Marchand Marie , Van Baren Nicolas , Boon Thierry
Published: March 2003

Summary: ‘Cancer‐germline’ genes such as the MAGE gene family are expressed in many tumors and in male germline cells but not in normal tissues. They encode shared tumor‐specific antigens, which have been used in therapeutic vaccination trials of metastatic melanoma patients. To establish whether there is a correlation between tumoral regressions and T‐cell responses against the vaccine antigen, we evaluated the responses of patients vaccinated with a MAGE‐3 antigenic peptide or a recombinant virus coding for the peptide. Blood lymphocytes were stimulated with antigenic peptide followed by detection with tetramer, T‐cell cloning, and TCR analysis. In 4/9 regressor patients and in 1/14 progressors we found a low level, usually monoclonal cytolytic T lymphocyte response against the MAGE‐3 peptide.
Antitumor cytotoxic T‐lymphocyte response in human lung carcinoma: identification of a tumor‐associated antigen
Authors: Mami‐Chouaib Fathia , Echchakir Hamid , Dorothée Guillaume , Vergnon Isabelle , Chouaib Salem
Published: March 2003

Summary: We have isolated several cytotoxic T lymphocyte (CTL) clones from lymphocytes infiltrating a lung carcinoma of a patient with long survival. These clones showed a CD3+, CD8+, CD4–, CD28– phenotype and expressed a T‐cell receptor (TCR) encoded either by Vβ8‐Jβ1.5 or Vβ22‐Jβ1.4 rearrangements. Functional studies indicated that these clones mediated a high human leukocyte antigen (HLA)‐A2.1‐restricted cytotoxic activity against the autologous tumor cell line. Interestingly, TCRβ chain gene usage indicated that CTL clones identified in vitro were selectively expandedin vivo at the tumor site as compared to autologous peripheral blood lymphocytes (PBL). These findings provide evidence that an immune response may take place in non‐small cell lung carcinoma and that effector T cells may contribute to tumor regression. Further study indicated that the CTL clones recognized the same decamer peptide encoded by a mutated α‐actinin‐4 gene. Using tetramers of soluble HLA‐A2 molecules loaded with the mutated antigenic peptide, we have derived several anti‐α‐actinin‐4 T‐cell clones from patient PBL. These CTL, recognizing a truly tumor‐specific antigen, may play a role in the clinical evolution of this lung cancer patient. Adoptive transfer of CTL clones in a SCID/NOD mice model transplanted with autologous tumor supported their antitumor effect in vivo.
GM‐CSF‐based cancer vaccines
Authors: Dranoff Glenn
Published: March 2003

Summary: The crafting of genetic and biochemical techniques to identify cancer antigens yielded the unexpected discovery that immune recognition of tumors regularly accompanies cancer development. The failure of the host to suppress tumor formation or attenuate disease progression may thus reflect the limited immunogenicity of nascent tumors. One critical determinant of host immunity is the mixture of cytokines produced in the tumor microenvironment. We have compared a large number of secreted and surface molecules for their relative abilities to augment tumor immunity following gene transfer into cancer cells. In multiple murine models, granulocyte‐macrophage colony stimulating factor (GM‐CSF) proved to be the most potent immunostimulatory product. Vaccination with irradiated tumor cells engineered to secrete GM‐CSF involves enhanced tumor antigen presentation by recruited dendritic cells (DCs) and macrophages; the coordinated functions of CD4+ and CD8+ T cells, CD1d‐restricted NKT cells and antibodies mediate protective immunity. The evaluation of this vaccination strategy in patients with advanced melanoma revealed the consistent induction of cellular and humoral antitumor responses capable of effectuating substantial necrosis of distant metastases. The formulation of simplified methods for manufacturing autologous, GM‐CSF‐secreting tumor cells has enabled more extensive clinical testing in diverse patient settings.
The secretory synapse: the secrets of a serial killer
Authors: Bossi Giovanna , Trambas Christina , Booth Sarah , Clark Richard , Stinchcombe Jane , Griffiths Gillian M.
Published: March 2003

Summary:  Cytotoxic T lymphocytes (CTLs) destroy their targets by a process involving secretion of specialized granules. The interactions between CTLs and target can be very brief; nevertheless, adhesion and signaling proteins segregate into an immunological synapse. Secretion occurs in a specialized secretory domain. Use of live and fixed cell microscopy allows this secretory synapse to be visualized both temporally and spatially. The combined use of confocal and electron microscopy has produced some surprising findings, which suggest that the secretory synapse may be important both in delivering the lethal hit and in facilitating membrane transfer from target to CTL. Studies on the secretory synapse in wild‐type and mutant CTLs have been used to identify proteins involved in secretion. Further clues as to the signals required for secretion are emerging from comparisons of inhibitory and activating synapses formed by natural killer cells.
Genetics of the immune response: identifying immune variation within the MHC and throughout the genome
Authors: Geraghty Daniel E. , Daza Riza , Williams Luke M. , Vu Quyen , Ishitani Akiko
Published: March 2003

Summary: With the advent of modern genomic sequencing technology the ability to obtain new sequence data and to acquire allelic polymorphism data from a broad range of samples has become routine. In this regard, our investigations have started with the most polymorphic of genetic regions fundamental to the immune response in the major histocompatibility complex (MHC). Starting with the completed human MHC genomic sequence, we have developed a resource of methods and information that provide ready access to a large portion of human and nonhuman primate MHCs. This resource consists of a set of primer pairs or amplicons that can be used to isolate about 15% of the 4.0 Mb MHC. Essentially similar studies are now being carried out on a set of immune response loci to broaden the usefulness of the data and tools developed. A panel of 100 genes involved in the immune response have been targeted for single nucleotide polymorphism (SNP) discovery efforts that will analyze 120 Mb of sequence data for the presence of immune‐related SNPs. The SNP data provided from the MHC and from the immune response panel has been adapted for use in studies of evolution, MHC disease associations, and clinical transplantation.
The formation and functions of the 21‐ and 23‐kDa tyrosine‐phosphorylated TCR ζ subunits
Authors: Pitcher Lisa A. , Young Jennifer A. , Mathis Meredith A. , Wrage Philip C. , Bartók Beatrix , Van Oers Nicolai S. C.
Published: March 2003

The interaction between the T cell receptor (TCR) and its cognate antigen/major histocompatibility complex (MHC) complex activates a cascade of intracellular protein phosphorylations within the T cell. The signals are initiated by the specific phosphorylation of two tyrosine residues located in a conserved sequence motif termed an ITAM (immune receptor‐based tyrosine activation motif). There are 10 ITAMs in the TCR complex, and 6 of these ITAMs are present in the TCR ζ homodimer. Following TCR stimulation, the TCR ζ subunit forms two tyrosine‐phosphorylated intermediates of 21‐ and 23‐kDa, respectively. The dramatic and diverse biological responses of T cells are proposed to be partly regulated by the relative ratios of the 21‐ vs. 23‐kDa phosphorylated forms of TCR ζ that are induced following TCR ligation. In this review, we describe a stepwise model of ζ phosphorylation required for the formation of these two phosphorylated derivatives. We describe the kinases and phosphatases controlling these phosphorylation processes. In addition, we present some preliminary findings from ongoing studies that discuss the contributions of each phosphorylated form of ζ on T cell development, TCR signaling, T cell anergy induction, and T cell survival.
Initiation of TCR signaling: regulation within CD3 dimers
Authors: Alarcón Balbino , Gil Diana , Delgado Pilar , Schamel Wolfgang W. A.
Published: March 2003

The number of possible T cell activation outcomes resulting from T cell receptor (TCR) engagement suggests that the TCR is able to differentially activate a myriad of signaling pathways depending on the nature of the stimulus. The complex structural organization of the TCR itself could underlie this diversity of responses. Assembly and stoichiometric studies have helped us to shed some light on the initiation of TCR signaling. The TCR is composed of TCR and CD3 dimers. Changes in the interaction between CD3 subunits within the CD3 dimers and in the interaction of these dimers with the TCR heterodimer could be the triggering mechanism that initiates the first activation events. One of the hallmarks of these early changes in TCR conformation is the induced recruitment of the adapter protein Nck to a proline‐rich sequence of the cytoplasmic tail of CD3ε, but there may be others. According to our most recent observations, the TCR is organized in pre‐existing clusters within plasma membrane microdomains, exhibiting a complexity above and beyond that of dimer composition complexity. How the presence of TCR in clusters influences TCR avidity and propagation of TCR signals is something that has yet to be investigated.
Mast cell subpopulations in chronic inflammatory hepatobiliary diseases
Authors: Matsunaga Yoshiko , Terada Tadashi
Published: March 2003

Abstract: Aim/Background: In various hepatobiliary diseases mast cells have been found to be associated with fibrogenesis. However, mast cell subpopulations have not been investigated in the human liver in normal subjects or in disease. Human mast cells are categorized into mast cells positive for tryptase (MCT) only and mast cells positive for both tryptase and chymase (MCTC). Methods: In this study we investigated mast cell subpopulations (MCT and MCTC) by double immunostaining for mast cell tryptase and chymase as well as by a computer‐aided quantitative morphometry in 13 normal livers and in 193 liver tissue specimens comprising of primary biliary cirrhosis (n=43), autoimmune hepatitis (n=11), chronic hepatitis B (n=37), chronic hepatitis C (n=41), alcoholic liver disease (n=40) and hepatolithiasis (n=21). Results: The densities of MCT and MCTC per 1 mm2 stroma were low in normal livers but high in chronic liver diseases, and correlated positively with the degree of fibrosis. The percentages of MCT and MCTC subpopulations were 25% and 75%, respectively. The percentage was almost the same in normal livers and various hepatobliliary diseases, as well as between less fibrotic cases and more fibrotic cases in liver diseases. Conclusions: These results suggest that MCT and MCTC subpopulations in healthy and diseased livers do not change during liver fibrosis of any etiology.
Androgen dependency of hepatocarcinogenesis in TGFα transgenic mice
Authors: Matsumoto Tatsuhiko , Takagi Hitoshi , Mori Masatomo
Published: March 2003

Abstract: Aims/Background: Sex difference has been shown to play a major role in susceptibility to the development of hepatocellular carcinoma in humans and rodents. In order to clarify the necessity of androgens in hepatic tumorigenesis in transgenic mice overexpressing transforming growth factor (TGF) α (MT42), androgen supplement after castration and the LH‐RH analogue, leuprolerin acetate, were tested in an experimental model in MT42. Methods: Male MT42 mice were castrated and supplemented with dihydrotestosterone (DHT) every three months up to 15 months and hepatic tumorigenesis was observed. Leuprolerin acetate was administered to both male and female MT42 mice once a month from 2 months after birth to 15 months to observe the effect on hepatic tumorigenesis. Northern hybridization was performed to detect messenger RNA (mRNA) of TGFα expression and the rate of proliferative cell nuclear antigen (PCNA) staining compared with the castrated and non‐treated mice. Results: Castration tended to decrease both body and liver weight in MT42 mice which was then restored by DHT. Untreated MT 42 males developed 11 liver tumors in 6 mice. Hormonal treatment including castration and DHT supplementation did not change the expression of TGFα‐mRNA. Castrated transgenic mice developed 2 liver tumors in 2 out of 6 mice and DHT supplementation after castration restored the number of liver tumors to 9 in 5 of 6 mice. PCNA labelling indexes of liver tumors and adjacent non‐tumorous‐liver were 7.1% (p<0.05): 0.6% in untreated MT42, 3.2%: 0.2% in castrated MT42 and 10.1% (p<0.05): 0.5% in MT42 with castration and DHT supplementation (significant difference compared with castrated mice). Leuprolerin acetate‐treated MT42 males developed one liver tumor in 6 mice compared to MT42 administered with saline as a vehicle control in which group 7 liver tumors in 6 male MT42 were observed. Tumors in castrated‐MT42 and leuprolerin treated‐MT42 were smaller than those in control MT42 mice. Conclusion: TGFα related hepatocarcinogenesis and hepatocyte proliferation are increased by androgenic stimulation. Suppression of androgens may be useful for the treatment of TGFα related liver tumors.
Clinical, virological and histopathological features: long‐term follow‐up in patients with chronic hepatitis C co‐infected with S. mansoni
Authors: Kamal Sanaa , Madwar Mohamed , Bianchi Leonardo , Tawil Ahmed E. L. , Fawzy Ragaa , Peters Thomas , Rasenack Jens W. F.
Published: March 2003

Abstract: Background/Aims: Infection with Schistosoma mansoni is endemic in Egypt leading to hepatic schistosomiasis and eventually portal hypertension. The prevalence of antibodies against hepatitis virus C among Egyptians is 14–51%. The aim of the present study was to investigate the influence of schistosomiasis on chronic hepatitis C with respect to the natural course of the disease, immunology, virology and histology. Patients and Methods: One hundred and twenty‐six Egyptian patients classified into three groups: group A: chronic hepatitis C (n=33); group B: chronic schistosomiasis (n=30) and group C: chronic hepatitis C and chronic schistosomiasis (n=63) were enrolled and prospectively followed for 62.7±22 months. Patients infected with other hepatic viruses and/or parasites were excluded. Detailed history, clinical examination, CD4+ and CD8+ lymphocyte counts in blood, hematological and blood chemical values, abdominal ultrasonography, upper endoscopy, HCV RNA titer by RT/PCR, genotype and histological activity index in the liver biopsy were determined. Results: Thirty patients (48%) with HCV and schistosomiasis had liver cirrhosis and Child‐Pugh class C vs. five (15%) in HCV patients and none in the schistosomal group. HCV RNA levels ranged between 0.07 and 13×105 copies/ml in group A, and between 1 and 25×105 copies/ml in group C. HCV genotype 4 was detected in 58 patients with co‐infection (92%) and 21 patients with HCV alone (64%). Patients with coinfection showed higher grading and staging scores in their liver biopsies. Hepatocellular carcinoma was detected only in patients with coinfection. During follow‐up, the mortality rate was 12%, 3% and 48% in group A, B and C, respectively. Conclusions: Patients with concomitant HCV and schistosomiasis infection were characterized by more advanced liver disease, higher HCV RNA titers, predominance of HCV genotype 4, higher histologic activity, higher incidence of cirrhosis and hepatocellular carcinoma as well as a much higher mortality rate.
Connective tissue growth factor in human liver cirrhosis
Authors: Abou‐Shady Mohamed , Friess Helmut , Zimmermann Arthur , Di Mola Fabio F. , Guo Xiao‐Zhong , Baer Hans U. , Büchler Markus W.
Published: March 2003

Abstract: Background: Connective tissue growth factor (CTGF) belongs to a family of factors that regulate fibrogenesis and wound healing. While the significance of transforming growth factor beta (TGF‐β) in liver fibrosis is well established, the role of CTGF in fibrosing hepatopathy is still unknown. Methods: CTGF was analyzed in 10 normal and in 16 cirrhotic liver tissue samples. Northern blot analysis was used to examine the concomitant expression of CTGF and TGF‐β1 mRNAs, and the cellular localization of CTGF mRNA was studied by in situ hybridization. For identification of myofibroblasts and activated hepatic stellate cells, α‐smooth muscle actin (α‐SMA) immunohistochemistry was used. Results: Northern blot analysis showed 6.5‐fold enhanced expression of CTGF mRNA and 7.8‐fold enhanced expression of TGF‐β1 mRNA in liver cirrhosis in comparison with normal controls (p<0.01). By in situ hybridization, CTGF mRNA was detectable in only a few spindle cells in the portal tracts in normal liver samples. In contrast, there was strong expression of CTGF mRNA in fibroblasts and myofibroblast‐like cells present in fibrous septa surrounding the cirrhotic nodules, in stellate cells, in endothelial cells and in mesenchymal cells around ductular proliferations, and in ductular epithelial cells. There was a strong correlation between CTGF mRNA and TGF‐β1 mRNA as well as the degree of fibrosis (p<0.01). Conclusions: Overexpression of CTGF in liver cirrhosis, especially in fibroblasts/myofibroblasts and stellate cells, suggests that this novel factor may play an important role in hepatic fibrosis.
Overexpressed growth hormone (GH) synergistically promotes carcinogen‐initiated liver tumour growth by promoting cellular proliferation in emerging hepatocellular neoplasms in female and male GH‐transgenic mice
Authors: Snibson Kenneth J. , Bhathal Prithi S. , Adams Timothy E.
Published: March 2003

Abstract: Background/Aims: Growth hormone (GH), when overexpressed in male and female GH‐transgenic mice, is known to induce liver tumours within 1 year. This study aimed to gain a clearer understanding of the interaction between GH and tumour cells in vivo. Methods/Results: The carcinogen diethylnitrosomine (DEN) was administered to neo‐natal transgenic and non‐transgenic mice maintained in a “hepatocarcinogenesis resistant” genetic background (C57BL/6J). Macroscopic, microscopic and liver weight/body weight ratio analyses revealed that carcinogen‐induced hepatocarcinogenesis was dramatically accelerated in young GH‐transgenic mice compared to non‐transgenic counterparts. Image analysis of microscopic hepatocellular neoplasms showed rapidly increasing tumour burdens, and neoplastic foci size over time in young adult GH‐transgenic mice. The magnitude of enhanced tumour growth was equivalent in both male and female transgenic mice, whereas much lower and sexually dimorphic tumour growth rates (males>females) were observed in non‐transgenic mice treated with DEN. BrdU labelling experiments demonstrated that rapid tumour growth in carcinogen‐treated GH‐transgenic mice was due to the promotion of cell proliferation in emerging lesions. Tumour cell proliferation in young GH‐transgenic mice was 2.6‐ and 4‐fold higher, respectively, than that observed in similar age male and female non‐transgenic mice. Interestingly, both GH‐transgenic and non‐transgenic mice displayed progressively slower tumour growth rates in older animals. Conclusion: Overall, GH synergistically promotes carcinogen‐induced hepatocarcinogenesis in both sexes of GH‐transgenic mice by stimulating tumour cell proliferation.
Expression of hepatic transporters OATP‐C and MRP2 in primary sclerosing cholangitis
Authors: Oswald Monika , Kullak‐Ublick Gerd A. , Paumgartner Gustav , Beuers Ulrich
Published: March 2003

Abstract: Background/Aims: In chronic cholestatic liver diseases, biliary excretion of organic anions from blood into bile is impaired. The aim of this study was to identify the underlying mechanism. Methods: Expression of the basolateral organic anion transporting polypeptide OATP‐C (SLC21A6) and the canalicular multidrug resistance protein 2 (MRP2) was studied in patients with primary sclerosing cholangitis (PSC) (n=4), a chronic cholestatic liver disease, and in non‐cholestatic controls (n=4) (two with chronic hepatitis C, one with idiopathic liver cirrhosis and one with fatty liver). Total RNA was isolated from liver tissue, reverse transcribed and subjected to polymerase chain reaction (PCR) amplification using primers specific for OATP‐C, MRP2 and β‐actin. PCR products were quantified densitometrically. Results: When normalized for β‐actin expression, the level of OATP‐C mRNA in liver tissue of patients with PSC was 49% of controls (OATP‐C/β‐actin 1.60±0.25 vs. 3.24±0.69; p<0.05) and the level of MRP2 mRNA was 27% of controls (MRP2/β‐actin 0.70±0.36 vs. 2.54±0.56; p<0.01). Conclusions: Both OATP‐C and MRP2 are decreased as measured by mRNA level in PSC. Downregulation of OATP‐C might be the consequence of impaired canalicular secretion of organic anions and could serve to reduce the organic anion load of cholestatic hepatocytes.
Severe veno‐occlusive disease after allogeneic bone marrow or peripheral stem cell transplantation – role of transjugular intrahepatic portosystemic shunt (TIPS)
Authors: Zenz Thorsten , Rössle Martin , Bertz Hartmut , Siegerstetter Volker , Ochs Andreas , Finke Jürgen
Published: March 2003

Abstract: Aims: Veno‐occlusive disease of the liver is a severe complication of allogeneic bone marrow or peripheral stem cell transplantation with a high mortality. In its severe form, the portal vein is used as an outflow tract for the arterial hepatic perfusion. A portosystemic side‐to‐side shunt, e.g. a transjugular intrahepatic portosystemic shunt, may facilitate portal outflow thus increasing hepatic (i.e. arterial) perfusion. Methods: The effect of a transjugular shunt on liver function and blood flow was studied in three patients receiving shunt treatment 0–2 days after the diagnosis of severe veno‐occlusive disease occurring 28, 20, and 17 days after allogeneic transplantation for acute myeloid leukemia, Hodgkin’s disease and chronic myeloid leukemia, respectively. Results: The transjugular shunt reduced the portosystemic pressure gradient from 23 to 8, 18 to 5, and 33 to 13 mmHg in patients 1, 2, and 3, respectively, increased the stagnant portal vein flow to normal, and decreased the arterial resistive index, indicating an increase in the arterial perfusion of the liver. This was accompanied by rapid relief from abdominal pain and removal of ascites. The AST concentration dropped from 1230, 417, and 2930 U/l before to 93, 20, and 41 U/l and the PT‐time ratio improved 3–7 days after shunt treatment while the bilirubin concentration continued to rise until the patients died 26, 42, and 33 days after transplantation from multiorgan failure (two patients) or intracerebral hemorrhage. Conclusions: The transjugular shunt may have improved abdominal and hepatic perfusion and prevented further necrosis of hepatocytes. It did not, however, affect jaundice or survival, which was limited by extrahepatic complications.
Serum thioredoxin elucidates the significance of serum ferritin as a marker of oxidative stress in chronic liver diseases
Authors: Sumida Yoshio , Nakashima Toshiaki , Yoh Takaharu , Kakisaka Yuko , Nakajima Yoshiki , Ishikawa Hiroki , Mitsuyoshi Hironori , Okanoue Takeshi , Nakamura Hajime , Yodoi Junji
Published: March 2003

Abstract: Background/Aims: Serum thioredoxin (TRX) levels have recently been established as an indicator of oxidative stress in various diseases. The aim of the present study was to clarify the clinical significance of serum ferritin in chronic liver diseases. Methods: Levels of ferritin, transferrin saturation (TS), aspartate aminotransferase (AST), and TRX were measured in the sera of patients with chronic hepatitis C (CH‐C, n=92), chronic hepatitis B (CH‐B, n=28), nonalcoholic fatty liver (FL, n=31), or alcoholic liver diseases (ALD, n=17). Serum TRX levels were evaluated with a recently established sandwich enzyme‐linked immunosorbent assay kit. Results: Serum TRX levels were significantly higher in CH‐C, FL, and ALD than in healthy volunteers. A larger proportion of patients with CH‐C, FL, and ALD had elevated levels of serum ferritin than CH‐B. Serum ferritin levels were positively correlated with levels of TS, AST, and TRX in CH‐C, but were merely correlated with TS values in CH‐B. Ferritin levels were also well correlated with AST and TRX, but not with TS in FL and ALD. Conclusion: Oxidative stress, which was evaluated by measuring serum TRX, in addition to storage iron and hepatocyte damage is a cause of increasing serum ferritin levels in chronic liver diseases. An elevated serum ferritin level, which was correlated with TS, indicates that iron‐induced oxidative stress contributes to CH‐C. Elevated ferritin levels in FL and ALD may be mostly due to iron‐unrelated stresses.