Search

The E3 ubiquitin ligase Cbl-b is an established nonredundant negative regulator of T-cell activation. Cbl-b fine-tunes the activation threshold of T cells and uncouples T cells from their vital need of a costimulatory signal to mount a productive immune response. Accordingly, mice deficient in cblb are prone to autoimmunity and reject tumors. The latter has been described to be mediated via CD8+ T cells, which are hyperactive and more abundant in shrinking tumors of cblb-deficient animals. This might at least also in part be mediated by resistance of cblb-deficient T cells to negative cues exerted by tumor-associated immuno-suppressive factors, such as TGF-βand regulatory T cells (Treg). Experiments using cblb-deficient T cells either alone or in combination with vaccines validate the therapeutic concept of enhancing the efficacy of adoptively transferred lymphocytes to treat malignant tumors. This paper summarizes the current knowledge about the negative regulatory role of Cbl-b in T-cell activation and its potential therapeutic implications for cancer immunotherapy. [ABSTRACT FROM AUTHOR]

Abstract: CD4 is a transmembrane glycoprotein fundamental for cell-mediated immunity. Its action as a T cell co-receptor increases the avidity of association between a T cell and an antigen-presenting cell by interacting with portions of the complex between MHC class II and TR molecules. In this paper we report the cDNA cloning, expression and structural analysis of a CD4 homologue from sea bass (Dicentrarchus labrax). The sea bass CD4 cDNA consists of 2071bp that translates in one reading frame to give the entire molecule containing 480 amino acids. The analysis of the sequence shows the presence of four putative Ig-like domains and that some fundamental structural features, like a disulphide bond in domain D2 and the CXC signalling motif in the cytoplasmic tail, are conserved from sea bass to mammals. Real-time PCR analysis showed that very high levels of CD4 mRNA transcripts are present in thymus, followed by gut and gills. In vitro stimulation of head kidney leukocytes with LPS and PHA-L gave an increase of CD4 mRNA levels after 4h and a decrease after 24h. Homology modelling has been applied to create a 3D model of sea bass CD4 and to investigate its interaction with sea bass MHC-II. The analysis of the 3D complex between sea bass CD4 and sea bass MHC-II suggests that the absence of a disulfide bond in the CD4 D1 domain could make this molecule more flexible, inducing a different conformation and affecting the binding and the way of interaction between CD4 and MHC-II. Our results will add new insights into the sea bass T cell immune responses and will help in the identification of T cell subsets in teleost fishes to better understand the evolution of cell-mediated immunity from fish to mammals. [Copyright &y& Elsevier]

The pathogenesis of B-cell lymphoproliferative disorders in general and B-cell chronic lymphocytic leukaemia in particular appears to involve dysfunctional regulation of humoral and cellular immunity with the subsequent development of genetic aberrations in B cells. In theory, either component may arise de novo or may be influenced by environmental exposures including infectious agents, antigens, genotoxic chemicals, or radiation. As an intermediary within the exposure-disease continuum, monoclonal B-cell lymphocytosis may be a helpful biomarker for teasing out these various contributions to risk. This article introduces a series of papers that resulted from an International Workshop held in May 2007 entitled ‘Monoclonal B-cell Lymphocytosis and Chronic Lymphocytic Leukemia: Environmental and Genetic Risk Factors’. Research efforts, such as those described in this issue, should lead to improved interventions, more predictive biomarkers, more effective treatments, and a greater appreciation of how the immune system functions over the entire human lifespan. [ABSTRACT FROM AUTHOR]

Abstract: Human T-cell lymphotropic virus I (HTLV-I) infection is linked to the development of adult T-cell leukemia/lymphoma (ATL), among many illness. The healthy CD4+ T cells infect HTLV-I through cell-to-cell contact with infected T-cells. The infected T cells can remain latent and harbor virus for several years before virus production occurs. Actively infected T cells can infect other T cells and can convert to ATL cells, whose growth is assumed to follow a classical logistic growth function. In this paper, we consider the classical mathematical model with saturation response of the infection rate. By stability analysis we obtained the condition for the infected T cells die out and the condition for HTLV-I infection becomes chronic. At the same time, we also obtained the condition for a unique endemic equilibrium is globally stable in the interior of the feasible region. [Copyright &y& Elsevier]

It is frequently useful in studies of transplantation to have available an antibody to a cell surface antigen, which is not itself responsible for transplant rejection. In this paper, we identify and describe such an antibody/antigen system in miniature swine. The monoclonal antibody, 1038H-10-9, was found to react to a pig allelic antigen (called PAA), found on a variety of pig cells and tissues, including peripheral blood mononuclear cells (PBMC), thymocytes, lymph node, bone marrow, and skin. Analysis for recipient sensitization against PAA was performed by in vitro cell-mediated lympholysis (CML) assay, mixed lymphocyte reaction (MLR) assay, antibody binding studies, and skin graft rejection patterns were examined. No evidence was found to indicate detection of PAA by any of these assays of alloreactivity. We therefore conclude that PAA is an allelic swine cell surface antigen, with wide tissue distribution, and that it is not a histocompatibility antigen. It should provide a powerful tool for studies of transplantation biology in miniature swine, such as identification and quantification of chimerism following organ transplantation. [ABSTRACT FROM AUTHOR]

Chronic lymphocytic leukemia (CLL) is among the most common types of leukemia. Recent studies suggest that a population of clonal B cells with the phenotype of CLL, can be detected in the general population, a condition now designated as monoclonal B-cell lymphocytosis (MBL). Although all cases of CLL appear to be preceded by MBL, the majority of individuals with MBL will not develop a hematologic malignancy. The biological characteristics and clinical implications of MBL appear to differ based on whether it is identified during the diagnostic evaluation of lymphocytosis or incidentally discovered through screening of individuals with normal lymphocyte counts as part of research studies using highly sensitive detection methods. In this paper, we provide a state of the art review on the nomenclature, diagnosis and the role of MBL in the etiology of CLL [ABSTRACT FROM AUTHOR]

Chronic lymphocytic leukemia (CLL) is among the most common types of leukemia. Recent studies suggest that a population of clonal B cells with the phenotype of CLL, can be detected in the general population, a condition now designated monoclonal B-cell lymphocytosis (MBL). Although all cases of CLL appear to be preceded by MBL, the majority of individuals with MBL will not develop a hematologic malignancy. The biologic characteristics and clinical implications of MBL appear to differ based on whether it is identified during the diagnostic evaluation of lymphocytosis or incidentally discovered through screening of individuals with normal lymphocyte counts as part of research studies using highly sensitive detection methods. In this paper, we provide a state of the art review on the nomenclature, diagnosis and the role of MBL in the etiology of CLL [ABSTRACT FROM AUTHOR]

Among the B-cell lymphoproliferative disorders, monoclonal gammopathy of undetermined significance (MGUS) is the humoral counterpart to monoclonal B-cell lymphocytosis. This review introduces the papers from the section devoted to MGUS at the International Workshop entitled ‘Monoclonal B-cell lymphocytosis and chronic lymphocytic leukaemia: environmental and genetic risk factors.’ [ABSTRACT FROM AUTHOR]

This article presents an obituary to John David McClelland who died on April 17, 2003. John McClelland belongs to the group of histocompatibility typers of the first hour, and his most outstanding contribution to the field was that he, together with Paul Terasaki, developed the microlymphocytotoxicity test. In a more general sense, McClelland was a host for the large numbers of foreign visitors to Paul Terasaki's laboratory at UCLA, which included myself for the first time in 1968 and many times later. McClelland, with the tacit agreement of Paul Terasaki, put himself in charge of the social and scientific welfare of the visitors and postdoctoral fellows and, in doing this, he developed a global network of friends. McClelland leaves behind two very promising young adult children, James and Colleen, his loyal canine companion Lizzie, and his wife Marie Lau, who continues to fascinate the HLA world in the UCLA International Cell Exchange. McClelland was also an author of the first paper describing the use of cryogenically preserved lymphocytes for tissue typing.