bluuebunny/crossref_metadata_2025_split huggingface dataset:
Isoform‐specific associations of CD45 with accessory molecules in human T lymphocytes
Authors: Dianzani Umberto , Redoglia Valter , Malavasi Fabio , Bragardo Manuela , Pileri Alessandro , Janeway Charles A. , Bottomly Kim 
Published: March 2007

AbstractAssociation of CD45 with surface molecules was investigated in human T lymphocytes by co‐capping. CD45 appeared to be associated with the CD3/T cell receptor complex and with CD4 or CD8 molecules in memory, but not in naive T cells, as previously reported in the mouse. Associations of CD45 isoforms with accessory molecules were then identified with seven anti‐CD45R monoclonal antibodies (mAb). An isoform‐specific association pattern was observed: CD2 co‐capped with CD45 molecules recognized by UCHL1 mAb (CD45R0), LFA‐1 with molecules bound by 2H4 mAb (CD45RA). and both CD4 and CD8 with molecules reacting with MCA. 347 mAb (whose isoform specificity was not known). Further information on the CD45 isoform(s) associated to CD4 and CD8 was sought by assessing the isoform specificity of MCA. 347. Cross‐competition experiments showed that it reacts with an epitope clearly different from those recognized by 2H4 and UCHL1, and only partially overlapping the PD7/26 epitope (CD45RB). Moreover, the competition between MCA. 347 and PD7/26 was maximal in naive T cells and minimal both in memory T cells and in a subset expressing CD11b, a marker of granular lymphocytes. Immunoprecipitation experiments showed that MCA. 347 binds to CD45 molecules with a molecular mass of 220, 205 and 190 kDa, the 190‐kDa molecules not being recognized by 2H4, PD7/26 or UCHL1. These data indicate that MCA. 347 recognizes amino acid sequences different from those coded by the exon A or B of the gene, and not expressed by CD45RO, suggesting that it binds to sequences coded by the exon C. In conclusion, this work shows that in human T cells different CD45 isoforms are associated to different surface molecules: LFA‐1 is associated to CD45RA, CD2 to CD45RO and CD4 and CD8 presumably to CD45RC. This peculiar behavior of CD45 suggests that it may play a crucial role in lymphocyte activation, probably by modulating the signals delivered to the cell by different receptor systems.
Preferential association of α and β chains of the T cell antigen receptor
Authors: Uematsu Yasushi 
Published: March 2007

AbstractThe cytotoxic T lymphocyte (CTL) clone B6.2.16 expresses a Vβ8.2/Jβ2.3/Cβ2‐encoded T cell receptor (TcR) β chain and an α chain that is encoded by a novel Vα gene segment, Jα27 and Cα. While expression of VαB6.2.16 and Jα27 is not detectable in lymph node cells of normal C57BL/6 mice, expression of these gene segments was readily seen in transgenic mice expressing the rearranged β chain gene of the B6.2.16 T cell clone. This finding indicates that only a limited number of α chains can associate with the B6.2.16 β chain and strongly suggests that the size of the TcR repertoire of mature T cells is not only limited by TcR ligand‐mediated thymic selection but also by restrictions in α‐β combinatorial chain association.
Vβ repertoire in rats and implications for endogenous superantigens
Authors: Smith Lawrence R. , Kono Dwight H. , Kammuller Michael E. , Balderas Robert S. , Theofilopoulos Argyrios N. 
Published: March 2007

AbstractEndogenous superantigens of mice, encoded by mammary tumor virus proviral integrants, induce intrathymic deletion of entire T cell populations that express specific Vβ gene products, a phenomenon proposed to be important in self‐tolerance and prevention of toxic responses to exogenous microbial superantigens. Evidence for the presence of Vβ selecting/deleting endogenous superantigens in other species is lacking. We report here that rats do not exhibit endogenous superantigen‐induced Vβ clonal deletions despite their strong response to bacterial superantigens. These findings indicate that endogenous superantigens are not obligatory in Vβ repertoire shaping.
Ly‐1 B (B‐1) cells are the main source of B cell‐derived interleukin 10
Authors: O'garra Anne , Chang Ray , Go Ning , Hastings Robin , Haughton Geoffrey , Howard Maureen 
Published: March 2007

AbstractWe have previously reported (O'Garra, A. et al., Int. Immunol. 1990. 2: 821) that murine B lymphomas and purified normal peritoneal B cells produce interleukin (IL) 10. We now show that this production of IL 10 B cells correlates with the presence of Ly‐1 (B‐1) B cells, in both normal and diseased mice. Using a semi‐quantitative modification of the polymerase chain reaction, we show that IL 10 expression is detectable in peritoneal B cells but only becomes apparent in splenic B cells of aged mice of which a high proportion are Ly‐1+. Furthermore, the expression of IL 10 is constitutive in splenic B cells from mice carrying the Ly‐1+ BCL1 lymphoma. Since IL 10 is a potent regulator of in vitro immune function, its production by Ly‐1 lineage B (B‐1) cells raises the possibility that this subset of B cells may regulate their own development and/or the function of other immunocompetent cells.
Tissue‐specific migration pathways by phenotypically distinct subpopulations of memory T cells
Authors: Mackay Charles R. , Marston Wendy L. , Dudler Lisbeth , Spertini Olivier , Tedder Thomas F. , Hein Wayne R. 
Published: March 2007

AbstractA proportion of T cells recirculate in a tissue‐selective manner. Recent studies which showed that the skin‐tropic subset of T cells was of memory/activated type, led us to examine whether the preferential homing of T cells to the gut also involved memory T cells, and if so whether these memory T cells were phenotypically distinct from other memory T cells. Lymphocytes migrating through the gut and the skin of sheep was collected by cannulating the lymphatic ducts draining these tissues. Both naive and memory T cells were found to recirculate through the gut, although only memory T cells migrated through the skin. However, when T cells from the gut were labeled with fluorescein isothiocyanate and assessed for their migration back to the gut, it was the memory population which showed a tropism for the gut. Gut‐tropic memory T cells migrated poorly through the skin, indicating that these cells were distinct from skin‐tropic memory T cells. This was confirmed by phenotypic analysis. Gut memory T cells expressed very low levels of the α6 and β1 integrins, in contrast to skin memory T cells which expressed high levels. There was no evidence for heterogeneity within the naive T cell population, which migrated preferentially to lymph nodes. This migration pattern could be explained in part by the high expression of the L‐selectin (lymph node homing receptor, LAM‐1) on naive T cells, in contrast to memory T cells from gut or skin which were mostly L‐selectin negative. These results in sheep indicate that subsets of α/β memory T cells show tissue‐selective migration patterns, which probably develop in a particular environment following encounter with antigen.
Memory T lymphocyte hyporesponsiveness to non‐cognate stimuli: a key factor in age‐related immunodeficiency
Authors: Flurkey Kevin , Stadecker Miguel , Miller Richard A. 
Published: March 2007

AbstractPrevious studies from our laboratory have suggested that aging leads to an accumulation of cells expressing high levels of CD44, thought to be a marker for memory lymphocytes, and that positively selected CD44hi T cells, from mice of any age, respond poorly to concanavalin A (Con A) in limiting dilution estimates of interleukin (IL)‐2‐producing cells. We now report the results of a more comprehensive analysis of memory T cell function, in old and young mice, to non‐cognate activators (Con A and the staphylococcal enterotoxin SEB). We report that memory T cells, isolated by removing cells bearing the CD45RB determinant, contain very few cells able to respond to either Con A or SEB under limiting dilution culture conditions, whether the responses are measured by IL‐2 or by IL‐3 accumulation. As a control, we show that memory T cells do respond strongly, at limiting dilution, to recently encountered priming antigens, i.e. Schistosoma mansoni egg antigen; the limiting dilution culture protocol thus does not preclude activation of memory T cells when cognate stimuli are presented to antigen‐specific cells. These data suggest that virgin and memory T cells may differ fundamentally in their activation requirements, and suggest further that the accumulation, with age, of memory T cells accounts for the low responsiveness of old mice to non‐cognate mitogens.
Induction of experimental autoimmune uveoretinitis in Lewis rats with purified recombinant human retinal S‐antigen fusion protein
Authors: Roberts Andrew J. , Kasp Eva , Stanford Miles , Dumonde Dudley C. , Paul Banga J. 
Published: March 2007

AbstractFull‐length human retinal cDNA for S antigen (S‐ag) and for the α subunit of transducin (α‐Td) were subcloned into a bacterial expression plasmid vector to generate recombinant fusion proteins with glutathione‐S‐transferase (GST). The recombinant GST‐S‐ag and rGST‐α‐Td fusion proteins were purified from bacterial extracts by continuous flow preparative gel electrophoresis under denaturing conditions, and were assessed for their ability to induce experimental autoimmune uveoretinitis (EAU). Immunization of Lewis rats with single doses of 10 μg‐100 μg rGST‐S‐ag in Freund's complete adjuvant supplemented with Bordetella pertussis readily induced clinical signs of EAU. Immunization with GST alone did not induce EAU indicating that disease activity was ascribable to the S‐ag residues in the fusion protein. Although the α‐Td shares limited sequence homology with S‐ag, the rGST‐α‐Td fusion protein was also not uveitogenic in Lewis rats. The clinical severity of EAU in Lewis rats sensitized with rGST‐S‐ag was found to be milder than that induced with native S‐ag preparations purified from human retina. However, humoral antibody responses to sensitization with the recombinant S‐ag fusion protein were of a higher magnitude than with native S‐ag. The availability of recombinant preparations of human S‐ag protein will be of value in studying its processing and presentation to T cells derived from patients with autoimmune retinal vasculitis.
Tumor necrosis factor‐mediated cell lysis in vitro: relationship to cAMP accumulation and guanine nucleotide‐binding proteins
Authors: Branellec Didier , De Cremoux Patricia , Barreau Patricia , Calvo Fabien , Chouaib Salem 
Published: March 2007

AbstractWe have investigated the modulation of tumor necrosis factor (TNF)‐mediated tumor cell lysis by cAMP. Among a panel of human breast tumor cell lines, MCF7 and MDA MB 231 were shown to be, respectively, sensitive and resistant to TNF‐mediated cell lysis in vitro. 125I‐labeled TNF‐binding experiments demonstrated that both cell lines bind TNF, indicating that the differential sensitivity to TNF was not related to TNF receptor expression. To study the relationship between TNF‐mediated cell lysis and cAMP accumulation, cAMP measurement was performed following TNF treatment. Our data show that TNF alone did not induce an enhancement of intracellular cAMP accumulation either in the TNF‐sensitive or in the TNF‐resistant cell line. Experiments in which cells were exposed to forskolin revealed that this cAMP elevating drug was efficient in enhancing the sensitivity to TNF of MCF7 cell line. This potentiating effect of forskolin was maximal for suboptimal concentrations of TNF (10 ng/ml), reaching up to 100% when forskolin was added at 100 μM. However, costimulation with forskolin of either MDA MB 231 or a TNF‐resistant MCF7 clone (MCF7‐R‐A1) did not induce any reversal of resistance to TNF.We further assessed the interaction of TNF with transmembrane signalling and the possible involvement of guanine nucleotide‐binding proteins (G‐proteins). Bacterial toxin‐catalyzed ADP ribosylation of MCF7 and MDA MB 231 membranes was, therefore, performed. Using cholera toxin, we demonstrate that TNF treatment did not quantitatively alter the activity of stimulatory G‐proteins either in MCF7 or MDA MB 231 cell line. In contrast, pertussis toxin‐catalyzed ADP ribosylation experiments suggest a functional coupling of TNF receptors to a 40‐kDa pertussis toxin‐sensitive G‐protein in the TNF‐sensitive MCF78 cell line but not in the TNF‐resistant MDA MB 231 cell line. Taken together, these data indicate that cAMP might play a role in TNF‐mediated cell lysis and are in support of the involvement of a pertussis toxin‐sensitive G‐protein in TNF‐mediated MCF7 cells lysis.
Interferon‐γ regulates expression of a novel keratin classe I gene
Authors: Flohr Thomas , Buwitt Ute , Bonnekoh Bernd , Decker Thomas , Böttger Erik C. 
Published: March 2007

AbstractInterferon (IFN)‐γ has been implicated in the pathogenesis of several autoimmune disorders and inflammatory skin diseases. To identify novel mediators involved in the IFN‐γ response we have used differential hybridization of a cDNA library prepared from IFN‐γ‐treated HeLa cells to isolate a gene that is induced following treatment with IFN‐γ. We report here the molecular cloning and characterization of a cDNA detecting a 1.6‐kb mRNA that accumulated in response to IFN‐γ but not in response to IFN‐α or IFN‐β. The gene is regulated by IFN‐γ in human cell lines of epithelial origin. The mRNA encodes a predicted protein of 432 amino acids and the primary structure of the protein demonstrates that it is a novel member of developmentally regulated keratin class I genes.
Polymorphism of human immunoglobulin VH4 germ‐line genes
Authors: Weng Nan‐Ping , Snyder James G. , Yu‐Lee Li‐Yuan , Marcus Donald M. 
Published: March 2007

AbstractThe human immunoglobulin VH4 gene family is thought to contain approximately 10 germ‐line genes and to exhibit little polymorphism. We report here an analysis of VH4 germ‐line genes that were amplified from DNA of two unrelated individuals. Ten unique (non‐repetitive) sequences were obtained from individual A and 11 from individual B. Nine of these sequences represent new germ‐line genes, and 8/9 exhibit only 89%–96% similarity to genes identified previously. Subsets of VH4 genes displayed distinctive nucleotide motifs that account for most of the differences between them. This observation suggests that diversity in the VH4 gene family arose from the acquisition of blocks of nucleotides, rather than by accumulation of point mutations. These nucleotide blocks could have been acquired by gene conversion or by homologous recombination. All of the VH4 genes have a potential N‐linked glycosylation site at Asn 60, and some genes encode a second site at Asn 52. The VH4 gene family is larger and more polymorphic than appreciated previously. Immunoglobulin gene polymorphism may make a significant contribution to hereditary variations in the immune response and to the genetic predisposition to autoimmune diseases.
A single mRNA encodes the α150 and α80/70 forms of the α subunit of VLA4
Authors: Rubio Miguel , Nueda Arsenio , Vara Alicia , Lopez Angel L. Corbí 
Published: March 2007

AbstractVLA4 is a cell surface heterodimer (α4β1, CD49d/CD29) which belongs to the integrin family and is involved in cell‐extracellular matrix interactions, as well as in intercellular adhesion. Unlike other integrin α subunits, the α subunit of VLA4 (α4) can appear as a 150‐kDa polypeptide (α150), or cleaved into two non‐covalently associated polypeptides (α70–80). The relative proportion of each form is highly variable among different cells and is dependent on the state of cellular activation. The α4 cleavage site has recently been shown to occur between residues Arg558‐Ser559. We report the isolation of genomic clones encoding the α4 subunit, the location of the cleavage site‐encoding nucleotides to a specific exon and the determination of the exon‐intron organization around the cleavage site. Comparison with the gpIIb (CD41) and the αx (p150,95α, CD11c) genes revealed a similar genomic structure in this region, with exons of similar length separated by introns of identical phase. The structure of the α4 mRNA in cells expressing the alternative forms of α4 has been analyzed by means of reverse transcription‐polymerase chain reaction. Our results indicate that the exon encoding the cleavage site is present in α4 mRNA molecules from cells expressing either the α150 or the α70–80 form on the cell surface. Moreover, the structure of the α4 mRNA around the cleavage site does not change during the switch towards the α70–80 form that takes place upon lymphocyte activation. Therefore, both forms of α4 arise from a common mRNA, the α150 form contains the cleavage sequence and the α70–80 form must be generated by a post‐translational proteolytic event.
γδ T cells and the immune response in visceral leishmaniasis
Authors: Raziuddin Syed , Telmasani Abdul Wahab , El‐Awad M. El‐Hag , Al‐Amari Omar , Al‐Janadi Mansour 
Published: March 2007

AbstractVisceral leishmaniasis (VL) caused by Leishmania donovani, a protozoan parasite, is a disease of high morbidity associated with hepatosplenomegaly, hypergammaglobulinemia, fever and death. One of the immunological hallmarks of VL is a remarkable increase in serum immunoglobulin levels as a result of polyclonal B cell activation. This study demonstrated that T lymphocytes expressing the T cell receptors (TcR) γδ in association with CD3 molecules are increased in circulation of patients with VL. A large proportions of TcR γδ‐bearing T cells had CD4+CD8− phenotype, and expressed CD25, CD38, CD71 and HLA‐DR activation antigens. Furthermore, we demonstrated wide functional differences in TcR γδ and TcR αβ T cells in their proliferative response, secretion of interleukin‐2 (IL‐2), B cell growth factor (BCGF) and B cell differentiation factor (BCDF). It was of interest that the TcR γδ T cells from patients with VL could be expanded by in vitro culture with human recombinant IL‐2. Although these TcR γδ cells secreted diminished levels of IL‐2, they produced highly augmented levels of both BCGF and BCDF, suggesting that secretion of these lymphokines in these T cell subsets is regulated independently. The relative increases in the CD4+ CDw29+ TcR γδ T cell subsets and their secretion of highly elevated levels of BCGF and BCDF largely accounted for the humoral immune system abnormality and hypergammaglobulinemia found in this disease. These observations may help to explain that TcR γδ T cells might be functional in vivo and are involved in immunological mechanisms of pathogenesis in VL.
Sublytic complement attack protects tumor cells from lytic doses of antibody and complement
Authors: Reiter Yoram , Ciobotarin Adina , Fishelson Zvi 
Published: March 2007

AbstractSublytic doses of the membrane attack complex (MAC) of complement are known to exert multiple stimulatory effects on metabolically active cells. Results presented herewith demonstrate that pretreatment of the human leukemic cells K562 and HL‐60 with sublytic doses of antibody and normal human serum protects them from lytic complement concentrations, a phenomenon proposed to be called “complement‐induced protection”. C7‐ and C8‐deficient human sera are ineffective in inducing resistance unless they are reconstituted with purified human C7 and C8, respectively. The complement‐induced protection is inhibitable by actinomycin D and cycloheximide indicating that the increased complement resistance depends on RNA and protein synthesis triggered by the sublytic complement doses. Free extracellular Ca2+ is also required to achieve maximal protection, indicating a role for Ca2+ ions in the cell stimulatory events which culminate in increased complement resistance. Quantitative analysis of bound complement components indicated that similar amounts of C3 and C9 molecules are deposited on “protected” and control cells during complement activation. The “protected” K562 and HL‐60 cells regain sensitivity to lytic MAC doses after about 8 or 3 h, respectively, of culture in growth medium, in the absence or presence of actinomycin D and cycloheximide. The “induced protection” is not species restricted and protection from human complement can be induced in K562 cells by treatment with sublytic doses of antibody and rabbit or guinea pig sera.
Kinetics of chicken embryonic thymocyte development in ovo and in organ culture
Authors: Davidson Natalie J. , Chen Chen‐lo H. , Boyd Richard L. 
Published: March 2007

AbstractThymocyte development was monitored in an embryonic thymus organ culture system to establish a model in the chicken in which the functional nature of the thymic microenvironment could be assessed. Thymus lobes were removed from 10‐day‐old embryos and cultured for 2–10 days. Cell yield increased to a maximum in 4–8 days of culture with a corresponding decrease in average cell size. An initial thymocyte population of predominantly CD3−CD4−CD8− cells gave rise to all CD3/CD4/CD8‐defined subpopulations in vitro, maintaining high levels of CD3−CD4−CD8+ and CD3+CD4−CD8+ cells and a low representation of CD3−CD4+CD8−, CD3+CD4+CD8−, CD3−CD4+CD8− and CD3+CD4+CD8+ thymocytes. This is the first observation of a CD3−CD4+CD8− population in the chicken. Developmental kinetics of CD3+ cells were similar to that in the embryo, suggesting that the in vitro environment is sufficient to promote and maintain thymocyte maturation. Thymocytes of both the γδ and αβ T cell receptor (TcR) lineages developed in that order, confirming in ovo data and the lineage potential of the first wave of thymocyte precursors. One unusual finding was a relative accumulation of γδ TcR+ thymocytes in culture, incorporating all CD4/CD8 subsets, including a previously undetected population, CD4+CD8−. This may indicate a favorable developmental environment or simply a lack of normal cellular emigration. A detailed comparison with T cell development in the embryo demonstrated that the chicken thymus organ culture system reflects thymic events in ovo during a limited time period and thus should prove useful in the identification of functionally relevant thymic molecules.
Immunity after treatment of human schistosomiasis: association between IgE antibodies to adult worm antigens and resistance to reinfection
Authors: Dunne David W. , Butterworth Anthony E. , Fulford Anthony J. C. , Curtis Kariuki H. , Langley Jane G. , Ouma John H. , Capron Andre , Pierce Raymond J. , Sturrock Robert F. 
Published: March 2007

AbstractPrevious studies in school children have demonstrated the slow development with age of resistance to reinfection after chemotherapy of Schistosoma mansoni infections, and have indicated that inappropriate (“blocking”) antibody responses prevent the expression of immunity in young children. The present study was designed to investigate further the nature of the protective responses, by serological studies on a group of 151 S. mansoni‐infected individuals resident in an endemic areain Machakos District, Kenya. Antibody levels against various antigens in blood samples before treatment were related to intensity of previous infections; antibodies in blood samples taken 6 months after treatment were related to cumulative reinfection rates over the following 30 months.IgE against an adult‐worm antigen preparation correlated positively with age andnegatively with reinfection. In contrast, IgE antibodies against other life‐cycle stages showed either no relationship or the reverse correlation. Furthermore, antibodies of other isotypes against adult‐worm antigens showed no correlations withreinfection.The correlation with IgE could be demonstrated for different preparations of adult worms, including a periodate‐treated preparation presumptively depleted of carbohydrate epitopes. For both the intact and the periodate‐treated preparations, multiple regression analysis of the results for children ≤16 years old demonstrated an IgEeffect after allowing for age, although this effect was not observed in a previouslystudied group of school children. Western blot analysis of the adult‐worm preparation revealed a limited set of antigens recognized by IgE, among which an antigen of 22 kDa was prominent. The qualitative presence of IgE against this antigen could also beshown to be related to a lack of subsequent reinfection.