摘要:

AbstractIn this study we report the characterization of monoclonal antibody (mAb) 8B4/20, raised against immature human thymocytes, that identifies a novel leukocyte antigen. The molecular characterization of the antigen by immunoprecipitation and immunoblotting yields, under nonreducing conditions, a specific band of 120 kDa which, under reducing conditions, displays a slightly lower molecular mass (110 kDa). mAb 8B4/20 detects a molecule found on the majority of thymocytes with an inverted gradient of expression when compared to CD3. It appears at high density on the CD3−/lowthymocytes, at reduced density on the CD3medand double‐positive thymocytes, and is absent on CD3hiand singlepositive thymocytes and on peripheral blood T cells. Immunohistochemistry on frozen sections demonstrates cortical staining of the thymic lobules. Flow cytometric analysis of the different subsets of peripheral blood mononuclear cells shows that mAb 8B4/20 detects an antigen expressed only on CD56+/CD16+natural killer cells and on a fraction of CD14+monocytes. T cells, B cells, erythrocytes, granulocytes and platelets are consistently negative. The expression of the molecule on tumor cell lines does not show lineage restriction. Analysis of phytohemagglutinin plus recombinant interleukin‐2‐activated peripheral blood lymphocytes shows that mAb 8B4/20 identifies an antigen expressed on CD3+cells by week 3 of culture. Thus, it recognizes a very late activation antigen (VLA) on mature T cells. The cell distribution and the electrophoretic pattern of the molecule identified by mAb 8B4/20 is distinct from that of known CD and of integrin/VLA molecules. Its function on thymocytes is so far unknown; however, the binding of mAb 8B4/20 to tumor lines induces changes in the morphology and adhesive properties of the 8B4/20+cells growing in suspension. We suggest that mAb 8B4/20 recognizes a molecule that may be involved in interactions between thymocytes and other thymic structures that may be relevant for the selection

ISSN:0014-2980    

DOI:10.1002/eji.1830240102

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractWe previously reported that infection of BALB/c mice with the parasitePlasmodium chabaudiinduces high production of natural autoantibodies. Here we demonstrate that such an infection of lupus‐prone (NZB × NZW)F1 (B/W) mice retards the development of their autoimmune disease. Survival and disease hallmarks (high‐grade proteinuria and IgG anti‐DNA antibodies) were delayed for 6 months when parasite inoculation was given at either 3 or 7 months of age,i.e.before or after the onset of the clinical symptoms. Similar beneficial effects, although less pronounced, were obtained when mice were treated with a total of 800 m̈g of IgG (P‐IgG) or IgM (P‐IgM) or 300 m̈g of cryoglobulin preparations isolated fromP. chabaudi‐infected BALB/c mice while similarly prepared fractions from uninfected mice had little effect. Compared to these fractions, P‐IgG and P‐IgM contained higher levels of natural antibodies bearing the D23 idiotype characteristic of polyreactive natural autoantibodies with enhanced activity against Fab and Fc fragments of IgG.In surviving mice, the level of anti‐DNA antibodies, particularly those of IgG1 isotype, were significantly decreased. Flow cytometric analysis of various T cell subsets showed that the number of cells expressing γδ T cell receptor (TcR) antigens which did not vary with age was not modified after P‐IgG or P‐IgM treatment. In contrast, the number of T cells expressing Vβ8.1,2, Vβ10 and Vβ14 TcR antigens, which increased with age, were significantly reduced. Taken together, these results indicate that parasite infection of mice induces the synthesis of populations of IgM and IgG natural autoantibodies with immunoregulatory properties and that these antibodies attempt, at least transitorily, to rescue a natural autoantibody network

ISSN:0014-2980    

DOI:10.1002/eji.1830240103

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractInterleukin‐2 (II‐2) gene expression, a critical early event during T lymphocyte activation, is severely suppressed in mice infected with the protozoan parasiteTrypanosoma cruzi, the causative agent of human Chagas disease. Our previous observation that reduction of IL‐2 mRNA in T cells fromT. cruzi‐infected mice is not due to an increased degradation of the mRNA suggests a repression of the IL‐2 gene at the transcriptional level. In this study, we have measured the level of nuclear factors that bind to specific sites on the IL‐2 enhancer. Splenocytes and splenic T cells from acutely infected mice show a marked decrease in the level of AP‐1, and a modest decrease in the level of NF‐xB and nuclear factor of activated T cells (NF‐AT). DNA‐binding activity of Oct‐1 was least affected in T cells from infected mice. Although the basal level of AP‐1 activity is comparable in cells from uninfected and infected mice, mitogen‐induced AP‐1 activation is absent in the cells fromT. cruzi‐infected mice. Sodium deoxycholate treatment slightly enhances NF‐xB‐binding activity in splenocyte nuclear and whole‐cell extracts from infected mice, suggesting that a blockage of the activation of NF‐xB is only partially responsible for the decrease in the level of NF‐xB in T cells fromT. cruzi‐infected mice. These data identify the molecular basis of IL‐2 gene regulation inT. cruziinfection and suggest that T cells

ISSN:0014-2980    

DOI:10.1002/eji.1830240104

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractAn intriguing feature of thymocyte differentiation is that the competence to express both interleukin‐(IL)2 and CD25 is acquired even prior to T cell recept or (TcR) expression. When T cell receptor‐independent stimuli are used, immature cells can express IL‐2 at levels comparable to mature cells, but unlike the mature cells, immature cells require IL‐1 as a costimulus. Here we present evidence that IL‐1 affects a variety of responses by members of the CD25+subset of immature thymocytes. Cells in this population are IL‐1 dependent not only for induction of IL‐2 expression, but also for high‐level maintenance of CD25 expression. CD25+expression is amplified by IL‐1 through a mechanism highly sensitive to changes in Ca2+ionophore concentration. The effects of IL‐1 on CD25 maintenance are not mediated by IL‐2, because of the divergent effects of cAMP on IL‐2 and CD25+expression. IL‐1 costimulation also increases RNA accumulation in the cell cycle, and this effect too seems to be separable from the effects on IL‐2 and CD25+expression. All these effects of IL‐1 are developmentally stage‐specific, manifest in the CD25+subset of immature thymocytes but not in later‐stage thymocytes or splenic T cells. Multiparameter cell sorting experiments that dissect the transitional stages between immature and TcR+thymocytes imply that all immature cells pass through an IL‐1 responsive state. Responsiveness to IL‐1 costimulation is then lost by these cells, apparently irreversibly, at a stage just prior to detectable cell‐surface TcR expression. These results indicate that IL‐1 responsiveness is a defining characteristic of the activation physiology of cells in a p

ISSN:0014-2980    

DOI:10.1002/eji.1830240105

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractT cell functional defects are a common aspect of human immunodeficiency virus (HIV) infection. Moreover, it has been suggested that indirect mechanisms are involved in CD4+cell depletion. Unresponsiveness to proliferative stimuli of lymphocytes incubated with HIV particles or with viral proteins is well documented. Nevertheless, drawing a clear picture of the anergy phenomenon is difficult because of several unresolved and controversial questions. Here we report that recombinant gp120 induces anergy in T helper lymphocytes cultured with different stimuli. The proliferative responses to interleukin (IL)‐2, IL‐4, IL‐6, anti‐CD2, anti‐CD3 and phorbol 12‐myristate 13‐acetate are inhibited. Moreover, anergic cells show a different distribution in cell cycle phases as compared to control cells, leading us to suggest that the progresion in the cell cycle is hampered and that a pre‐mitotic block takes place. Furthermore, since chimpanzees are susceptible to HIV‐1 infection without showing immunodeficiency signs, we analyzed the proliferation of chimpanzee lymphocytes without observing anergy in cells preincubated with gp120. Taken together, these results support the hypothesis that anergy plays an important role in HIV

ISSN:0014-2980    

DOI:10.1002/eji.1830240106

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractIntegrins are a family of cell surface heterodimers which mediate both cell‐cell and cell‐extracellular matrix interactions and affect cellular differentiation through their signal transduction capacity. Integrin expression is regulated during differentiation as well as by numerous growth factors and cytokines. We have analyzed the changes in p150,95 (CD11c/CD18 or αX/β2) and VLA‐4 (CD49d/CD29 or α4/β1) integrin subunits mRNA levels that take place during the myeloid differentiation of HL60 and U937 cells, and compared them to other integrins with similar functional activities. Northern blot analysis revealed that the monocytic differentiation of U937 and HL60 cells alters the αX and α4 mRNA steady‐state levels: αX mRNA is inducedde novowhereas α4 mRNA decreases to undetectable levels. Both changes were dependent on the activity of protein kinase C and were also observed upon granulocytic differentiation of HL60 cells. Parallel analysis of other integrin subunits mRNA (β1, α5, β7) demonstrated that the mRNA levels for the α subunits of the fibronectin receptors α4/β1 (VLA‐4) and α5/β1 (VLA‐5) are differentially regulated during the monocytic differentiation of myeloid cell lines, and suggested that myeloid cells express a heterodimer formed by the association of β7 with an integrin α subunit distinct from α4. Nuclear transcription assays and functional analysis of the αX and α4 promoter regions demonstrated that the transcription rate of the αX gene is considerably elevated after phorbol 12‐myristate 13‐acetate treatment of U937 cells, while that of α4 is almost unaffected, suggesting that posttranscriptional mechanisms are causing the extremely low α4 mRNA level

ISSN:0014-2980    

DOI:10.1002/eji.1830240107

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractProgrammed cell death (PCD) is involved in the physiological regulation of lymphocyte turnover, as well in the antigen‐driven selection of T and B cells. Here it is shown that the immunomodulator linomide (quinoline‐3‐carboxamide) inhibits the apoptotic decay of peripheral T lymphocytes in response to three different stimuli. First, linomide reduces the superantigen‐mediated apoptosis and deletion of specific T lymphocytes of both the CD4+and the CD8+subsets without affecting other superantigen‐triggered phenomena such as T cell expansion and anergy. Second, linomide abolishes the T lymphopenia and inhibits PCD of splenic CD4+and CD8+T cells induced by exogenous glucocorticoids. This effect is restricted to peripheral T lymphocytes and does not concern thymocytes. Finally, linomide abolishes the development of lymphopenia that follows infection with vaccinia virus, while reducing PCD of CD4+and CD8+peripheral T cells. The anti‐apoptotic effect of linomide could account for its immunostimulatory properties and might be relevant to the treatment of immunodeficiencies associated with an increased apoptotic decay of T

ISSN:0014-2980    

DOI:10.1002/eji.1830240108

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractThis study is the first to analyze the cross‐reactivity ofin vivoactivated B cells from patients with systemic lupus erythematosus. A chamber ELIspot assay was used to determine whether lymphocytes secreting antibodies that bound to DNA or 2,4,6‐trinitrophenol (TNP)‐keyhole limpet‐hemocyanin (KLH) could simultaneously bind to the unrelated antigens actin or ovalbumin.IgM anti‐DNA‐, IgM anti‐TNP‐KLH‐ and IgG anti‐TNP‐KLH‐secreting B cells from patients and controls showed similar levels of cross‐reactivity (ranging from 6% to 23%, depending upon the antibody isotype and antigen pair examined). In general, IgG‐producing cells were less cross‐reactive than IgM producers from the same individual (on the average threefold,p<0.001).In contrast, IgG anti‐DNA‐secreting B cells from lupus patients (i) showed no decrease in cross‐reactivity when compared to IgM anti‐DNA‐secreting cells and (ii) were significantly more cross‐reactive than control IgG anti‐DNA‐secreting cells and IgG anti‐TNP‐KLH secreting cells from patients (p<0.001). The degree of IgG anti‐DNA cross‐reactivity correlated with disease activity (r= 0.52,p<0.02). The implications of these findings with respect to reperto

ISSN:0014-2980    

DOI:10.1002/eji.1830240109

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractThe B cell immune response to 2,4‐dinitrophenyl (DNP) keyhole limpet hemocyanin was compared in antigen‐free, germ‐free and conventional BALB/c mice. The numbers of total and of DNP‐specific IgM‐, IgG‐ and IgA‐secreting cells in the spleen were determined by enzyme‐linked immunosorbent plaque assays after primary, secondary and hyperimmunization. Three days after primary immunization a peak of DNP‐specific IgM‐secreting cells was seen in conventional mice only. However, this specific response was accompanied by a rise in the total number of IgM‐secreting cells. At day 6 after primary immunization the total number and the frequency of DNP‐specific IgG‐secreting cells were higher in antigen‐free mice, compared to germ‐free and conventional mice. After secondary immunization in conventional mice only, a considerable bystander IgG response was seen together with the DNP‐specific IgG response. At the end of the secondary response 90% of all IgG‐secreting cells were DNP specific in antigen‐free mice, while the corresponding figure in germ‐free and conventional mice was 63% and 14%, respectively. After hyperimmunization, the absolute number of DNP‐specific IgG‐secreting cells in the spleen was 5‐fold and 11‐fold higher in antigen‐free mice then in germ‐free and conventional mice, respectively. Approximately 48% of all IgG‐secreting cells were DNP specific in antigen‐free mice, while the corresponding figure in germ‐free and conventional mice was 17% and 12%, respectively. The results show that the exogenous antigenic load of animals influences the immune response to newly introduced antigens. The higher absolute and relative numbers of antigen‐specific IgG‐secreting cells after hyperimmunization in antigen‐free mice compared to germ‐free and conventional mice may provide a better source for antigen‐spec

ISSN:0014-2980    

DOI:10.1002/eji.1830240110

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractWe have recently demonstrated that polyomavirus BK and isolated BK double‐stranded (ds)DNA have a strong potential for induction of anti‐dsDNA antibodies. Here, data are presented that demonstrate that normal mice (a term used in this report for mice not predisposed to a lupus‐like syndrome) of four different strains responded to both BK virus and BK dsDNA by producing transient antibodies binding preferentially to the viral dsDNA itself. These antibodies did not bind in theCrithidia luciliaeassay, and did not seem to be of pathogenic significance, as neither signs of proteinuria nor immunochemical signs of glomerulonephritis developed in these mice. In contrast, 5‐week‐old (NZBxNZW)F1mice developed strong and persistent anti‐dsDNA antibodies in response to BK virus and BK dsDNA, with similar features to those of anti‐dsDNA antibodies from individuals with systemic lupus erythematosus: they reacted strongly in theCrithidia luciliaeassay and cross‐reacted with viral as well as with mammalian dsDNA. Furthermore, persistent proteinuria and glomerulonephritis, with demonstrable heavy mesangial deposits of immune complexes containing IgG anti‐dsDNA antibodies, developed 2‐‐3 months earlier than in spontaneously autoimmune control mice. The relevance of these observations to a viral origin of anti‐dsDNA antibodie

ISSN:0014-2980    

DOI:10.1002/eji.1830240111

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY