摘要:

AbstractHuman Langerhans cells (LC) express CD45, but clear data about the isoform(s) and their function(s) are lacking. In the present study, double labeling experiments reveal that freshly isolated LC from normal skin are CD45RO+/RA−/RB−. However, after isolation and short‐time culture where LC undergo anin vitromaturation resembling that to lymphoid dendritic cells, CD45RB emerges whereas CD45RO expression decreases. This evolution results from dynamic alternative RNA splicing. Addition of granulocyte‐macrophage colony‐stimulating factor or tumor necrosis factor‐α to short‐time cultures has no significant effect on CD45RB, but both cytokines accelerate the loss of CD45RO. LC isolated from lesional skin of atopic eczema highly express CD45RO and CD45RB. Cross‐linking of CD45 on LC isolated from atopic individuals inhibits the calcium mobilization in response to activation via Fcε receptor type I(FcεRI). Hence, the protein tyrosine phosphatase CD45 from human LC is subjected to a splicing phenomenon related to the differentiation and activation stage of these cells and regulates their FcεRI

ISSN:0014-2980    

DOI:10.1002/eji.1830250202

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractCirculating spontaneous antibody‐secreting cells (ASC) induced by mucosal and systemic immunizations in human volunteers have been characterized with respect to differentiation stage and homing commitments. Irrespective of the immunization route, the large majority of ASC co‐expressed CD19 and HLA‐DR, which are normally lost during the transition of plasmablasts to plasmocytes, as well as CD38, a marker of activated B cell blasts, expressed also by plasmocytes. However, these cells expressed neither CD28, a molecule acquired by plasmocytes, nor CD22 and CD37, which are lost during the transition of plasmablasts to plasmocytes. Therefore, the large majority of ASC found in peripheral blood after oral and parenteral immunizations are terminally differentiated B cells, but not fully differentiated plasmocytes. As a whole, the mucosally derived ASC population seemed to be more homogenously differentiated. CD25 was detected on few ASC, whereas ASC expressing CD71 were more numerous, especially among systemically derived ASC. Almost all ASC expressed the adhesion molecules CD44 and α4‐integrins, irrespective of immunization route. However, virtually all systemically derived ASC expressed L‐selectin, recognizing the peripheral lymph node addressin, whereas only a minority of mucosally induced blood ASC expressed L‐selectin. These studies are the first to demonstrate in humans that circulating precursors of mucosal B cell immunoblasts utilize organ‐specific recognition mechanisms distinct from those of corresponding systemic B cells and appear to be more advanced in the B lineage maturation pathway. Specialization of receptor expression could explain both the unification of immune responses in diverse mucosal sites and the physiologic segregation of mucosal from non‐mucosal immune mech

ISSN:0014-2980    

DOI:10.1002/eji.1830250203

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractRat thymocytes of the T cell receptorlow(TcRlow) CD4+8+subset which is the target of repertoire selection are heterogeneous with respect to expression of the cell interaction (CI) molecules CD2, CD5, CD11a/CD18 (LFA‐1), CD28 and CD44. We show that this heterogeneity is due to the developmental regulation of these CI molecules during passage through the CD4+8+compartment, and to up‐regulation by TcR engagement. Thus, cohorts of CD4+8+cells differentiating synchronouslyin vitrofrom their direct precursors, the immature CD4−8+cells, were homogeneous with regard to CI molecule expression. Upon entry into the CD4+8+compartment, they expressed relatively high levels of CD2 and CD44, and moderate levels of CDS, CD28 and CD11a. CD2, CD28 and CD44 were slightly down‐regulated during the following 2 days, whereas CD5 slightly increased and CD11a remained constant. TcR stimulation using immobilized monoclonal antibodies resulted in rapid and dramatic up‐regulation of CD2, CD5 and CD28 and, to a lesser extent, of CD11a and CD44. Finally CD53, a triggering structure absent from unstimulated CD4+8+thymocytes was also rapidly induced by TcR stimulation. Inclusion of interleukin (IL)‐2, IL‐4, or IL‐7 in thisin vitrodifferentiation system did not affect the levels of CI molecules studied. Since the high levels of CI molecules induced by TcR‐stimulation correspond to those foundin vivoon TcRintermediatethymocytes known to be undergoing repertoire selection, these results suggest that upregulation of CI molecules by TcR engagement provides a mechanism by which thymocytes that have entered the selection process gain preferential access to further interactions with stromal and lymphoid ce

ISSN:0014-2980    

DOI:10.1002/eji.1830250204

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractActivated T cells induce IgE switching in B cells via a combination of lymphokines and direct T:B cell contact. As CD28‐deficient mice have reduced basal levels of IgG1 and IgG2a and diminished Ig class switching, we investigated whether the CD28/B7.1 (CD80) ligand pairing might also be involved in human IgE regulation. Co‐incubation of an allergen‐specific, human T cell clone with tonsillar B cells caused a marked up‐regulation of CD28 expression, whereas, in contrast, CD45 RB expression was unaffected. To test whether blocking the CD28:B7.1 interaction affected IgE synthesis, a dialyzed anti‐CD28 monoclonal antibody (mAb) was added to cultures containing tonsillar B cells, pre‐activated T cell clones and interleukin‐4. Anti‐CD28 treatment caused a reproducible, dose‐dependent inhibition of IgE, but not IgG synthesis that was accompanied by a visible decrease in cell aggregate formation. Conversely, an anti‐B7.1 mAb had no effect in this system. The effect of blocking CD28‐ligand interactions on lymphocyte adhesion was formally assessed on human T cell clones and B cell lines using dual intracellular staining and flow cytometry. Co‐incubation with an anti‐CD28 mAb, but not control IgG or anti‐B7.1 mAb, resulted in a marked impairment of conjugate formation that correlated well with T cell surface expression of CD28. Using this system we found that an anti‐CTLA‐4 mAb but not an anti‐B7.2 mAb inhibited T:B cell conjugate formation. Lastly, in addition to a direct effect of anti‐CD28 mAb on conjugate formation, 14‐day culture of T and B cells in the presence of anti‐CD28 caused a marked decrease of ICAM‐1 (CD54) expression on aggregated lymphocytes. In contrast, LFA‐1 (CD18) expression was unaffected. We, therefore, conclude that the T cell co‐stimulatory molecule CD28 is involved in the regulation of IgE synthesisin vitro. CD28 may act to a limited extent as an adhesion molecule, though apparently not by pairing with B7.1 or B7.2. It is more likely that ligation of CD28 under certain conditions modulates the expre

ISSN:0014-2980    

DOI:10.1002/eji.1830250205

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractWe have studied the patterns of antigens recognized by autologous cytolytic T lymphocytes (CTL) on two melanoma cell lines derived from metastases that were removed from patient LB33 at several years distance. Cell line LB33‐MEL. A was obtained after surgery in 1988. A large number of CTL clones directed against LB33‐MEL. A was obtained with blood lymphocytes collected from the patient in 1990.In vitroselection of melanoma cells that were resistant to these CTL clones indicated that at least five different antigens were recognized on LB33‐MEL. A by autologous CTL. Four of these antigens were found to be presented by HLA‐A28, B13, B44 and Cw6, respectively. The patient remained disease‐free until 1993 when a metastasis was detected and was used to obtain cell line LB33‐MEL. B. This cell line proved resistant to lysis by all the CTL clones directed against the LB33‐MEL. A cells and showed no expression of HLA class I molecules except for HLA‐A24. Using LB33‐MEL. B cells to stimulate blood lymphocytes collected from the patient in 1994 we derived CTL clones that lysed these cells. All these CTL clones recognized a new antigen presented by HLA‐A24. These results suggest that in patient LB33 the melanoma cells may have lost the expression of several HLA molecules under the selective pressure of an anti

ISSN:0014-2980    

DOI:10.1002/eji.1830250206

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractNeutralizing autoantibodies to interleukin‐6 (aAb‐IL‐6) have been reported in healthy individuals, in patients with autoimmune diseases, and in pharmaceutically prepared pooled IgG (IVIg). We investigated the ability of aAb‐IL‐6 derived from IVIg to interfere with IL‐6 binding to the undifferentiated monocytic cell line U‐937. High‐affinity aAb‐IL‐6, primarily of the IgG1subclass, constituted approximately 1:106of the total IgG in IVIg preparations. IL‐6 binding to cellular receptors was strongly inhibited by one class of aAb‐IL‐6. These antibodies recognized epitope(s) on IL‐6 essential for the binding of IL‐6 to the α subunit of the IL‐6 receptor (IL‐6R). Another class of aAb‐IL‐6 recognized epitope(s) on IL‐6, which is not essential for the binding to IL‐6R but nevertheless important for the formation of high‐affinity cellular IL‐6 binding. These antibodies presumably interfered with the association of IL‐6 receptor β chains (gp130) with IL‐6/IL‐6R complexes, implicating that small IL‐6/aAb‐IL‐6 immune complexes bound saturably (low affinity/high capacity) to cellular IL‐6 receptors. There was no detectable binding of IL‐6 through aAb‐IL‐6 and Fc receptors on U‐937, and IVIg had no direct IL‐6 receptor antagonizing activity. Dissociation kinetics of IL‐6/aAb‐IL‐6 complexes at 37 °C revealed that IL‐6 was liberated from 75% of the aAb‐IL‐6 with a half‐time (t/2) ≈ 4 h but bound almost irreversibly to the remaining aAb‐IL‐6 (t/2>20 h). Cellular IL‐6 uptake and degradation was suppressed by aAb‐IL‐6. Taken together, the data suggest that loss of immunologic tolerance against IL‐6 might be a novel physiological mechanism by which IL‐6 activities are effectively attenuated. Finally, binding of IL‐6 in complex with IgG1 aAb‐IL‐6 on cells expressing IL‐6 receptors implicates

ISSN:0014-2980    

DOI:10.1002/eji.1830250207

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractTo study the relevance of γδ T cells in multiple sclerosis (MS) we analyzed the T cell receptor (TCR) γδ repertoire and the antigen reactivity of γδ clones isolated from cerebrospinal fluid (CSF). In T cell cultures derived from CSF we found an increased percentage of Vδ1+cells as compared to peripheral blood of the same donors. Phenotypic analysis of cells from MS CSF with Vγ‐ and Vγ‐specific monoclonal antibodies (mAb) showed that the Vγ1 chain is most frequently associated with γ chains belonging to the VγI family. Sequence analysis of TCR genes revealed heterogeneity of junctional regions in both δ and γ genes indicating polyclonal expansion. γδ clones were established and some recognized glioblastoma, astrocytoma or monocytic cell lines. Stimulation with these targets induced serine esterase release and lymphokine expression characteristic of the TH0‐like phenotype. Remarkably, these tumor‐reactive γδ cells were not detected in the peripheral blood using PCR oligotyping, but were found in other CSF lines independently established from the same MS patient. Altogether, these results demonstrate that in the CSF there is a skewed TCR γδ repertoire and suggest that γδ cells reacting against brain‐derived antigens m

ISSN:0014-2980    

DOI:10.1002/eji.1830250208

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractLittle is known about the etiology of the graft‐versus‐host disease (GVHD) occuring after transplantation of lymphoid cells incompatible for minor histocompatibility antigens (mHAg). Here, the potential role of host endogenous mouse mammary tumor virus (Mtv)‐encoded superantigens (SAg) in the development of lethal GVHD was investigated. In a combination of H‐2dcompatible mice, the presence ofMtv‐7and, to a lesser extent, ofMtv‐1, ‐6, ‐13in the host genome, highly increases the rate and severity of GVHD. Kinetic analyses of TCR Vβ gene expression in recipient mice consistently indicate a dramatic but transient infiltration of GVHD target organs byMtv‐SAg‐specific T cells. This suggests that SAg encoded by endogenousMtv, by activating large T cell subpopulations, would help the response to mHAg and thus play a critical role in the initiation or

ISSN:0014-2980    

DOI:10.1002/eji.1830250209

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractFour monoclonal antibodies (mAb) termed NKTA255, NKTA72, 1F1 and 1B1 were selected on the basis of their ability to inhibit the cytolytic activity of natural killer (NK) cell clones against P815 target cells. These mAb selectively reacted with normal or tumor cells of hematopoietic origin and displayed a cellular distribution similar to that of CD45 or CD11a/CD18 antigens. Immunoprecipitation experiments showed that they reacted with molecules with an apparent molecular mass of 40 kDa under both reducing and nonreducing conditions (“p40” molecules), thus differing from CD45 or CD11a/CD18 antigens as well as from the “inhibitory” receptors for HLA class I molecules (i.e. p58, CD94 and NKB1 molecules). Double‐immunofluorescence analysis of peripheral blood mononuclear cells allowed the identification of three distinct populations on the basis of the fluorescence intensity of cells stained with anti‐p40 mAb. p40brightcells were homogeneously HLA‐DR‐positive, p40mediumcells were HLA‐DR‐negative but co‐expressed CD56 antigens, while p40dullcells were all CD3+. Anti‐p40 mAb strongly inhibited the lysis of K562 target cells, mediated by fresh NK cells, as well as the lysis of P815 target cells by NK or T cell clones. In addition, in redirected killing assays, anti‐p40 mAb strongly reduced the anti‐CD16 mAb‐induced cytolytic activity of NK cell clones. On the contrary, they did not inhibit either the anti‐CD3 or anti‐T cell receptor mAb‐mediated cytolytic activity of T cell clones or the lysis of allogeneic phytohemagglutinin blasts mediated by specific cytolytic T cell clones. The p40‐induced inhibition of the NK cytotoxicity required optimal cross‐linking, as anti‐p40 mAb could inhibit the lysis of Fcγ receptor (FcγR)‐positive but not of FcγR‐negative target cells. In addition, (Fab')2fragments of anti‐p40 mAb failed to inhibit the lysis of FcγR‐positive target cells. In conclusion, p40 molecules represent a new type of inhibitory surface molecule that appears to play a

ISSN:0014-2980    

DOI:10.1002/eji.1830250210

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractKnock‐out mice with defined major histocompatibility complex (MHC) deficiencies were infected intravenously withMycobacterium bovisbacille Calmette Guérin (M. bovisBCG) to assess the relative impact of MHC class I‐ and II‐dependent immune responses. Heterozygous control mice were capable of controlling growth ofM. bovisBCG, although infection progressed chronically, as assessed by determination of colony‐forming units. Furthermore, infected controls developed granulomatous lesions at the site of mycobacterial growth and delayed‐type hypersensitivity (DTH) reactions after challenge with purified protein derivative of tuberculin.In vitro, spleen cells from heterozygous control mice produced high concentrations of interferon‐γ (IFN‐γ) after restimulation with mycobacterial antigens. In contrast, the MHC class II‐deficient Aβ−/−mice, which are virtually devoid of functional CD4 T cells, succumbed toM. bovisBCG infection. Furthermore, Aβ−/−mice lacked DTH reactions to tuberculin and only few minute picnotic lesions were formed in livers of infected mice. Finally, spleen cells from infected Aβ−/−mice failed to produce measurable IFN‐γ concentrations after restimulationin vitrowith various mycobacterial antigen preparations. The capacity of β2‐microglobulin (β2m)‐deficient mice, which are devoid of CD8α/β T cells, to inhibit growth ofM. bovisBCG was only slightly affected at low inocula, although significantly higher colony‐forming units were detected in spleens. These knock‐out mice developed strong DTH responses to tuberculin and their spleen cells produced high levels of IFN‐γ once reactivated by mycobacterial antigens. Furthermore, in livers of infected β2m‐deficient mice, extravascular infiltrates developed which were more diffuse than those in infected control littermates. Remarkably, the β2m‐deficient mice were substantially more susceptible to higher inocula ofM. bovisBCG than their control littermates. Our data formally prove the essential role of MHC class II‐dependent immune mechanisms in all relevant aspects of immunity toM. bovisBCG. In addition, our findings emphasize an important contribution of MHC class I‐dependent immunity to effective anti‐mycobacterial protection. We assume that CD4 T cells are highly effective in containingM. bovisBCG within distinct granulomatous lesions, but fail to eradicate their intracellular pathogens. It appears most

ISSN:0014-2980    

DOI:10.1002/eji.1830250211

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY