摘要:

AbstractTolerant T cells are characterized by their partial or full resistance to activation by antigen. We investigated whether tolerant T cells were still receptive to further tolerogenic signals. T cells expressing a transgenic T cell receptor (TCR) specific for the major histocompatibility complex (MHC) class I molecule Kbwere deleted in mice carrying Kbbut not in mice expressing the mutant Kb‐molecule Kbm1[TCR (H‐2bm1 × k) mice]. These T cells were tolerantin vivobut could be activatedin vitroby the Kbantigen. Thisin vitroreactivity was abolished after the tolerant T cells encountered Kb‐positive cells that had been intravenously injected. Furthermore, in TCR (H‐2bm1 × k), mice expressing Kbonly on hepatocytes, no T lymphocytes bearing the transgenic TCR could be found in the periphery, indicating that the additional contact with Kbon hepatocytes led to deletion of the tolerant T cells. These findings demonstrate that tolerance induction can be a multi‐s

ISSN:0014-2980    

DOI:10.1002/eji.1830240202

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractGp41, the transmembrane glycoprotein of HIV‐1, has been shown to be non‐covalently associated with gp120. We have shown that it also binds human C1q. To analyze the interaction site(s) of gp41 with these two molecules, we established an enzyme‐linked immunosorbent assay (ELISA) system using recombinant soluble gp41 [amino acids (aa) 539–684] and peptides thereof. In the cell‐external part of gp41 three sites (aa 526–538, aa 590–613 and aa 625–655) were found to bind both gp120 and C1q. That gp120 and C1q use the same sites was evidenced by the fact that these proteins competed with each other for the same sites in recombinant soluble gp41 and gp41 peptides. It could be demonstrated by ELISA, that rabbit antibodies against human C1q recognized gp120, and rabbit antibodies against gp120 cross‐reacted with C1q. Rabbit anti‐gp120, HIV‐1‐positive human sera and anti‐gp120 obtained from such sera agglutinated sensitized sheep erythrocytes with human C1q (EAC1q).These data suggest that in addition to functional homology between C1q and gp120 structural homology between these two molecules exists. This molecular mimicry might become the basis for immunologically rele

ISSN:0014-2980    

DOI:10.1002/eji.1830240203

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractThe aim of the present study was to explore the role of post‐translational isoprenoid modification of cellular proteins in the proliferation of human lymphocytes. We here report that treatment of phytohemagglutinin‐stimulated peripheral blood mononuclear cells with monoterpenes includingd‐limonene, perillic acid and perillyl alcohol (0.5–5 mM) which selectively inhibit the isoprenylation of 21–26‐kDa proteins resulted in a dose‐dependent inhibition of DNA synthesis. Cell cycle analysis revealed that perillic acid arrested cells in G1and prevented cells from entering S phase in a manner similar to that induced by the specific 3‐hydroxy‐3‐methylglutaryl‐CoA reductase inhibitor, compactin. However, unlike compactin, the perillic acid‐induced effects on lymphocyte proliferation were not prevented by addition of mevalonate. We also examined the incorporation of [3H]mevalonate into proteins in resting and phytohemagglutinin‐stimulated lymphocytes during the first 30 h of culture. While in unstimulated lymphocytes radioactivity was predominantly incorporated into a cluster of 21–26‐kDa proteins, mitogenic stimulation was associated with a striking increase in [3H]mevalonate incorporation into a protein (≈︁68 kDa) with migration characteristics similar to that of nuclear lamin B. Treatment of phytohemagglutinin‐stimulated lymphocytes with 5 mMd‐limonene, 2.5 mM perillic acid or 1.25 mM perillyl alcohol strongly suppressed [3H]mevalonate‐labeling of proteins to a degree that correlated with the level of DNA synthesis inhibition. These findings suggest that those mevalonate‐derived products required for lymphocyte proliferation may include one or more isoprenylated proteins and that the isoprenylation of these protei

ISSN:0014-2980    

DOI:10.1002/eji.1830240204

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractAn interferon (IFN)‐γ immunoreactive molecule, localized to small neurons in peripheral sensory ganglia (N‐IFN‐γ), has been detected with two mouse monoclonal antibodies (DB1 and DB16) directed against different epitopes of rat IFN‐γ. To define N‐IFN‐γ with regard to its protein characteristics and bioactivities, DB1 and DB16 were used to purify N‐IFN‐γ from rat trigeminal ganglia in a two‐step sequential antibody‐affinity procedure. Sodium dodecylsulfate polyacrylamide gel electrophoresis (PAGE) and silver staining of purified N‐IFN‐γ displayed three bands with an approximate molecular mass of 66, 62 and 54 kDa. The N‐IFN‐γ bioactivity was confined to the protein stained on gel when native material was run on PAGE. Biological effects of pure N‐IFN‐γ were examined and compared with those of lymphocyte‐derived recombinant IFN‐γ. N‐IFN‐γ had antiviral effectsin vitroand induced major histocompatibility complex class I and II antigens on macrophages and in cells in skeletal muscle cell cultures. N‐IFN‐γ also stimulated myoblast proliferation and affected cholinergic receptor distribution on myotubes similar to recombinant IFN‐γ. Both molecules potently stimulatedTrypanosoma brucei bruceigrowth. These data suggest that, although N‐IFN‐γ is a protein distinct from lymphocyte‐derived IFN‐γ, the two molecules have enough structural similarities to allow for antibody recognition of at least two epitopes, and actio

ISSN:0014-2980    

DOI:10.1002/eji.1830240205

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractWe examined the ability of epidermal Langerhans cells and splenic dendritic cells to present tumor‐associated antigens (Ag) to immune T cells. Methylcholanthrene (MCA)‐induced subcutaneous fibrosarcomas derived from C57BL/6 mice were used as tumor models. Our data demonstrate that both murine Langerhans cells and splenic dendritic cells have the capacity to present tumor‐associated Ag to primed T cells. We found that variously treated tumor preparations (irradiated viable tumor cells, irradiated frozen‐stored tumor cells, mitomycin C‐treated viable tumor cells, and snap freeze‐thawed tumor cell lysates) can be utilized for tumor Ag‐pulsing. Primed CD4+T cells demonstratedin vitrospecificity towards their respective tumors and did not cross‐react to other syngeneic MCA‐induced or non‐MCA‐induced tumors. The T cell proliferative response critically depended on the presence of immune CD4+T cells. We discuss the implications of these findings for the adoptive immunotherapy of cancer usi

ISSN:0014-2980    

DOI:10.1002/eji.1830240206

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractThe proliferative response of peripheral blood T cells to the spirochete,Borrelia burgdorferi, can be as pronounced in unexposed normal individuals as it is in Lyme disease patients. This finding was observed using three geographically distinct isolates ofB. burgdorferi. The response is not due to a lipopolysaccharide effect of the spirochete, is sensitive to Proteinase K, and requires antigen processing. It does not result from cross‐reactivity of memory T cells that may be reactive to another antigen; the proliferative response toB. burgdorferiis equally distributed between naive (CD29−, CD45RO−) and memory (CD29+, CD45RO+) T cells, whereas the tetanus response is confined to the memory subset. In support of this notion, cord blood specimens that contain almost entirely naive T cells, respond as vigorously toB. burgdorferias T cells from normal adult peripheral blood. A large panel of CD4+T cell clones has been derived that are specific forB. burgdorferi. The majority of these clones are reactive toB. burgdorferiin the presence only of autologous HLA‐DR molecules. Collectively, these data suggest that the T cell response from normal individuals is more likely due to multiple antigenic epitopes within Borrelial proteins than a superantigen r

ISSN:0014-2980    

DOI:10.1002/eji.1830240207

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractGroup I Burkitt's lymphoma cell lines and the B104 lymphoma cell line which expresses a phenotype of immature B cells undergo apoptosis after cross‐linking of their surface immunoglobulin (Ig) receptors or after exposure to a calcium ionophore, while protein kinase C (PKC)‐activating phorbol esters prevent such apoptosis. We show here that blockade of the phosphoprotein phosphatase calcineurin or phosphatase 2B by cyclosporin A (CsA) also protects these B cell lines against Ca2+‐dependent apoptosis but not against apoptosis triggered by the PKC inhibitor chelerythrine or by serum deprivation. Okadaic acid, an inhibitor of phosphatases 1, 2A and 2C was ineffective. Among a series of human cytokines tested, only interferon‐α and tumor necrosis factor‐α were shown to protect against Ca2+‐dependent apoptosis when used alone or in combination with CsA. In contrast to phorbol esters which block the progression into the S/G2phases of the cell cycle, CsA partially restored the proliferation of cells exposed to the calcium ionophore. Altogether these data provide indirect evidence for the control of B cell apoptosis by the serine/threonine phosphorylation status of yet undefined key cellul

ISSN:0014-2980    

DOI:10.1002/eji.1830240208

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractIn the present study, we examined the participation of CD40 ligand (L)‐CD40 interaction in T cell‐dependent B cell responses. To this end, purified B lymphocytes were cultured over irradiated CD4+cloned T cells activated with immobilized anti‐CD3 antibody. The anti‐CD40 mAb 89 strongly blocked, in a specific fashion, both proliferation and Ig secretion of tonsil B cells. Interestingly, proliferation of surface (s)IgD+B cell was significantly less inhibited by anti‐CD40 than that of sIgD−cells. Preactivated T cells induced B cells to grow and secrete immunoglobulins preferentially in response to IL‐2. This contrasts with the CD40 system where B cells are essentially responsive to IL‐4 and IL‐10 but not to IL‐2 alone. Collectively, these data indicate that CD40L‐CD40 interaction plays an important role in IL‐2‐mediated T cell‐dependent B cell responses. However, the activation of a subset of sIgD+cells may be inde

ISSN:0014-2980    

DOI:10.1002/eji.1830240209

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractF1hybrid resistance (HR) to parental bone marrow grafts is mediated by natural killer (NK) cells, and thought to be controlled by the non‐class I hemopoietic histocompatibility (Hh) genes linked to the major histocompatibility complex (MHC). However, as in thein vitroNK cytotoxicity against hemopoietic targets, expression of certain class I MHC molecules does affect HR, although mechanisms underlying such an effect are not understood. In this study, we examine the relevance of the “self/non‐self” property of class I molecules and the molecular domains responsible for this function. H‐2b/Hh‐1blymphoma cells were transfected with class 1 H‐2Ddor Ldgene, and its effect on the Hh‐1 phenotype was examined by testing the transfectant's ability to competitively inhibit thein vivorejection of parental H‐2b/Hh‐1bbone marrow grafts by irradiated F1hybrid hosts. Multiple independent clones of transfectants show that the genomic or cDNA of the Ddgene, but not of Ld, renders the Hh‐1b‐positive cells incapable of inhibiting HR in F1mice, although both genes belong to the same region of the same haplotype. The same effect could be observed not only in H‐2b/dF1mice for which Ddand Ldare self, but also in H‐2b/kF1mice for which both Ddand Ldare non‐self. Thus, this function of the Ddmolecule is an intrinsic property, not necessarily related to its self/non‐self characteristic relative to the effector cells. Furthermore, given the nature of the assay used in this study, the results favor a “target interference” model as the underlying mechanism of the Ddeffect. To locate the relevant domain(s) of the Ddmolecule, mutant Ddm1gene was tested and found to have the same effect as the non‐mutant Dd. Ddm1is a hybrid molecule between Ddand Ld, sharing with Ddonly the α1 domain and a portion of the α2 domain. The two N‐terminal domains of Ddm1differ from those of Ddby three amino acid substitutions, two of which affect

ISSN:0014-2980    

DOI:10.1002/eji.1830240210

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractThe influence of interleukin (IL)‐12 and IL‐4 on the differentiation of naive CD4+T cells was studied in an accessory cell‐freein vitrosystem. Dense CD4+T cells were purified from unimmunized mice and activated using immobilized anti‐CD3 monoclonal antibodies (mAb) in the presence of IL‐4, IL‐12, or a combination of both cytokines, and restimulated after 6 days by re‐exposure to anti‐CD3‐coated culture wells. T cells initially activated in the presence of IL‐4 produced substantial amounts of IL‐4 and trace amounts of interferon (IFN)‐γ after restimulation at day 6 with plate‐bound anti‐CD3 mAb. By contrast, T cells primed in the presence of IL‐12 produced high levels of IFN‐γ and only minimal amounts of IL‐4, thus indicating that IL‐12 and IL‐4 by acting directly on stimulated naive CD4+T cells support the development of TH1 and TH2 cells, respectively. When naive CD4+T cells were stimulated in the presence of IL‐12 together with IL‐4 in comparable concentrations, the effect of IL‐12 on TH1 differentiation was largely inhibited by IL‐4. On the other hand, IL‐12 exerted no inhibitory effect on IL‐4‐induced TH2 differentiation but rather enhanced the production of IL‐4 after restimulation of the respective T cells. Decreasing amounts of IL‐4 in combination with a high level of IL‐12 led to an increasing production of IFN‐γ by the emerging T cells and, simultaneously, to a relatively high production of IL‐4. These data were confirmed by time‐course experiments which revealed that the delayed addition of IL‐4 to IL‐12‐primed T cell cultures resulted in a gradual restoration of IFN‐γ production whereas in parallel the secretion of IL‐4 was not reduced over a wide period of delay (6–72 h). These results, therefore, demonstrate that (a) IL‐4 dominates the effect of IL‐12, (b) IL‐12 promotes the development of TH1 cells; however, in the presence of IL‐12 and relatively high levels of IL‐4 also the development of TH2‐like cells is slightly but significantly enhanced by IL‐12, and (c) high amounts of IL‐12 in combination with relatively low levels of IL‐4 give rise to a

ISSN:0014-2980    

DOI:10.1002/eji.1830240211

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY