摘要:

AbstractAfter immunization of BALB/c mice with a low molecular mass fraction (FrD; ≦ 31 kDa) isolated from a soluble extract ofLeishmania majorpromastigotes, a panel of monoclonal antibodies (mAb) was obtained. One of these antibodies (mAb 9C) recognized a cytosol‐associated antigen fromL. majorof approximately 21 kDa as shown by Western blot and immunoprecipitation. In addition, mAb 9C reacted with surface structures of murine splenic T cells and T cell clones. Reactivity was confined to murine cells, but was not strain restricted. Immunoprecipitation studies and surface‐labeling experiments with CD4+T cell clones and the T cell receptor (TCR)−CD3−T cell line TG40 transfected with V α/β chains from human TCR and concomitant co‐expression of murine CD3 suggested that mAb 9C binds to an epitope located within the murine CD3‐TCR complex. In addition, mAb 9C induced strong T cell proliferation. We conclude thatL. majorparasites share an epitope with the murine CD3‐TCR complex which is functionally important for

ISSN:0014-2980    

DOI:10.1002/eji.1830240302

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractIn this study we have investigated whether anti‐CD3‐induced human T cell help for immunoglobulin production could be enhanced by co‐stimulation of the T cells via other T cell surface molecules, and the contribution of CD40‐CD40 ligand interaction to the execution of T helper effector function induced by these different stimulatory signals. In a system in which irradiated tonsillar T cells were stimulated with immobilized anti‐CD3 monoclonal antibody (mAb), it was found that ligation of CD2 with a mitogenic pair of mAb considerably enhanced anti‐CD3‐induced T cell help for immunoglobulin production. Likewise, ligation of CD28 with mAb enhanced T helper activity, although to a lesser extent. Upon addition of anti‐CD28 and anti‐CD2 mAb together, an even higher immunoglobulin production was observed. This combination resulted in a four‐ to fivefold increase in immunoglobulin production as compared to cultures in which T cells were stimulated with anti‐CD3 mAb alone. The effect of ligation with B7, the natural ligand of CD28, was studied in a system which utilizes the presentation of anti‐CD3 mAb on human FcγRII‐expressing mouse fibroblasts which were co‐transfected with human B7. It appeared that B7 could stimulate help for immunoglobulin production much more efficiently than ligation of CD28 with mAb did. Physical separation of B cells from T cells led to complete abrogation of immunoglobulin production. Blocking of CD40 with specific mAb, which have no intrinsic B cell stimulatory properties, or the CD40 ligand with a soluble CD40‐human IgM fusion protein, resulted in dose‐dependent, but only partial, inhibition of T cell‐dependent immunoglobulin production with all modes of T cell activation tested. A clear correlation was found between the induction of CD40 ligand expression on the T cells by the different modes of co‐stimulation and subsequent immunoglobulin production by the B cells. It is concluded that ligation of CD28 and/or CTLA‐4, and of CD2 can generate co‐stimulatory signals for T cell help for immunoglobulin production, which was found to be only partially depen

ISSN:0014-2980    

DOI:10.1002/eji.1830240303

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractWhereas C5a is a well‐established potent activator of eosinophils, the functional role of C3a in the activation of eosinophils is, so far, poorly understood, Here, the activation of human eosinophils stimulated with C3a was analyzed and compared to C5a activation. Flow‐cytometrical measurements revealed that stimulation of eosinophils by C3a resulted in a transient elevation of the intracellular calcium concentration ([Ca2+]i) in a dose‐dependent manner. In addition, the production of reactive oxygen radical species (ROS) of eosinophils after C3a and C5a stimulation was measured by lucigenin‐dependent chemiluminescence and quantified by superoxide dimutase‐inhibitable reduction of ferricytochrom C. Half maximal and maximal ROS production in response to C3a was observed at 50 ng/ml and 1000 ng/ml, respectively, whereas C3a‐desArg was inactive. To ensure that C3a stimulation was not caused by contamination with C5a, monoclonal antibodies were used to demonstrate the specificity of C3a. The effect of C3a was completely abolished in the presence of monovalent antigen‐binding fragments of a functionally blocking anti‐C3a monoclonal antibody. In addition, blockade of the C5a receptor by the monoclonal anti‐C5a receptor antibody S5/1 totally inhibited the C5a‐evoked ROS production, whereas the C3a response in the presence of S5/1 was unaffected. Finally, desensitization experiments revealed a homologous desensitization of C3a after restimulation with C3a. In contrast, no cross‐desensitization was observed upon stimulation with C5a. Furthermore, the C3a‐ and C5a‐induced production of ROS of eosinophils was totally inhibited by pertussis toxin, indicating the involvement of guanine nucleotide‐binding proteins (Gi‐proteins). In summary, these results demonstrate that C3a is a potent activator for eosinophils initiating transient [Ca2+]ichanges and production of reactive oxygen species. C3a therefore may play a part in the pathophysiology of diseases with eosinop

ISSN:0014-2980    

DOI:10.1002/eji.1830240304

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractIt is well established that triggering interleukin‐2 (IL‐2) secretion by helper T cells requires the T cell to receive at least two discrete signals. One signal is transduced by the CD3 complex, usually as the result of T cell receptor (TcR) occupancy, the second, or co‐stimulatory, signal involves a non‐cognate interaction between cell surface accessory molecules on the antigen‐presenting cell (APC) and the T cell. A molecular interaction that has been implicated in the provision of co‐stimulatory signals is that between B7/BB1 on the APC and its ligands, CD28 and CTL‐A4 on the T cell.We have studied the ability of HLA‐class II antigen‐positive human T cells and a population of DR1‐expressing transfected human fibroblasts to stimulate a proliferative response by human T cell clones, and by freshly isolated peripheral blood T cells. Despite their high levels of B7 expression, the T cell clones, were unable to induce proliferation or IL‐2 secretion by DR‐restricted, antigen‐specific T cells. In contrast, the DR1‐expressing transfectants, that were B7 negative, induced a strong proliferative response. When these two populations of DR‐expressing cells were used to stimulate a primary alloresponse the results were reversed, in that the T cell clones induced a strong alloresponse but the transfected fibroblasts induced no proliferation.These results suggest that the expression of B7 may be necessary for co‐stimulation of unprimed T cells, but not of established T cell clones. Furthermore the data show that the expression of B7 by an APC does not necessarily lead to IL‐2 production or protection from the induction of tolerance. The mechanisms responsible for the inability of these T cells to provide full activation signals when used as APC

ISSN:0014-2980    

DOI:10.1002/eji.1830240305

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractIn the present study the requirements forin vitroinfection of antigen‐specific CD8+cytotoxic T lymphocytes (CTL) with human immunodeficiency virus –1(HIV‐1) were investigated. CD3+CD8+CD4−HIV‐1 nef‐specific CTL become infected with HIV‐1 after short‐term co‐culture with HLA‐matched HIV‐1‐infected CD20+B lymphoblastoid cells (B‐LCL) which are specifically killed. Similar results were observed with an allospecific CD8+CTL population. In addition, co‐culture experiments showed that once infected with HIV‐1, these CD8+CTL could spread the infection further to uninfected CD4+lymphocytes. In contrast, CD8+CTL did not become infected with HIV‐1 when co‐cultured with HLA‐mismatched HIV‐1‐infected B‐LCL which are not killed.These observationsin vitrocould have relevance in peripheral lymphoid organs contributing to the progressive decrease of HIV‐specific CD8+CTL activity that

ISSN:0014-2980    

DOI:10.1002/eji.1830240306

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractMurine bone marrow‐derived hemopoietic cells, dependent on interleukin (IL)‐3 for their growth in culture, undergo programmed cell death, or apoptosis, upon cytokine withdrawal. The topoisomerase II inhibitor etoposide causes a more rapid onset of apoptosis in the IL‐3‐dependent cell line BAF3, deprived of IL‐3. This acceleration of apoptosis by etoposide is prevented by inhibitors of RNA and protein synthesis and by the nucleases inhibitor aurintricarboxylic acid. The presence of IL‐3 or overexpression of the oncogene bcl‐2 caused a marked delay in the induction of apoptosis by etoposide, acting in a cooperative manner. The time at which the apoptotic program is irreversible is close to the induction of endonuclease activity as indicated by the effect of the delayed addition of either IL‐3 or aurintricarboxylic acid on the onset of apoptosis, suggesting the importance of endonuclease activation in the development of apoptosis in he

ISSN:0014-2980    

DOI:10.1002/eji.1830240307

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractSite‐directed mutagenesis has been used to change amino acid residues of a recombinant Fc‐hinge fragment derived from the murine immunoglobulin (Ig)G1 molecule, and the effects of these mutations on the pharmacokinetics of the Fc‐hinge fragment have been determined. Specifically, Ile‐253, His‐310 and Gln‐311 of the CH2 domain and His‐433 and Asn‐434 of the CH3 domain have been changed. In the three dimensional structure of an antibody, these amino acids are in close proximity to each other at the CH2‐CH3 domain interface. The mutated Fc‐hinge fragments have been purified from recombinantEscherichia colicells and their pharmacokinetic parameters determined in mice and compared with those of the wild‐type Fc‐hinge fragment. The results show that the site of the IgG1 molecule that controls the catabolic rate (the ‘catabolic site’) is located at the CH2‐CH3 domain interface and overlaps with the Staphylo

ISSN:0014-2980    

DOI:10.1002/eji.1830240308

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractWe have previously defined four murine CD4+peripheral T cell subsets, fractions (Fr.) I – IV, based on expression of the 6C10 and 3G11 determinants (Hayakawa, K. and Hardy, R. R.,J. Exp. Med.1988.168: 1825). These subsets also show distinctive levels of other cell surface markers: the two minor subsets, Fr. III and Fr. IV, are both CD45RBlow/‐, L‐selectin (Mel‐14)−and CD44hi, characteristic of secondary T cells. The patterns and levels of cytokine production by individual cells in each subset were determined by bioassay for interleukin (IL)‐2/IL‐4 or IL‐4/interferon (IFN)‐γ production after anti‐CD3 stimulation. Our data revealed that these four phenotypically defined subsets largely coincide with clusters of cells showing uniform distinctive cytokine profiles,i.e.IL‐2+/IFN‐γ−/IL‐4−(Fr. I and Fr. II, L‐selectin+), IL‐2+/IFN‐γ+/IL‐4+(Fr. III, L‐selectin−), and IL‐2−/IFN‐γlow/‐/IL‐4+(Fr. IV, L‐selectin−). Besides these subsets, an L‐selectin‐negative cell subfraction within Fr. II appears to represent a transitional population between the IL‐2+/IFN‐γ−/IL‐4−stage and the IL‐2+/IFN‐γ+/IL‐4+stage. Taken together, these results demonstrate the presence of two IL‐4+secondary T cell subsets with distinct cytokine production patterns, and show that the majority of IL‐4+cells found in healthy a

ISSN:0014-2980    

DOI:10.1002/eji.1830240309

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractT cells freshly isolated from the peripheral lymph nodes of autoimmune MRLlpr/lpr (lpr)mice contain a large proportion of functionally non‐mature T cell receptor (TcR)‐αβ+CD3+CD2−CD4−CD8−T cells displaying the B cell isoform of CD45, B220. These cells are hyporesponsive as defined by minimal interleukin‐2 (IL‐2) production and proliferation in response to stimulation. However, increased levels of inositol phosphates and a rapid mobilization of Ca2+do occur upon stimulation of the TcR/CD3 complex. Furthermore,lprCD4−CD8−T cells contain high levels of transcripts for the src‐family tyrosine kinase p59fyn, and express a constitutively tyrosine‐phosphorylated CD3‐ζ chain. These features bear a certain resemblance to anergized T cells. These similarities are extended to show that culturing oflprCD4−CD8−T cells in the presence of IL‐2 in combination with phorbol 12‐myristate 13‐acetate and ionomycin initiates cell cycling and results in the gain of function; re‐stimulation now yields IL‐2‐dependent proliferation in the absence of exogenous IL‐2. In parallel with this gain in function, the population of cells obtained after 1 week in culture retains the TcR‐αβ+CD4−CD8−phenotype, yet displays increased levels of CD2, decreased surface B220, and normal amounts of p59fyn‐specific transcripts. These findings show that cell cycling is associated with the recovery of functional capabilities bylprCD4−CD8−T cells and is closely allied with surface CD2 expression. Thus

ISSN:0014-2980    

DOI:10.1002/eji.1830240310

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractThe relationship between CD26/dipeptidyl peptidase IV, an ectopeptidase involved in T cell activation, and the binding protein for adenosine deaminase (ADAbp) was studied. Monoclonal antibodies (mAb) against CD26 and ADAbp, respectively, showed a similar binding profile on various lymphocyte subsets from the peripheral blood. The adenosine deaminase (ADA) itself blocked the binding of a specific set of anti‐CD26 mAb (among these the anti‐TA5.9 mAb) on lymphocytic CD26; ADA also hindered the binding of soluble CD26 to the same immobilized anti‐CD26 mAb. In addition, the interaction between immobilized ADA and purified CD26/DPP IV was inhibited by the anti‐TA5.9 mAb. ADA did not inhibit the specific peptidase activity of CD26. Neither soluble nor immobilized ADA was able to down‐modulate CD26 on the lymphocyte surface. Our data thus confirm the identity between ADAbp and CD26 and identify some epitopes, crucial in the binding of AD

ISSN:0014-2980    

DOI:10.1002/eji.1830240311

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY