bluuebunny/crossref_metadata_2025_split huggingface dataset:
Efficient recognition by rat T cell clones of an epitope of mycobacterial hsp 65 inserted in Escherichia coli outer membrane protein PhoE
Authors: Hogervorst Els J. M. , Agterberg Marja , P. A. Wagenaar Josée , Adriaanse HenriëTte , Boog Claire J. P. , Zee Ruurd Van Der , Van Embden Jan D. A. , Eden Willem Van , Tommassen Jan 
Published: March 2007

AbstractPhoE is a pore‐forming protein, abundantly expressed in the Escherichia coli outer membrane. Previous investigations have shown the possibility of inserting antigenic determinants in cell surface‐exposed regions of PhoE by recombinant DNA techniques without disturbing the biogenesis and the functioning of the protein. This method proved to be successful for foot‐and‐mouth disease virus B cell determinants.We have now shown for the first time that PhoE can also be used as a carrier molecule for Tcell epitopes. A well‐characterized Tcell epitope (180–188) of the 65‐kDa heat‐shock protein (hsp 65) of Mycobacterium tuberculosis was expressed in PhoE and tested for recognition by specific Tcell clones. Specific and efficient T cell proliferation was found after stimulation with this protein construct in vitro. Interestingly, paraformaldehyde fixation of antigen‐presenting cells did not abrogate Tcell recogition. Thus, in contrast to hsp 65 itself, recognition of epitope 180–188 in the context of PhoE appeared to be independent of antigen‐processing events. At the level of polyclonal Tcell responses the epitope in the context of PhoE is recognized more efficiently than 180–188 as synthetic peptide or in the context of the hsp 65 molecule itself. These findings indicate that PhoE may serve as attractive vaccine carrier not only for B, but also for Tcell epitopes. Furthermore, the possibility for expression of PhoE constructs in attenuated Salmonella typhimurium strains offers the exciting prospect of new types of live oral vaccines expressing selected combinations of B and Tcell epitopes.
HLA class II molecules on monocytes regulate T cell proliferation through physical interaction in the CD3 activation pathway
Authors: Ruggiero Giuseppina , Racioppi Luigi , Manzo Ciro , Pirozzi Giuseppe , D'Oro Ugo , Ferrone Soldano , Zappacosta Serafino , Fontana Silvia 
Published: March 2007

AbstractHLA class II molecules are involved in the OKT3‐induced T cell activation, since monoclonal antibodies (mAb) to monomorphic determinants of class II antigens are able to inhibit T cell proliferation. This effect involves several of the events leading to T cell activation and proliferation, i.e. interleukin (IL) 1, IL 6 and IL 2 secretion and IL 2 receptor expression. The main target of the inhibition is represented by monocytes, and the interference of anti‐class II mAb in the direct interaction of monocytes with T cells is likely to play a relevant role in the inhibition mechanism. To test this hypothesis, we investigated in the present study the effect of anti‐class II mAb on the proliferation of T cells stimulated with mAb OKT3 in the presence of paraformaldehyde‐treated monocytes. We show that the inhibition of proliferation is specific and dose dependent, and seems to involve particular class II epitopes. Addition of fixed monocytes to inhibited T cell cultures restores proliferation to a moderate extent, only if monocytes are added within the first 12 h of culture, suggesting that class II antigens or spatially related molecules deliver signals concurrently with the mitogenic stimulus. The blocking capability of anti‐class II mAb was not restricted to the CD4+ or the CD8+ T cell subsets, suggesting that, under inhibitory conditions, these mAb affect other structures on the T cell surface, relevant to the monocyte‐T cell interaction.
The effect of peripheral immunization with Mls‐12 on the emigration of antigen‐specific cells from the thymus
Authors: Kelly Katherine A. , Scollay Roland 
Published: March 2007

AbstractMature T cells found in the lymph nodes and spleen have the capacity to become activated and to proliferate in response to foreign antigens. The response of the thymus to such immunization is less well understood. We have examined one aspect of the thymic response by determining the effect of peripheral immunization upon cell emigration from the thymus. BALB/c (Mls‐1b) mice were injected with spleen cells from DBA/2 (Mls‐13) mice, and Vβ6+ (Mls‐13‐reactive) thymic emigrants were identified 3–30 days after immunization. Neither the rate of total cell migration from the thymus nor the proportion of Vβ6+ cells was altered, even though the immunizing spleen cells elicited an immune response in the draining (parathymic) lymph nodes. The same immunogen caused deletion of Vβ6+ cells in both the thymus and lymph nodes after intraperitoneal injection into the neonate. The inability of DBA/2 splenocytes to modify the development of adult thymocytes after intrathymic injection of the cells precluded the lack of entry into the thymus as the reason for the lack of any observed effect in the adult. Our results, therefore, indicate that the development of adult thymocytes is not modified by immunization, and suggest that the differing thymic response of mice injected as adults or neonates is related to changes in the intrathymic antigen presentation capacity associated with age.
Identification of a major antigenic epitope on CNBr‐fragment 11 of type II collagen recognized by murine autoreactive B cells
Authors: Burkhardt Harald , Holmdahl Rikard , Deutzmann Rainer , Wiedemann Hanna , Von Der Mark Helga , Goodman Simon , Von Der Mark Klaus 
Published: March 2007

AbstractImmunization of certain strains of mice with native type II collagen (CII) induces both development of arthritis and an antibody response to autologous CII. The autoantibody response in a high‐responder strain, the DBA/1 mouse, has been described earlier, and a number of monoclonal antibodies have been characterized for arthritogenicity and autoreactive binding to cartilage in vivo and in vitro. Here we map the antigenic epitope of one of these arthritogenic monoclonal antibodies (CII‐C1). It belongs to a group of antibodies recognizing the CNBr fragment α1(II)‐CB11 of CII. Using the enzyme‐linked immunosorbent assay technique, we show that the antibody reacts only with native, triplehelical CII, but not with other collagens. The antibody is able to stain specifically the CB11 fragment by immunoblotting, suggesting some partial renaturation of the CNBr fragment into triple‐helical structures after blotting. The binding site of CII‐C1 on CB11 was further focused by rotary shadowing of antibody‐labeled CII to a site 89 ± 8 nm from the amino end of CII, corresponding to the middle of CB11. This location was confirmed by cleavage of CB11 with trypsin, separation of the tryptic peptides by high‐performance liquid chromatography and dot‐blot analysis of the antigenic peptides with the CII‐C1 antibody. Sequencing of the single positive peptide located the antigenic epitope within the sequence GFAGQAGPAGAT‐GAPGRP (residues 316–333). Assuming 0.29 nm per residue, this corresponds to a position within 92–96.5 nm from NH2 terminal end of CII. Apart from glycine residues, which are not exposed on the triple‐helical structure, only two amino acid residues (F‐x‐y‐Q) are conserved in CII from different species but are not found in the triple‐helix of other collagens except type IV collagen. Therefore, this structure is likely to be of critical importance for the binding of the CII‐C1 antibody. Of potential importance is that this structure is also found in certain other arthritogenic proteins such as 65‐kDa mycobacterial protein, in CMV and EBV.
The identification of the β2‐microglobulin binding antigen encoded by the human CDID gene
Authors: Bilsland Caroline A. G. , Milstein César 
Published: March 2007

AbstractHuman cluster of differentiation (CD1) is a family of cell surface glycoproteins composed of a 43–49‐kDa heavy chain non‐covalently associated with β2‐microglobulin. Five human CD1 genes have been detected and cloned. Three genes (CD1A, ‐B and ‐C) encode the serologically defined CD1a, ‐b and ‐c antigens. Thus two genes remain, CD1D and CD1E, whose protein products have not been characterized so far. This report describes how a β‐galactosidase‐CD1D fusion protein was used to raise specific antisera and a monoclonal antibody against the CD1D gene product. The monoclonal antibody defines a cell surface molecule expressed on a cortical thymocyte cell line and is composed of a 49‐kDa heavy chain associated with β2‐microglobulin, which is serologically distinct from CD1a.
Allorecognition of HLA‐DR and ‐DQ transfectants by human CD45RA and CD45R0 CD4 T cells: Repertoire analysis and activation requirements
Authors: Merkenschlager Matthias , Ikeda Hitoshi , Wilkinson David , Beverley Peter C. L. , Trowsdale John , Fisher Amanda G. , Altmann Daniel M. 
Published: March 2007

AbstractWe have investigated the requirements for allogeneic stimulation of human CD4 T cells using HLA class II products expressed on various cellular backgrounds. Human (class II‐negative RJ2.2.5 mutant) B cell lines transfected with HLA‐DR or ‐DQ cDNA clones were efficient stimulators for highly purified CD4 T cells. HLA‐DR‐transfected mouse L cells or IFN‐γ‐induced human fibroblasts, although able to function as accessory cells for T cell responses to the mitogen PHA, failed to stimulate strong T cell alloresponses. On the basis of these observations, we have employed class II transfectants to address the following questions: (a) do CD45RA and CD45R0 subpopulations differ in their allogeneic activation requirements, (b) are these subpopulations skewed in their recognition of HLA‐DQ vs. HLA‐DR in a manner which might support the concept that CD45RA T cells are involved in HLA‐DQ‐restricted suppressor inducer functions and (c) by using transfectants expressing individual HLA‐DR or ‐DQ heterodimers in combination with limiting dilution analysis, can one for the first time obtain estimates of precursor frequencies for allogeneic cells recognizing each of these class II isotypes? Our results show that CD45RA and CD45R0 T cells respond comparably to optimal numbers of stimulator cells. However, when CD45RA and CD45R0 T cell populations depleted of endogenous accessory cells were cultured with limiting numbers of stimulator cells, CD45R0 cells generally responded more strongly, consistent with the elevated levels of various adhesion molecules known to be expressed by this population. Further, we found a similar representation of responses to HLA‐DR and ‐DQ antigens among populations expressing CD45RA and CD45R0 isoforms. Finally, the precursor frequencies of allogeneic CD4 T cells responding to particular HLA‐DQ alleles were higher than to ‐DQ, but only by a factor of about 1.6, indicating that HLA‐DQ recognition may occur more frequently than implied from previous antibody blocking studies.
Lymphocytes infected with Theileria parva require both cell‐cell contact and growth factor to proliferate
Authors: Dobbelaere Dirk A. E. , Roditi Isabel J. , Coquerelle Thérr̀se M. , Kelke Christina , Eichhorn Margarete , Williams Richard O. 
Published: March 2007

AbstractLymphocytes infected with the intracellular parasite Theileria parva proliferate continuously as lymphoblastoid cell lines. We have previously shown that the continuous proliferation of the T. parva‐infected (Tpi) cell line TpM(803) is mediated in part by an autocrine mechanism (Dobbelaere, D. A. E. et al., Proc. Natl. Acad. Sci. USA 1988. 85: 4730). We now report that continuous proliferation also requires surface stimulation through cell‐cell contact. Under standard culture conditions this surface stimulus is provided by the infected cells themselves, but it can also be provided by uninfected lymphocytes or macrophages. The ability to respond to surface stimulation is critically dependent on the presence of the parasite in the host cell and is lost within 48 h after the elimination of the parasite from the host cell cytoplasm by treatment with the theilericidal drug BW720c. Tpi cells also secrete a growth factor which is able to support the proliferation of diluted Tpi cells. Growth factor secretion is rapidly lost upon elimination of the parasite. Moreover, inhibition experiments using antiinterleukin 2 (IL 2) antibodies show that IL 2 is involved in the proliferation of the Tpi cell lines TpM(803) and IN10. T cell proliferation is dependent on a number of costimulatory signals which are normally provided by accessory cells. The finding that Tpi cells can mutually stimulate each other to grow in the absence of conventional accessory cells helps to explain how they can escape the normal constraints on T cell growth, allowing them to invade and multiply in non‐lymphoid as well as lymphoid tissues.
Interleukin 4 induces interleukin 6 production by endothelial cells: Synergy with interferon‐γ
Authors: Howells Gareth , Pham Phuong , Taylor David , Foxwell Brian , Feldmann Marc 
Published: March 2007

AbstractInterleukin (IL) 4 induces IL 6 production by human umbilical vein endothelial cells (HUVEC) in a dose‐dependent manner, as shown by bioassay and immunoprecipitation. Interferon (IFN)‐γ, which antagonizes IL 4 effects on leukocytes, synergized with IL 4 in the induction of IL 6 production by HUVEC. Contamination with endotoxin was excluded by heat‐inactivated IL 4, preincubating with anti‐IL 4 polyclonal antibody and the use of polymyxin B. The presence of IL 4 receptors on HUVEC was shown by affinity cross‐linking with 125I‐IL 4, revealing a 110‐kDa binding protein. However, compared with the amount seen on T cells the 60–70‐kDa cross‐linked doublet was present at much lower levels. Additional lower molecular weight cross‐linked proteins were isolated only with HUVEC, but the origin of these is unclear. IL 6 is a pluripotent cytokine produced by many cells which promotes the differentiation and growth of lymphocytes and the production of acute phase protein by hepatocytes, and is important in the regulation of immunity at the systemic and local levels. Since IL 4 and IFN‐γ are produced by T cells, which are frequently associated with vascular endothelium during chronic inflammation, IL 4 is likely to be an important cytokine in the regulation of IL 6 and perhaps other cytokine production by endothelium in vivo.
Proliferative responses induced by the activation of protein kinase C during the development of human T lymphocytes
Authors: González‐Fernández Africa , Diaz‐Espada Fernando , Kreisler Miguel , Deza Francisco Gambón 
Published: March 2007

AbstractWe have studied the effects of phorbol‐dibutyrate (PBu2), a protein kinase C (PKC) activator, on the proliferation of peripheral human T cells and thymocyte subpopulations selected by treatment with monoclonal antibodies and complement: pre‐thymocytes (CD1a−CD3−CD4−CD8−), cortical thymocytes (CD3−, class I− antigens) and medullary thymocytes (enriched as CD1a− cells). PBu2 induces a dose‐dependent proliferative response in human peripheral blood T cells at concentrations > 6 ng/ml, this proliferation being mediated by the autocrine interleukin 2 (IL2)/IL2 receptor (IL2R) pathway. Pre‐thymocytes respond to PBu2 in a way similar to T cells, being able to secrete IL2 in significant amounts and express the p55 chain of IL2R. On the other hand, cortical thymocytes are not induced to proliferate after PKC activation and neither expression of the p55 chain of IL2R nor IL2 secretion is observed. Human medullary thymoctes, phenotypically identical to peripheral blood T cells, show no proliferation in response to PBu2 at any concentration tested unless IL2 is supplied to the cultures. The activation of PKC induces the expression of IL2R in these cells, but not IL2 secretion. The implications of PKC activation in thymic maturation, the role of IL2 and the relevance of the differences between medullary thymocytes and peripheral blood T cells are discussed.
Role of the adhesion molecule ICAM‐1 (CD54) in staphylococcal enterotoxin‐mediated cytotoxicity
Authors: Dohlsten Mikael , Hedlund Gunnar , Lando Peter A. , Trowsdale John , Altmann Daniel , Patarroyo Manuel , Fischer Hans , Kalland Terje 
Published: March 2007

AbstractStaphylococcal enterotoxin A (SEA) binds to major histocompatibility complex (MHC) class II molecules on target cells and directs human cytotoxic T lymphocytes (CTL) of irrelevant nominal specificity to mediate strong cytotoxicity against target cells. In this report we describe the importance of ICAM‐1(CD54) expression on the target cell in SEA‐dependent cell‐mediated cytotoxicity (SDCC), utilizing murine L cells co‐transfected with HLA‐DR and ICAM‐1. Human CTL mediated a low but significant cytotoxicity against HLA‐DR2‐and HLA‐DR7‐transfected cells after preincubation with SEA, but no reactivity towards uncoated HLA‐DR2 and HLA‐DR7 cells or SEA‐coated ICAM‐1‐transfected and untransfected L cells. In contrast, a strong cytotoxic response was mediated by CTL against L cells co‐transfected with HLA‐DR/ICAM‐1 and HLA‐DR7/ICAM‐1. Similar cytotoxic activity of the CTL was seen at a 30‐fold lower effector‐to‐target cell ratio when comparing the HLA‐DR2/ICAM‐1‐expressing cells with the HLA‐DR2‐expressing cells. SEA dose‐response analysis demonstrated that the HLA‐DR2/ICAM‐1‐expressing target cells enabled the CTL to respond to a 1000‐fold lower concentration of SEA in comparison to the HLA‐DR2‐expressing cells. CD3+CD4+ and CD3+CD8+ cytotoxic T cell lines were equally dependent on the expression of ICAM‐1 on the target cell. The strong CTL activity against HLA‐DR2/ICAM‐1‐transfected cells could be blocked by anti‐CD11a or anti‐CD18 monoclonal antibodies (mAb), but not by anti‐CD11b, anti‐CD11c, anti‐CD2 or unrelated control mAb. The great sensitivity of HLA‐DR2/ICAM‐1 expressing target cells to SDCC was strongly reduced by preincubation with various anti‐ICAM‐1 mAb but not by mAb against monomorphic HLA‐DR or murine MHC class I determinants. The result in this study clearly demonstrates that efficient re‐targeting of human CTL by SE is dependent on a proper interaction with the heterodimer CD11a/CD18 (Leu‐CAMa, LFA‐1) on the CTL and its target cell ligand ICAM‐1.
Identification and functional analysis of the transcriptional enhancer of the human T cell receptor β gene
Authors: Prosser Haydn M. , Lake Richard A. , Wotton David , Owen Michael J. 
Published: March 2007

AbstractThe productive rearrangement and transcription of T cell receptor (TcR) β genes is confined to T lymphocytes and is subject to both tissue‐specific and developmental regulation. In addition to their function in transcriptional control. cis‐acting elements are likely to play a role in the regulation of the rearrangement process. In this report we describe the location of a strong and inducible transcriptional enhancer 3′ to the human TcR Cβ2 gene segment. The core enhancer, defined by deletion analysis using a transient transfection assay, resided within 362 bp of DNA. This enhancer core was able to activate transcription from a heterologous promoter and functioned well in T and B lymphocytes, but only minimally in HeLa cells. In contrast, a longer fragment containing the enhancer core showed marked T cell specificity. The enhancer was highly inducible by phorbol esters, the molecular basis for the inducibility residing within a 118‐bp region of the enhancer core. This inducibility may be important in modulation of TcR β gene expression during T cell differentiation and/or activation.
Heterodimeric, disulfide‐linked α/β T cell receptors in solution
Authors: Slanetz Alfred E. , Bothwell Alfred L. M. 
Published: March 2007

AbstractStructural and functional analysis of T cell receptor (TcR)‐ligand binding would be greatly advanced by the availability of an intact, assembled TcR in soluble form. We have produced such a molecule, by splicing the extracellular domains of a TcR to the glycosyl phosphatidylinositol membrane anchor sequences of Thy‐1. The molecule is expressed in the absence of CD3 on the cell surface, and can be cleaved from the membrane by treatment with phosphatidylinositol‐specific phospholipase C. The α and β chains of the soluble molecule are paired in the native conformation as judged by reactivity with the anti‐Vβ8 monoclonal antibody F23.1, and with the anti‐clonotypic monoclonal antibody 1B2; it is a disulfide‐linked dimer with a mol. mass of 95 kDa on sodium dodecyl sulfate‐polyacrylamide gel electrophoresis under nonreducing conditions, and 47 kDa after reduction. We conclude that we have generated an α/β TcR in soluble form.
Inhibition of tumor necrosis factor‐α transcription by Epstein‐Barr virus
Authors: Gosselin Jean , Menezes José , D'Addario Mario , Hiscott John , Flamand Louis , Lamoureux Gilles , Oth Daniel 
Published: March 2007

AbstractTumor necrosis factor‐α (TNF‐α), which is produced mainly by monocyte/macrophage cells, has diverse physiological functions on lymphoid cells. Moreover, it has been shown that TNF‐α exhibits antiviral activities. Here we report that Epstein‐Barr virus (EBV), a B lymphotropic human herpes virus that interacts intimately with the immune system, exerts a strong inhibitory effect on TNF‐α production by lipopolysaccharide‐treated peripheral blood leukocytes as well as by monocytic cell lines, HL‐60 and U‐937. Flow cytometric analysis following staining with OKB7 monoclonal antibody showed that about 20% of cells from these monocytic lines express the CR2 antigen. Direct binding of fluorescein isothiocyanate‐labeled EBV indicated that the virus binds to approximately 22% of cells of both monocytic lines. However, no virus‐specific antigens were detected in the infected cells by immunofluorescence, suggesting that the infection was of the abortive type. The use of UV‐ or heat‐inactivated EBV and EBV treated with neutralizing antibodies resulted in the abrogation of the EBV inhibitory effect on TNF‐α synthesis. These results suggest that infectious virus is necessary to obtain such an inhibitory effect. Analysis of TNF‐α mRNA by polymerase chain reaction amplification indicated that the EBV suppressive effect is manifested at the transcriptional level. In contrast, EBV did not inhibit interleukin 1 mRNA production by these cells. These results indicate that EBV interacts directly with monocytes/macrophages to exert its immunomodulatory effect.
Isotype commitment of human B cells that are transformed by Epstein‐Barr virus
Authors: Miyawaki Toshio , Butler Joseph L. , Radbruch Andreas , Gartland G. Larry , Cooper Max D. 
Published: March 2007

AbstractEpstein‐Barr virus (EBV) can transform a subpopulation of preactivated B cells thus promoting their growth and differentiation into plasma cells. In EBV‐transformed clones of IgM‐producing cells, the heavy chain constant region (CH) genes on the productive allele are fixed in germ‐line configuration, whereas in isotype‐switched clones the CH genes proximal to the expressed CH gene are deleted. In order to define more precisely the EBV‐susceptible B cells, we sorted subpopulations of B cells on the basis of their cell surface Ig (sIg) isotypes, infected them with EBV, and determined which isotypes they could produce following transformation. Most precursors of IgM‐producing plasma cells expressed both IgM and IgD on their surface, while a minority expressed IgM alone. Some B cell precursors of IgG‐ and IgA‐producing cells also expressed sIgM, but surprisingly none expressed IgD. Those precursors of IgG and IgA producers, which bore sIgM, expressed it in relatively low levels, whereas B cells expressing high levels of sIgM were incapable of generating IgG and IgA producers. All of the precursors of IgG and IgA plasma cells expressed these isotypes on their cell surface. Interestingly, precursor B cells capable of producing the IgG3 and IgA2 subclasses could be respectively enriched on the basis of the presence or absence of cell sIgM. These results demonstrate the isotype precommitment of EBV‐transformable B cells. They further suggest that residual IgM is transiently expressed on the surface of the IgG‐ and IgA‐committed B cell precursors, whereas sIgD expression is extinguished earlier in the process of isotype switching via CH gene deletion.