bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rapid transformant selection by human complement using HRF20 (CD59) cDNA as a selection marker
Authors: Takizawa Hisao , Takahashi Kazuhiro , Murakami Tomoko , Okada Noriko , Okada Hidechika 
Published: March 2007

AbstractThe 20 kDa homologous restriction factor (HRF20, CD59) prevents formation of membrane attack complexes of human complement. Transfection of the cDNA of HRF20 to heterologous cells, which are sensitive to human complement, thereby renders these cells resistant to human complement attack. This property can then be used as a selection marker of transfection. In addition, the procedure is short and can be performed within 8 h. Since only 1 h is required for incubation with complement, the damage to the transfected cells is limited compared with damage resulting from selection for drug resistance which requires 10 days or more of incubation in the presence of harmful agents.
Coordinate expression of β1 and β2 integrin “activation” epitopes during T cell responses in secondary lymphoid tissue
Authors: Picker Louis J. , Treer John R. , Nguyen Mai , Terstappen Leon W. M. M. , Hogg Nancy , Yednock Ted 
Published: March 2007

AbstractThe monoclonal antibodies (mAb) 15/7 and 24 recognize unique activation‐dependent, conformational epitopes on β1 and β 2‐integrins, respectively. The expression of both of these epitopes closely correlates with the ligand binding ability of their respective integrins, and thus serves as indicators of functional integrin “activation”. Here, we have used six‐parameter flow cytometry to examine the expression of these epitopes and conventional β1‐ and β2‐integrin epitopes during human T cell activation in secondary lymphoid tissues in vivo, focusing particularly on the virgin to memory/effector cell transition. Fresh tonsil lymphocytes were stained with mAb against conventional or activation‐dependent integrin epitopes, followed by staining with mAb against CD3, CD45RA, and CD45RO, thus allowing the determination of integrin epitope expression on virgin (CD3+) T cells (CD45RA+/RO−to±), memory/effector (CD45RA−/RO++) T cells, and T cells undergoing the virgin to memory/effector transition: transition region‐1 (T1; CD45RA+to++/RO+); ‐2 (T2; CD45RA++/RO++); and ‐3 (T3; CD45RA+/RO++). Conventional β1‐ and β2‐integrin epitopes progressively increase during the virgin to T3 stages of the transition in tonsil, in keeping with the generally higher levels of these adhesion molecules on memory/effector vs. virgin T cells. Expression of both the β1 (15/7)‐and β2 (24)‐integrin activation epitopes first appears on transitional T cells, and is maintained on a relatively constant number of cells (averaging 25‐30%) throughout the T1‐T3 stages. These epitopes are also noted on a subset of activated memory/effector T cells. Importantly, on both transitional and activated memory/effector T cell subsets, the expression patterns of the 15/7 and 24 epitopes vs. a variety of T cell activation antigens are identical, and the expression of these epitopes relative to each other is linearly correlated, findings strongly supporting the coordinate activation of β1 and β2 integrins duringT cell activation in vivo. These results provide the first evidence of integrin activation during an in vivo immunologic response, and demonstrate the usefulness of mAb recognizing conformational epitopes and multiparameter flow cytometry in delineating the dynamic interplay of adhesion molecules during complex physiologic processes.
Global analysis of antibody repertoires. II. Evidence for specificity, self‐selection and the immunological “homunculus” of antibodies in normal serum
Authors: Nobrega Alberto , Haury Matthias , Grandien Alf , Malanchère Evelyne , Sundblad Anne , Coutinho Antonio 
Published: March 2007

AbstractThe serum IgM repertoires of C57BL/6, DBA/2 and BALB/c mouse strains were analyzed using a recently developed global and quantitative assay that measures antibody reactivities to a very large number of antigens. A characteristic repertoire could be assigned to each strain. The different repertoires could be successfully classified with multivariate statistics. Many common reactivities were also observed among the different strains, which allows the definition of a mouse‐specific repertoire. Analysis of human sera support this notion. To investigate the impact of minor genetic differences on the serum IgM repertoire, the congenic strains B10.D2/oSn and B10.D2/nSn, which differ in the expression of the C5 component of complement, were analyzed. The two strains could be separated based on the reactivity profiles obtained. The analysis of the results reveals that many antigenic proteins are not recognized at all by natural antibodies, while others are disproportionately reactive, the resulting patterns giving rise to what could be the definition of an “immunological homunculus”. The relevance of this type of analysis for clinical applications is discussed.
The human immunoglobulin χ locus. Characterization of the partially duplicated L regions
Authors: Huber Christian , Huber Erwin , Lautner‐Rieske Andrea , Schäble Karlheinz F. , Zachau Hans G. 
Published: March 2007

AbstractThe L regions are parts of the Cχ proximal (p) and distal (d) copies of the human immunoglobulin x locus and are therefore called the Lp and Ld regions. The two regions with their 25 Vχ genes and pseudogenes have now been cloned, thus completing the cloning of the x locus. Lp has been linked to the neighboring Ap and B regions, while Ld was linked to Ad. There is good evidence that at the other side of Ld, i.e. towards the centromere, the end of the locus has been reached. Most of the cloning and linking was achieved by chromosomal walking, employing cosmid and phage λ clones. No such clones could be found for three small gaps. Two of them were closed by a polymerase chain reaction strategy; the third one was characterized by genomic blot hybridization experiments and eventually bridged by a yeast artificial chromosome clone.Early in evolution, a stretch of about 25 kb which comprised three VK genes near the 5′ end of the L region precursor must have been duplicated, such that the later duplication of large parts of the x locus resulted in the appeareance of two very similar three‐gene regions in each, Lp and Ld. Two deletions in the central parts of the L regions, on the other hand, must have occurred after the duplication of the locus, since they are found in Lp and Ld in different positions.
Multiple signaling pathways mediate anti‐Ig and IL‐4‐induced early response gene expression in human tonsillar B cells
Authors: Murphy John J. , Norton John D. 
Published: March 2007

AbstractWe have analyzed the relationship between the signaling pathways coupled to surface immunoglobulin and interleukin (IL)‐4 receptors in human B cells from the patterns of expression of a panel of phorbol ester‐inducible early response genes (ERG) activated by anti‐IgM and IL‐4 stimulation in vitro. Anti‐IgM stimulation led to the induction of all eleven ERG tested. Two of these, the proto‐oncogene, c‐fos and an anonymous ERG 1R20 were insensitive to protein kinase C (PKC) inhibition with the drug, staurosporine and retained inducibility after down‐regulation of PKC activity by purging with phorbol ester. These observations are consistent with previous data showing anti‐IgM signaling through both PKC‐dependent and PKC‐independent pathways, c‐fos and 1R20 were also the only ERG inducible in response to IL‐4 stimulation and whilst ionomycin induced only c‐fos, dibutyryl cyclic adenosine monophosphate stimulation led to induction of both c‐fos and 1R20. These observations lend support to a role for the adenylate cyclase pathway being important for coupling of IL‐4‐generated signals to B cells responses. None of the anti‐IgM‐responsive ERG was further induced when B cells were co‐stimulated with a combination of anti‐IgM and IL‐4, suggesting that the signaling cascades from these two agents are integrated downstream of third messenger pathways to synergistically promote B cell proliferation.
Patterns of major histocompatibility complex class II expression by T cell subsets in different immunological compartments. 2. Altered expression and cell function following activation in vivo
Authors: Hopkins John , McConnell Ian , Dalziel Robert G. , Dutia Bernadette M. 
Published: March 2007

AbstractThis study characterizes antigen‐induced phenotypic and functional aspects of major histocompatibility complex (MHC) class II expression on recirculating T cells in efferent lymph. In vivo secondary, but not primary challenge is associated with both kinetic and phenotypic alterations in class II expression by T cells. All three major T cell subsets, CD4+, CD8+ and T19+ (γδ T cell receptor), show an approximate four fold increase in the level of MHC class II expression during secondary responses. No changes in B cell expression of class II were seen. Resting efferent lymph T cells are predominantly either class II− or DR+DQ− but this changes to DR+DQ+ after antigenic challenge.The antigen‐presenting function of these class II+ T cells was investigated at daily intervals after in vivo antigenic challenge. T cells from non‐activated lymph nodes could not induce proliferation of antigen‐specific T cells with soluble antigen but were weakly stimulatory in allo‐mixed lymphocyte reaction (MLR) at high (> 2:1) stimulator cell ratios. Activated T cells isolated during secondary in vivo responses, and expressing increased quantities of MHC class II, were positive stimulator cells in the MLR. In contrast these cells could not present soluble antigen or trypsin‐digested antigen to the T cell lines. In the MLR assays, the relative stimulation by class II+ T cells correlates with the levels of class II expression. We conclude from these experiments that both quantitative and qualitative changes in MHC class II, induced on T cells under physiological conditions, play a role in the regulation of the immune response in vivo but that that role is not simply one of presentation of soluble antigen.
Cyclosporin A enhances T cell‐mediated induction of E‐selectin
Authors: Doǧan Ahmet , MacDonald Thomas T. , Spencer Jo 
Published: March 2007

AbstractIn a fetal intestinal organ culture model of intestinal inflammation, activation of T cells by a lectin, superantigen or anti‐CD3 antibodies induces E‐selectin expression which peaks 6‐10 h after activation and disappears by 24 h. We now show that addition of cyclosporin A (Cys A) increases the number of E‐selectin‐expressing endothelial cells and the intensity of expression, and it prolongs expression up to at least 60 h after stimulation. The dynamics of E‐selectin expression on tumor necrosis factor activated human umbilical‐vein endothelial cell cultures is not affected by Cys A. Furthermore, other immunosuppressive agents FK 506 and dexamethasone inhibit E‐selectin expression, indicating that the enhancement observed in the presence of Cys A is not a consequence of general immunosuppression.
L1 adhesion molecule on mouse leukocytes: regulation and involvement in endothelial cell binding
Authors: Hubbe Marcus , Kowitz Aiga , Schirrmacher Volker , Schachner Melitta , Altevogt Peter 
Published: March 2007

AbstractLI is a cell surface glycoprotein of the immunoglobulin superfamily which was initially shown to mediate adhesion between neural cells. Recently we have reported that LI is expressed by bone marrow cells and the majority of mature lymphocytes (Kowitz et al., Eur. J. Immunol. 1992. 22: 1199‐1205). To analyze the function of LI on leukocytes we studied its regulation following cell activation. In vitro activation of B lymphocytes with lipopolysaccharide or T lymphocytes with phorbol 12‐myristate 13‐acetate/Ca2+ ionophore, concanavalin A or anti‐CD3 monoclonal antibody as well as in vivo activation of Vβ8+ T cells with staphylococcal enterotoxin B (SEB) revealed a down‐regulation of LI within 48 h. A rapid loss of LI expression was seen when mouse neutrophils were activated with PMA alone. This rapid loss paralleled the shedding of L‐selectin.We also studied a possible role of LI in the binding of leukocytes to endothelial cells. ESb‐MP lymphoma cells with a high expression of L1 (L1hi) could bind to bend3 endothelioma cells without prior activation with inflammatory cytokines. The interaction was inhibited by anti‐L1 antibodies. In contrast, ESb‐MP cells with low LI expression (L110) were only marginally bound. Latex beads coated with affinity‐isolated LI antigen were also able to bind to the endothelioma cells in a specific fashion. The binding of ESb‐MP lymphoma cells required Ca2+ and Mg2+ ions and was sensitive to cold temperature. Since the endothelioma cells did not express LI the binding mechanism studied here is distinct from the established L1‐L1 homotypic interaction. It is possible that the novel L1‐mediated adhesion pathway involves an unidentified ligand and could play a role in leukocyte migration.
Fine restriction analysis and inhibition of antigen recognition in HLA‐DQ‐restricted T cells by major histocompatibility complex blockers and T cell receptor antagonists
Authors: Serra Horacio M. , Crimi Claire , Sette Alessandro , Celis Esteban 
Published: March 2007

AbstractThe role of polymorphic residues of the β chain of human histocompatibility leukocyte antigen‐DQw5/w6 in antigen presentation to a hepatitis B surface antigen‐specific Tcell clone was studied. The results obtained demonstrate that the residue situated at position 57 of the β chain (a valine) is critical for presentation of antigen by antigen‐presenting cells to the DQ‐restricted T cell clone. Experiments were also done to study the feasibility of peptide blocking of antigen recognition by DQ‐restricted T cells. The results indicate that peptides known to associate with DQ molecules are capable of blocking the presentation of antigen to the DQ‐restricted Tcell clone, presumably by competing with antigen for binding to major histocompatibility complex (MHC) molecules. Moreover, truncations of the stimulatory antigenic peptide resulted in the production of Tcell receptor antagonists, which inhibited the response of the T cells to antigen at 10–100‐fold lower concentrations than conventional MHC blockers. The role of DQ‐restricted Tcell responses and peptide blocking approaches in autoimmunity are discussed.
TH2 activated cells prevent experimental autoimmune uveoretinitis, a TH1‐dependent autoimmune disease
Authors: Saoudi Abdelhadi , Kuhn Joelle , Huygen Kris , de Kozak Yvonne , Velu Thierry , Goldman Michel , Druet Philippe , Bellon Blanche 
Published: March 2007

AbstractMercuric chloride (HgCl2) injections protect (Lewis x Brown‐Norway) F1 (F1) rats against experimental autoimmune uveoretinitis (EAU) induced by immunization with the retinal S antigen (S‐Ag); in contrast HgCl2‐injected F1 rats develop EAU following transfer of lymph node (LN) cells from rats immunized with S‐Ag alone. In the present study we demonstrate that the ability of LN cells from rats protected against EAU to transfer the disease into naive F1 rats was considerably reduced. These LN cells neither produced interleukin (IL)‐2 nor (interferon (IFN)‐γ but exhibited mRNA for IL‐4. In contrast, LN cells from diseased rats easily transferred EAU into naive F1 rats, produced significant IL‐2 and IFN‐γ levels but barely exhibited mRNA for IL‐4. Furthermore protected rats predominantly produced IgG2b anti‐S‐Ag antibodies, while diseased rats produced IgG2b anti‐S‐Ag antibodies and the increase in expression of MHC class II molecules on B cells was higher in protected rats than in diseased rats. These data suggest that (1) to exert a protective effect, HgCl2 must act at an early stage of differentiation of precursors of S‐Ag specific T cells, and (2) this effect is related to the preferential activation of TH2 cells to the detriment of uveitogenic TH1 cells. Finally, these results indicate that activation of TH2 cells protect from a TH1‐dependent autoimmune disease.
Interleukin‐5 expressed by a recombinant virus vector enhances specific mucosal IgA responses in vivo
Authors: Ramsay Alistair J. , Kohonen‐Corish Maija 
Published: March 2007

AbstractSeveral in vitro studies have shown that murine interleukin‐5 (mIL‐5) enhances IgA production by activated mucosal B cells. To date, however, there is no evidence that this factor significantly up‐regulates mucosal IgA responses in vivo. Here, we show that expression of the gene for mIL‐5 in a recombinant vaccinia virus vector markedly increases IgA responses to co‐expressed heterologous antigen in the lungs of mice given intranasal inocula of the virus. The elevated local IgA responses to vectors expressing mIL‐5 peaked at a fourfold higher level than those elicited by control virus at 14 days after infection and were sustained for at least 4 weeks. Increased IgA responses were abrogated in mice treated with monoclonal antibody against mIL‐5 and were not detected in systemic lymphoid tissue. No enhancement of specific IgG levels was found either locally or systemically. Our results indicate that mIL‐5 selectively enhances the development of mucosal IgA responses in vivo and suggest that expression of this factor in mucosal vaccine vectors may stimulate local immune reactivity.
β2‐Adrenergic stimulation causes detachment of natural killer cells from cultured endothelium
Authors: Benschop Robert J. , Oostveen Frank G. , Heijnen Cobi J. , Ballieux Rudy E. 
Published: March 2007

AbstractPhysical exercise, mental stress, or infusion of β‐adrenergic agonists result in an increase in the number of natural killer (NK) cells in the peripheral circulation. In view of the specific migration pattern of NK cells in vivo, it has been suggested that these cells may be released from the marginating pool in blood vessels. In the present report, the in vitro effect of catecholamines on the adhesion of NK cells to unstimulated human endothelial cells (EC) was characterized. Peripheral blood mononuclear cells were allowed to adhere to monolayers of EC, after which the adherent lymphocyte fraction was analyzed phenotypically by flow cytometry. NK cells were found to adhere preferentially to EC, a process that was reversed by the addition of various adrenergic agonists. Catecholamines selectively affected adhesion of NK cells and had no effect on T cell adhesion to EC, as was determined by the use of purified cell populations. Detachment of NK cells from EC could be achieved by short incubations (5 min) with epinephrine (EPI) and was concentration‐dependent, with an ED50 of 2 × 10 −10M. Using a panel of α and β‐adrenergic agonists and antagonists, we show that the detachment of NK cells is mediated via β2‐adrenergic receptors. In line with the lower affinity for β2‐adrenergic receptors, norepinephrine was less effective than EPI in inducing detachment of NK cells from EC. Direct activation of adenylate‐cyclase with forskolin gave similar results as observed with EPI, indicating that signaling through cAMP is necessary to induce detachment of NK cells from EC. The results of the present study lend support to the hypothesis that catecholamines, via β2‐adrenergic receptors, can induce recruitment of NK cells from the marginating pool to the circulating pool, by changing the adhesive interactions between NK cells and EC.
Expressed human immunoglobulin ϰ genes and their hypermutation
Authors: Klein Ralph , Jaenichen Rita , Zachau Hans G. 
Published: March 2007

AbstractThe question of which germ‐line Vϰ genes are expressed was studied by sequencing 70 different cDNA clones from a human spleen library and one clone from a fetal liver library. The sequences were compared to a data base containing all germ‐line Vϰ gene and pseudogene sequences. In addition, 51 rearranged genomic Vϰ genes, 170 cDNA and 74 × proteins from the literature were assigned to specific germ‐line Vϰ genes and included in the comparisons. Not all the known, potentially functional Vϰ genes were found to be expressed, while some genes with minor defects are. The total number of expressed genes is smaller than expected: so far 21 germ‐line genes and 5 pairs of duplicated identical genes are known to be transcribed. The corresponding numbers for rearranged genomic VH genes and x proteins are 17 plus 4 and 7 plus 7, respectively. A second aim of the study was to find out whether the expressed repertoire contains derivatives of germ‐line Vϰ genes still missing in our data base; no evidence for the existence of such genes was found.Several cDNA clones contained additional nucleotides between the Vϰ and Jϰ gene segments, which may be germ‐line derived, inserted by terminal deoxynu‐cleotidyl transferase or introduced by other mechanisms. Somatic gene conversion seems not to play a major role in creating the human ϰ gene diversity. Various aspects of the hypermutation of ϰ genes are discussed and the formation of block mutations, i.e. the alterations of two or more adjacent nucleotides is stressed as a remarkable feature of the process.
Chemical reactivity of an HLA‐B27 thiol group
Authors: Whelan Michael Anthony , Archer James Ronald 
Published: March 2007

AbstractTechniques have been developed to measure the reactivity of free thiols in the HLA class I antigen‐binding cleft. HLA‐B27, which sequencing predicts has a free cysteine at position 67, reacts rapidly with the positively charged thiol reagent monobromotrimethyl‐ammoniobimane bromide (qBBr) to give products which are identifiable by isoelectric focusing. HLA‐B38, B39, B64 and B65, all of which have a similar Cys 67, react less strongly. Several other class I molecules, notably HLA‐C antigens, are reactive in this system, and it may be capable of recognizing subtypes such as A*0207 which also carry free cysteine. The accessibility of thiol to qBBr depends both on the chemistry of the class I molecule and other factors in the cell. Two human cell lines which are known to carry identical B27 genes but do not present the same peptides, differ considerably in the accessibility of their B27 thiol. Evidence from mouse cells transfected with mutant B27 genes suggests that a unique lysine at position 70 in the wild‐type molecule increases reactivity to thiol‐reactive metabolites. The failure of B27 to give a complete reaction with qBBr in our model systems suggests that it can exist in more than one chemical form. This may leave the molecule susceptible to oxidation, causing errors in T cell recognition and an exaggerated inflammatory response.
A role for antigen‐presenting cells and bacterial superantigens in reversal of human T lymphocyte anergy
Authors: Burns James , Littlefield Kimberly 
Published: March 2007

AbstractThe induction of anergy in T lymphocytes generates T cells incapable of proliferation in response to a conventional antigenic stimulus. To investigate the induction and maintenance of anergy in human T cells, we used T cell‐T cell presentation of myelin basic protein (MBP) or MBP synthetic peptides to induce anergy in vitro. Although anergic T cells responded normally to interleukin‐2 (IL‐2), these T cells did not produce IL‐2 or IL‐4 when peripheral blood mononuclear cells presented MBP or MBP peptides. Proliferation of anergic T cells was reduced by greater than 95% compared to nonanergic, control T cells. However, when autologous B cell lines were used to present MBP, anergy was partially reversed with a proliferation response about 50% of nonanergic levels. Bacterial superantigens also partially restored proliferation in anergic T cells following presentation by either B cell lines or macrophage isolated from peripheral blood mononuclear cells. Anergic, MBP‐reactive T cells fully retained antigen‐specific cytolytic activity against both B cell and T cell targets presenting MBP. These results suggest that T cell proliferative anergy may be reversible with both the type of antigen‐presenting cell and superantigens potentially contributing to the initiation or maintenance of an autoimmune response.