bluuebunny/crossref_metadata_2025_split huggingface dataset:
Further characterization and subcellular localization of Sm and Ul ribonucleoprotein antigens
Authors: Habets Winand J. , Berden Jo H. M. , Hoch Sallie O. , van Venrooij Walther J. 
Published: February 2007

AbstractSera from patients with systemic autoimmune diseases often contain antibodies against small nuclear ribonucleoprotein (snRNP) particles. Anti‐Sm antibodies react with the entire set of U1, U2, U4, U5 and U6 (Ul‐U6) RNP particles whereas anti‐(U1)RNP sera specifically recognize particles containing U1 RNA. Here we performed semi‐quantitative immunoblotting using 16 human anti‐Sm, 15 human anti‐(U1)RNP sera and two mouse monoclonal antibodies to establish which snRNA‐associated proteins carry antigenic determinants. Almost every (15/16) human anti‐Sm sera recognized epitopes present on a 28‐kDa (B/B') protein doublet and on a 16‐kDa (D) polypeptide. Nine anti‐(U1)RNP sera also recognized the B/B' doublet, but in all cases a much stronger reaction was observed with one or more of the specifically U1 RNA‐associated 70 kDa, A or C antigens. With affinity‐purified antibody fractions eluted from individual antigen bands on nitrocellulose blots it is shown that the anti‐Sm‐reactive polypeptides B/B' and D contain common epitopes. We also report the finding of one human anti‐Sm serum with exclusive specificity for the B/B' doublet and a mouse monoclonal anti‐Sm antibody recognizing only the D protein, indicating that these antigens also carry unique epitopes. In immunoprecipitation assays, purified anti‐B/B' and ‐D antibodies react with (Ul‐U6) RNP while purified anti‐70 kDa, anti‐A and anti‐C antibodies precipitate exclusively U1 RNP particles. Finally, we established the subcellular localization of Sm and U1 RNP antigens using a biochemical cell fractionation procedure. Part of the 70 kDa and BIB' antigens were found in a nuclease and high salt‐resistant nuclear substructure, usually referred to as nuclear matrix, while the A and D antigens could be extracted completely from HeLa nuclei by ribonuclease treatment and subsequent high salt extraction.
Ontogenic development of “natural” and induced plaque‐forming cell isotypes in normal mice
Authors: Bjorklund Mariana , Pettersson Sven , Coutinho Antonio 
Published: February 2007

AbstractThe numbers of cells and background plaque‐forming cells (PFC) in the spleen of C3H/HeJ mice increase exponentially during the first 2 weeks after birth, but much slower in bone marrow (BM). IgGl and IgG2a PFC are the first non‐IgM PFC detectable, while IgG3 and IgA PFC appear only around weaning. Adult‐type PFC numbers and isotype pattern are present in spleen and BM at 4 and 15 weeks, respectively. Neonatal splenic C3H/Tif B cells produce non‐IgM Ig classes in vitro in response to polyclonal activation by lipopolysaccharide or by helper T cells. These responses are of low magnitude during the first 2 weeks of life, but both secreted and membrane‐bound IgG1 and IgG3 isotypes are detectable already a few days after birth, in a pattern that is identical to that typical of T cell‐dependent or independent responses of adult cells. These results indicate full maturity of B cells in “switch” abilities already from birth, in spite of a general deficiency in terminal maturation. In addition, they demonstrate the complexity of isotype regulation in “background” antibody production in vivo.
The limited immunocompetence of thymocytes within murine thymic nurse cells
Authors: Andrews Paul , Boyd Richard L. , Shortman Ken 
Published: February 2007

AbstractThymic nurse cells, cortical epithelial cells enclosing 20–200 lymphocytes, were prepared from mouse thymus by enzyme digestion and repetitive sedimentation. Individual nurse cells were then isolated free of any exogenous thymocytes by micromanipulation, and the endogeneous thymocytes released from inside the nurse cells by a brief period of culture. The thymocytes from within individual nurse cells were tested, at the one cell/well level, for their capacity to proliferate in high cloning efficiency mitogen‐stimulated limiting dilution cultures. The resultant clones were tested for their cytolytic capacity in a lectin‐mediated isotype‐release assay. Most intra‐nurse cell thymocytes were unresponsive, like typical cortical thymocytes, but an average of 1/30, or around 2–6 lymphocytes/nurse cell, were able to proliferate in response to concanavalin A. The clones produced were of a relatively small size, similar to those characteristic of helper‐lineage T cells. No cytolytic clones at all were obtained, despite stringent positive controls showing an efficient cytolytic response from known sources of cytolytic precursor cells. This finding disagrees with earlier studies on nurse cell lymphocytes, where there may have been a possibility of contamination with exogenous thymocytes. These results suggest either that the nurse cell represents a selective environment for helper‐lineage T cell differentiation, or that further steps after the nurse cell stage are needed to produce mature cytolytic‐lineage T cells.
Early events during primary activation of T cells: antigen receptor cross‐linking and interleukin 1 initiate proliferative response of human T cells
Authors: Scheurich Peter , Ücer Ugur , Wrann Michael , Pfizenmaier Klaus 
Published: February 2007

AbstractTo study early events during primary activation of human T cells, a simple method was developed which simultaneously allows positive selection of T cells from peripheral blood lymphocytes (PBL) and their polyclonal, antigen receptor‐mediated stimulation with anti‐T3 monoclonal antibodies. In the absence of accessory cells, T cells activated with matrix‐bound OKT3 express high levels of the Tac antigen within 15 h and produce interleukin 2 (IL 2). Tac expression was further enhanced by addition of exogenous IL 2. However, under these conditions purified T cells were unable to mount a proliferative response, whereas unfractionated PBL proliferated already after 24 h of culture. This unresponsiveness of purified T cells could be overcome by either re‐addition of low numbers of autologous accessory cells or semipurified human IL 1. As IL 1 had no significant effect on Tac expression of T3‐stimulated T cells, we conclude from these data that IL 1 exerts in addition to its influence on IL 2 production an effect, which allows antigen receptor‐triggered T cells to enter the cell cycle.
Trypanosoma cruzi: modulation of parasite‐cell interaction by plasma fibronectin
Authors: Ouaissi Mohamed Ali , Cornette Jocelyne , Capron André 
Published: February 2007

AbstractTreatment of either rat peritoneal macrophages (RPM), cloned 3T3 fibroblasts (3T3FR) or Trypanosoma cruzi trypomastigote culture forms with human plasma fibronectin (huFN) enhanced their association with the untreated counterpart and this related to the concentration of huFN used. When treatment was performed at 4°C, the enhancing effect of huFN on parasite‐cell interaction was greater than that observed at 37 °C. This observation could be related to the indirect immunofluorescence antibody assay showing that a significant increase of fibronectin staining was observed on the cell and parasite surfaces upon incubation with huFN and that the extent of fibronectin staining was greater at 4°C. Incubation of huFN‐treated or nontreated parasites or cells with anti‐huFN antibodies exerted an inhibitory effect on the parasite‐cell association. The region of fibronectin that interacts with the trypomastigote surface is unknown. Inhibition experiments suggested that the domain of fibronectin which interacts with parasite surface receptors would probably be localized close to the NH2‐terminal region of the molecule. Taken together, these results suggest that fibronectin may play a role in the binding of parasites to the vertebrate host cell surface.
Nude mice are nonpermissive towards the anti‐dextran response of congenic cells
Authors: Weiler Ivan Jeanne , Sprenger Renate , Weiler Eberhardt 
Published: February 2007

AbstractNude mice bearing allotype Ighb on a BALB/c genetic background (= CB nu/nu) are nonresponders to α(1 → 3)dextran (Dex), in contrast to BALB/c or BALB/c nu/nu. Although CB nu/nu mice accept transplants of congenic BALB/c, or BALB nu/nu lymphocytes, as shown by the expression of donor allotype Igha, they are not permissive for a primary anti‐Dex response by the grafted cells. BALB/c or BALB nu/nu cells, however, give a strong anti‐Dex response when grafted onto irradiated CB nu/nu or CB23 (Ighb) euthymic mice.A thymus‐independent, radiation‐sensitive suppressor cell population is postulated, which specifically hinders the anti‐Dex response, and which is exhibited by strains bearing that portion of chromosome 12 which codes for CH allotype Ighb, not containing the germ‐line anti‐Dex V/D genes. The suppressive action of Ighb lymphocytes could be demonstrated directly in staggered co‐transfer experiments.
The effects of stress in normal and adrenalectomized mice
Authors: Rocha Benedita 
Published: February 2007

AbstractMany of the present concepts in lymphocyte physiology were established using experimental protocols involving surgery in cortico‐sensitive rodents. In the present report we demonstrate that commonly used operative procedures in mice result in a depletion of 50‐90% of cells from primary or secondary lymphoid organs 24 to 48 h post‐ surgery. Adrenalectomy, by itself, induces considerable depletion, and does not abolish the effects of stress in lymphocyte populations. These findings indicate that questions concerning the dynamics of production renewal rate and life‐span of lymphocytes cannot be investigated by approaches involving surgery in the mouse.
VH‐gene expression in murine lipopolysaccharide blasts distributes over the nine known VH‐gene groups and may be random
Authors: Dildrop Renate , Krawinkel Ulrich , Winter Ekkehard , Rajewsky Klaus 
Published: February 2007

AbstractVH‐gene expression in hybridomas derived from lipopolysaccharide‐activated B cells was analyzed. Isolated cytoplasmic RNA was hybridized to probes representing the 9 known VH‐gene groups or subjected to mRNA sequencing. In the collection of hybridomas VH genes of all 9 groups are expressed at frequencies which in most correlate reasonably well with the relative complexities of the groups. In 51 out of 54 RNA samples VH‐gene transcripts could be identified and corresponded to one of the known VH‐gene groups. It therefore appears that the latter essentially represent the Vn‐gene cluster of the mouse.
Synergy of B cell growth factor and interleukin 2 in the proliferation of activated human B cells
Authors: Romagnani Sergio , Giudizi Grazia M. , Maggi Enrico , Almerigogna Fabio , Biagiotti Roberta , Delprete Gianfranco , Mazzetti Marcello , Aiessi Anna , Vercelli Donata , Ricci Mario 
Published: February 2007

AbstractThe activity of purified interleukin 2 (IL2), obtained by the recombinant DNA technology, on the proliferative response of human B cells stimulated with low concentrations of anti‐μ antibody was investigated. Recombinant IL2 was capable of augmenting the proliferative response of anti‐μ‐activated B cells and the T cell activation (Tac) antigen was expressed on a substantial proportion of normal B cells stimulated with anti‐μ antibody. However, crude supernatants from protein A‐stimulated peripheral blood mononuclear cells, which were found to possess both IL2 and B cell growth factor (BCGF) activities, maintained the ability to promote proliferation of anti‐μ‐ activated B cells after depletion of IL2. In addition, supernatants from some T cell clones, apparently free of IL2 activity, displayed strong BCGF activity in the costimulation assay with anti‐μ antibody. This BCGF activity was found in 25 kDa fractions by gel filtration and it was unaffected by addition to the cultures of anti‐Tac antibody, which consistently inhibited the B cell proliferative response promoted by recombinant IL2.The proliferative response of anti‐μ‐activated B cells to clonal, IL2‐free supernatants containing BCGF and recombinant IL2 present together from the beginning of culture was close to the sum of responses to the two stimulants, separately. In addition, the presence of clonal supernatant containing BCGF from the beginning of culture had a synergistic effect in the response of activated B cells to the subsequent addition of IL2, whereas the initial presence of IL2 had no such an effect on the reactivity of anti‐μ‐stimulated B cells to the late addition of clonal supernatant containing BCGF. The synergistic effect of BCGF in the IL2‐promoted B cell proliferation was probably the result of the recruitment of a greater number of IL2‐reactive B cells. In fact, the number of Tac‐positive cells was significantly higher in 36‐h cultures established in the presence of anti‐μ antibody plus clonal supernatant containing BCGF than in cultures stimulated with anti‐μ antibody alone.Taken together, these data indicate that anti‐μ antibody promotes the expression by normal human B cells of distinct receptors for IL2 and a BCGF distinct from IL2. They also suggest that BCGF can exert a synergistic effect in the IL2‐promoted proliferation of activated B cells.
Defined antigens secreted by the larvae of schistosomes protect against schistosomiasis: induction of cytotoxic antibodies in the rat and the monkey
Authors: Auriault Claude , Damonneville Marline , Joseph Michel , Capron Monique , Verwaerde Claudie , Billaut P. , Capron Andrè 
Published: February 2007

AbstractThe study of the immunology of schistosomiasis has allowed a clear understanding of the basic mechanisms of resistance, emphasizing the important role played by cellular and humoral factors. Whereas the production of polyclonal or monoclonal antibodies and the precise inventory of immune effector mechanisms in the rat and in man have led to the identification of potentially protective antigens, immunization with soluble schistosome components has not allowed a successful control of the destruction of schistosomula after infection. The experiments reported here show that schistosomulum‐released products (SRP) were able to induce the production of antibodies, in the rat and the monkey, highly cytotoxic in antibody‐dependent cellular cytotoxicity, using monocyte monolayers, platelets or eosinophils as effector cells. The immunization of rats with either total SRP or 25‐30‐kDa molecules purified from schistosomula conferred a significant protection towards a challenge infection by the parasite. IgE and to a lesser extent IgG antibodies represented the major humoral factors of cell activation leading to the schistosomulum killing when anti‐SRP antisera, obtained after immunization of the monkey, were incubated with human effector cells.
Cytotoxic T lymphocyte‐mediated lysis via the Fc receptor of target cells
Authors: Staerz Uwe D. , Bevan Michael J. 
Published: February 2007

AbstractThe murine monoclonal antibody F23.1 reacts with an allotypic determinant on the T cell receptors of about 25% of peripheral T lymphocytes in most common mouse strains. In this report we demonstrate that this IgG2, antibody bound to the receptor of a cytotoxic effector T cell can direct that cell to lyse any target cell which expresses receptors for IgG2,. Thus, allotype‐positive, Lyt‐2′ T lymphocytes from either concanavalin A‐ or F23.1‐activated cell cultures are recruited as cytotoxic effector cells which lyse targets via the Fc receptor. Concanavalin A‐induced T cell blasts depleted of Lyt‐2′ cells do not mediate cytotoxic effects in this system. The data presented here confirm earlier observations that monoclonal anti‐T cell receptor antibodies attached to the surface of a cell can act as target structures for T cell‐mediated lysis.
Inhibition of helper function with anti‐Lyt‐2 or anti‐L3T4 monoclonal antibodies depending on stimulating antigens
Authors: Guimezanes Annick , Schmitt‐Verhulst Anne‐Marie 
Published: February 2007

AbstractThe role of L3T4+ and Lyt‐2+ cells in the induction of cytotoxic T cells (CTL) after stimulation with trinitrobenzene sulfonate (TNBS)‐treated syngeneic cells, or with cells differing for the entire major histocompatibility complex or for class I molecules alone was investigated using anti‐L3T4 and anti‐Lyt‐2 monoclonal antibodies (mAb). Anti‐L3T4 mAb inhibited both induction of CTL and interleukin 2 (IL2) production by T cells stimulated with allogeneic (class I + class II differences) or by TNBS‐treated syngeneic cells. In the same culture conditions, anti‐Lyt‐2 mAb inhibited CTL induction but had no effect on IL2 production. By contrast, only anti‐Lyt‐2 mAb inhibited both CTL induction and IL2 production when T cells were stimulated by allogeneic cells differing only for class I antigens. Anti‐L3T4 mAb had no inhibitory effect in this situation.These results indicate that two helper pathways can be activated, depending on the type of T cell stimulation: one, implicating L3T4+ cells, is used when stimulation involves class I and class II alloantigens or hapten on syngeneic cells; the other, involving Lyt‐2+ T cells, is preferentially stimulated when responding and stimulating cells differ only for class I major histocompatibility complex antigen.
2,4‐Dinitrophenyl (DNP)‐specific continuous B cell lines as a model system for studying B cell activation and tolerance
Authors: Aldo‐Benson Marlene , Scheiderer Linda , Dwulet Francis E. 
Published: February 2007

AbstractVarious model systems have been used to study isolated B cell response to receptor cross‐linking and to lymphokines. Although each model is useful it is advantageous to have continuous cell lines of nonmalignant antigen‐specific B lymphocytes to study antigen‐induced B cell function. We further studied the characteristics of the 2,4‐dinitrophenyl (DNP)‐specific continuous B lymphocyte lines which we previously described (J. Exp. Med. 1983. 157: 342). If the cell line lymphocytes are cultured with the antigen DNP‐Ficoll without the presence of T cell factors or filler cells they do not produce an immune response above background, but the addition of supernatant from EL4 lymphoma and irradiated normal spleen filler cells results in a 7‐ to 10‐fold increase in plaque‐forming cells. The kinetics of the immune response is the same as that seen with normal B cells. Each cell line has a majority of cells which are small surface (s)IgM− lymphocytes which have cytoplasmic IgM and react with 14.8 antibody. There are also large sIgM+‐bearing cells, which may be either in the resting or activated state. Some of the sIgM+ cells also bear IgD and Ia antigens but they do not bear IgG. From these studies we conclude that the continuously growing antigen‐specific B cell lines can be a useful model to study B cell function.
The high idiotypic connectivity of “natural” newborn antibodies is not found in adult mitogen‐reactive B cell repertoires
Authors: Holmberg Dan , Wennerström Gunilla , Andrade Luis , Coutinho António 
Published: February 2007

AbstractUnselected IgM‐secreting hybridoma collections were established either from unprimed naturally activated newborn spleen cells or from mitogen‐stimulated adult B cells. These were then screened for reactivity with a panel of monoclonal anti‐idiotypic antibodies and haptens. While the finding of hapten‐specific antibodies was equally frequent in either collection, newborn antibodies reacted at least 10 times more frequently with the anti‐idiotypic reagents. The reactivity patterns of individual antibodies readily demonstrated the overall specificity of these V‐region interactions. Since some of the idiotopes screened are characteristically not expressed in immune responses by the strains analyzed, and are in fact not expressed in the adult induced hybridoma collection, we explain these findings by a unique property of the set of natural (newborn) antibodies i.e. the high levels of idiotypic connectivity previously described within this repertoire.
Molecular requirement for interleukin 1 induction by lipopolysaccharide‐stimulated human monocytes: Involvement of the heptosyl‐2‐keto 3‐deoxyoctulosonate region
Authors: Lebbar Souad , Cavaillon Jean‐Marc , Caroff Martine , Ledur Annick , Brade Helmut , Sarfati Robert , Haeffner‐Cavaillon Nicole 
Published: February 2007

AbstractExperiments were undertaken to localize in the lipopolysaccharide (LPS) the minimal structural determinants sufficient to initiate the signal leading to interleukin 1 (IL 1) secretion by human monocytes. Our results clearly demonstrated that this signal is triggered by structures present in the so‐called inner‐core region which chemically consists of 2‐keto‐3‐deoxy‐wD‐manno‐octulosonic acid (KDo) and heptose in many LPS of gram‐negative bacteria. Thus, the isolated polysaccharide region of Bordetella pertussis endotoxin as well as fragments derived therefrom containing the reducing KDO unit were able to induce similar levels of IL1 induction as the native LPS. Similarly, the trisaccharide α‐D‐manno‐heptopyranosyl‐(1–3)‐α‐D‐manno‐heptopyranosyl‐(1–5)‐3‐deoxy‐D‐manno‐octulosonic acid (hep‐hep‐KDO), representative for the inner‐core region of a large number of enterobacterial LPS, was a very potent IL 1 inducer. Neither KDO monosaccharide, nor the α‐(2–4)‐linked 3‐deoxy‐D‐manno‐octulosonic acid disaccharide isolated from Salmonella rough‐form LPS promoted the signal indicating that the minimal structure of endotoxin able to induce IL 1 secretion resides in the hep (1–5)‐KDO disaccharide.
A 30‐kDa protein is disulfide linked to IgM on normal and neoplastic murine B lymphocytes
Authors: Haustein Dieter , Ahe Dietmar Von Der 
Published: February 2007

AbstractFour cloned continuously cultured mouse B lymphoma cells of the lines WEHI‐279, BCL1 and 38C‐13 were used to study the surface presentation of IgM. Cells of all lines expose, in addition to μ2L2, various disulfide‐linked subunits as already shown for normal B lymphocytes (Koch, N. and Haustein, D., Mol. Immunol. 1982. 19: 477). In contrast to normal B cells, B lymphoma cells also carry IgM structures of higher molecular weight than μ2L2 on their surface. Furthermore, B lymphoma cells of all investigated lines expose a μ2L2 structure to which a 30‐kDa protein is disulfidelinked. This 30‐kDa protein could also be identified on normal mouse B lymphocytes when more drastic conditions were employed. μ2L2 disulfide linked to this 30‐kDa protein is the main IgM structure on normal and neoplastic B cells whereas only small amounts of μ2L2 (unlinked to this protein) can be detected.