bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hemolytic anemia in non‐obese diabetic mice
Authors: Baxter Alan G. , Mandel Thomas E. 
Published: March 2007

AbstractThe non‐obese diabetic mouse (NOD mouse) is widely used as a model of organ‐specific autoimmunity because it develops specific autoimmune destruction of pancreatic β cells mediated by T cells and culminating in insulin‐dependent diabetes mellitus. Here, we report that the NOD mouse also develops Coombs'‐positive hemolytic anemia, a B cell‐mediated autoimmune disease.Aged NOD mice were found to have splenomegaly and jaundice predominantly due to raised unconjugated serum bilirubin. Their hematocrits were markedly lowered, and there was a reciprocal increase in the reticulocyte count. Red blood cells (RBC) from anemic mice showed a normal lytic response to hypotonicity. RBC from non‐anemic mice had normal half lives in non‐anemic, non‐diabetic NOD mice by 51Cr labeling but, dramatically shortened half lives in anemic mice. Similar results were obtained with RBC from anemic mice. Hemolysis could be transferred with serum from anemic mice resulting in reticulocytosis. The antibody‐mediated nature of the anemia was confirmed with the direct Coombs' test. Anemia was found only in mice aged > 200 days and was more common in diabetic (4/8) than non‐diabetic (1/16) mice at 300 days. However, by 550 days, 14/17 non‐diabetic mice were affected.
Cytotoxic T lymphocyte precursor cells specific for the major histocompatibility complex class I‐like antigen, Qa‐2, require CD4+ T cells to become primed in vivo and to differentiate into effector cells in vitro
Authors: Muraoka Shizuko 
Published: March 2007

AbstractExperiments were performed to determine whether CD4+ T cells are required for the generation of cytotoxic T lymphocytes (CTL) specific for the nonpolymorphic major histocompatibility complex (MHC) class I‐like antigen, Qa‐2. Splenic T cells from BALB/cBy (Qa‐2b) mice that had been immunized with irradiated BALB/cJ (Qa‐2a) splenocytes generated CTL following in vitro stimulation with BALB/cJ splenocytes. These CTL lysed all Qa‐2+, but not Qa‐2− targets, regardless of the H‐2 haplotypes of target cells or their non‐MHC backgrounds. This apparent MHC class I‐unrestricted recognition of Qa‐2 antigen was confirmed using Qa‐2‐specific CTL clones. The Qa‐2‐primed CTL precursor cells (CTLp) and CTL were found to be CD8+ T cells. Primed splenocytes depleted of CD4+ T cells prior to culture failed to generate CTL, but addition of lymphokines to the culture restored the CTL generation. Stimulation of primed splenic T cells with irradiated Qa‐2+ T blast cells, instead of splenocytes or B blast cells, led to little to no CTL generation, suggesting that MHC class II molecules are involved in the presentation of Qa‐2 antigen to CD4+ T cells. This was also supported by the results of experiments using Qa‐2+, class II− thymoma cells of BALB/c origin. Stimulation of the thymoma‐primed splenic T cells with the mitomycin C‐treated thymoma cells resulted in no generation of anti‐Qa‐2 CTL, despite the fact that high levels of CTL specific for minor histocompatibility (H) antigens and H‐2d were generated by immunizing the corresponding allogeneic hosts with the thymoma. However, the addition of lymphokines rendered thymoma‐primed T cells capable of generating anti‐Qa‐2 CTL. Both CD4+ and CD8+ T cell populations, isolated from the BALB/cJ splenocyte‐primed responder cells, proliferated in vitro in response to the Qa‐2+ splenocytes, suggesting that Qa‐2‐reactive CD4+ T cells were present in the immunized mice. Depletion of CD4+ T cells from thymectomized BALB/cBy mice with anti‐L3T4 monoclonal antibodies markedly reduced, but did not eliminate anti‐Qa‐2 CTL generation, In contrast, depletion of CD8+ T cells led to a complete abrogation of the CTL response. Addition of lymphokines to the culture of responder cells depleted of either T cell subset did not restore their reactivity. It is concluded that anti‐Qa‐2 CTLp need “help” from CD4+ T cells to become primed in vivo. Furthermore, primed CTLp also need “help” or lymphokines provided by CD4+ T cells to differentiate into effector CTL in vitro. This dependency of anti‐Qa‐2 CTLp on CD4+ T cells is different from that of CTLp specific for Qa‐1, minor H antigens, or MHC class I antigens.
Differential activity of recombinant lymphokines on mouse B cell proliferation and cell cycle progression are revealed by 5‐bromo‐2′‐deoxyuridine/Hoechst 33258 dye flow cytometry
Authors: Seyschab Helga , Hoehn Holger , Rabinovitch Peter S. , Chen Una 
Published: March 2007

AbstractActivation of resting mouse B cells with anti‐μ chain antibodies (anti‐μ) leads to cell proliferation. We have investigated the effect of recombinant T cell interleukins (IL 2 to IL 6) on such anti‐μ‐induced proliferation. No proliferative response was detected when IL 2, IL 3 and IL 6, either alone or in combination with anti‐μ, were studied. Furthermore, neither IL 4 nor IL 5 could induce proliferation when added alone to B cell cultures. However, when combined with anti‐μ, IL 4 as well as IL 5 stimulated cell growth. Analysis by 5‐bromo‐2′‐deoxyrudine/Hoechst 33258 flow cytometry revealed distinct effects of IL 4 and IL 5 on B cell growth. In the presence of anti‐μ, both IL 4 and IL 5 co‐stimulated unfractionated splenic B cells. However, when B cells were separated into subpopulations by density, IL 4 proved to be a cell cycle progression factor, stimulating the majority of resting B cells to enter the cell cycle. In contrast, IL 5 had little effect on the resting fraction of B cells. Rather, IL 5 acted as a co‐competence factor, stimulating predominantly low‐density B cells. Following exposure of anti‐μ alone, most B cells accumulated in the G1 of the second cycle. Upon addition of IL 4, the cells acquired the ability to progress into the next S phase compartment. Contrary to what is seen when B cells are stimulated by other mitogens, very few cells are in the G2 compartments after anti‐μ plus IL 4 stimulation. This phenomenon was not due to a differential cell cycle progression rate. Our findings provide an analytical basis for fractionating cell‐cycle‐compartment‐specific B cells for their molecular study.
Involvement of both T cell receptor Vα and Vβ variable region domains and α chain junctional region in viral antigen recognition
Authors: Brändle Daniel , Bürki Kurt , Wallace Valerie A. , Rohrer Urs Hoffmann , Mak Tak W. , Malissen Bernard , Hengartner Hans , Pircher Hanspeter 
Published: March 2007

AbstractWe have studied the lymphocytic choriomeningitis virus (LCMV)‐specific cytotoxic T cell response in transgenic mice expressing either the T cell receptor (TcR) α (Vα2/JαTA31) or the corresponding TcR β (Vβ8.1/Dβ/Jβ2.4) chain originally isolated from the LCMV glyconrotein specific (residues 32–42), H‐2Db‐restricted T cell clone P14. The expression of single transgenic TcR chains did not influence the corresponding endogenous TcR V gene usage in unstimulated T cells indicating that one particular TcR α or β chain can randomly pair with different Vβ or Vα chains without any obvious bias. However, upon infection with LCMV, reactive cytotoxic T lymphocytes (CTL) from P14 β‐transgenic mice were predominantly Vα2+ whereas CTL from P14 α‐transgenic mice preferentially expressed Vβ8.1 and unexpectedly also Vβ8.3 (but not Vβ8.2). Correspondingly the LCMV‐specific CTL response in both α and β TcR‐transgenic mice was strongly biased to the original P14 T cell epitope (LCMV glycoprotein residues 32–42). Sequence analysis of a large panel of LCMV‐reactive “half‐transgenic” TcR from P14 single receptor chain‐transgenic mice revealed a highly conserved VJα and a more diverse VDJβ junctional region. This report demonstrates that the antigen specificity of the studied TcR depends on the specific combination of both TcR α and β chains which implies that amino acids located in the TcR Vα and Vβ segments as well as in the junctional region are involved in binding of the viral antigenic fragment.
Structural requirements of the cytoplasmic domains of the human macrophage Fcγ receptor IIa and B cell Fcγ receptor IIb2 for the endocytosis of immune complexes
Authors: Engelhardt Waltraud , Gorczytza Harald , Butterweck Anette , Mönkemann Heike , Frey Jürgen 
Published: March 2007

AbstractTwo isotypes of the monocyte/macrophage as well as B cell Fcγ receptor type II (FcRIIa and FcRIIb2, respectively) mainly differ in the length (76 vs. 44 amino acids) and amino acid sequence of their cytoplasmic domains. Only the eight amino acids just behind the putative transmembrane region are identical. Despite this marked difference, both FcRII mediate endocytosis of immune complexes. To determine the functional significance of the cytoplasmic domains, we expressed truncated FcRIIa and FcRIIb2 in FcR− BHK‐21 cells. Mutants of both receptors containing only one amino acid (tail‐minus) of the cytoplasmic domain failed to mediate immune complex uptake. The significance of the cytoplasmic domain of the receptors could be further demonstrated using a chimeric FcRIII‐FcRIIa construct. Therefore we expressed an FcRIII lacking the hydrophobic carboxyl terminus (containing the putative phosphatidyl — inositol — glycan anchor site) fused inframe to the transmembrane and cytoplasmic domain of the FcRIIa in BHK‐21 cells. In contrast to the wild type FcRIII, this chimeric receptor mediated immune complex uptake indistinguishable from that mediated by the FcRIIa. Receptor mutants with relatively short cytoplasmic domains (FcRIIb2: 13, and FcRIIa: 16 amino acids) revealed, that these short amino acid stretches are sufficient to allow reduced receptor‐mediated endocytosis of bound ligand. Furthermore, using FcRIIa deletion mutants with a cytoplasmic domain consisting of 62, 46, and 28 amino acids, respectively, we found that the capability of these mutants to mediate immune complex uptake decreased gradually with the truncation of the cytoplasmic tails. Thus, only short amino acid sequences of the cytoplasmic domain are sufficient to enable an, albeit reduced, receptor‐mediated endocytosis.
Clonal persistence of B lymphocytes in normal mice is determined by variable region‐dependent selection
Authors: Thomas‐Vaslin Véronique , Andrade Luiz , Freitas Antonio , Coutinho Antonio 
Published: March 2007

AbstractMany adult splenic B cells die within 1 week in the spleen of adoptive adult recipient mice; in contrast, the cellular environment of newborn recipients allows for their expansion and persistence for several weeks. In the present study, we show that the local environment of adult peritoneal cavity also allows adult splenic B cells to persist for over 2 weeks after intraperitoneal transfer. In order to determine whether the persistence of donor B cells in newborn hosts and in the peritoneum of adult recipients results from a selection process involving the clonal specificities expressed, the variation in time of VH gene family repertoires of donor B cells was analyzed in the hosts. At different times after the transfer of splenic cells from lipopolysaccharide (LPS)‐reactive mice into LPS‐non responder histocompatible recipients, mRNA colony blot assays were performed. The results show that among the donor adult LPS‐reactive B cells, the VH genes are differently used by the expanding or persisting B cells, in both kinds of recipients. Thus, cells expressing J558 or VH11 gene families are, in particular, positively selected, while those expressing D‐proximal or J606 and 36‐30 VH gene families are less selected. These findings demonstrate that the propensity of B cells to persist and expand is determined by their selection through their immunoglobulin variable regions, rather than by genetic properties linked to particular B cell subsets.
Coordinate secretion and functional synergism of T cell‐associated serine proteinase‐1 (MTSP‐1) and endoglycosidase(s) of activated T cells
Authors: Vettel Ulrike , Bar‐Shavit Rachel , Simon Markus M. , Brunner Georg , Vlodavsky Israel , Kramer Michael D. 
Published: March 2007

AbstractCell lysates and exocytosed soluble mediator(s) (ESM) released from CD8+ T cell lines (TCL) by receptor‐triggered secretory exocytosis were tested for degradation of proteoglycahs associated with in vitro produced subendothelial extracellular matrix (ECM). ESM was found to release low‐molecular weight (kav 0.5–0.6) fragments from the sulfated proteoglycans in ECM. In the presence of heparin, an inhibitor for endoglycosidase activity, only high‐molecular‐weight products (kav 0.2) were formed. Preincubation of ESM with HD‐prolylphenylalanyl‐arginyl‐chloromethylketone (PFR‐CK) an inhibitor for the T cell‐associated serine proteinase‐1 (MTSP‐1) totally prevented release of high‐ and low‐molecular weight proteoglycan fragments. Furthermore, it was shown that purified MTSP‐1 is able to release from ECM high‐molecular weight proteoglycans and that this process is inhibitable by PFR‐CK but not by heparin. Further treatment of these soluble high‐molecular weight sulfated proteoglycans with ESM from TCL 1.D9 led to appearance of low‐molecular weight split products (kav 0.5–0.6). This conversion was inhibitable by heparin but not by PFR‐CK. These findings indicate that activated T cells contain two enzymatic activities, i.e. MTSP‐1 and at least one endoglycosidase, which after receptor‐triggered secretion can synergize in the degradation of sulfated proteoglycans in subendothelial ECM.
Differential migration of T and B cells during an acute inflammatory response
Authors: Lee Chee‐Seong , Meeusen Els , Brandon Malcolm 
Published: March 2007

AbstractInflammation in the liver and mammary glands of sheep caused by challenge infection with Taenia hydatigena or infusion of killed Staphylococcus aureus, respectively were characterized by the recruitment of both T and B cells. The patterns of migration of these two major lymphocyte subpopulations were distinctly different. While T cells seemed to migrate out of existing, flat endothelium‐lined blood vessels resulting in a diffuse distribution at the sites of inflammation, B cells were characteristically present as clusters of tightly packed cells at restricted sites in the inflamed tissue. Within these B cell clusters distinct capillary vessels lined with plumb endothelial cells were always present suggesting that they were the sites of intense migration of B cells originating from the draining lymph nodes. These results indicate differential regulation of adhesion molecules on B and T cells and/or their ligands on endothelium during acute inflammatory reactions.
Lack of H‐2 restriction of the Plasmodium falciparum (NANP) sequence as multiple antigen peptide
Authors: Pessi Antonello , Valmori Danila , Migliorini Paola , Tougne Chantal , Bianchi Elisabetta , Lambert Paul‐Henri , Corradin Giampietro , Del Giudice Giuseppe 
Published: March 2007

AbstractThe major surface antigen of malaria sporozoites, the circumsporozoite protein, contains a region of tandem amino acid repeats, which in the case of the human malaria parasite Plasmodium falciparum, consist of four amino acids Asn‐Ala‐Asn‐Pro (NANP) repeated up to about 40 times. This repetitive sequence has been considered as the basis for the development of subunit vaccines against P. falciparum malaria. We and others had previously shown that synthetic and recombinant NANP peptides were immunogenic only in H‐2b mice. In the present report we show that, when mice with different H‐2 haplotypes are immunized with the repetitive NANP sequence incorporated in a synthetic branching multiple antigen peptide (MAP), all except one of the mouse strains tested mounted an anti‐peptide antibody response. Such a response does not appear to be due to the peculiar assembly of the NANP sequence. In fact, MAP containing repetitive sequences from circumsporozoite proteins of other malaria parasites did not overcome the genetic restriction of the immune response to the linear peptides. These data show that in the case of the P. falciparum NANP repeats, their immunogenicity can be dramatically changed and increased when these peptides are assembled as MAP. This unexpected finding may be of interest in the design of synthetic candidate malaria vaccines.
Exogenous β2‐microglobulin is required for antigenic peptide binding to isolated class I major histocompatibility complex molecules
Authors: Kane Kevin P. , Sherman Linda A. , Mescher Matthew F. 
Published: March 2007

AbstractBinding of antigenic peptides to purified class I major histocompatibility complex (MHC) molecules, as measured by antigen‐specific cytolytic T lymphocyte (CTL) degranulation, was found to occur in the presence of serum but not in its absence. The role of soluble β2‐microglobulin (β2m), a normal component of serum, in class I‐peptide complex formation was therefore examined. Sera depleted of β2m did not support effective peptide binding to class I, but binding was restored in the presence of low concentrations of purified human β2m. Sequential incubation of immobilized class I with human β2m first, followed by peptide, resulted in antigenic complex formation, while reversing the order of pulsing could not. Similar results were obtained in experiments examining H‐2Db, Kb and Kd with appropriate peptides and CTL. These results demonstrate that mature class I proteins are not able to directly bind peptide, but that interaction with exogenous β2m results in a structure that will subsequently bind peptide. Binding of exogenous β2m appears to result in “empty” class I molecules, possibly by exchange for endogenous β2m, with a concomitant loss of endogenous peptide.
Efficiency of peptides and lipopeptides for in vivo priming of virus‐specific cytotoxic T cells
Authors: Schild Hansjörg , Deres Karl , Wiesmüller Karl‐Heinz , Jung Günther , Rammensee Hans‐Georg 
Published: March 2007

AbstractSynthetic peptides and a novel type of lipopeptide vaccine, both containing T cell epitopes recognized by Kd‐restricted, influenza virus‐specific cytotoxic T cells (CTL) were compared in their efficiency to induce virus‐specific CTL in vivo. All attempts to induce virus‐specific CTL with synthetic peptide (in the absence of adjuvants) failed. However, a latent immunization was observed, resulting in an increased response to the injected peptide seen only after boosting the recipients with immunogenic virus. In contrast, priming with synthetic lipopeptide vaccine (tripalmitoyl‐S‐glycerylcysteinyl‐seryl‐serine [P3CSS] coupled to peptide) was successful under most conditions, and matched the priming efficiency seen with infectious virus. The requirements for in vivo priming of virus‐specific CTL using lipopeptide suggest that attachment of the lipopeptide to a hydrophobic entity, such as the cell membrane, is responsible for its efficiency.
The chicken D locus and its contribution to the immunoglobulin heavy chain repertoire
Authors: Reynaud Claude‐Agnès , Anquez Viviane , Weill Jean‐Claude 
Published: March 2007

AbstractSixteen D elements were characterized from the chicken genome, 15 of which are extremely homologous. Early expression of this D repertoire was studied for both DJ and VDJ alleles. No N diversification occurs at either DJ or VD junctions. Only P additions were observed, the length of which does not appear restricted to a dinucleotide. A selection for the almost exclusive usage of the first reading frame of the D elements takes place during B cell expansion in the bursa, in parallel with the selection of productive rearrangements. All three reading frames were observed for the DJ allele at each developmental stage, although some bias for the first reading frame occurs already at the junctional stage. The high incidence of D‐D junctions observed (25% among DJ sequences) might represent the major functional contribution of this multigene cluster in a system in which diversity will be generated later on by successive superimposed gene conversions. Other possible functions are discussed. The onset of D diversification through gene conversion between day 15 and day 18 of embryonic development is further documented.
Terminal differentiation of human bone marrow cells capable of spontaneous and high‐rate immunoglobulin secretion: Role of bone marrow stromal cells and interleukin 6
Authors: Roldán Ernesto , Brieva José A. 
Published: March 2007

AbstractHuman bone marrow (BM) is a major site for in vivo immunoglobulin (Ig) formation. A subset of BM cells has been described which is capable of high‐rate Ig secretion for 14 days in vitro without additional stimuli. Therefore, it provides a suitable model for analyzing the terminal B cell differentiation within the BM. The pleiotropic cytokine interleukin (IL) 6 was found to be essential for the further maturation of BM spontaneous Ig‐secreting cells, as can be deduced from the following findings: (a) the addition of anti‐IL‐6 antibodies inhibited most of their Ig production; (b) when endogenous IL6 synthesis in the culture was restricted by using serum‐free medium, the missing IgG secretion could be restored by the addition of exogenous IL6; and (c) active IL6 synthesis by BM cells in fetal calf serum‐containing cultures was confirmed by direct quantitation (range 0.37‐2.1 ng/ml). The presence of IL 6 during the first 3 days of culture was necessary for the induction of Ig secretion. Since neither the proliferation of these cells was elicited by IL6 nor the inhibition of the DNA synthesis in these cultures prevented the IL6‐mediated Ig secretion, IL6 must act on the BM Ig‐secreting cells as a differentiation factor. The source of the endogenous IL6 was, apparently, an adherent cell, since most of the IL 6 production was present in this cell fraction. In contrast, the nonadherent BM cell fraction contained all of the mature Ig‐secreting cells even though it produced little, if any, IL6; the combination of both populations completely restored Ig secretion. Finally, homogeneous populations of fibroblastic stromal cells derived from long‐term BM cultures were totally efficient in inducing Ig secretion by purified BM CD38+ cells; this phenomenon was also demonstrated to be IL6 mediated. Taken together, these findings appear to indicate that BM Ig‐secreting cells are not terminally differentiated, suggesting that their final maturation could be mediated by the BM microenvironment via the paracrine production of IL6.
Interferon‐γ and growth factor production by murine T cells derived from three different lymphoid tissues
Authors: Höién Ingmarie , Möller Göran 
Published: March 2007

AbstractVarious antigen‐presenting cells and the environment in different lymphoid tissues have been suggested to influence the type of lymphokine produced by T cells. We have investigated the mitogen‐induced proliferation, interferon‐γ (IFN‐γ) and growth factor production by cells isolated from spleen, mesenteric and peripheral (axilliary, brachial and inguinal) lymph nodes (LN). We found that stimulation with concanavalin A or staphylococcus enterotoxin B induced IFN‐γ synthesis in spleen cells but not in LN cells. Proliferation and growth factor production were comparable in the three cell populations. The addition of the phorbol ester phorbol 12‐myristate 13‐acetate (PMA), which is commonly used as a substitute for accessory cells, did not influence the IFN‐γ synthesis by LN cells. The growth factor production was, on the other hand, elevated by the addition of PMA. A high number of IFN‐γ‐producing peripheral LN cells were obtained if they were stimulated in the presence of splenic adherent cells. The growth factor synthesis was marginally affected by the presence of these cells. Thus, splenic adherent cells provide a co‐stimulatory signal to the T cell necessary for IFN‐γ synthesis.