bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immunosuppression by lymphocytic choriomeningitis virus infection: competent effector T and B cells but impaired antigen presentation
Authors: Althage Alana , Odermatt Bernhard , Moskophidis Demetrius , Kündig Thomas , Hengartner Urs Hoffman‐Rohrer Hans , Zinkernagel Rolf M. 
Published: March 2007

AbstractLymphocytic choriomeningitis virus (LCMV) may cause a severe immunosuppression in mice. Its pathogenesis is apparently dependent on LCMV‐specific CD8 effector T cells that mediate the destruction of virus‐infected cells which are normally essentially involved in immune responses. Evaluation of various LCMV isolates in this study established a general correlation between their tropism for lymphohemopoietic cells and immunosuppression. When immune responses were assessed as the capacity of mice to mount an anti‐vaccinia virus cytotoxic T cell response or an IgG response to vesicular stomatitis virus (VSV), after a primary LCMV infection, LCMV‐Armstrong, WE, Clone 13 and Docile were increasingly immunosuppressive in a dose‐dependent fashion with respect to both extent and duration. Analysis of lymphocyte subpopulations showed variable effects of the various LCMV isolates that did not reveal patterns readily explaining immunosuppression. To evaluate whether LCMV infection affected T and/or B cell functions directly or whether antigen presentation was impaired, adoptive transfer experiments were performed. Untreated or irradiated but uninfected normal recipient mice receiving adoptively transferred T or B cells from LCMV‐WE or Docile‐infected immunosuppressed donor mice responded within 30%–100% of normal ranges in both assay systems. In contrast, when T or B cells from normal donors were transferred to irradiated or non‐irradiated LCMV‐immunosuppressed recipients, they failed to mount a significant cytotoxic T cell response against vaccinia virus or an IgG response to VSV. Thus, the T and B cells from LCMV‐immunosuppressed mice were able to function within normal ranges; in contrast, histologically and functionally, antigen presentation was severely impaired in LCMV‐immunosuppressed mice.
Identification of an immunodominant type‐II collagen peptide recognized by T cells in H‐2q mice: self tolerance at the level of determinant selection
Authors: Michaëlsson Erik , Andersson Mikael , Holmdahl Rikard , Engström Åke 
Published: March 2007

AbstractThe T cell recognition of type‐II collagen (CII) in H‐2q mice, susceptible to CII‐induced arthritis, was analyzed. With the use of T cell hybridomas derived from rat CII‐immunized mice, a peptide corresponding to amino acids 245–270 on chick CII was found to harbor a T cell epitope which is present on heterologous CII (chick, rat, human, and bovine CII) but not on autologous CII. It was shown that this epitope was located within amino acids 260–270, although flanking regions in either direction were necessary for proper recognition. A peptide corresponding to human CII (256–270) was used for further studies. A single amino acid difference at position 266 between mouse CII (aspartic acid) and heterologous CII (glutamic acid) strongly influenced recognition of this peptide. No response towards the mouse peptide was seen with any of the T cell hybridomas. Inhibition studies revealed that the mouse peptide did not bind as well to major histocompatibility complex as the corresponding heterologous peptide. Both peptides gave rise to a T cell response after immunization. However, immunization with the heterologous peptide resulted in a response strictly directed to rat CII and the immunogen while immunization with the autologous peptide elicited T cells which reacted in a heteroclitic fashion, with a stronger response to the heterologous peptide than to the autologous peptide, and did respond to rat CII but not to mouse CII. We suggest that aspartic acid in position 266 results in a cryptic determinant in mouse CII which is neither recognized after CII immunization nor capable of tolerance induction. A glutamic acid at position 266, however, gives rise to an immunodominant epitope which is recognized by a large proportion of the T cells activated after immunization with heterologous CII.
The murine IgG1/IgE class switch program
Authors: Siebenkotten Gregor , Esser Charlotte , Radbruch Andreas , Wabl Matthias 
Published: March 2007

AbstractImmunoglobulin class switching is controlled by cytokines. Thus, interleukin‐4 (IL‐4) directs class switching to both IgG1 and IgE. Consistent with this are the results reported here on restriction endonuclease analysis of active and inactive alleles of the IgH locus in IgE‐producing cells. In cells that were stimulated in vitro by lipopolysaccharide and IL‐4 the silent alleles preferentially switched to γ1, whereas in cells that were stimulated by antigen in vivo both active and inactive alleles switched to γ1. Thirty percent of the recombined switch regions (Sμ/Sϵ) contain Sγ1 sequences, which we interpret as footprints of a previous switch to γ1. Since this percentage is a minimum estimate, between 30% and 100% of switching to ϵ must occur sequentially via γ1.
T cell clones with normal or defective O‐galactosylation from a patient with permanent mixed‐field polyagglutinability
Authors: Thurnher Martin , Berger Eric G. , Clausen Henrik , Fierz Walter , Lanzavecchia Antonio 
Published: March 2007

AbstractTo delineate the extent of O‐galactosyltransferase deficiency within the lymphoid lineage, monoclonal antibody specific for the Thomsen‐Friedenreich (TF) antigen (Galβ1 → 3GalNAcα1‐O‐Ser/Thr) and its precursor the Tn antigen (GalNAcα1‐O‐Ser/Thr) were applied to the flow cytometric analysis of peripheral blood lymphocytes from a patient with permanent mixed‐field polyagglutinability (PMFP). We show that only a minor population of 4% expressed the Tn antigen which is in contrast to 93% of the patient's erythrocytes carrying the defect. Tn+ lymphocytes mainly belonged to the CD3+ subset, but were also CD19+ or CD16+. Both Tn+ and TF+ T cell clones from patient R. R. were established and shown to belong to the CD4+ or CD8+ antigenic subset. Three glycosyltransferase activities were determined in lysates from these clones: all Tn+ clones were deficient in UDP‐Gal: GalNAcα1‐O‐Ser/Thr β1 → 3 galactosyl‐transferase (β3Gal‐T) activity; by contrast this activity was present in all lysates from TF‐expressing clones. UDP‐GalNAc:polypeptide α‐N‐acetyl‐galactosaminyltransferase (GalNAc‐T) and UDP‐Gal:GlcNAc‐Rβ1 → 4 galactosyl‐transferase (β4Gal‐T) exhibited similar activities in both Tn+ and TF+ T cell clones. As a consequence of defective O‐galactosylation in Tn+ T cells, cell surface sialic acid of Tn+ clones was reduced by > 50% when compared to TF+ clones as demonstrated by sialic acid‐specific labeling using fluoresceinated Limax flavus agglutinin(LA) and flow cytometry. The Tn phenotype of T cell clones was stable for more than 1 year of continuous expansion in vitro. These data demonstrate that in PMFP, T cells may also be affected by the O‐galactosyltransferase deficiency which is accompanied by a substantial loss of cell surface sialic acid. However, the frequency of Tn+ lymphocytes in peripheral blood from patient R.R. was strikingly low. These T cell clones should be useful to study the defect at a genetic level and the importance of O‐linked carbohydrates for proper T cell function.
Four CD45/P56lck‐associated phosphorproteins (pp29‐pp32) undergo alterations in human T cell activation
Authors: Schraven Burkhart , Schirren Albrecht , Kirchgessner Henning , Siebert Brigitte , Meuer Stefan C. 
Published: March 2007

AbstractIn human T lymphocytes a functional complex is formed between the protein tyrosine phosphatase CD45, the protein tyrosine kinase p56lck and a phospho‐protein, pp32, a possible common substrate. Here we demonstrate that the previously described pp32 protein is composed of two distinct molecules (pp29 and pp32) in both resting human T lymphocytes and continuously proliferating T lymphoma lines. Importantly, T lymphocyte activation employing CD2 monoclonal antibodies (mAb), CD3 mAb or phorbol 12, 13 dibutyrate results in loss of pp29 and pp32 from the CD45/p56lck molecular complex and concomitant association of two distinct phosphoproteins with different molecular weights (pp30 and pp31). These events appear to be unrelated to clonal T cell growth but rather depend on receptor‐mediated differentiation signals. Reprecipitation experiments employing an antiserum directed at a consensus sequence of GTP‐binding proteins suggest that all four pp29‐pp32 molecules might represent proteins with GTP‐binding properties. Biochemical analysis of pp29‐pp32 employing V8‐protease digestion indicates that they differ in low‐molecular weight fragments of 8, 5, 4.5, 4 and 3 kDa, respectively.
Electroporation of exogenous antigen into the cytosol for antigen processing and class I major histocompatibility complex (MHC) presentation: weak base amines and hypothermia (18°C) inhibit the class I MHC processing pathway
Authors: Harding Clifford V. 
Published: March 2007

AbstractWhile endogenous antigens are presented by class I major histocompatibility complex (MHC) molecules, exogenous antigens generally require a means for penetration into the cytosol for processing prior to class I MHC presentation. We have optimized conditions for electroporation as a means to experimentally introduce exogenous antigens into the cytosol, providing a system with a number of advantages for dissecting the class I MHC processing pathway. Presentation was assessed by the response of class I or class II MHC‐restricted T hybridoma cells. Essentially instantaneous antigen delivery by electroporation facilitated kinetic analysis of the class I pathway and investigation of the effects of various inhibitors or hypothermic conditions on class I MHC antigen processing. This pathway was inhibited by weak base amines (e.g. chloroquine and NH4Cl), cycloheximide, and hypothermia (18°C, which inhibits certain intracellular vesicular processing pathways). The electroporation technique provides a simple, consistent approach for rapid cytosolic antigen delivery for analysis of class I MHC processing.
Expression of the complement regulatory proteins CD21, CD55 and CD59 on Burkitt lymphoma lines: their role in sensitivity to human serum‐mediated lysis
Authors: Kuraya Mikio , Klein George , Klein Eva , Yefenof Eitan 
Published: March 2007

AbstractOn a panel of nine human B cell lines we showed that the expression of the complement regulatory factors complement receptor type 2 (CR2; CD21), decay‐accelerating factor, (DAF; CD55) and homologous restriction factor (HRF20, CD59) is not correlated. All lines expressed DAF, six lines carried detectable amounts of CR2 and three carried HRF20. Upon incubation in human serum, under conditions which allowed the activation of complement through the alternative pathway, the CR2‐carrying lines bound C3 fragments and two of them (Ramos and one of its two sublines) were damaged. These two lines had the lowest DAF expression, less than 50% of the cells reacted with the IA10 monoclonal antibody.By modulating the expression of the complement regulatory molecules, the lytic sensitivity of the B cell lines could be altered. Blockade of DAF on the HRF20−, CR2+ lines with the specific monoclonal antibodies increased their sensitivity to lysis by human serum. With the DAF− and HRF20+ cells significant lytic effect was obtained only when they were pretreated with both of the specific antibodies.Interferon‐γ or tumor necrosis factor‐α treatment elevated the amount of CR2 on the low‐CR2 expressor line (Ramos/HR1K) which thereafter bound higher amounts of C3 fragments and was lysed when incubated in human serum. This line had relatively low DAF level and lacked HRF20. The cytokine treatment did not alter the expression of these molecules.The CR2+ Ramos and the CR2− Rael cells were treated with 5‐azacytidine which induced HRF20 and increased DAF expression. In parallel with this change Ramos cells became resistant to C‐mediated lysis.The experiments with the panel of human B cell lines showed thus that cytolysis through activation of complement in homologous serum can be regulated at several steps by cell surface molecules. While expression of CR2 was required for C3 fixation, DAF and HRF20 inhibited lysis. By independent modulation of the quantities of these molecules, cells acquired or lost their sensitivity.
Regulation of interleukin‐2 responses by phosphatidic acid
Authors: Cano Eva , Angeles Muñoz‐Fernández M. , Fresno Manuel 
Published: March 2007

AbstractInterleukin‐2 (IL‐2) plays a central role in the immune system by regulating the proliferation and differentiation of T lymphocytes. However, the molecular mechanism of the signal transduction through the IL‐2 receptor is poorly understood. We have studied the role of phosphatidic acid (PA) on IL‐2 signal transduction using cloned T lymphocytes. IL‐2 stimulated a transient increase in the PA concentration in resting CTLL‐2 cells prelabeled with [3H]palmitic acid. This effect was detected as early as 1 min after IL‐2 addition and peaked at 5 min. IL‐2 similarly increased phospholipase D activity in intact CTLL‐2 cells, as inferred by phosphatidylethanol production. By contrast, IL‐2 did not affect [3H]palmitic acid‐labeled diacylglycerol levels. Furthermore, exogenous addition of several natural or synthetic PA to T cells mimicked IL‐2 activity. Thus, PA were able to induce DNA synthesis on CTLL‐2 cells, although this effect was only 10%–20% of that observed with IL‐2. PA showed a synergistic effect with low doses of IL‐2. In addition, PA was able to induce c‐myc RNA transcription in CTLL‐2 cells as well as IL‐2 receptor (CD25) expression on the cell membrane with equal potency as saturating doses of IL‐2. It is likely that IL‐2‐induced PA accumulation is a consequence of phospholipase D activation. This hypothesis is further supported by the fact that the addition of exogenous phospholipase D but not phosphatidylinositol‐specific phospholipase C also reproduced the IL‐2 or PA effects mentioned above. In summary, our results suggest a role of phospholipase D activation and PA formation as second messengers of IL‐2 activity.
The calcium‐binding proteins MRP8 and MRP14 form a membrane‐associated heterodimer in a subset of monocytes/macrophages present in acute but absent in chronic inflammatory lesions
Authors: Bhardwaj Ranjit S. , Zotz Claudia , Roth Johannes , Goebeler Matthias , Mahnke Karsten , Falk Matthias , Meinardus‐Hager Georg , Sorg Clemens , Zwadlo‐Klarwasser Gabriele 
Published: March 2007

AbstractMonocytes/macrophages expressing an epitope recognized by a monoclonal antibody 27E10 are present in acute but are absent in chronic inflammatory disorders. This report shows that the 27E10 antigen is formed by noncovalent association of the two Ca2+‐binding proteins MRP8 and MRP14 which belong to the S100 protein family. Identification has been confirmed immunochemically, by matrix‐assisted UV‐laser desorption/ionization spectrometry and by partial amino acid sequencing. Surface expression of the MRP8/MRP14 complex on a subset of monocytes is reported for the first time and shown to be up‐regulated in a Ca2+‐dependent manner. The 27E10 surface‐positive monocytes isolated by cell separation techniques release high amounts of tumor necrosis factor‐α and interleukin‐1β in contrast to their 27E10 surface‐negative counterparts thus emphasizing their role in inflammation.
Species‐specific restriction of complement by HRF20 (CD59) generated by cDNA transfection
Authors: Takizawa Hisao , Okada Hidechika , Takahashi Kazuhiro , Murakami Tomoko , Okada Noriko 
Published: March 2007

AbstractThe 20‐kDa homologous restriction factor (HRF20, CD59) is a phosphatidyl inositol‐anchored membrane glycoprotein that inhibits the formation of human complement membrane attack complexes. The cDNA of HRF20 was transfected into Chinese hamster ovary (CHO) cells resulting in expression of human HRF20 protein on the cell surface anchored via glycosylphosphatidyl inositol. The transfected CHO cells were resistant to human complement‐mediated cell killing. However, the cells remained sensitive to rat and guinea pig complement. Therefore, species specificity between HRF20 and complement is maintained in HRF20 generated on the CHO cells following transfection with HRF20 cDNA.
Distinct in vivo functions of two macrophage subpopulations as evidenced by studies using macrophage‐deficient op/op mouse
Authors: Wiktor‐Jedrzejczak Wieslaw , Szperl Malgorzata , Urbanowska Elzbieta , Ansari Aftab A. 
Published: March 2007

AbstractThe op/op mice totally lack macrophage growth factor colony‐stimulating factor (CSF)‐1 and thus, by definition are completely depleted of CSF‐1‐dependent functions of the macrophage cell lineage. Moreover, they possess a severe and generalized macrophage deficiency. However, residual macrophages of these mice should still have normal CSF‐1‐independent functions. Studies designed to elucidate this issue have revealed that op/op mice are capable of normal in vivo phagocytic function and demonstrate normal humoral and cellular response postimmunization with sheep red blood cells. However, release of monokines such as tumor necrosis factor and granulocyte CSF following administration of endotoxin is severely impaired in op/op mice as compared with littermate controls. These studies suggest that the CSF‐1‐dependent macrophage population (absent in the op/op mouse) is primarily responsible for regulatory functions of these cells mediated by monokines, while the CSF‐1‐independent macrophage population (present in the op/op mouse) is primarily responsible for the classical macrophage functions in immunity such as phagocytosis, antigen processing and presentation.
Anti‐human interleukin‐6 receptor antibody inhibits human myeloma growth in vivo
Authors: Suzuki Hiroshi , Yasukawa Kiyoshi , Saito Takashi , Goitsuka Ryo , Hasegawa Atsuhiko , Ohsugi Yoshiyuki , Taga Tetsuya , Kishimoto Tadamitsu 
Published: March 2007

AbstractMyeloma is one of the interleukin (IL)‐6‐related diseases to which abnormal expression of IL‐6 has been reported to be linked. We examined the in vivo inhibitory effect of anti‐human IL‐6 receptor (IL‐6R) antibody on human myeloma cell growth in mice. SCID mice were subcutaneously inoculated with solid tumor of the myeloma cell line S6B45 in which human IL‐6 was acting as an autocrine growth factor. Ten intraperitoneal administrations of 100 μg of the anti‐human IL‐6R antibody PM1 at 48‐h intervals strongly inhibited the growth of S6B45 cells when the administration started 24 h after tumor inoculation. The tumor growth inhibition in vivo was also observed by administration of the anti‐human IL‐6 antibody MH166 using the same procedure as for PM1. The inhibitory effect of PM1 was not significant when the administration started 5 or more days after tumor inoculation. This work indicates that anti‐human IL‐6R antibody, as well as anti‐human IL‐6 antibody inhibits human myeloma growth in vivo, and provides an animal model for testing the therapeutic value of agents such as antibodies to human IL‐6, IL‐6R and gp130, an IL‐6R‐associated signal transducer, in the treatment of human myelomas.
Strong serum inhibition of specific IgE correlated to competing IgG4, revealed by a new methodology in subjects from a S. mansoni endemic area
Authors: Rihet Pascal , Demeure Christian E. , Dessein Alain J. , Bourgois Alain 
Published: March 2007

AbstractA method allowing the immunopurification of human IgE from small volumes of sera with a yield close to 100% (mean = 97.8%; SEM = 0.7) has been developed. The immunopurification eluates were cleared of other class antibodies that could compete with IgE in specific assays. Immunopurification of IgE followed by specific IgE enzyme‐linked immunosorbent assay (ELISA) (IMMEL) was then applied to sera of 160 individuals from an area endemic for Schistosoma mansoni. In comparison with radioimmunosorbent test (RAST) and ELISA performed on unfractionated sera, IMMEL provided the highest specific IgE signals. Furthermore, the best correlations between the specific IgE levels and either the specific basophil histamine release levels (r = 0.84; p<10−4) or the anti‐S. mansoni skin test values (r = 0.45; p = 10−4) were obtained with IMMEL.Measurement of anti‐S. mansoni IgE levels in immunopurified fractions and in unfractionated sera of these 160 individuals revealed a strong serum inhibition (geometric means of 98.6% and 96.8% for the adult worms and the larvae, respectively) of the specific IgE reactivity in ELISA. This inhibition was correlated with the anti‐adult worm and anti‐larval IgG4 levels (r = 0.65; p < 10−4) and r = 0.58;p < 10−4, respectively). In contrast, this inhibition did not correlate with the specific IgG1, IgG2, IgG3 and IgM levels. Furthermore, the level of specific IgG4 was clearly lower than that of specific IgG1, suggesting that the major contribution of IgG4 in the competition effect is not due to higher levels but rather to a specificity spectrum close to that of the specific IgE. These results support the idea that a specific function of IgG4 in serum might be to control antigen recognition by IgE and consequently, to regulate anaphylactic reactions and IgE‐mediated immunity.
Identification of a source of biologically active CD40 ligand
Authors: Armitage Richard J. , Sato Timothy A. , Macduff Brian M. , Clifford Ky N. , Alpert Alan R. , Smith Craig A. , Fanslow William C. 
Published: March 2007

AbstractWe have identified the murine thymoma line EL4 as a source of biologically active CD40 ligand. Using a biotin‐labeled soluble CD40.Fc fusion protein, consisting of the extracellular domain of human CD40 and the Fc region of human IgG1, EL4 cells were subjected to repeated flow cytometric cell sorting to select for cells with enhanced biotinylated CD40.Fc binding. After nine rounds of sorting, the number of CD40.Fc binding sites/cell had risen from 450 on the unsorted parental EL4 cells to 15000 on EL40.9 cells (EL4 cells sorted with biotinylated CD40.Fc for nine rounds). Scatchard analysis of radiolabeled CD40.Fc binding revealed that the surface‐expressed CD40 ligand on parental EL4 and EL40.9 cells bound its receptor with a single class of high‐affinity sites (Kd = 0.5 nM). Supernatant (SN) from the sorted EL40.9 cells was found to contain human and murine B cell stimulatory activity which could be removed by preclearing with immobilized CD40.Fc, confirming the presence of soluble CD40 ligand in the preparations. EL40.9 supernatant enhanced soluble CD23 (sCD23) release and induced IgE secretion from interleukin 4‐stimulated human B cells. In addition, EL40.9 SN contained proliferative activity for anti‐IgM‐activated murine B cells which could be removed by treatment with immobilized CD40.Fc. However, the same SN had no demonstrable activity on the proliferation of human B cells. The results presented here describe, for the first time, a source of membrane‐bound and soluble CD40 ligand. The soluble form of this murine ligand has activity on murine and human B cells and induces some of the functional responses predicted for the ligand based on the action of stimulatory antibodies directed against the human CD40 surface molecule.
Molecular analysis of a pro‐T cell clone transformed by Abelson‐murine leukemia virus, displaying progressive γδ T cell receptor gene rearrangement and surface expression
Authors: Heuze Françoise , Pardoll Drew , Diez Elisabeth , Ezine Sophie , Jotereau Francine 
Published: March 2007

AbstractWe present a molecular analysis of T cell differentiation in a set of clones derived from in vitro Abelson murine leukemia virus (A‐MuLV) infection of fetal liver cells. The parental clone had partial rearrangement of the β and γ loci and spontaneously displayed progressive rearrangement of Vγ genes during in vitro culture. Further differentiation of these clones leading to δ gene rearrangement and CD4 expression, then CD8, CD3 and T cell receptor γδ chain surface expression was obtained after intrathymic transfer followed by in vitro co‐culture with thymic tissue. These A‐MuLV clones, therefore, appear to represent a powerful model sytem for studying the early molecular events of T cell development at the clonal level.