bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sequence analysis of human IgVH genes indicates that ileal lamina propria plasma cells are derived from Peyer's patches
Authors: Dunn‐Walters Deborah K. , Isaacson Peter G. , Spencer Jo 
Published: March 2007

AbstractThe origin of human ileal lamina propria (LP) plasma cells has been investigated using a technique based on microdissection of cells from immunohistochemically stained tissue sections. We have sequenced rearranged IgVH4.21, IgVH 5 family and IgVH6 genes from Peyer's patch germinal center (GC) cells and plasma cells from the ileal LP. Clonally related cells were identified by comparison of their complementarity determining region (CDR) 3 sequences and patterns of somatic mutation. We observed Ig genes from B cells in the GC of Peyer's patches which were related to Ig genes from plasma cells in the ileal LP, demonstrating that clonally related cells span these sites. In addition, groups of clonally related, but diversified plasma cells were common in the lamina propria. All Ig genes isolated from LP plasma cells were heavily mutated. The distribution of mutations in the CDR of the Ig heavy chain variable region (VH) genes which were considered to be the expressed alleles in LP plasma cells was consistent with an affinity‐matured response. These observations provide compelling evidence for the origin of human ileal plasma cells from the Peyer's patches.
The CD94 and NKG2‐A C‐type lectins covalently assemble to form a natural killer cell inhibitory receptor for HLA class I molecules
Authors: Carretero Marta , Cantoni Claudia , Bellón Teresa , Bottino Cristina , Biassoni Roberto , Rodríguez Antonio , Pérez‐Villar Juan J. , Moretta Lorenzo , Moretta Alessandro , López‐Botet Miguel 
Published: March 2007

AbstractCD94, a type II membrane protein containing a C‐type lectin domain, has been shown to be involved in natural killer (NK) cell‐mediated recognition of different HLA allotypes. The inhibitory form of the CD94 receptor has recently been identified by the specific monoclonal antibody (mAb) Z199. Herein, we demonstrate that the inhibitory receptor is in fact a complex formed by the covalent association of CD94 with the NKG2‐A molecule (Mr ∼ 43 kDa), another member of the C‐type lectin superfamily, and that Z199 mAb specifically recognize NKG2‐A molecules. Although the NKG2‐A‐encoding cDNA has been known for several years, the corresponding protein and its possible function remained undefined. Moreover, we show that the NKG2‐B protein, an alternatively spliced product of the NKG2‐A gene, can also assemble with CD94. Remarkably, both NKG2‐A and NKG2‐B proteins contain cytoplasmic immunoreceptor tyrosine‐based inhibitory motifs (ITIM). This may provide the molecular basis of the inhibitory function mediated by the CD94/NKG2‐A receptor complexes.
Binding of a soluble p70 killer cell inhibitory receptor to HLA‐B*5101: Requirement for all three p70 immunoglobulin domains
Authors: Rojo Susana , Wagtmann Nicolai , Long Eric O. 
Published: March 2007

AbstractLysis of target cells by natural killer (NK) cells can be prevented by killer cell inhibitory receptors (KIR) specific for major histocompatibility complex class I molecules. Functional studies have identified two distinct p58 KIR, each reactive with a different group of HLA‐C allotypes, and distinct p70 KIR specific for some HLA‐B or HLA‐A allotypes. The NK specificities for each group of HLA‐C allotypes have been reproduced by direct binding of recombinant soluble p58 molecules. Here, we show that a soluble p70 KIR binds to HLA‐B*5101, but not to HLA‐A or HLA‐C molecules. Truncated soluble forms of the HLA‐B*5101‐specific p70 KIR, including one with two immunoglobulin (Ig) domains reactive with a monoclonal antibody that blocks p70 KIR function, did not bind to HLA‐B*5101, indicating that all three Ig domains are required for binding.
Multiple sites of post‐activation CD8+ T cell disposal
Authors: Wack Andreas , Corbella Paola , Harker Nicola , Crispe I. Nicholas , Kioussis Dimitris 
Published: March 2007

AbstractAntigen‐triggered activation of T cells leads to a sequence of differentiation steps including up‐regulation of activation markers, blast formation, proliferation, delivery of effector functions, and ultimately apoptosis. It is still controversial in which anatomical site activation‐induced apoptosis and elimination of T cells occur. To address this question, we used mice transgenic for a T cell receptor (F5) specific for an influenza virus nucleoprotein peptide (NP68) presented on the major histocompatibility complex H‐2 Db molecule. Accumulation and apoptosis of T cells was studied using terminal deoxynucleotidyl transferase‐mediated dUTP‐biotin nick end‐labeling in situ combined with immunohistology after intraperitoneal injection of the cognate peptide into F5 mice which are wild type or deficient for Rag‐1. After 4 days of peptide treatment, large perivascular infiltrations of CD8+ cells were observed in liver, lung, and kidney of F5 mice. CD8+ cell numbers were also increased in skin and small intestine, but not in brain or heart muscle of peptide‐treated animals. The infiltrating CD8+ cells show an increased percentage of apoptosis in liver, lung and, most strikingly, the kidney. These data suggest that in the F5 system, T cell disposal after activation occurs in a number of organs. Essentially identical findings were obtained in Rag‐1+/+ and Rag‐1‐/‐ F5 mice, suggesting that the deletion mechanism did not involve other T or B cells.
Assembly of an abundant endogenous major histocompatibility complex class II/peptide complex in class II compartments
Authors: Morkowski Stanislaw , Raposo Graça , Kleijmeer Monique , Geuze Hans J. , Rudensky Alexander Y. 
Published: March 2007

AbstractTo identify the intracellular site(s) of formation of an endogenous class II/peptide complex in a human B cell line, we employed kinetic pulse‐chase labeling experiments followed by subcellular fractionation by Percoll density gradient centrifugation and immunogold labeling on ultrathin cryosections. For direct demonstration of assembly of such complexes, we used the monoclonal antibody YAe, which detects an endogenous complex of the mouse class II molecule I‐Ab with a 17‐amino acid peptide derived from the α chain of HLA‐DR (DRα52–68). We show that in human B lymphocytes, these class II/peptide complexes assemble and transiently accumulate in major histocompatibility complex class II‐enriched compartments before reaching the cell surface.
Dimerization of Fab fragments enables ready screening of phage antibodies that affect hepatocyte growth factor/scatter factor activity on target cells
Authors: Zaccolo Manuela , Griffiths Andrew P. , Prospero Terence D. , Winter Greg , Gherardi Ermanno 
Published: March 2007

AbstractA number of applications of antibodies in diagnosis and therapy require multivalent reagents either because of the polymeric nature of the antigens or because biological activity depends on an effect on the formation of homodimeric species. Here, we report a procedure for mass screening of phage‐derived monomeric antibody fragments that depend on valency for activity. As a model system, a set of 13 phage‐derived human Fab fragments were first selected against mouse and human recombinant hepatocyte growth factor/scatter factor (HGF/SF), a high molecular weight polypeptide growth factor related to the blood protease plasminogen and involved in development and cancer. These Fab fragments were subsequently screened for an effect on HGF/SF activity either as monomeric fragments or after dimerization with a monoclonal antibody (9E10) directed against a peptide tag on the fragments. Fab were identified that either inhibited or enhanced HGF/SF activity on target cell lines, but dimerization was required for this effect. The approach proposed should facilitate mass screening of phage‐derived antibody fragments that depend on multiple valency for activity.
Regulation of I‐309 gene expression in human monocytes by endogenous interleukin‐1
Authors: Selvan Rathinam S. , Zhou Liang‐Ji , Krangel Michael S. 
Published: March 2007

AbstractActivated human monocytes are a source of numerous γ‐chemokines. The present study was conducted to determine whether these cells produce the human γ‐chemokine I‐309 and to compare the induction requirements of I‐309 to those of other γ‐chemokines. We demonstrate that appropriately stimulated adherence‐purified human peripheral blood monocytes express I‐309 transcripts and secreted I‐309 protein. Two stimuli, immobilized IgG and lipopolysaccharide (LPS), synergize strongly to induce I‐309 gene expression. We further demonstrate that the production of endogenous interleukin (IL)‐1α plays a crucial role in I‐309 induction. Thus, neutralization of endogenous IL‐1α using an anti‐IL‐1α antiserum inhibits the induction of I‐309 transcripts in response to stimulation with immobilized IgG and LPS, and exogenous IL‐1α or IL‐1β induces I‐309 transcripts in monocytes stimulated with immobilized IgG. Immobilized IgG and LPS have the opposite effect on monocyte chemoattractant protein‐1 (MCP‐1) gene expression, in that the induction observed with either stimulus alone is diminished using the two stimuli in combination. Furthermore, endogenous and exogenous IL‐1 can be either stimulatory or inhibitory for MCP‐1 gene expression depending on other signals delivered to the monocytes. Immobilized IgG and LPS synergize to induce macrophage inflammatory protein‐1α transcripts, but endogenous IL‐1 does not play a significant role. Thus, each of these γ‐chemokine genes is under distinct regulatory control in human monocytes.
Qualitatively distinct signaling through T cell antigen receptor subunits
Authors: Jensen Wayne A. , Pleiman Christopher M. , Beaufils Phillippe , Wegener Anne‐Marie K. , Malissen Bernard , Cambier John C. 
Published: March 2007

AbstractT cell antigen receptors (TCR) contain several subunits including CD3γ, δ, and ϵ, and TCRζ and η which are capable of mediating signal transduction. It is unclear whether the signaling function of these subunits is completely redundant. To assess the relative signaling capabilities of TCR subunits, we compared proximal events in signal transduction by wild‐type TCR complexes and TCR devoid of functional ζ subunits, as well as chimeric receptors containing the cytoplasmic domains of TCRζ or CD3ϵ. Results demonstrate that in BW5147 wild‐type TCR, tail‐less ζ TCR, CD3ϵ, and TCRζ transduce signals leading to tyrosine phosphorylation of similar sets of cellular substrates, including the receptor subunits, Fyn, ZAP‐70, and phospholipase Cγ1 (PLCγ1). Surprisingly, unlike wild‐type TCR, tail‐less ζ TCR, and CD3ϵ, TCRζ was incapable of transducing signals resulting in inositol triphosphate (IP3) generation or intracellular free calcium ([Ca2+]i) mobilization. These data indicate that tyrosine phosphorylation of PLCγ1 is not sufficient to drive IP3 production and [Ca2+]i mobilization. Most importantly, data presented indicate that TCRζ and CD3ϵ engage partially distinct signaling pathways.
Differences in mutational patterns between rheumatoid factors in health and disease are related to variable heavy chain family and germ‐line gene usage
Authors: Børretzen Marie , Chapman Caroline , Natvig Jacob B. , Thompson Keith M. 
Published: March 2007

AbstractThe sequences of the heavy chain variable (VH) segment and dissociation constants (Kd) of 14 IgM rheumatoid factors (RF) derived from 11 different germ‐line gene segments from five healthy immunized donors (HID) are described. We extend a previous analysis of two clones from one donor using only the germ‐line segment DP‐10. In the present study, the mutation patterns of these new RF and the two earlier reported HID RF clones are analyzed in relation to VH family, germ‐line origin, and Kd. The panel of HID RF is further compared with 33 previously described IgM RF from patients with rheumatoid arthritis (RA). There is a high rate of mutation in the panel of HID RF (mean of ten mutations/VH). RF originating in RA patients have a comparable mutation rate (mean of 11 mutations/VH), suggesting that hypermutation of IgM RF is not disease related. The HID RF have, however, a significantly lower affinity for IgG than the RA RF. We found that the structural basis of the differences between HID and RA RF is related to VH family usage. RF of the VH1 family use very similar germ‐line genes in HID and RA patients. HID RF of the VH1 family have, however, a low ratio of replacement‐to‐silent (R : S) mutations of only 0.41 in the heavy chain complementarity region (CDRH) 1 and 2. This is statistically significantly lower than the corresponding ratio of 3.14 in the VH1 RA RF. In contrast, RF of the VH3 family from HID and RA patients have very similar R : S ratios of 1.75 and 1.71 in CDRH1 and 2, respectively. The VH3 RA RF are, however, predominantly encoded by genes not encoding any HID RF. Thus, both repertoire differences and hypermutation resulting in significantly lower R : S ratios can be observed in RF from HID compared with RA RF.
Failure to down‐regulate Bcl‐2 protein in thymic germinal center B cells in myasthenia gravis
Authors: Shiono Hiroyuki , Fujii Yoshitaka , Okumura Meinoshin , Takeuchi Yukiyasu , Inoue Masayoshi , Matsuda Hikaru 
Published: March 2007

AbstractThe most unusual characteristic of myasthenia gravis (MG) is that the thymus has germinal centers (GC). Cultured thymic lymphocytes from MG patients spontaneously produce anti‐acetylcholine receptor antibodies, indicating that autoreactive B cells have escaped negative selection. To investigate the underlying mechanism, we examined the expression of the apoptosis‐related protein Bcl‐2 in GC B cells (defined as CD19+ CD38+ cells) in the thymus in 14 MG patients using three‐color flow cytometry. GC in MG patients did not show the normal down‐regulation of Bcl‐2 (the frequency of Bcl‐2+ GC B cells in the MG thymus and in control tonsils 54.3 ± 16.2% versus 20.6 ± 8.0%; mean ± SD, p < 0.0001). In contrast, Bcl‐2 in GC in the mediastinal lymph nodes from four patients was down‐regulated to a relatively normal level. Using the terminal deoxynucleotidyl transferase‐mediated dUTP‐biotin nick end‐labeling (TUNEL) method to detect DNA fragmentation in situ, the frequency of TUNEL+ cells in GC in the MG thymus was lower than in control tonsils. These results suggest that autoreactive B cells which normally undergo apoptosis in GC may survive because of Bcl‐2 up‐regulation in this unusual location.
Engagement of a T cell receptor by major histocompatibility complex irrespective of peptide
Authors: Rupert Vessey S. J. , Barouch Dan H. , McAdam Stephen N. , Tussey Lynda G. , Davenport Miles A. , O'Callaghan Christopher A. , Bell John I. , McMichael Andrew J. , Jakobsen Bent K. 
Published: March 2007

AbstractT cell receptors (TCR) identify target cells presenting a ligand consisting of a major histocompatibility complex molecule (MHC) and an antigenic peptide. A considerable amount of evidence indicates that the TCR contacts both the peptide and the MHC components of the ligand. In fully differentiated T cells the interaction between the peptide and the TCR makes the critical contribution to eliciting a cellular response. However, during the positive selection of thymocytes the contribution of peptide relative to MHC is less well established. Indeed it has been suggested that the critical interaction for positive selection is between the TCR and the MHC molecule and that peptides can be viewed as either allowing or obstructing this contact. This predicts that a given TCR is capable of engaging multiple MHC/peptide complexes. In this study a system is described which detects simply engagement of the TCR by MHC/peptide complexes rather than the functional outcome of such interactions. Using this approach the extent to which peptides can influence contacts between the TCR and the MHC molecule has been examined. The results show that the TCR does in fact engage a wide range of ligands in an MHC‐restricted but largely peptide‐independent manner, suggesting that only a few peptides are able to prevent the TCR from contacting the MHC molecule.
Natural killer‐like T cells develop in SJL mice despite genetically distinct defects in NK1.1 expression and in inducible interleukin‐4 production
Authors: Beutner Ulrich , Launois Pascal , Ohteki Toshiaki , Louis Jacques A. , MacDonald H. Robson 
Published: March 2007

AbstractAn unusual subset of mature T cells expresses natural killer (NK) cell‐related surface markers such as interleukin‐2 receptor β (IL‐2Rβ CD122) and the polymorphic antigen NK1.1. These “NK‐like” T cells are distinguished by their highly skewed Vα and Vβ repertoire and by their ability to rapidly produce large amounts of IL‐4 upon T cell receptor (TCR) engagement. The inbred mouse strain SJL (which expresses NK1.1 on its NK cells) has recently been reported to lack NK1.1+ T cells and consequently to be deficient in IL‐4 production upon TCR stimulation. We show here, however, that SJL mice have normal numbers of IL‐2Rβ+ T cells with a skewed Vβ repertoire characteristic of “NK‐like” T cells. Furthermore lack of NK1.1 expression on IL‐2Rβ+ T cells in SJL mice was found by backcross analysis to be controlled by a single recessive gene closely linked to the NKR‐P1 complex on chromosome 6 (which encodes the NK1.1 antigen). Analysis of a panel of inbred mouse strains further demonstrated that lack of NK1.1 expression on IL‐2Rβ+ T cells segregated with NKR‐P1 genotype (as assessed by restriction fragment length polymorphism) and thus was not restricted to the SJL strain. In contrast, defective TCR induced IL‐4 production (which appeared to be a unique property of SJL mice) seems to be controlled by two recessive genes unlinked to NKR‐P1. Collectively, our data indicate that “NK‐like” T cells develop normally in SJL mice despite genetically distinct defects in NK1.1 expression and inducible IL‐4 production.
HLA‐DR‐restricted presentation of purified myelin basic protein is independent of intracellular processing
Authors: Vergelli Marco , Pinet Valerie , Vogt Anne B. , Kalbus Matthias , Malnati Mauro , Riccio Paolo , Long Eric O. , Martin Roland 
Published: March 2007

AbstractAntigen presentation to CD4+ T cells involves intracellular antigen processing and loading of peptides onto newly synthesized major histocompatibility complex (MHC)‐class II molecules. Some antigens, such as the lipid‐bound, native form of myelin basic protein (LB‐MBP) can also be presented by recycling of cell surface MHC class II molecules. The data reported here demonstrate that a preparation of highly purified, delipidated MBP (HP‐MBP) follows yet another presentation pathway. Similar to LB‐MBP, presentation of HP‐MBP to HLA‐DR1‐restricted T cells was independent of HLA‐DM, of newly synthesized proteins, and of invariant chain expression. However, in contrast to LB‐MBP, presentation of HP‐MBP was also independent of internalization of surface HLA‐DR molecules. The different requirements for the presentation of the two molecular forms of MBP were further confirmed by use of the protease inhibitor E64: presentation of LB‐MBP but not of HP‐MBP was inhibited after treatment of target cells with E64. Furthermore, intact HP‐MPB bound to isolated HLA‐DR molecules in vitro with an association rate that was considerably faster than that of short peptides. These results show that presentation of HP‐MBP is independent of intracellular processing and suggest that it may be presented to T cells by direct binding to surface HLA‐DR molecules.
DNA fragmentation is not the primary event in glucocorticoid‐induced thymocyte death in vivo
Authors: Nakamura Masanori , Yagi Hideki , Ishii Tadashi , Kayaba Shoichi , Soga Hiroyuki , Gotoh Takahiro , Ohtsu Susumu , Ogata Masaki , Itoh Tsunetoshi 
Published: March 2007

AbstractThymocyte death has been recognized as one of the best models for studying apoptosis. Our recent study, however, indicated that most thymocytes die without DNA fragmentation and become terminal deoxynucleotidyl transferase (TdT)‐mediated dUTP‐biotin nick end‐labeling‐positive (TUNEL+) only after being phagocytosed by macrophages. In this study, we used histological techniques using the TUNEL method, histochemistry, immunohistochemistry, and transmission electron microscopy as well as flow cytometry to examine in vivo the effect of glucocorticoid (GC), a well‐known agent for inducing thymocyte apoptosis in vitro, on thymocyte death to determine whether or not DNA fragmentation was the first event of GC‐induced thymocyte death. At 2 h and 4 h after GC injection, a large number of cortical thymocytes were TUNEL+. Most TUNEL+ cells were aggregated to form clusters. Double staining of the section showed that the TUNEL+ thymocytes were phagocytosed by acid phosphatase+ and Mac‐2+ macrophages. An ultrastructural study indicated that a far greater number of small pyknotic thymocytes were present in the cortex of the GC‐treated thymus than were observed in the control thymus, that all those pyknotic thymocytes were TUNEL−, and moreover, that at the electron microscopic level, TUNEL+ cells were all phagocytosed by macrophages. Flow cytometric analysis did not detect a single TUNEL+ thymocyte even 4 h after the GC treatment, suggesting that virtually no free dead thymocytes were present after DNA fragmentation. These results indicate that, consistent with our previous findings with normal thymocyte death and B cell death in the germinal centers, DNA fragmentation is not involved in the cell death process of the GC‐induced rapid thymocyte death in vivo.
Fcγ receptor II dependency of enhanced presentation of major histocompatibility complex class II peptides by a B cell lymphoma
Authors: Berg Matthias , Uellner Ruth , Langhorne Jean 
Published: March 2007

AbstractHere we show that the B cell lymphoma A20.292 is capable of enhanced antigen presentation to CD4+ T cells in the presence of specific antibodies. This enhancement was inhibited by anti‐Fcγ receptor (R) antibodies, suggesting that it might be due to preferential uptake of the antigen/antibody complex through the FcγRII receptor. However, immunoprecipitation studies revealed that the FcR of A20.292 cells was of the B cell type, FcγRIIb1, which is not thought to be able to internalize antigen/antibody complexes via clathrin‐coated pits. It was considered unlikely that A20.292 had an altered form of the B cell FcγR (RIIb1) receptor that enabled internalization, since similar enhancing effects were also observed using an FcγRII− cell line that had been transfected with FcγRIIb1. To reconcile these findings with the expression of FcγRIIb1, it is postulated that immune complexes are concentrated on the cell surface by the FcγRIIb1 and are thus available for preferential uptake by random fluid‐phase endocytosis. This results in more efficient generation of the epitopes recognized by these T cell hybridomas.