bluuebunny/crossref_metadata_2025_split huggingface dataset:
VH CDR3‐dependent positive selection of murine VH12‐expressing B cells in the neonate
Authors: Clarke Stephen H. , McCray Suzanne K. 
Published: March 2007

AbstractFive to fifteen percent of peritoneal B1 (CD5+) cells from unmanipulated mice produce antibodies that bind bromelain‐treated mouse red blood cells and the hapten phosphatidylcholine (PtC). The majority of these B cells express either of two VH/Vϰ gene combinations, VH12/Vϰ4 or VHH/Vϰ9. Both the VH11 and VH12 genes are rearranged to JH1 and encode third complementarity determining regions (CDR3) of restricted length and sequence. These and other observations argue strongly that PtC‐specific Bl cells are antigen selected. To determine when selection of PtC‐specific Bl cells begins in mice we have used the polymerase chain reaction to amplify VH12‐D‐Jh1 rearrangements from livers of fetal and neonatal mice, and determined the CDR3 encoding sequences of individual clones. We find an unusually low ratio of productive (P) to non‐productive (NP) rearrangements (0.4–1.0) at both developmental stages. P rearrangements in day 1 neonates are biased in D gene use and in the sequence and length of their deduced VH CDR3. These biases are similar to those of PtC‐specific B1 cells in the adult peritoneum. D gene use and CDR3 length and sequence are significantly less biased among VH12 P rearrangements 2 to 3 days earlier in the day 18 fetal liver. We suggest that this rapid change in repertoire is due to positive ligand selection that is dependent on the sequence of VH CDR3. We suggest further that the majority of VH12‐expressing cells are not ligand selected and consequently undergo programmed cell death. The evidence of restriction in day 1 neonatal livers and the low P/NP ratio in the fetus suggests that selection of VH12‐expressing cells begins before birth.
Expression of the mucosal T cell integrin αM290β7 by a major subpopulation of dendritic cells in mice
Authors: Kilshaw Peter J. 
Published: March 2007

AbstractDendritic interdigitating cells isolated from lymph nodes, Langerhans' cells from skin and dendritic cells from the spleen have been tested for expression of the mucosal T cell integrin αM290β7. Almost all interdigitating cells isolated from mesenteric lymph nodes expressed the integrin at high levels; 50‐60% of those from lymph nodes draining non‐mucosal sites also expressed this adhesion molecule. In contrast, αM290β7 was not detected on either Langerhans' cells or splenic dendritic cells. Because this integrin has recently been shown to recognize a ligand that seems to be expressed mainly or exclusively by epithelial cells, it is proposed that this adhesion pathway may be important for antigen sampling by dendritic cells in mucosal tissues.
Costimulation by interleukin‐1 of multiple activation responses in a developmentally restricted subset of immature thymocytes
Authors: Rothenberg Ellen V. , Diamond Rochelle A. 
Published: March 2007

AbstractAn intriguing feature of thymocyte differentiation is that the competence to express both interleukin‐(IL)2 and CD25 is acquired even prior to T cell recept or (TcR) expression. When T cell receptor‐independent stimuli are used, immature cells can express IL‐2 at levels comparable to mature cells, but unlike the mature cells, immature cells require IL‐1 as a costimulus. Here we present evidence that IL‐1 affects a variety of responses by members of the CD25+ subset of immature thymocytes. Cells in this population are IL‐1 dependent not only for induction of IL‐2 expression, but also for high‐level maintenance of CD25 expression. CD25+ expression is amplified by IL‐1 through a mechanism highly sensitive to changes in Ca2+ ionophore concentration. The effects of IL‐1 on CD25 maintenance are not mediated by IL‐2, because of the divergent effects of cAMP on IL‐2 and CD25+ expression. IL‐1 costimulation also increases RNA accumulation in the cell cycle, and this effect too seems to be separable from the effects on IL‐2 and CD25+ expression. All these effects of IL‐1 are developmentally stage‐specific, manifest in the CD25+ subset of immature thymocytes but not in later‐stage thymocytes or splenic T cells. Multiparameter cell sorting experiments that dissect the transitional stages between immature and TcR+ thymocytes imply that all immature cells pass through an IL‐1 responsive state. Responsiveness to IL‐1 costimulation is then lost by these cells, apparently irreversibly, at a stage just prior to detectable cell‐surface TcR expression. These results indicate that IL‐1 responsiveness is a defining characteristic of the activation physiology of cells in a particularly important developmental stage.
Different proliferative response of human and chimpanzee lymphocytes after contact with human immunodeficiency virus type 1 gp120
Authors: Di Rienzo Anna Maria , Furlini Giuliano , Olivier René , Ferris Stephane , Heeney Jonathan , Montagnier Luc 
Published: March 2007

AbstractT cell functional defects are a common aspect of human immunodeficiency virus (HIV) infection. Moreover, it has been suggested that indirect mechanisms are involved in CD4+ cell depletion. Unresponsiveness to proliferative stimuli of lymphocytes incubated with HIV particles or with viral proteins is well documented. Nevertheless, drawing a clear picture of the anergy phenomenon is difficult because of several unresolved and controversial questions. Here we report that recombinant gp120 induces anergy in T helper lymphocytes cultured with different stimuli. The proliferative responses to interleukin (IL)‐2, IL‐4, IL‐6, anti‐CD2, anti‐CD3 and phorbol 12‐myristate 13‐acetate are inhibited. Moreover, anergic cells show a different distribution in cell cycle phases as compared to control cells, leading us to suggest that the progresion in the cell cycle is hampered and that a pre‐mitotic block takes place. Furthermore, since chimpanzees are susceptible to HIV‐1 infection without showing immunodeficiency signs, we analyzed the proliferation of chimpanzee lymphocytes without observing anergy in cells preincubated with gp120. Taken together, these results support the hypothesis that anergy plays an important role in HIV infection in vivo.
Cross‐reactivity of IgG anti‐DNA‐secreting B cells in patients with systemic lupus erythematosus
Authors: Klinman Dennis M. , Shirai Akira , Conover Jacqueline , Steinberg Alfred D. 
Published: March 2007

AbstractThis study is the first to analyze the cross‐reactivity of in vivo activated B cells from patients with systemic lupus erythematosus. A chamber ELIspot assay was used to determine whether lymphocytes secreting antibodies that bound to DNA or 2,4,6‐trinitrophenol (TNP)‐keyhole limpet‐hemocyanin (KLH) could simultaneously bind to the unrelated antigens actin or ovalbumin.IgM anti‐DNA‐, IgM anti‐TNP‐KLH‐ and IgG anti‐TNP‐KLH‐secreting B cells from patients and controls showed similar levels of cross‐reactivity (ranging from 6% to 23%, depending upon the antibody isotype and antigen pair examined). In general, IgG‐producing cells were less cross‐reactive than IgM producers from the same individual (on the average threefold, p < 0.001).In contrast, IgG anti‐DNA‐secreting B cells from lupus patients (i) showed no decrease in cross‐reactivity when compared to IgM anti‐DNA‐secreting cells and (ii) were significantly more cross‐reactive than control IgG anti‐DNA‐secreting cells and IgG anti‐TNP‐KLH secreting cells from patients (p < 0.001). The degree of IgG anti‐DNA cross‐reactivity correlated with disease activity (r = 0.52, p < 0.02). The implications of these findings with respect to repertoire expression and disease pathogenesis are discussed.
The T cell antigen receptor α and β chains interact via distinct regions with CD3 chains
Authors: Manolios Nicholas , Kemp Owen , Li Zhan Guo 
Published: March 2007

AbstractSelective pairwise interactions between CD3 chains and the clonotypic T cell antigen receptor (TCR)‐α, ‐β chains has recently been established. In this study, the region of interaction between clonotypic and CD3 chains involved with assembly was examined. To determine the site of protein interaction a variety of genetically altered TCR chains were constructed. These included: truncated proteins, lacking transmembrane and or cytosolic domains; chimeric proteins, in which extracellular, transmembrane or cytosolic domains were replaced with similar domains derived from either the Tac antigen or CD4; and point mutagenized TCR chains. COS‐1 cells were transfected with cDNA, metabolically labeled, and immunoprecipitates analyzed using non‐equilibrium pH gel electrophoresis (NEPHGE)‐SDS/PAGE. The results demonstrated that assembly between TCR‐α and TCR‐β chains occurred at the extracellular level. Assembly of the TCR‐α chain with CD3‐δ, and CD3‐ε was localized to an eight‐amino acid motif within the transmembrane domain of TCR‐α. Site‐specific mutations of the TCR‐α charged residues within this motif ( arginine, lysine) to leucine and similar point mutations of the transmembrane CD3‐ε and CD3‐δ charge groups resulted in the abrogation of assembly. In contast, TCR‐β and CD3‐ε binary complexes interacted via their extracellular domain. Analogous to TCR‐α, the site of TCR‐β and CD3‐δ assembly was at the transmembrane region. Despite multiple genetic manipulations on CD3‐γ and ζ; these proteins failed to assemble with TCR‐α. Similarly, there was no interaction between TCR‐β and ζ. These findings when coupled with the information on pairwise interactions and formation of higher order subcomplexes extend our model for the structure of the TCR complex.
Joint‐derived T cells in rheumatoid arthritis react with self‐immunoglobulin heavy chains or immunoglobulin‐binding proteins that copurify with immunoglobulin
Authors: van Schooten Wim C. A. , Devereux Deirdre , Ho Charles H. , Quan Jeanette , Aguilar Barbara A. , Rust Chantal J. J. 
Published: March 2007

AbstractRheumatoid arthritis patients were found to have CD4+ T cells that proliferate in response to autologous synovial fluid and plasma. T cell clones and polyclonal T cell lines were found to respond to antigen(s) eluted from protein A Sepharose and anti‐human immunoglobulin (Ig) antibody Sepharose. The antigen(s) was further resolved to fractions that contained intact Ig or Ig heavy chain since the T cells responded to > 100 kDa and 40‐‐60 kDa polypeptides derived from purified Ig under nonreducing and reducing conditions, respectively. These results indicated that the antigen(s) is either Ig heavy chain or Ig‐binding proteins that copurify with Ig and Ig subunits. Pepsin and papain digestion of the antigenic fractions eluted from protein A destroyed the T cell reactivity. Since most Fab regions are resistant to these enzymes, further analyses are required to localize the antigenic epitope(s). The presence of Ig‐ or Ig‐antigen complex‐reactive T cells in arthritic joints implies that B cells expressing anti‐Ig antibody (i.e. rheumatoid factor) may play an important role in antigen presentation to autoreactive T cells.
Assembly of monoclonal antibodies with IgG1 and IgA heavy chain domains in transgenic tobacco plants
Authors: Ma Julian K‐C. , Lehner Thomas , Stabila Paul , Fux Charles I. , Hiatt Andrew 
Published: March 2007

AbstractThe genes encoding the heavy and light chains of a murine monoclonal antibody (mAb Guy's 13) have been cloned and expressed in Nicotiana tabacum. Transgenic plants have been regenerated that secrete full‐length Guy's 13 antibody. By manipulation of the heavy chain gene sequence, constant region domains from an immunoglobulin alpha heavy chain have been introduced, and plants secreting Guy's 13 mAb with chimeric gamma/alpha heavy chains have also been produced. For each plant antibody, light and heavy chains have been detected by Western blot analysis and the fidelity of assembly confirmed by demonstrating that the antibody is fully functional, by antigen binding studies. Furthermore, the plant antibodies retained the ability to aggregate streptococci, which confirms that the bivalent antigen‐binding capacity of the full length antibodies is intact. The results demonstrate that IgA as well as IgG class antibodies can be assembled correctly in tobacco plants and suggest that transgenic plants may be suitable for high‐level expression of more complex genetically engineered immunoglobulin molecules. Since mAb Guy's 13 prevents streptococcal colonization in humans, transgenic plant technology may have therapeutic applications.
Infiltrating T cells from patients with primary Sjögren's syndrome express restricted or unrestricted T cell receptor Vβ regions depending on the stage of the disease
Authors: Legras Fabienne , Martin Thierry , Knapp Anne‐Marie , Pasquali Jean‐Louis 
Published: March 2007

AbstractOrgan‐specific autoimmune diseases are usually considered to be mediated by autoreactive T cells which infiltrate the target tissue. Conceivably, these T cells could represent pathogenic autoreactive cells which recognize their specific antigen (peptide or superantigen) within the pathological tissue. Extensive studies dealing with the clonality of the infiltrating autoreactive cells gave conflicting results both in humans and animals. One possibility for explaining these contradictory data could rely on the stage of the disease when the T cell population is studied. Here, we report on this parameter by analyzing T cell receptor β‐chain variable regions of infiltrating T cells involved during one of the most frequent human organ‐specific autoimmune disease, the primary Sjögren's syndrome. Six patients were selected on the basis of the duration of the disease before the biopsy procedure (two early and four late stages) to analyze initial and late T cell waves within the abnormal tissue. Using short‐term interleukin‐2‐stimulated T cells, polymerase chain reactions, Southern and sequence analysis, we conclude that: (a) there is a clear restriction in the Vβ usage by the infiltrating T cells only during the early stage of the disease, (b) this Vβ restriction is related to a monoclonal T cell expansion, (c) the expanded Vβ families are different from one patient to the other, and (d) there is no clear homology in length or amino acid composition in the CDR3 of the analyzed Vβ regions. These results could provide an explanation to conflicting results on the Vβ restriction usage during autoimmune diseases and could indicate time limitations in anti‐Vβ treatment. Furthermore, the monoclonal expansion of particular Vβ‐bearing T cells argues against a role for a superantigen during this disease.
CD45RA expression on γδ and αβ T cells emigrating from the fetal and postnatal thymus
Authors: Witherden Deborah A. , Abernethy Nevin J. , Kimpton Wayne G. , Cahill Ross N. P. 
Published: March 2007

AbstractWe have compared the expression of CD45RA on αβ and γδ T cells emigrating from the fetal and postnatal thymus. The fetal and postnatal thymus export both CD45RA+ and CD45RA‐ T cells. The number of γδ+CD45RA+ T cells was remarkably constant regardless of stage of ontogeny or T cell maturity. Around 5‐‐8% of γδ thymic emigrants, thymocytes and peripheral blood lymphocytes expressed CD45RA in both fetal and postnatal animals. In contrast to γδ T cells, up to one quarter of both fetal and postnatal αβ emigrants expressed CD45RA. Post‐thymic maturation of CD45RA expression on αβ emigrants, which occurred both before and after birth, appeared to be antigen independent.
Control of Mac‐2 surface expression on murine macrophage cell lines
Authors: Sato Sachiko , Hughes R. Colin 
Published: March 2007

AbstractMac‐2 antigen, a 32‐kDa murine macrophage cell‐surface protein expressed on thioglycollate‐elicited peritoneal exudate cells at higher levels than other macrophages, is a member of the S‐(soluble) galactoside‐binding lectin family with homologies to carbohydrate‐binding proteins of other cell types. Murine macrophage cell lines can be ordered in a linear differentiation sequence according to their expression of Mac‐2 and other surface markers (Leenen et al., Differentiation 1986. 32: 157.) We show here that antigen expression in macrophage cell lines can be regulated at the level of protein secretion. WEHI‐3 cells, classified as immature macrophages by virtue of their low level of surface Mac‐2 expression synthesize similar amounts of the antigen as more mature J774.2 and P388.D1 cells that express high amounts of surface Mac‐2, but unlike these latter cell lines WEHI‐3 cells fail to secrete the protein. Exogenously added Mac‐2 binds efficiently to WEHI‐3 cells and putative Mac‐2‐binding carbohydrates are expressed equally on WEHI‐3, J774.2 and P388.D1 cells as judged by binding of plant lectins of known carbohydrate‐binding specificities. Mac‐2 secretion and surface expression in WEHI‐3 cells is not significantly enhanced by calcium ionophore A23187, a powerful stimulator of Mac‐2 secretion in other cells and a moderate stimulator in J774.2 and P388. D1 cells. WEHI‐3 cells provide a valuable system for studying the mechanism of intracellular transport and secretion of Mac‐2, a protein that lacks a signal sequence and does not enter the classical secretory pathway.
Activation of phosphatidylinositol‐3‐kinase in Jurkat T cells depends on the presence of the p56lck tyrosine kinase
Authors: von Willebrand Maria , Baier Gottfried , Couture Clément , Burn Paul , Mustelinm Tomas 
Published: March 2007

AbstractActivation of resting T lymphocytes by ligands to the T cell receptor (TcR)/CD3 complex is initiated by phosphorylation of a number of key regulatory proteins on specific tyrosine residues. One such protein is the heterodimeric enzyme phosphatidylinositol‐3‐kinase (PI3K). We recently found that this enzyme is also rapidly activated following TcR/CD3 triggering and that immunoprecipitated PI3K was activated in vitro by direct tyrosine phosphorylation. Here we show that TcR/CD3‐induced tyrosine phosphorylation and activation of PI3K in Jurkat T leukemia cells depend on the presence of the p56lck tyrosine kinase: in a variant of the Jurkat T cell line lacking p56lck, JCaM1, these responses were absent. We also show that p56lck directly activates PI3K purified from transfected COS‐1 cells, indicating that other T cell‐specific proteins are not required for the process. Finally, tryptic peptide maps show that p56lck phosphorylates three tyrosine residues in the p85α subunit of PI3K and two in p110 of PI3K. Our results suggest that p56lck is required for activation of PI3K in Jurkat T cells and can itself directly activate it by phosphorylating one or several stimulatory sites.
B cell differentiation induced by helper T cell membranes: evidence for sequential isotype switching and a requirement for lymphokines during proliferation
Authors: Hodgkin Philip D. , Castle Brian E. , Kehry Marilyn R. 
Published: March 2007

AbstractSmall dense B cells are stimulated to proliferate by membranes prepared from activated helper T (Th) cell clones. In combination with Th2 lymphokines, Th membranes stimulate B cells to differentiate to secrete predominantly immunoglobulin (Ig)M, IgG1 and IgE. The activity in Th membrane requires the expression of CD40 ligand by the T cells, and initiation of the B cell response occurs through the ligation of CD40 on the B cell surface. We have further characterized the properties of the B cell response and found that Th membranes stimulated B cell proliferation and Ig secretion in a cell density independent manner and the majority of the stimulated B cells underwent a limited number of division rounds between day 2 and 5 of culture. IgM‐secreting cells appeared in culture by day 3 and increased to reach a maximum, comprised of 30% of the viable cells, on day 5. IgG1‐secreting cells appeared 12‐‐24h after IgM‐secreting cells, and IgE‐secreting cells did not appear until day 5. These data are consistent with a sequential model of isotype switching related to cell division. As lymphokines were absolutely required for antibody production we were able to determine when during culture they were essential. Lymphokines needed to be present prior to and during B cell proliferation for differentiation to Ig‐secreting cells to proceed. This period corresponded closely to the time of maximum DNA synthesis. Consistent with sequential switching of Ig isotypes, differentiation to IgM secretion required the shortest exposure to lymphokines and IgE the longest. These experiments strongly suggest that the lymphokine‐induced commitment to differentiate is made before DNA synthesis begins, although the lymphokine‐delivered signals are necessary during DNA synthesis to support Ig class switching.
T cell receptor stimulation, but not CD28 costimulation, is dependent on LFA‐1‐mediated events
Authors: Green Jonathan M. , Zheng Xiang‐Guang , Shimizu Yoji , Thompson Craig B. , Turka Laurence A. 
Published: March 2007

AbstractAccessory molecules play a crucial role in the development of the T cell response to antigenic challenge. In this manuscript we specifically examine the role of two accessory molecules, CD28 and LFA‐1, in modulating the T cell proliferative response to a variety of stimuli. We demonstrate that the proliferation induced by staphylococcal enterotoxins A and B in combination with CD28 costimulation is dependent on LFA‐1‐mediated events. This requirement for LFA‐1 is independent of T cell‐accessory cell adhesion. Similarly, an allogeneic mixed lymphocyte reaction, which has previously been shown to be a CD28‐dependent response, can be inhibited by blockade of LFA‐1. This suggests LFA‐1 plays an essential role in these responses, either by enhancing intercellular adhesion or by an independent signal transduction event. In contrast, when the primary activating stimulus is delivered by immobilized anti‐CD3 antibody or by PMA, and the secondary stimulus by either α‐CD28 or cell‐bound CD28 ligand B7, there is no requirement for LFA‐1. In addition, we demonstrate that cross‐linking of LFA‐1 with immobilized monoclonal antibody, or engagement of LFA‐1 with ICAM‐1 expressed on the surface of a CHO cell, provide an insufficient costimulus for T cell proliferation initiated by enterotoxin, immobilized α‐CD3 or phorbol ester. Our data suggests that LFA‐1, in contrast to CD28, functions not as a costimulatory molecule, but serves primarily to modulate the signal delivered through the T cell receptor.
Prominent T lymphocyte response to Borrelia burgdorferi from peripheral blood of unexposed donors
Authors: Roessner Karen , Russell Jennifer Q. , Cooper Sheldon M. , Budd Ralph C. , Fikrig Erol , Flavell Richard A. 
Published: March 2007

AbstractThe proliferative response of peripheral blood T cells to the spirochete, Borrelia burgdorferi, can be as pronounced in unexposed normal individuals as it is in Lyme disease patients. This finding was observed using three geographically distinct isolates of B. burgdorferi. The response is not due to a lipopolysaccharide effect of the spirochete, is sensitive to Proteinase K, and requires antigen processing. It does not result from cross‐reactivity of memory T cells that may be reactive to another antigen; the proliferative response to B. burgdorferi is equally distributed between naive (CD29−, CD45RO−) and memory (CD29+, CD45RO+) T cells, whereas the tetanus response is confined to the memory subset. In support of this notion, cord blood specimens that contain almost entirely naive T cells, respond as vigorously to B. burgdorferi as T cells from normal adult peripheral blood. A large panel of CD4+ T cell clones has been derived that are specific for B. burgdorferi. The majority of these clones are reactive to B. burgdorferi in the presence only of autologous HLA‐DR molecules. Collectively, these data suggest that the T cell response from normal individuals is more likely due to multiple antigenic epitopes within Borrelial proteins than a superantigen response.