bluuebunny/crossref_metadata_2025_split huggingface dataset:
Isolation of early immunoglobulin λ‐like gene transcripts in human fetal liver
Authors: Schiff Claudine , Milili Michèle , Fougereau Michel 
Published: March 2007

AbstractIn an attempt to identify early events of human Ig gene expression, we have screened a human fetal liver cDNA library (< 90 days of gestation) with Cμ‐, Cγ‐, Cχ‐, Cλ‐specific probes and we report the characterization of two clones, Fλ1 and Fλ8, that hybridized with a human Cλ gene. These two clones, which are only 85% homologous to the functional Cλ genes, were shown to be additional nonallelic members of the 14.1/16.1 Cλ‐like family. Using pulsed field gel electrophoresis these three Cλ‐like genes were shown to be present on a 200‐kb DNA fragment, defining a cluster distinct from that of the Cλ one. Fλ1 and Fλ8 contained an identical Cλ‐like region, and differed from each other by a splicing event which joins a Jλ‐like to the Cλ‐like exon in the Fλ1 clone in the absence of any rearrangement. Homologies observed between Fλ1 and the mouse λ5 gene suggest that this human clone may contain the exon 2 and 3 equivalents of λ5. Since λ5 is selectively expressed in pre‐B cells, our proposal is also supported by the early expression of this clone, together with the presence of full‐length μ and γ transcripts and the absence of functional Ig light chain transcripts. The presence of one nucleotide deletion in the C region of Fλ1 conferring it a pseudogene status, the actual λ5 equivalent might be either one of the 14.1 or 16.1 human Cλ‐like genes, the function of which is so far unknown.
Regulation of surface igm‐ and igd‐mediated inositol phosphate formation and ca2+ mobilization in murine b lymphocytes
Authors: Harnett Margaret M. , Holman Mary J. , Klaus Gerry G. B. 
Published: March 2007

AbstractCross‐linking of surface IgM or IgD receptors on B cells initiates a signaling cascade involving the activation of an (uncharacterized) G‐protein: this in turn activates a polyphosphoinositide‐specific phosphodiesterase (PPI‐PDE), thereby leading to the release of inositol phosphates. In order to investigate if the two isotypes of sIg share a common G‐protein, we stimulated B cells sequentially with anti‐μ and anti‐δ antibodies. Ligation of either class of receptor for 1 h led to the activation of the PPI‐PDE, which persisted for several hours. However, this was accompanied by inhibition of further stimulation of the enzyme via the heterologous receptors. This desensitization was shown to operate at the level of the coupling between G‐protein and the PPI‐PDE. These effects waned after 4–8 h of stimulation, when signaling via the heterologous receptors had essentially returned to normal. In addition, stimulation of B cells by anti‐μ and anti‐δ together did not elicit additive responses, either in terms of increases in inositol phosphate production, or in terms of increases in intracellular Ca2+ levels. Taken together, these results indicate that sIgM and IgD receptors share a common G‐protein and that signaling via these receptors is under both positive and negative feedback control. The mechanisms involved are unknown, but these effects may well be due to modulation of the activities of components of the signaling cascade by protein kinase C.
Major histocompatibility complex‐linked and t cell‐dependent selection of antibody repertoires. quantitation of i‐e‐related specificities in normal mice*
Authors: Rossi Claudia Peña , Pereira Pablo , Portnoï Denis , Coutinho António 
Published: March 2007

AbstractAutoreactive B cell repertoires with major histocompatibility complex (MHC) class II (I‐E)‐related specificities were investigated by quantitating frequencies of specific B lymphocyte clonal precursors in unmanipulated normal and athymic BALB/c mice and in I‐E‐negative, MHC‐congenic BALB.B10 mice. Clonal culture supernatants containing anti‐I‐E antibodies were identified by their selective binding to I‐Ekα Edβ‐transfected fibroblasts, and those containing anti‐anti‐I‐E antibodies were detected by their selective binding to anti‐I‐E monoclonal antibodies. Analysis of splenic B lymphocytes from BALB/c mice revealed high frequencies of both specificities in the compartment of large, naturally activated cells, but not among small, resting lymphocytes. The selection of such clones was found to be MHC linked because of their absence in BALB.B10 mice, and T cell dependent because of their reduced frequency in athymic BALB/c mice. The positive selection of V regions representing complementarities and mimicries of self‐class II antigens may suggest a set of mechanisms participating in the maintenance of natural tolerance.
Syngeneic t cell transfer of diabetes into nod newborn mice: in situ studies of the autoimmune steps leading to insulin‐producing cell destruction
Authors: Bedossa Pierre , Bendelac Albert , Bach Jean‐François , Carnaud Claude 
Published: March 2007

AbstractTo overcome the limitations of in situ studies during the chronic spontaneous autoimmune process leading to insulin cell destruction and diabetes in non‐obese diabetic (NOD) mice, we have developed a model of acute transfer of diabetes into healthy syngeneic newborns. The injection of 20 × 106 T cells from adult diabetic mice produced synchronous insulitis within 3 weeks and diabetes within 4–5 weeks in young recipients, at a time when non‐injected control mice do not even exhibit histological changes in their pancreases. Sequential studies of pancreases from T cell‐transferred mice showed that lymphoid infiltration was preceded by a strong tissue expression of Ia antigen which was restricted to the vessel‐associated cells limiting the islet of Langerhans, and which might play a role in the recruitment of circulating T cells inside the islets. Acute destruction of most of the insulin‐producing cells, leading to diabetes, could take place within a few days after insulitis had begun. A majority of the inflammatory cells were T lymphocytes, ∼30% of which expressed interleukin 2 receptors. L3T4+ T cells largely predominated at the early phase of islet invasion whereas the proportion of Ly‐2+ T cells substantially increased later when β cell destruction occurred. In contrast, only a minority of B cells and macrophages participated to the inflammatory process. These data are in keeping with previous demonstrations that both T cell subsets contribute to the autoimmune disease. Furthermore, they suggest that β cell injury is mediated through a cytotoxic process, which requires the sequential involvement of L3T4+ (helper) and Ly‐2+ (cytotoxic) T cells.
Conformational analysis of t immunogenic peptides by circular dichroism spectroscopy
Authors: Abergel Chantal , Loret Erwann , Claverie Jean‐Michel 
Published: March 2007

AbstractThe structure of two T‐immunogenic peptides, one from the gag p24 protein of the human immunodeficiency virus, the other from the 11.1 gene product of Plasmodium falciparum, was studied by circular dichroism spectroscopy in various pH and solvent conditions. Although both sequences are predicted to adopt an alpha‐helical conformation and one of them is a repeat of a perfect alpha‐amphipathic sequence pattern, these two peptides exhibit a strong propensity to adopt an extended, turn or aperiodical conformation in solution.
Transcription of unrearranged t cell receptor ∂ genes in cd3‐ major histocompatibility complex‐unrestricted cytotoxic cells
Authors: Biassoni Roberto , Ferrini Silvano , Sekaly Rafick P. , Long Eric O. 
Published: March 2007

AbstractTranscription of the T cell receptor (TcR) δ gene was detected in clones and in enriched populations of CD3‐ major histocompatibility complex‐unrestricted cytotoxic cells. The transcripts were derived, at least in part, from unrearranged TcR δ genes, as shown by hybridization to a synthetic oligonucleotide probe corresponding to germ‐line sequences just upstream of Jδ1. Transcripts from unrearranged TcR δ genes are similar in size to those from productively rearranged genes. The fact that the bulk of δ transcripts was derived from unrearranged genes was supported by the observation that TcR δ gene rearrangements were not detected in DNA isolated from an enriched CD3‐ cytotoxic cell population. Transcription of the TcR δ gene in CD3‐ cytotoxic cells is consistent with the notion that these cells belong to a T cell lineage.
Recruitment of alloreactive cytotoxic T lymphocytes by an antigenic peptide
Authors: Staerz Uwe D. , Zepp Fred , Schmid Rita , Hill Mark , Rothbard Jonathan 
Published: March 2007

AbstractTo investigate the requirements for induction of cytotoxic T lymphocytes (CTL) by peptides we chose the 16‐residue nucleoprotein peptide (NPP; 365–380) from the influenza virus A/NT/60/68 as model substrate that is recognized in conjunction with major histocompatibility complex H‐2d. Here we present that CTL can be raised from naive animals by repeated in vitro stimulation with high concentrations of peptide. The frequency of this response can be boosted by immunization of the animals with NPP‐conjugated to ovalbumin as a carrier. However, in contrast to NPP‐specific CTL lines raised from virus‐primed animals none of the peptide‐induced CTL lines were able to lyse virus‐infected targets. Although they did not show an apparent difference in fine specificity of the peptide recognized, their affinity to the target cells was 100‐fold lower than that of CTL from virus‐primed animals as estimated from the peptide concentration needed to achieve significant lysis. In addition, the activity of peptide‐induced CTL was very sensitive to blocking by anti‐CD8 antibodies as compared to virus‐specific CTL. Furthermore, all peptide‐induced CTL showed a high second reactivity for allogeneic H‐2k targets. Therefore, it is argued that high epitope density achieved by high peptide concentrations can in vitro recruit lymphocytes of another specificity. For the tested peptide the reactive T lymphocytes showed high alloreactivity.
Universally immunogenic T cell epitopes: promiscuous binding to human MHC class II and promiscuous recognition by T cells
Authors: Panina‐Bordignon Paola , Tan Agnes , Termijtelen Annemarie , Demotz Stefan , Corradin Giampietro , Lanzavecchia Antonio 
Published: March 2007

AbstractTo understand the effect of human MHC class II polymorphism on antigen recognition, we analyzed the memory T cell response to three tetanus toxin epitopes defined by three short synthetic peptides (p2, p4 and p30). We found that p2 and p30 are universally immunogenic, since they are recognized by all primed donors, irrespective of their MHC haplotypes. The analysis of specific clones indicates that both peptides are very promiscuous in their capacity to bind to class II. p30 can be recognized in association with DRw11(5), 7, 9 and with DPw2 and DPw4, while p2 can be recognized in association with DR1, DRw15(2), DRw18 (3), DR4Dw4, DRw11(5), DRw13(w6), DR7, DRw8, DR9, DRw52a and DRw52b. On the contrary, the third peptide, p4, can be recognized by only half of the donors in association with only DRw52a and DRw52c.Analysis of truncated peptides shows that p30 contains three distinct epitopes, each recognized in association with different class II molecules. Therefore, the restriction specificity is already set at the level of the peptide‐MHC complex and, in all cases, T cells discriminate p30 bound to different class II molecules. On the contrary, p2 contains only one epitope, which is recognized in association with all DR molecules. In this case we found two different restriction patterns. Some clones are monogamous, since they recognize the peptide in association with one DR allele, while others are promiscuous, since they recognize the peptide in association with several different DR molecules. Thus, in this case, the restriction specificity is also set at the level of the T cell receptor.We suggest that both the promiscuous binding of peptides and the promiscuous recognition by T cells are dependent on the particular structure of the DR molecules, having a monomorphic α chain associated with a polymorphic β chain.
Mast cell stimulation by monoclonal antibodies specific for the Fcϵ receptor yields distinct responses of arachidonic acid and leukotriene C4 secretion
Authors: Ortega Enrique , Hazan Bella , Zor Uriel , Pecht Israel 
Published: March 2007

AbstractThe release of arachidonic acid ([3H]AA) and leukotriene C4 (LTC4) from the rat mucosal mast cells of the RBL‐2H3 line stimulated by Fcϵ receptor‐specific monoclonal antibodies (mAb), by IgE and multivalent antigen, or by Ca2+ ionophores, was investigated. In parallel, secretion of the granular enzyme β‐hexosaminidase was also assayed. The release of [3H]AA and LTC4 in response to stimulation by three FcϵRI‐specific mAb shows similar quantitative differences to those observed for the secretion of granule‐stored mediators. The mAb F4 induced a substantial release of both [3H]AA and LTC4, which is as high as that induced by IgE and multivalent antigen. mAb J17 and H10 were found to induce an insignificant release of [3H]AA, but while J17 did induce release of LTC4, H10 failed to induce it, even though both J17 and H10 caused substantial release of β‐hexosaminidase. Ca2+ ionophores were found to be relatively more effective in inducing release of [3H]AA and LTC4 than in causing the secretion of granular mediators, as compared to cell stimulation by FcϵRI aggregation. These results illustrate that the cell responses of degranulation and de novo synthesis and release of mediators have different sensitivities to stimulation by (a) configurationally distinct FcϵRI dimers, (b) FcϵRI aggregates induced by IgE and multivalent antigen, and (c) Ca2+ ionophores.
Recombinant soluble receptors for the Fcγ portion inhibit antibody production in vitro
Authors: Varin Nadine , Sautès Catherine , Galinha Annie , Even Jos , Hogarth P. Mark , Fridman Wolf H. 
Published: March 2007

AbstractThe problem of the structural relationship between suppressive IgG‐binding factor and low‐affinity receptors for the Fc portion of IgG (FcγRII) has not yet been solved. In the present work we have isolated a recombinant soluble FcγRII containing only the two external domains of FcγRII, and analyzed its biochemical characteristics and biological activity. A cDNA encoding FcγRII was mutated by the creation of a stop codon at the Lys175 codon. L cells have been transfected with this cDNA inserted into an expression vector.A cell line was obtained that secretes recombinant soluble FcγRII which reacts with a monoclonal anti‐FcγRII antibody and binds to IgG1, IgG2a and IgG2b murine isotypes but not to IgG3 or F(ab')2 fragments of IgG2a. The secreted molecule contains two molecular species of relative molecular mass (Mr) 44 000 and 34 000–38 000 and of pI 4.5 and 6.3. They correspond to different glycosylations of a single polypeptide of Mr 19 000. After purification to homogeneity, soluble FcγRII has found to suppress secondary and primary in vitro antibody responses in a dose‐dependent way. The present work shows that recombinant soluble FcγRII has biochemical characteristics, immunoreactivity and biological activity similar to those of suppressive IgG‐binding factor.
Heterogeneity in the ability of IgG1 monoclonal anti‐D to promote lymphocyte‐mediated red cell lysis
Authors: Kumpel Belinda M. , Leader Katherine A. , Merry Anthony H. , Hadley Andrew G. , Poole Geoffrey D. , Blancher Antoine , Goossens Dominique , Hughes‐Jones Nevin C. , Bradley Benjamin A. 
Published: March 2007

AbstractThirty‐four IgG anti‐D human monoclonal antibodies (mAb) derived from 18 donor were assessed for their ability to mediate lysis of D+ red cells by lymphocytes in antibody‐dependent cell‐mediated cytotoxicity assays. Cell‐bound antibody was quantified and the mAb were compared at similar levels of sensitization. The majority (23/31) of IgG1 and all (3/3) IgG3 mAb were ineffective; two donors produced both lytic and non‐lytic anti‐D mAb. Greater sensitivity was achieved using fluid‐phase antibody (as culture supernatants) in the assay than was obtained with pre‐sensitized red cells. Minimum levels of 2000 anti‐D molecules per cell were required for lysis using pre‐sensitized cells. Partial D red cells (DIVa, DVa and DVI) were lysed by three mAb that were lytic with normal D+ cells. There was no relationship between lytic ability and Gm allotype or D epitope specificity of the antibodies. Four mAb to other blood group specificities were tested: two (anti‐E and anti‐G) were lytic and two (anti‐c and anti‐Kell) were not lytic. Possible reasons for the heterogeneity of the lytic activity by the mAb are discussed.
Subsets of thymopoietic rat thymocytes defined by expression of the CD2 antigen and the MRC OX‐22 determinant of the leukocyte‐common an
Authors: Law Debbie A. , Spruyt Louise L. , Paterson David J. , Williams Alan F. 
Published: March 2007

AbstractThe MRC OX‐22 monoclonal antibody recognizes a restricted determinant of the rat leukocyte‐common antigen (L‐CA, CD45), which is expressed on most peripheral T cells and all B cells. In contrast only 2%–3% of thymocytes are OX‐22+ and these are now shown to be mostly of the immature CD4−CD8− (double‐negative, DN), phenotype with very few of the mature phenotype cells being OX‐22+. Analysis of immunoperoxidase sections suggests that the DN OX‐22+ cells are located in the cortex. Among the DN cells about 60% are OX‐22+ and a similar percentage are positive for CD2 antigen. Double staining showed that OX‐22+CD2−, OX‐22+CD2+, and OX‐22−CD2+ populations can be defined and that these three sets account for ∼95% of the DN cells. Measurement of the thymopoietic activity of DN subsets showed that OX‐22+CD2− and OX‐22+CD2+ cells have regenerative capacity whilst OX‐22−CD2+cells do not.
T cell receptor gene expression in sheep: differential usage of TcR 1 in the periphery
Authors: Hein Wayne R. , Dudler Lisbeth , Beya Marie‐FranÇOise , Marcuz Anne , Grossberger Dario 
Published: March 2007

AbstractWe have isolated cDNA clones for each chain of the sheep T cell receptor (TcR) and used these to analyze TcR gene expression in thymocyte and peripheral T cell subsets. Outer cortical thymocytes expressed a low level of mature message for all TcR chains suggesting that intrathymic precursors for the α/β and γ/δ lineages occur in this population. Inner cortical and medullary thymocytes expressed high levels of mature α/β transcripts, low levels of mature δ transcripts but no detectable γ message. Mature α/β transcripts were detected in peripheral CD4+ lymphocytes and these as well as CD8+ cells expressed a surface heterodimer of 85 kDa which resolved into 40‐ and 50‐kDa subunits after reduction. Peripheral CD4−CD8− lymphocytes, which in sheep are marked by the T19 antigen and may account for up to 60% of T cells in blood, expressed a surface heterodimer of 75 kDa. The T19+ cells had high levels of mature δ and truncated β transcripts in their cytoplasm but did not express the Cγ gene detected in DN thymocytes, although they seem to share Vγ and/or Jγ elements. Both forms of the sheep TcR are associated with CD3 molecules on the cell surface. These results show that (a) in contrast to the situation in rodents and humans, a large proportion of peripheral sheep lymphocytes use TcR γ/δ; (b) the proportion of T cells in the periphery which use TcR γ/δ is greater than in thymus; and (c) CD4−CD8− cells in thymus and periphery (T19+) use the same Cδ gene but appear to use different Cγ genes, suggesting that in sheep there may be more than one lineage of lymphocytes expressing TcR γ/γ.
Structure and expression of the T cell receptor gamma locus in pre‐B and early hemopoietic cells
Authors: Mccubrey James A. , Steelman Linda S. , Risser Rex G. , Mckearn John P. 
Published: March 2007

AbstractThe genetic structure and expression of the T cell receptor (TcR) loci were examined in pre‐B and early hemopoietic cells. Thirty‐eight percent of Abelson murine leukemia virus‐transformed pre‐B cell lines were rearranged at TcRγ. Moreover, many pre‐B cell lines were rearranged at two distinct γ loci, Vγ1.2 and Vγ2. The γ rearrangements in the pre‐B cell lines were similar to those observed previously in T cell lines. V + C‐containing γ mRNA was detected in two pre‐B cell lines. In all other pre‐B and interleukin (IL) 3‐dependent lymphoid and myeloid lines examined, smaller Cγ‐containing mRNA were detected. These Cγ transcripts were independent of the genetic configuration of the γ locus. In contrast, the TcR α and β loci were in the germ‐line configuration in all non‐T cell lines examined and mRNA encoding these loci were not detected. When IL 3‐dependent lymphoid and myeloid cell lines were transformed to growth factor independence by a non‐autocrine mechanism, no mRNA transcripts encoding TcR Cγ were detected. However, TcR Cγ mRNA transcripts were detected in factor‐independent cell lines that arose by an autocrine mechanism. The cell cycle expression of Cγ was compared with protooncogenes and other marker genes previously shown to be cell cycle specific. mRNA transcripts encoding Cγ were detected in the highest amounts 4–8 h after IL 3, but not phorbol myristate acetate, addition. A similar time period of expression was observed with ornithine decarboxylase which has been shown to be expressed in G1 phase. These observations indicate that TcRγ is often rearranged in pre‐B cell lines and may be directly regulated by IL 3 in IL 3‐dependent cells.
In vitro production of IL 1β, IL 1α, TNF and IL 2 in healthy subjects: distribution, effect of cyclooxygenase inhibition and evidence of independent gene regulation
Authors: Endres Stefan , Cannon Joseph G. , Ghorbani Reza , Dempsey Roy A. , Sisson Stephen D. , Lonnemann Gerhard , Meer Jos W. M. Van Der , Wolff Sheldon M. , Dinarello Charles A. 
Published: March 2007

AbstractNumerous studies have reported altered in vitro cytokine production in various diseases. In the present study we used specific immunoassays to quantitate production of interleukin 1β (IL 1β), IL 1α, tumor necrosis factor (TNF) and IL 2 from human peripheral blood mononuclear cells (PBMC). The distribution of cell‐associated and secreted cytokines was studied in PBMC of 21 individuals; in response to lipopolysaccharide (LPS) the proportion of cell‐associated IL 1β ranged from 13% to 56%, for IL 1α 29% to 98%, and for TNF 2% to 17%. In a larger cohort of 32 subjects, the total amount of immunoreactive cytokines produced in response to LPS or phytohemagglutinin was normally distributed within the study group. Mean production of IL 1α in response to LPS was 10.1 ng/ml and exceeded production of IL 1β (5.6 ng/ml) and TNF (2.2 ng/ml). The distribution pattern was characterized by high intersubject variability extending over two orders of magnitude and the presence of high and low “producers”. Production of IL 1α and IL 1β correlated (R = 0.69). In contrast, production of IL 1β did not correlate with production of TNF or IL 2. Indomethacin present during stimulation of PBMC increased the amount of IL 1β produced and showed a high correlation (R = 0.83) compared to cultures without indomethacin. Thus, low production of IL 1β in certain subjects appears not to be due to inhibitable levels of cyclooxygenase products. In a retrospective study, PBMC from 12 subjects who had taken oral cyclooxygenase inhibitors during the preceding 7 days produced 43% more IL 1β than subjects who did not take these drugs (p < 0.05). These studies demonstrate that the amount of cytokine synthesized by PBMC (a) is regulated independently for IL 1, TNF and IL 2; (b) correlates for IL 1β and IL 1α; (c) is intrinsic for low and high “producers”, and (d) production of IL 1β increases with the use of oral cyclooxygenase inhibitors.