bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selective inhibition of interleukin‐1β gene expression in activated RAW 264.7 macrophages by interferon‐γ
Authors: Chujor Chujor S. N. , Klein Lilian , Lam Charles 
Published: March 2007

AbstractThe ability of interleukin‐1 (IL‐1) to activate epidermal cell populations supports its role as a key cytokine in the pathogenesis of a number of inflammatory skin diseases. In the present study, we have examined the effect of interferon (IFN)‐γ on the expression of the IL‐β gene in mouse RAW 264.7 macrophages activated by lipopolysaccharide (LPS) plus tumor necrosis factor (TNF)‐α. Incubation of macrophages with both LPS and TNF‐α resulted in the expression of both IL‐1β and inducible nitric oxide synthase (iNOS) mRNA transcripts and increased the release of IL‐1β protein and nitrite production in culture supernatants. Addition of IFN‐γ up‐regulated the expression of the iNOS gene in cells activated by LPS + TNF‐α, but significantly suppressed the induction of IL‐1β gene expression in a dose‐dependent manner. The suppression required neither de novo protein synthesis nor involved destabilization of the mRNA transcripts. Together, these findings suggest that IFN‐γ can be an important regulatory cytokine in a chronic inflammatory site and may explain its purported anti‐inflammatory effects in certain dermatological diseases.
Determination of the allele‐specific antigen‐binding site on I‐Ak and I‐Ab molecules
Authors: Itoh Yasushi , Kajino Kiichi , Ogasawara Kazumasa , Katoh Masahito , Namba Kenichi , Takami Kimitaka , Iwabuchi Kazuya , Braunstein Ned S. , Onoé Kazunori 
Published: March 2007

AbstractResidues 46 and 54 on a pigeon cytochrome c 43–58 analog, 50E, function as major histocompatibility complex class II contact sites. A peptide, 46F50E54A, with phenylalanine (F) at position 46 and alanine (A) at 54 on 50E bound to Ab and a peptide, 46D50E54A, with aspartic acid (D) at 46 and alanine at 54, bound to Ak. To determine the allele‐specific peptide contact sites on I‐A molecules corresponding to the I‐A contact sites of the peptides, we analyzed responses of Ak‐ and/or Ab‐restricted T cell hybridomas to 46F50E54A or 46D50E54A using L cell transfectants expressing recombinant I‐A molecules between Ak and Ab or point mutants of Ak as antigen presenting cells. It was shown that the N‐terminal half of the α helix of the Aα chain determined the allele‐specific T cell responses. Furthermore, with arginine (k type amino acid) or alanine (b type amino acid) at position 56 of the Ak α chain, these T cell hybridomas were stimulated predominantly by 46D50E54A (Ak binding peptide) or 46F50E54A (Ab binding peptide), respectively. Thus, the amino acid at position 56 of the Aα chain determines allele‐specific antigen presentation. This postulate was confirmed by direct binding analysis of 50E analogs of various I‐A molecules. A single amino acid change (arginine to alanine) at position 56 of the Ak α chain altered the peptide binding specificity (46D50E54A to 46F50E54A).
Human and rodent interferon‐γ as a growth factor for Trypanosoma brucei
Authors: Bakhiet Moiz , Olsson Tomas , Mhlanga Jama , Büscher Philippe , Lycke Nils , van der Meide Peter H. , Kristensson Krister 
Published: March 2007

AbstractAn example for the bidirectional exchange of activating signals between a pathogen and immunocompetent cells in the host is presented. Trypanosoma brucei, which include subspecies that cause African sleeping sickness, secrete a molecule that triggers lymphocytes to produce interferon (IFN)‐γ. We now report that proliferation of T. brucei is stimulated in axenic cultures by IFN‐γ. The growth‐enhancing effect on the pathogen is inhibited by anti‐IFN‐γ receptor (R) antibodies and does not occur after exposure to other cytokines, i.e. IFN‐α, IFN‐β and tumor necrosis factor (TNF)‐α. While rodent‐pathogenic T. brucei strains are stimulated by rat IFN‐γ, human pathogenic strains are more potently stimulated by human IFN‐γ. Rat and human IFN‐γ can partially block each others effects. Mice with disrupted IFN‐γ genes have reduced parasitemia and prolonged survival, while the outcome is reversed in mice that lack the IFN‐γR gene.
Elevated proliferation and interleukin‐4 release from CD4+ cells after chemotherapy in human Schistosoma haematobium infection
Authors: Grogan Jane L. , Kremsner Peter G. , Deelder Andre M. , Yazdanbakhsh Maria 
Published: March 2007

AbstractCellular immune responses to schistosomal antigens were examined in 110 Schistosoma haematobium‐infected individuals before and 5 weeks after treatment with praziquantel. Chemotherapy resulted in significant decrease in worm load as measured by egg output and circulating antigens. The proliferative responses to adult worm antigen (AWA) increased significantly after treatment p < (0.001) whereas purified protein derivative of tuberculin or phytohemagglutinin responsiveness was unaffected. Interleukin (IL)‐4 production in response to both AWA and soluble egg antigen (SEA) increased markedly after treatment (p < 0.001), but IL‐5 remained unchanged. None of the studied subjects released any measurable IL‐2 and only 21% produced interferon (IFN)‐γ in response to parasite antigens. The deficiency in either IFN‐γ or IL‐2 release was not restored by chemotherapy. Thus chronic infection with S. haematobium is associated with the reversible down‐regulation of T cell proliferative responses and IL‐4 release. Results from cell depletion experiments indicated that CD4+ T cells were the target of this down‐modulation.
Triggering of CD23b antigen by anti‐CD23 monoclonal antibodies induces interleukin‐10 production by human macrophages
Authors: Dugas Nathalie , Vouldoukis Ioannis , Bécherel Pierre , Arock Michel , Debré Patrice , Tardieu Marc , Mossalayi Djavad M. , Delfraissy Jean François , Kolb Jean Pierre , Dugas Bernard 
Published: March 2007

AbstractThe aim of this study was to evaluate the capacity of human macrophages to produce interleukin (IL)‐10 upon stimulation of membrane CD23. An anti‐CD23 monoclonal antibody (mAb) was found to elicit the expression of the specific mRNA for IL‐10 in CD23‐bearing macrophages, and to induce a time‐dependent production of this cytokine with a maximal effect reached after 12 h. Inasmuch as we previously reported that CD23 ligation evoked the generation of nitric oxide and of cAMP, the effect of the Rp diastereoisomer of adenosine 3′, 5′‐cyclic phosphorothioate (Rp‐cAMP, an inhibitor of the cAMP pathway) and of NG‐monomethyl‐L‐arginine (L‐NMMA, an inhibitor of the nitric oxide pathway) were evaluated on CD23‐induced IL‐10 production. In the presence of Rp‐cAMP, the CD23‐induced production of IL‐10 and of the pro‐inflammatory cytokine tumor necrosis factor‐γ (TNF‐γ) was totally abrogated, whereas, in the presence of L‐NMMA, IL‐10 production was enhanced and TNF‐γ production was suppressed. In addition, neutralization of IL‐10 with an anti‐IL‐10 mAb increased both the magnitude and duration of CD23‐driven TNF‐α production. Such an inducing effect was observed with different anti‐CD23 mAb (clone 135, MHM6 and 25), indicating that the triggering of the CD23 molecule at the surface of human macrophages induced the generation of IL‐10 through a cAMP‐dependent mechanism. Concomitantly this generation of IL‐10 was down‐regulated by nitric oxide, which was also produced after triggering of the CD23 antigen. Taken together these data indicated that human macrophages produced IL‐10 after triggering of the CD23 molecule and that this production could regulate the inflammatory state of these cells.
Epitope‐specific engagement of the protein tyrosine phosphatase CD45 induces tumor necrosis factor‐α gene expression via transcriptional mechanisms
Authors: Estoppey Olivier , Sauty Alain , Espel Enric , Menoud Véronique , Frei Philippe C. , Spertini François 
Published: March 2007

AbstractThe common leukocyte antigen CD45 plays a central role in T cell activation in coupling the T cell receptor (TCR) to the phosphatidylinositol pathway via interactions with TCR‐associated protein tyrosine kinases lck and fyn. We here demonstrate that engagement of CD45 by monoclonal antibodies (mAb) on activated T cells induces tumor necrosis factor (TNF)‐α as well as TNF‐β, interleukin (IL)‐2 and IL‐3 gene expression. When human alloreactive T cells are stimulated with mAb 4B2, which recognizes a determinant common to all CD45 isoforms, a vigorous production of TNF‐α mRNA was detected, which peaked 2 h later. Anti‐CD45 mAb cross‐linking was required. In contrast, neither mAb 10G10, which recognizes an epitope distinct from the one recognized by mAb 4B2, nor mAb UCHL‐1, a CD45RO‐specific antibody, induced any significant increase in TNF‐α transcription. Nuclear run‐on transcription assays demonstrated that CD45 cross‐linking caused transcriptional activation of the TNF‐α gene. De novo protein synthesis was not required, since incubation with cycloheximide (CHX) did not block transcriptional activation. CHX in contrast up‐regulated TNF‐α gene expression and increased transcript half‐life, an effect that was under the control of post‐transcriptional mechanisms. Engagement of CD45 by itself did not affect transcript stability. CD45 ligation resulted in TNF‐α secretion. These results indicate that in addition to its role in TCR/CD3‐mediated T cell activation, CD45, in an epitope‐specific manner, may act as a primary signaling molecule, leading to the transcriptional regulation and secretion of a major pro‐inflammatory cytokine.
Flt3 ligand supports the differentiation of early B cell progenitors in the presence of interleukin‐11 and interleukin‐7
Authors: Ray Robert J. , Paige Christopher J. , Furlonger Caren , Lyman Stewart D. , Rottapel Robert 
Published: March 2007

AbstractB cell development is influenced by interactions between B cell progenitors and stromal cells. The precise mechanisms by which these interactions regulate B cell differentiation are currently unknown. Flt3 ligand (FL) is a growth factor which stimulates the proliferation of stem cells and early progenitors. Mice deficient for the FLT3 receptor exhibit severe reductions in early B lymphoid progenitors. We have previously described a clonal assay in vitro which allows us to follow the entire B cell differentiation pathway from uncommitted progenitors to mature, immunoglobulin‐secreting plasma cells. The growth factor combination of interleukin (IL)‐11, mast cell growth factor (MGF) and IL‐7 was shown to maintain the differentiation of these hematopoietic precursors into B cell progenitors capable of giving rise to functionally mature B cells in secondary cultures. Here, we show that FL in combination with IL‐11 and IL‐7 is sufficient to support the differentiation of uncommitted progenitors from day 10 yolk sac (AA4.1+) or day 12 fetal liver (AA4.1+ B220− Mac‐1− Sca‐1+) into the B lineage. The frequency of B cell progenitors obtained in these conditions was similar, if not better, than the frequency of B cell precursors that arose when cultured in IL‐11+MGF+IL‐7. Furthermore, the growth factor combination of IL‐11+FL+IL‐7 was able to maintain the potential of bipotent precursors giving rise to both the B and myeloid lineages in secondary cultures. We also show that FL synergizes with IL‐7 in the proliferation of committed B220+ pro‐B cells and may contribute to the maintenance of an earlier pro‐B cell population. Together, these results show that FL is important in supporting the differentiation and proliferation of early B cell progenitors in vitro.
Genetically resistant mice lacking interleukin‐12 are susceptible to infection with Leishmania major and mount a polarized Th2 cell response
Authors: Mattner Frank , Magram Jeanne , Ferrante Jessica , Launois Pascal , Padova Karin Di , Behin Reza , Gately Maurice K. , Louis Jacques A. , Alber Gottfried 
Published: March 2007

AbstractMice with homologous disruption of the gene coding for either the p35 subunit or the p40 subunit of interleukin‐12 (IL‐12) and derived from a strain genetically resistant to infection with Leishmania major have been used to study further the role of this cytokine in resistance to infection and the differentiation of functional CD4+ T cell subsets in vivo. Wild‐type 129/Sv/Ev mice are resistant to infection with L. major showing only small lesions which resolve spontaneously within a few weeks and develop a type 1 CD4+ T cell response. In contrast, mice lacking bioactive IL‐12 (IL‐12p35−/− and IL‐12p40−/−) developed large, progressing lesions. Whereas resistant mice were able to mount a delayed‐type hypersensitivity (DTH) response to Leishmania antigen, susceptible BALB/c mice as well as IL‐12‐deficient 129/Sv/Ev mice did not show any DTH reaction. To characterize the functional phenotype of CD4+ T cells triggered in infected wild‐type mice and IL‐12‐deficient mice, the expression of mRNA for interferon‐γ (IFN‐γ) and interleukin‐4 (IL‐4) in purified CD4+ lymph node cells was analyzed. Wild‐type 129/Sv/Ev mice showed high levels of mRNA for IFN‐γ and low levels of mRNA for IL‐4 which is indicative of a Th1 response. In contrast, IL‐12‐ deficient mice and susceptible BALB/c mice developed a strong Th2 response with high levels of IL‐4 mRNA and low levels of IFN‐γ mRNA in CD4+ T cells. Similarly, lymph node cells from infected wild‐type 129 mice produced predominantly IFN‐γ in response to stimulation with Leishmania antigen in vitro whereas lymph node cells from IL‐12‐deficient mice and susceptible BALB/c mice produced preferentially IL‐4. Taken together, these results confirm in vivo the importance of IL‐12 in induction of Th1 responses and protective immunity against L. major.
Activated T cells induce expression of E‐selectin in vitro and in an antigen‐dependent manner in vivo
Authors: Sunderkötter Cord , Steinbrink Kerstin , Henseleit Ute , Bosse Roland , Schwarz Agatha , Vestweber Dietmar , Sorg Clemens 
Published: March 2007

AbstractE‐selectin is an endothelial adhesion molecule for polymorphonuclear cells, monocytes and skin‐homing T cells. We have analyzed whether murine T cells are able to induce expression of E‐selectin in vitro and in vivo. Using models of inflammation in which T cells play either a significant or only a minor role, we compared induction of E‐selectin between normal mice and mice lacking functional T cells (athymic nude mice). In irritant contact dermatitis, a model without a major role for T cells, E‐selectin was transiently expressed within the first 24 h in both normal and nude mice. In experimental leishmaniasis (where specific T cells play an important role), a high expression of E‐selectin was maintained for 48 h in normal mice, whereas in nude mice expression was only transient. However, reconstitution of nude mice with 108 T cells from draining lymph nodes (LN) of Leishmania‐infected normal mice could restore sustained expression of E‐selectin. Transfer of T lymphocytes from normal LN or from LN of mice sensitized to the contact allergen trinitrochlorbenzene (TNCB) did not have this effect. T cells from TNCB‐sensitized mice, however, did induce sustained expression of E‐selectin in nude mice when TNCB was applied locally; here, reconstitution with Leishmania‐specific T cells had no effect. In vitro, T cells from infected or TNCB‐sensitized normal mice increased expression of E‐selectin on microvascular endothelial cells after 4 h of co‐culture. T cells from untreated mice were less effective. Induction was dependent on direct cell‐cell contact, but not on the action of interleukin‐1α, interleukin‐1β, tumor necrosis factor‐α or interferon‐γ. We conclude that sensitized T cells induce sustained expression of E‐selectin in vivo in an antigen‐dependent manner. This novel way of regulation could be relevant for cell‐mediated immunity and chronic disease. The mechanisms are unknown, but, as in vitro, might require direct cell‐cell contact.
Administration of anti‐interleukin‐2 receptor α antibody in vivo induces localized autoimmune disease
Authors: Taguchi Osamu , Takahashi Toshitada 
Published: March 2007

AbstractNeonatal thymectomy (Tx) of mice at day 3 after birth (Tx‐3), but not day 7 (Tx‐7), induces organ‐localized autoimmune diseases such as oophoritis and gastritis. Lesions in Tx‐3 mice can be prevented by injection of splenic CD4+ cells from syngeneic normal mice, and this CD4+ population with suppressor activity is activated extrathymically by self antigens. Since it is speculated that these CD4+ T suppressor cells (Ts) express the interleukin‐2 receptor (IL‐2R) as an activated T cell population, an attempt was made to eliminate these Ts from the developing immune system of Tx‐7 mice and normal mice by i.p. injection of anti‐IL‐2Rα monoclonal antibodies. Interestingly, organ‐localized autoimmune disease with quite similar characteristics to those observed after neonatal Tx developed in not only Tx‐7 mice, but also normal mice. The results thus indicate that CD4+ cells expressing IL‐2Rα play an important role, as Ts in the periphery, in maintaining immune tolerance.
Permissive residues within the minimal epitopes of neutralizing monoclonal antibodies to the V3 loop of HIV‐1
Authors: Laisney Isabelle L. , Benjamin Howard , Gefter Malcom , Strosberg A. Donny 
Published: March 2007

AbstractNeutralizing monoclonal antibodies (mAb) specific for the third variable (V3) domain of gp120, the HIV‐1 surface envelope protein, are mainly isolate specific. We have studied the composition and the permissivity of the minimal epitopes interacting with two of these, the 110‐A and 19.26.4 mAb, which are strictly LAI isolate specific. Screening a hexapeptide phage library displayed on the surface of filamentous phage with the 110‐A mAb has allowed selection of 49 phage sequences, permitting the definition of a consensus sequence. Based on this sequence, substituted synthetic peptides were prepared and used in binding assays. Our results show that both mAb interact with the same narrow region (316–320) of the V3 domain. The minimal epitope of the 110‐A mAb was identified as a five amino acid sequence, Hy x R G p, where Hy represents any non‐aromatic hydrophobic amino acid. By contrast, the minimal epitope of the 19.26.4 mAb was identified as x Q Pos G P, where Pos is any positively charged amino acid. Core residues of the epitope, critical for the binding to the mAb (written in uppercase letters), were set apart from permissive amino acid positions that tolerate substitutions (written in lowercase letters). Interestingly, the identified core residues Q2/317 (19.26.4 mAb) and R3/318 (110‐A mAb) do not tolerate substitution and correspond to the QR insertion in the V3 domain, characteristic of the LAI isolate as compared to other isolates. This result may explain the strict isolate specificity of most anti‐V3 LAI mAb. The two epitopes have totally different patterns of permissivity; thus, the effect of substitutions will differ depending on the mAb involved in the interaction. This suggests that the diversity of the antibody response is high enough to delay the emergence of HIV‐1 variants resistant to neutralization by V3‐specific antibodies.
OX40 is differentially expressed on activated rat and mouse T cells and is the sole receptor for the OX40 ligand
Authors: Al‐Shamkhani Aymen , Birkeland Marian L. , Puklavec Michael , Brown Marion H. , James William , Barclay A. Neil 
Published: March 2007

AbstractOX40, a member of the tumor necrosis factor (TNF) receptor/nerve growth factor (NGF) receptor superfamily was first identified as a marker of activated rat CD4+ cells with the MRC OX40 monoclonal antibody (mAb). A ligand for OX40 (called OX40 ligand or OX40L) has recently been identified and has sequence similarity to TNF. Mouse OX40L‐immunoglobulin fusion protein (OX40L‐Ig) binds to activated mouse CD4+ and CD8+ cells (Baum, P. R. et al., EMBO J. 1994. 13: 3992) suggesting that OX40 could have a differential pattern of expression on mouse and rat T cells. This, however, did not rule out the presence of an alternative receptor on CD8+ cells that also binds the OX40L. We have compared the binding of the MRC OX40 mAb with that of OX40L‐Ig to activated rat lymph node cells and show that both recognize the same protein, namely OX40 which is expressed on CD4+ and CD4+ CD8α+ cells, but not on CD4−CD8+ cells. We have raised a new mAb (MRC OX86) using recombinant mouse OX40 protein and show by two‐color flow cytometry that mouse OX40 is expressed on CD4 and CD8 single‐positive cells. In addition, the new MRC OX86 mAb, unlike the MRC OX40 mAb, did not block binding of the OX40L. We conclude that OX40 is differentially expressed on activated mouse and rat T cells and is the sole receptor for the OX40L.
Translocation of long peptides by transporters associated with antigen processing (TAP)
Authors: Koopmann Jens‐Oliver , Post Markus , Neefjes Jacques J. , Hämmerling Günter J. , Momburg Frank 
Published: March 2007

AbstractThe major histocompatibility complex (MHC)‐encoded transporters associated with antigen processing (TAP) translocate peptides from the cytosol into the lumen of the endoplasmic reticulum (ER) where they associate with MHC class I molecules. The length of class I‐binding peptides is usually 8–11 amino acids, but examples of significantly longer peptides have been described. The preferred lengths and upper and lower size limits for peptides translocated by TAP have not been determined in detail because in the currently used test systems, peptides are subject to proteolytic degradation. In the present study, three sets of individual peptides or partially randomized peptide libraries ranging between 6 and 40 residues were used that contained a radiolabeled tyrosine and a consensus sequence for ER‐specific N‐glycosylation at opposite ends, thus ensuring that only nondegraded peptides were monitored in the transport/glycosylation assay. For three different transporters, rat TAP1/2a, rat TAP1/2u and hTAP, the most efficient ATP‐dependent transport was observed for peptides with 8–12 amino acids. Hexamers and longer peptides of up to 40 amino acids were also translocated, albeit less efficiently. For two of the three sets of peptides analyzed, rat TAP1/2a showed a less stringent length selection than rat TAP1/2u and human TAP. The superior transport of the decamer of the TNKT. Y series was not due to faster degradation or less efficient glycosylation of shorter or longer length variants. A binding assay with TAP‐containing microsomes revealed a high affinity for the radiolabeled decamer (KD = 580 nM), while other length variants were clearly inferior in their binding affinities. Thus, TAP binds and preferentially translocates peptides with a length suitable for binding to MHC class I molecules, but peptides that are considerably longer may also be substrates. About 105 peptide binding sites per cell equivalent of microsomes were determined, providing an estimate for the number of TAP complexes in the ER membrane.