bluuebunny/crossref_metadata_2025 huggingface dataset:
Orthodeoxia‐platypnea due to intracardiac shunting relief with transcatheter double umbrella closure
Authors: Landzberg Michael J. , Sloss Laurence J. , Faherty Chris E. , Morrison Brian J. , Bittl John A. , Bridges Nancy D. , Casale Paul N. , Keane John F. , Lock James E.
Published: March 2007

The safety and efficacy of transcatheter clamshell occlusion of patent foramen ovale for relief of severe arterial desaturation and dyspnea in the upright position due to intracardiac shunting were examined in eight patients with excessive risk of surgical patent foramen ovale closure. All patients had successful reduction of intracardiac shunting with an immediate rise in oxygen saturation −95% by implantation of a clamshell device on the atrial septum. Despite two early incidents of device embolization, retrieval and immediate re‐implantation, and one patient with nonsustained atrial and ventricular arrhythmias, there were no adverse clinical sequelae. In follow‐up evaluation transcatheter clamshell closure of patent foramen ovale has provided persistent relief from shuntrelated arterial desaturation and symptomatology in all living patients. © 1995 Wiley‐Liss, Inc.
New technique for exchanging an “over‐the‐wire” balloon dilatation catheter
Authors: Agarwal Rajdeep , Shah Dipen , Samuel Mathew K
Published: March 2007

We describe here an indigenous technique of “over‐the‐wire” balloon exchanges that avoids use of an extension guidewire. © 1995 Wiley‐Liss, Inc.
Use of RDCs in rigid organic compounds and some practical considerations concerning alignment media
Authors: Thiele Christina M.
Published: March 2007

A molecule that is introduced into a liquid crystal or alignment medium forfeits its isotropic tumbling motion. The resulting partial alignment leads to observable anisotropic interactions, dipolar couplings being one. To control the degree of alignment that the molecule experiences is essential to retain the quality of high‐resolution solution‐state spectra. An overview of alignment media is given. The problems associated with very large residual dipolar couplings (RDCs) are pointed out, and means to reduce residual dipolar couplings (RDCs) for strychnine in substituted polyglutamate liquid crystals are described. The use of RDCs for the assignment of diastereotopic protons and for the determination of the relative configuration in rigid compounds is then described in detail, also pointing out some pitfalls. © 2007 Wiley Periodicals, Inc. Concepts Magn Reson Part A 30A: 65–80, 2007.
Spins as probes of different electronic states
Authors: Suter Dieter , Klieber Robert
Published: March 2007

Nuclear spins are efficient probes of electronic states. Because most NMR experiments are performed in thermal equilibrium, they probe the electronic ground state—the only state that is significantly populated under ambient conditions. Probing electronically excited states becomes possible, if magnetic resonance techniques are combined with optical (laser) excitation. Depending on the nature of the electronic state, drastic changes of the magnetic resonance parameters may be observed. We discuss the basic principles of this type of investigation. Depending on the lifetime of the electronically excited state, it is possible to measure separate spectra of ground and excited state if the lifetime is long on the NMR timescale, or an averaged spectrum if the lifetime is short. We present examples for both limiting cases using rare earth ions and semiconductor heterostructures. © 2007 Wiley Periodicals, Inc. Concepts Magn Reson Part A 30A: 116–126, 2007.
Upfront window trial of topotecan in previously untreated children and adolescents with poor prognosis metastatic osteosarcoma
Authors: Seibel Nita L. , Krailo Mark , Chen Zhengjia , Healey John , Breitfeld Philip P. , Drachtman Richard , Greffe Brian , Nachman James , Nadel Helen , Sato Judith K. , Meyers Paul A. , Reaman Gregory H.
Published: March 2007

BACKGROUND.

Patients with metastatic osteosarcoma have a poor prognosis. The objectives of the study were to determine the antitumor activity and toxicity of topotecan (daily ×5) in newly diagnosed patients with metastatic osteosarcoma followed by chemotherapy (ifosfamide, carboplatin, etoposide [ICE], alternating with cisplatin and doxorubicin [CD]).

METHODS.

Newly diagnosed patients (≤30 years of age) with extensive metastatic disease (primary and ≥5 pulmonary nodules and/or bone metastases) with normal hepatic, renal, and cardiac function were eligible. Patients were eligible to receive further topotecan after standard chemotherapy if they exhibited a response. Twenty‐eight patients were enrolled. Seventeen had metastases to the lung only and 11 had metastases to the bone or multiple sites. Of 28 patients enrolled, 27 could be evaluated for response. A limited dose escalation was incorporated.

RESULTS.

No responses were seen in the 11 patients treated at 3 mg/m2/day. One partial response (PR) and 1 clinical response (CLR) were reported among 15 patients who received topotecan at 3.5 mg/m2/day. No dose‐limiting toxicity was observed. Principal nondose‐limiting toxicities were hematologic and gastrointestinal. The 2‐ and 5‐year event‐free survival rates were low, 7% and 4%, respectively, but the 2‐ and 5‐year overall survival rates were 44% and 22%, respectively.

CONCLUSIONS.

Topotecan at dose of 3.5 mg/m2/day can be safely administered upfront to newly diagnosed patients without excessive toxicity. Insufficient activity was seen with topotecan in this schedule to warrant further studies in osteosarcoma. The combination of ICE and CD was tolerable when delivered after initial topotecan therapy. Cancer 2007. © 2007 American Cancer Society.
Emerging roles for zic genes in early development
Authors: Merzdorf Christa S.
Published: March 2007

Members of the Zic family of zinc finger transcription factors play critical roles in a variety of developmental processes. They are involved in development of neural tissues and the neural crest, in left‐right axis patterning, in somite development, and in formation of the cerebellum. In addition to their roles in cell‐fate specification, zic genes also promote cell proliferation. Further, they are expressed in postmitotic cells of the cerebellum and in retinal ganglion cells. Efforts to determine the role of individual zic genes within an array of developmental and cellular processes are complicated by overlapping patterns of zic gene expression and strong sequence conservation within this gene family. Nevertheless, substantial progress has been made. This review summarizes our knowledge of the molecular events that govern the activities of zic family members, including emerging relationships between upstream signaling pathways and zic genes. In addition, advancements in our understanding of the molecular events downstream of Zic transcription factors are reviewed. Despite significant progress, however, much remains to be learned regarding the mechanisms through which zic genes exert their function in a variety of different contexts. Developmental Dynamics 236:922–940, 2007. © 2007 Wiley‐Liss, Inc.
Pan‐myocardial expression of Cre recombinase throughout mouse development
Authors: Breckenridge Ross , Kotecha Surendra , Towers Norma , Bennett Michael , Mohun Tim
Published: March 2007

Mouse‐lines expressing Cre recombinase in a tissue‐specific manner are a powerful tool in developmental biology. Here, we report that a 3 kb fragment of the Xenopus laevis myosin light‐chain 2 (XMLC2) promoter drives Cre recombinase expression in a cardiac‐restricted fashion in the mouse embryo. We have isolated two XMLC2‐Cre lines that express recombinase exclusively within cardiomyocytes, from the onset of their differentiation in the cardiac crescent of the early embryo. Expression is maintained throughout the myocardium of the embryonic heart tube and subsequently the mature myocardium of the chambered heart. Recombinase activity is detected in all myocardial tissue, including the pulmonary veins. One XMLC2‐Cre line shows uniform expression while the other only expresses recombinase in a mosaic fashion encompassing less than 50% of the myocardial cells. Both lines cause severe cardiac malformations when crossed to a conditional Tbx5 line, resulting in embryonic death at midgestation. Optical projection tomography reveals that the spectrum of developmental abnormalities includes a shortening of the outflow tract and its abnormal alignment, along with a dramatic reduction in trabeculation of the ventricular segment of the looping heart tube. genesis 45:135‐144, 2007. © 2007 Wiley‐Liss, Inc.
Influence of interleukin‐6 (IL‐6) autoantibodies on IL‐6 binding to cellular receptors
Authors: Hansen Morten Bagge , Svenson Morten , Abell Kathrine , Yasukawa Kiyoshi , Diamant Marcus , Bendtzen Klaus
Published: March 2007

Neutralizing autoantibodies to interleukin‐6 (aAb‐IL‐6) have been reported in healthy individuals, in patients with autoimmune diseases, and in pharmaceutically prepared pooled IgG (IVIg). We investigated the ability of aAb‐IL‐6 derived from IVIg to interfere with IL‐6 binding to the undifferentiated monocytic cell line U‐937. High‐affinity aAb‐IL‐6, primarily of the IgG1 subclass, constituted approximately 1:106 of the total IgG in IVIg preparations. IL‐6 binding to cellular receptors was strongly inhibited by one class of aAb‐IL‐6. These antibodies recognized epitope(s) on IL‐6 essential for the binding of IL‐6 to the α subunit of the IL‐6 receptor (IL‐6R). Another class of aAb‐IL‐6 recognized epitope(s) on IL‐6, which is not essential for the binding to IL‐6R but nevertheless important for the formation of high‐affinity cellular IL‐6 binding. These antibodies presumably interfered with the association of IL‐6 receptor β chains (gp130) with IL‐6/IL‐6R complexes, implicating that small IL‐6/aAb‐IL‐6 immune complexes bound saturably (low affinity/high capacity) to cellular IL‐6 receptors. There was no detectable binding of IL‐6 through aAb‐IL‐6 and Fc receptors on U‐937, and IVIg had no direct IL‐6 receptor antagonizing activity. Dissociation kinetics of IL‐6/aAb‐IL‐6 complexes at 37 °C revealed that IL‐6 was liberated from 75% of the aAb‐IL‐6 with a half‐time (t/2) ≈ 4 h but bound almost irreversibly to the remaining aAb‐IL‐6 (t/2 > 20 h). Cellular IL‐6 uptake and degradation was suppressed by aAb‐IL‐6. Taken together, the data suggest that loss of immunologic tolerance against IL‐6 might be a novel physiological mechanism by which IL‐6 activities are effectively attenuated. Finally, binding of IL‐6 in complex with IgG1 aAb‐IL‐6 on cells expressing IL‐6 receptors implicates that such cells could be targets of antibody‐dependent immunological reactions, including cytotoxic reactions.
Murine macrophage scavenger receptor: in vivo expression and function as receptor for macrophage adhesion in lymphoid and non‐lymphoid organs
Authors: Hughes Derralynn A. , Fraser Iain P. , Gordon Siamon
Published: March 2007

Macrophage scavenger receptors are trimeric integral membrane glycoproteins which have been implicated in various macrophage functions including uptake of oxidized lipoprotein and the serum‐dependent, divalent cation‐independent adhesion of macrophages to tissue culture‐treated plastic. In this study we have used a recently defined monoclonal antibody (2F8) which recognizes murine macrophage scavenger receptor, to explore its expression in lymphoid and non‐lymphoid organs of the normal adult. Scavenger receptor was detected in the red pulp and marginal zone of normal adult mouse spleen, medulla of the thymus and subcapsular region of lymph nodes. Kupffer cells in the liver, alveolar macrophages in the lung and lamina propria macrophages in the gut all reacted with 2F8 monoclonal antibody. The antigen was not detected on any nonmacrophage cells, with the exception of sinusoidal endothelial cells in the liver. In the spleen, lymph node and liver, scavenger receptor antigen expression was associated specifically with phagocytic cells which had taken up colloidal carbon.

To examine macrophage adhesion in a context relevant to the interactions occurring within lymphoid and non‐lymphoid organs, and the contribution of macrophage scavenger receptor to this adhesion, we designed an assay of macrophage adhesion to frozen tissue sections. Adhesion to most tissues was high and uniform in the absence of any chelating agents. The chelation of Ca2+ and Mg2+ revealed specific patterns of macrophage adhesion in lymphoid and non‐lymphoid organs which was completely inhibited by 2F8. The ability of this antibody to block the EDTA‐resistant adhesion correlated with tissue expression of the antigen in some tissues. Unlike adhesion to tissue culture‐treated plastic, macrophage scavenger receptor‐dependent adhesion of macrophages to frozen tissue sections did not exhibit an absolute requirement for exogenous fetal bovine serum indicating the presence of an endogenous ligand for scavenger receptor within the tissues. We propose that macrophage scavenger receptor is a candidate homing or retention molecule for macrophage localization within ligand‐rich tissues.
Acute rejection of vascular heart allografts by perforin‐deficient mice
Authors: Schulz Manfred , Schuurman Henk‐Jan , Joergensen Joanne , Steiner Carolina , Meerloo Timo , Kägi David , Hengartner Hans , Zinkernagel Rolf M. , Schreier Max H. , Bürki Kurt , Ledermann Birgit
Published: March 2007

To study the role of perforin in cell‐mediated graft rejection, vascularized hearts were grafted to perforin‐deficient C57BL/6 and control C57BL/6 recipient mice. Fully allogeneic heart grafts (BALB/c) were acutely rejected by both recipients within 6 days. Peritoneal exudate lymphocytes from control mice but not from perforin‐deficient mice exhibit a strong alloreactive cytotoxic activity in vitro. Histological analysis of the rejected tissues demonstrated extensive mononuclear cell infiltrates in both recipients. Flow cytometry analysis and immunohistology of graft‐infiltrating cells showed similar proportions of lymphocyte subsets (CD8 ≧ CD4). Collectively, these data indicate that perforin is not essential in the cell‐mediated acute rejection of a fully mismatched heart allograft. However, perforin‐dependent effector mechanisms appeared to be limiting in the T cellmediated rejection of heart allografts differing only at a single major histocompatibility complex class I antigen (bm1), because these grafts survived longer (mean 87.8 days) in perforin‐deficient than in control mice (mean 31.5 days).
Regulation of 4‐1BB expression by cell‐cell interactions and the cytokines, interleukin‐2 and interleukin‐4
Authors: Pollok Karen E. , Kim Seung H. , Kwon Byoung S.
Published: March 2007

4‐1BB expression increased gradually following T cell activation, and by day 3 post‐stimulation with immobilized anti‐CD3 (anti‐CD3i) or concanavalin A (Con A), splenic T cells were routinely 35–45% 4‐1BB+ by flow cytometric analysis. 4‐1BB was expressed on activated CD8+, CD4+, CD28+ and CD45RB+ T cells. Optimal 4‐1BB expression was seen by day 6 post‐stimulation and was cell density dependent. When T cells were cultured for 6 days at 1 × 106/well in a 24‐well plate with anti‐CD3i, 82% of the cells were 4‐1BB+. In contrast, at lower cell densities (4 × 105, 2 × 105 and 1 × 105), optimal 4‐1BB expression was observed only if the cultures were supplemented with recombinant interleukin‐2 (IL‐2) or recombinant IL‐4 (IL‐4). In agreement, with these results, modes of inducing endogenous IL‐2 production such as cross‐linking the costimulatory molecule, CD28, or the addition of syngeneic accessory cells to T cells activated with anti‐CD3i, resulted in high levels of 4‐1BB expression. The addition of interleukin‐1α(IL‐1α) or interferon‐γ (IFN‐γ) did not increase 4‐1BB expression on anti‐CD3i‐activated T cells. In addition, if T cells were incubated with IL‐2, IL‐4, IL‐1α, IFN‐γ or anti‐CD28 alone, no 4‐1BB expression was induced. T cells activated with soluble anti‐CD3 (anti‐CD3s) in the presence of IL‐2, IL‐4, or accessory cells, did not express higher levels of 4‐1BB on their cell surface. These data suggest that initial events crucial for efficient T cell activation, such as signals delivered through the T cell receptor/CD3 complex and the CD28 molecule, are instrumental in regulating subsequent 4‐1BB expression.
Cytokine expression and regulation of human plasma cells: disappearance of interleukin‐10 and persistence of transforming growth factor‐β1
Authors: Matthes Thomas , Werner‐Favre Christiane , Zubler Rudolf H.
Published: March 2007

Less is known about the cytokine expression and regulation of normal plasma cells compared to that of activated B cells or myeloma cells. This study shows that nonproliferating (hydroxyurea‐treated), immunoglobulin (Ig)‐secreting cells generated from human B cells in the EL‐4 culture system no longer express interleukin (IL)‐6 mRNA, progressively lose IL‐10 mRNA, but continue to express transforming growth factor (TGF)‐β1 mRNA. Secretion of TGF‐β1 protein was demonstrated. On the other hand, and in contrast to the suppression of B cell proliferation and Ig secretion, the basal or the IL‐6/IL‐10 stimulated Ig secretion of nonproliferating cells was not inhibited by recombinant TGF‐γ1. Plasma cells isolated from human bone marrow expressed neither IL‐6 nor IL‐10 mRNA; only TGF‐β1 mRNA was detected by reverse transcription–polymerase chain reaction analysis. Such plasma cells may be on average more “aged” cells than those generated in vitro. Thus, plasma cells persistently express TGF‐β1, a known suppressor of various lymphoid and hemopoietic cell activities, but do not limit their own Ig secretion via this cytokine.
Location and sequence of rearranged immunoglobulin genes in human thymus
Authors: Dunn‐Walters Deborah K. , Howe Caroline J. , Isaacson Peter G. , Spencer Jo
Published: March 2007

Thymic B cells are a proliferating B cell population concentrated in normal thymic medulla. They are large cells, some with dendritic morphology, and are not associated with any organized follicular structure. Previous work in this laboratory has shown that most of these B cells are surrounded by tightly adherent thymocytes. The literature on human thymic B cells contains many inconsistencies. There is no consensus on whether they express CD5. Even the existence of thymic B cells has been questioned. In this study we have undertaken the first analysis of rearranged immunoglobulin (Ig) genes, looking in particular for evidence of affinity maturation. The Ig VH genes of human thymic B cells in this study are those of the fetal repertoire, though the resemblence to fetal Ig genes is limited in other respects. They are mostly unmutated, but the presence of mutated sequences suggests that this is not a uniform population, as has been previously indicated by phenotypic studies.
Inhibition of CD28‐mediated T cell costimulation by the phosphoinositide 3‐kinase inhibitor wortmannin
Authors: Ward Stephen G. , Wilson Anne , Turner Lynn , Westwick John , Sansom David M.
Published: March 2007

T lymphocyte activation requires at least two signals, one via the antigen‐specific T cell receptor and a second via the surface molecule CD28 which provides signals critical to interleukin‐2 (IL‐2) production and T cell proliferation. We have previously shown (Ward S. G., Westwick J., Hall N. and Sansom D. M. Eur. J. Immunol. 1993. 23: 2572) that CD28 stimulates phosphoinositide (PI) 3‐kinase activity, indicating that D‐3 phosphoinositides may act as mediators of CD28‐induced T cell costimulation. Here, we report that immunoprecipitation of CD28 molecules from Jurkat cells stimulated with the CD28‐ligand B7, results in a ligand‐dependent association of CD28 with PI 3‐kinase. This association correlates with the appearance of PI 3‐kinase enzymatic activity in CD28 immunoprecipitates and the formation of D‐3 phosphoinositides. Consistent with the hypothesis that D‐3 phosphoinositides are important mediators of CD28 signaling, treatment of T cells with the PI 3‐kinase inhibitor wortmannin, inhibited both T cell proliferation and production of IL‐2, but not the response of T cells to exogenous IL‐2. Hence, abrogation of PI 3‐kinase activity by wortmannin, appears sufficient to disrupt the costimulatory pathway utilized by CD28, indicating a central role for this enzyme in the CD28 signaling pathway.
Studies on the interdependence of gp39 and B7 expression and function during antigen‐specific immune responses
Authors: Roy Meenakshi , Aruffo Alejandro , Ledbetter Jeffrey , Linsley Peter , Kehry Marilyn , Noelle Randolph
Published: March 2007

Interactions between T and B cells are dynamic and regulated by interacting receptor: co‐receptors. Interactions between CD40 and its ligand, gp39, and the CD28/CTLA‐4 and B7 family members play a decisive role in regulating the progression of cognate interactions. The interdependence of gp39‐CD40 and CD28/CTLA‐B7 expression and function was studied in vitro during an antigeninduced immune response using T cells from mice expressing a transgenic T cell receptor (TCR). gp39 was induced on pigeon cytochrome c (PCC)‐transgenic T cells in the presence of antigen and antigen‐presenting cells. The antigen‐induced expression of gp39 on transgenic T cells was inhibited by antibodies to class II major histocompatibility complex, CD4 and LFA‐1, but not by CTLA‐4 Ig, anti‐B7‐1 or anti‐B7‐2. These data established that the antigen‐induced expression of gp39 was not dependent on co‐stimulation via CD28/CTLA‐4. The addition of PCC also resulted in the modest expression of B7‐1 and a more robust expression of B7‐2 on the cognate B cells. The addition of anti‐gp39 blocked the up‐regulated expression of B7‐1 and partially blocked the up‐regulated expression of B7‐2. The addition of anti‐gp39 and anti‐interleukin‐4 inhibited antigen‐induced expression of B7‐2 on B cells to near background levels. Studies on the up‐regulation of B7‐1 and B7‐2 on resting B cells showed that soluble gp39 up‐regulated B7‐1 and B7‐2 expression on B cells. In addition, interleukin‐4 and interferon‐γ up‐regulated B7‐2 expression on B cells. Taken together, these data demonstrate that the antigen‐induced expression of gp39 is dependent on TCR‐derived signals, yet independent of CD28/CTLA‐4 co‐stimulatory signals. Cognate interactions also resulted in the modest enhancement of B7‐1 expression and a more profound expression of B7‐2 which were completely or partially dependent on gp39‐CD40 interactions.
Soluble lipopolysaccharide receptor (CD14) is released via two different mechanisms from human monocytes and CD14 transfectants
Authors: Bufler Philip , Stiegler Gabor , Schuchmann Marcus , Hess Sigrun , Krüger Christian , Stelter Felix , Eckerskorn Christoph , Schütt Christine , Engelmann Hartmut
Published: March 2007

The receptor for lipopolysaccharide LPS (CD14) exists in a membrane‐associated (mCD14) and a soluble form (sCD14). Previous studies indicate that monocytes produce sCD14 by limited proteolysis of the membrane‐bound receptor. In this study we demonstrate that human monocytes also produce sCD14 by a protease‐independent mechanism. To investigate the molecular nature of this second pathway we studied sCD14 formation in the monocytic cell line Mono Mac 6 (MM6) and in CD14 transfectants. Both MM6 and the CD14 transfectants constitutively produce sCD14 by a protease‐independent mechanism. Structural analysis of sCD14 produced by the CD14 transfectants reconfirmed the presence of the COOH terminus predicted from the cDNA. Since glycosylphosphatidyl‐inositol anchor attachment is associated with the removal of a hydrophobic C‐terminal signal peptide, our finding demonstrates that the transfectants secrete sCD14 which escaped this posttranslational modification. Identical results obtained for sCD14 derived from peritoneal dialysis fluid of a patient with kidney dysfunction show the in vivo relevance of this pathway for sCD14 production.
Encephalitogenic, myelin basic protein‐specific T cells from naive rat thymus: preferential use of the T cell receptor gene Vβ8.2 and expression of the CD4− CD8− phenotype
Authors: Lannes‐Vieira Joseli , Goudable Bernard , Drexler Klaus , Gehrmann Jochen , Torres‐Nagel Nora , Hünig Thomas , Wekerle Hartmut
Published: March 2007

Using a primary limiting dilution approach to generate T cell lines, we compared myelin basic protein (MBP)‐specific T cell clones from naive unprimed Lewis rat thymuses with the corresponding T cell repertoire of primed rats. We found that in the naive thymus repertoire MBP‐specific, encephalitogenic T cell clones preferentially use T cell receptor Vβ8.2 genes, along with CDR3 sequences typical for the primed Lewis anti‐MBP response. In contrast to T cells from primed immune organs, which all display the CD4+ CD8− phenotype, the majority of naive thymus‐derived T cell clones expressed reduced levels of the CD4 co‐receptor. Some clones were completely CD4−CD8−, while others included CD4− CD8− subpopulations along with CD4+CD8− T cells. In the one mixed population examined in detail, the CD4−CD8− and CD4+CD8− T cell subpopulations used a T cell receptor with identical β chain sequence. The data suggest that in the Lewis rat the biased T cell receptor gene usage by encephalitogenic T cells is a property of the natural thymic T cell repertoire, possibly as a consequence of positive selection. The unusually low expression of CD4 in the major histocompatibility complex class II‐restricted autoreactive T cells could be related to their escape from negative selection within the thymus.
Antibodies that activate β2 integrins can generate different ligand binding states
Authors: Ortlepp Susan , Stephens Paul E. , Hogg Nancy , Figdor Carl G. , Robinson Martyn K.
Published: March 2007

A human erythroleukemic cell line (K562) that does not normally express β2 integrins has been transfected with the genes encoding these integrins. The resulting cell lines show minimal background adhesion but can be stimulated to bind to appropriate substrates when activated with either of two different antibodies to CD18. The two antibodies appear to generate different ligand binding states in LFA‐1 such that different members of the ICAM family are recognized. Antibody‐activated complement receptor type 3 and p150,95‐transfected cells bind protein‐coated surfaces, although they require slightly different activation conditions for optimal binding.
The distribution of CD10 (NEP 24.11, CALLA) in humans and mice is similar in non‐lymphoid organs but differs within the hematopoietic system: absence on murine T and B lymphoid progenitors
Authors: Kalled Susan L. , Siva Niranjan , Stein Harald , Reinherz Ellis L.
Published: March 2007

Prior studies in the human have implied an important function for CD10 (CALLA, neutral endopeptidase 24.11) in early lymphoid development. To examine the role of this ectoenzyme in an experimental system, a rat mAb specific for mouse CD10, termed R103, was generated. Immunohistological and flow cytometric analyses indicate that the distribution of CD10 in non‐lymphoid anatomical compartments is virtually identical in human and mouse. However, CD10 expression within the hematopoietic system is strikingly different. In contrast to human spleen, lymph node and thymus, the corresponding mouse organs contain no detectable CD10+ cells. Mouse granulocytes, unlike human granulocytes, also lack CD10 expression. Five‐color flow cytometric studies of adult bone marrow (BM) from C57BL/6 and BALB/c mice with mAb specific for CD43, B220, HSA, BP‐1 and immunoglobulin M fail to detect any significant number of CD10+ cells at pro‐B, pre‐B or B cell stages. In addition, lymphoid cells in both (rIL‐7) independent and rIL‐7‐dependent in vitro pro‐B cell cultures lack CD10 expression. Consistent with this result, CD10 mRNA is not detected. Unlike the AA4.1+ population from day 13 and 14 fetal liver, the CD10+ subset is unable to reconstitute T and B lymphoid compartments in RAG‐2−/− mice. Nevertheless, mouse CD10 is readily found on BM stromal elements known to support early B lineage lymphoid development. Given the common expression of CD10 on human and mouse BM stromal elements, this enzyme may have an important function in the stromal cell‐dependent phase of hematopoiesis.
HLA‐dependent variations in human immunodeficiency virus Nef protein alter peptide/HLA binding
Authors: Couillin Isabelle , Connan Francine , Culmann‐Penciolelli Béatrice , Gomard Elisabeth , Guillet Jean‐Gérard , Choppin Jeannine
Published: March 2007

In human immunodeficiency virus (HIV) infection, sequence variations within defined cytotoxic T lymphocyte (CTL) epitopes may lead to escape from CTL recognition. In a previous report, we have shown that the variable central region of HIV Nef protein (amino acids 73–144) that contains potential CTL epitopes, can escape the CTL response. We suggested that this non recognition occurs through a variety of mechanisms. In particular, we provided evidence that HIV Nef sequences recovered from HLA‐A11‐expressing individuals have alterations in the major anchor residues essential for binding of the two Nef epitopes (amino acids 73–82 and 84–92) to the HLA‐A11 molecule. Here, we investigate in more detail whether variations in autologous Nef sequences affect HLA binding, leading to CTL escape. Potential epitopes were sought by testing Nef peptides containing the HLA‐A11‐specific motif or related motifs. We confirmed that only the two previously described epitopes identified in cytolysis tests have optimal reactivity with the HLA‐A11 molecule. We then sequenced several viral variants from donors that do not express the HLA‐A11 molecule and compared the variability of these epitopes with those obtained from HLA‐A11‐expressing individuals. One substitution (Leu85) found in the sequences isolated from both populations increase the reactivity of the HLA‐A11‐restricted epitope 84–92, and might explain the difference in immunogenicity observed between the two HLA‐A11‐restricted epitopes from HLA‐A11+ individuals. In addition, selective variations were only detected in virus isolated from HLA‐A11‐expressing individuals. Furthermore, examination of the association of variant peptides with the HLA‐A11 molecule demonstrated that a single substitution within the minimal epitope could not always completely abrogate HLA binding, suggesting that multiple alterations within a particular epitope may accumulate during disease progression, allowing the virus to escape CTL recognition.
Intrathymic T cell receptor (TcR) targeting in mice lacking CD4 or major histocompatibility complex (MHC) class II: Rescue of CD4 T cell lineage without co‐engagement of TcR/CD4 by MHC class II
Authors: Müller Klaus‐Peter , Kyewski Bruno A.
Published: March 2007

A critical step during intrathymic T cell development, termed positive selection, is associated with rescue of short‐lived, immature thymocytes from programmed cell death, T cell lineage commitment, and induction of lineage‐specific differentiation programs. T cell receptor (TcR)‐major histocompatibility complex (MHC) interactions during positive selection can be closely mimicked by targeting TcR on immature thymocytes to cortical epithelial cells in situ via hybrid antibodies. Here, we show that antibody‐mediated TcR signaling in mice deficient for CD4 or MHC class II expression induces polyclonal differentiation of the CD4 T cell lineage. Following a single TcR signal pulse in situ, a temporal sequence of phenotype changes can be discerned: CD69 up‐regulation (< 1 day), CD8 down‐regulation, TcR up‐regulation (1–1.5 days) and down‐regulation of the heat‐stable antigen (1.5–2 days). Differentiation of phenotypically and functionally mature CD4 T cells in situ is attained within 3 days. Rescue of CD4 lineage T cells in the absence of TcR/CD4 co‐engagement by MHC class II in this experimental system supports the stochastic/selective model of T cell lineage commitment.
Identification of a major T cell immunogen in the anti‐schistosome response of adult residents in an area endemic for Schistosoma mansoni
Authors: Couissinierhyphen;Paris Patricia , Bourgois Alain , Dessein Helia , Bacellar Olivia , Rodrigues Virmondes , Kohlstädt Sybille , Buonavista Nathalie , Pène Jérome , Dessein Alain‐Jacques
Published: March 2007

Vaccine‐induced immunity to Schistosoma mansoni infection depends on the specific priming of certain T cell subsets and on the recall of this response by natural infections months or years after vaccine administration. Thus, those schistosome proteins that activate T cells in individuals stimulated by natural infections are potential candidate vaccine antigens. In the present study, we identified and purified one such T cell‐stimulating antigen and evaluated its immunological properties in subjects living in an area endemic for Schistosoma mansoni. Chromatography fractions (gel filtration, followed by ion exchange chromatography) of soluble extracts of schistosomula were screened for their ability to stimulate schistosome‐specific T cell clones derived from a subject sensitized by natural infection. A fraction stimulating most clones was identified and characterized. A few nanograms of this fraction, containing a major 9‐10‐kDa component, stimulated the T helper cells of most adults living in an endemic area of Brazil, and was able to trigger a strong cutaneous immediate hypersensitivity reaction. In contrast, children reacted weakly to this antigen preparation both in blastogenesis and in skin tests, although they mounted a significant reaction to crude larval antigen preparations. In conclusion, this work identifies a schistosomula antigen that induces a strong T cell response in adults sensitized by natural infections. This T cell response develops gradually in children and adolescents, is apparently not restricted by the HLA haplotypes common in the study area, and allows the production of parasite‐specific IgE antibodies. Thus, this T cell response has some features of the immune response that is believed to protect chronically exposed humans from reinfection.
Interactions between the tyrosine kinases p56lck, p59fyn and p50csk in CD4 signaling in T cells
Authors: Baldari Cosima T. , Di Somma M. Maddalena , Milia Elisabetta , Bergman Mathias , Telford John L.
Published: March 2007

Interaction of the CD4 co‐receptor with major histocompatibility complex (MHC) class II molecules during antigen presentation results in enhancement of antigen receptor signaling. The synergism between the two receptors is believed to result from the juxtaposition of the CD4‐associated tyrosine kinase p56lck with the cytoplasmic domains of CD3 complex components. Here, we report that cross‐linking of CD4 on the surface of Jurkat cells using monoclonal antibodies results in activation of the CD3‐associated kinase p59fyn. Co‐cross‐linking of CD4 and CD3 results in synergistic activation of p59fyn. The p59fyn kinase is also hyperactive in a Jurkat cell line stably transfected with a constitutively active p56lck mutant, indicating that p56lck mediates CD4 activation of p59fyn. In support of this hypothesis, expression of a dominant inhibitory mutant of p59fyn blocks CD4 signals involved in gene activation. In addition, the p59fyn dominant inhibitor mutant blocks gene‐activating signals induced by expression of a constitutively active mutant of p56lck. Overexpression of the regulatory kinase p50csk, which attenuates TcR signaling by inactivation of p59fyn, inhibits signaling from the constitutively active form of p56lck. Taken together, these data suggest that CD4/p56lck enhancement of TcR signaling is, at least in part, mediated by activation of p59fyn, and may be regulated by p50csk.
Resistance to anti‐IgM‐induced apoptosis in a WEHI‐231 subline is due to insufficient production of ceramide
Authors: Gottschalk Alexander R. , McShan Carol L. , Kilkus John , Dawson Glyn , Quintáns Jose
Published: March 2007

We describe the properties of a physiological cell death (PCD)‐resistant subline of WEHI‐231 generated from the PCD‐susceptible WEHI‐231.7 JM cell line maintained in our laboratory. The PCD‐resistant WEHI‐231.7 JMRE subline was uniquely resistant to anti‐immunoglobulin (Ig)M‐induced PCD but not to irradiation and etoposide. In these sublines, we compared the expression of genes implicated in regulating PCD. Northern analysis of c‐myc, c‐fos, egr‐1, Fas, p53 and retinoblastoma revealed similar basal levels of expression in all sublines tested and comparable responses to anti‐IgM treatment. Similarly, the expression of bcl‐2, bcl‐x, bax and IL‐1β converting enzyme did not correlate with susceptibility to anti‐IgM‐induced PCD. Next, we systematically studied signal transduction events including: tyrosine phosphorylation, Ca++ flux, and ceramide production in the JM and JMRE sublines. The tyrosine phosphorylation patterns and the Ca++ influx generated following sIgM engagement were very similar in the JM and JMRE sublines. In contrast, the generation of ceramide differed in the PCD‐resistant and PCD‐susceptible sublines. Ceramide is produced following cross‐linking sIgM on WEHI‐231.7 JM cells and causes PCD. Ceramide levels in anti‐IgM‐treated WEHI‐231.7 JMRE cells are low and appear to be insufficient to induce PCD.
Hepatitis B virus small surface antigen particles are processed in a novel endosomal pathway for major histocompatibility complex class I‐restricted epitope presentation
Authors: Schirmbeck Reinhold , Melber Karl , Reimann Jörg
Published: March 2007

We investigated the major histocompatibility complex (MHC) class I‐restricted presentation of an epitope of the hepatitis B virus small surface (S) antigen particle to cloned murine cytotoxic T lymphocytes (CTL). Efficient Ld‐restricted presentation of the S28–39 epitope to CTL is observed in cells of different tissue origin pulsed in vitro, either with the antigenic S28–39 12‐mer S‐peptide, or with particulate S‐antigen. The kinetics of epitope presentation differ in S‐peptide‐pulsed and in S‐particle‐pulsed cells: while a 15‐min pulse with the antigenic peptide sensitizes targets for class I‐restricted CTL lysis, presentation of S‐particles requires 30–60 min to sensitize cells for CTL lysis. Uptake of antigenic material and active metabolism of the presenting cell are required for processing of S‐particles, but not for sensitizing targets with S‐peptides. Intracellular processing and presentation of S‐particles is blocked in cells treated with chloroquine, NH4Cl, primaquine, or leupeptin, but not by treatment with cycloheximide or brefeldin A. This processing pathway operates efficiently in peptide‐transporter‐deficient, Ld‐transfected T2 cells, revealing a novel endosomal/lysosomal processing pathway for class I‐restricted presentation of peptides derived from exogenous S‐particles.
Interleukin‐10 differentially regulates cytokine inhibitor and chemokine release from blood mononuclear cells and fibroblasts
Authors: Seitz Michael , Loetscher Pius , Dewald Beatrice , Towbin Harry , Gallati Harald , Baggiolini Marco
Published: March 2007

In this study we have examined the effects of interleukin‐10 (IL‐10) on blood mononuclear cells (MNC) and on skin as well as on synovial fibroblasts. In unstimulated MNC, we found that IL‐10 is a potent stimulator of interleukin‐1 receptor antagonist (IL‐1ra) and monocyte chemoattractant protein‐1 (MCP‐1) production and an inhibitor of IL‐8 release. In cells exposed to IL‐1β, it also moderately stimulated IL‐1ra production and release of soluble tumor necrosis factor receptor p75 (sTNF‐R p75) and inhibited IL‐8 and MCP‐1 production. In addition, we have evidence that the biological effects of IL‐10 are not restricted to hematopoietic cells. IL‐10 stimulated sTNF‐R p55 dose‐dependently and inhibited MCP‐1 release from IL‐1β‐activated fibroblasts, whereas IL‐8 production was not affected. Taken together, these findings identify novel biological actions of IL‐10 on blood mononuclear and connective tissue cells which support its regulatory functions as a suppressor of inflammatory processes.
Analysis of the fine specificity of rat, mouse and human TAP peptide transporters
Authors: Neefjes Jacques , Gottfried Eva , Roelse Joost , Grommé Monique , Obst Reinhard , Hämmerling Günter J. , Momburg Frank
Published: March 2007

Prior to their association with major histocompatibility complex (MHC) class I molecules, peptides generated from cytosolic antigens need to be translocated by the MHC‐encoded peptide transporter (TAP) into the lumen of the endoplasmic reticulum (ER). While class I molecules possess well‐known binding characteristics for peptides, the fine specificity of TAP for its peptide substrates has not been analyzed in detail. Previously, we have studied the effect of amino acid variations at the N‐terminal, the C‐terminal, and the penultimate residue on the efficiency of peptide translocation. Using permeabilized cells, we have shown that TAP pre‐selects peptides in an allele‐ and species‐specific manner, for which only the C‐terminal residue is crucial. This finding is confirmed in the present study by using microsomes containing different TAP. The influence of amino acid substitutions at positions 2 to 7 of 9‐residue model peptides on TAP‐dependent peptide translocation is systematically examined. Only a few amino acid substitutions at these positions affect the efficiency of peptide translocation significantly, e.g. Pro at position 2 or 3 negatively influences transport whereas Glu at positions 6 and 7 enhances transport. The differences in translocation by the rat TAP alleles a or u, mouse TAP and human TAP are, however, minor for the peptide with internal substitutions used in this study. These results show that the C‐terminal residue essentially governs the species‐specific substrate specificity of TAP.
T cells made deficient in interleukin‐2 production by exposure to staphylococcal enterotoxin B in vivo are primed for interferon‐γ and interleukin‐10 secretion
Authors: Florquin Sandrine , Amraoui Zoulikka , Goldman Michel
Published: March 2007

The superantigen staphylococcal enterotoxin B (SEB) induces a defect in interleukin (IL)‐2 production by T cells expressing specific T cell receptor Vβ domains. The present study was undertaken to determine the capacity of T cells, made deficient in IL‐2 production by exposure to SEB in vivo, to secrete interferon (IFN)‐γ and IL‐10 and to induce pathology upon SEB rechallenge. For this purpose, BALB/c mice received two intraperitoneal injections of 100 μg SEB with a 48‐h interval. First, we compared peak serum levels of IL‐2, IFN‐γ and IL‐10 after SEB rechallenge with those measured after a single SEB injection in control mice. The expected defect in IL‐2 production in SEB‐pretreated mice was associated with a major increase in IL‐10 and IFN‐γ levels which were about fivefold higher than in controls. Experiments in mice depleted of CD4+ or CD8+ cells as well as studies in which purified T cell populations were rechallenged with SEB in vitro indicated that both CD4+ and CD8+ cells from SEB‐pretreated mice were primed for IL‐10 and IFN‐γ production. Furthermore, SEB‐pretreated mice were sensitized to the toxic effects of the superantigen as indicated by a 30‐70% lethality rate (vs. 0% in naive mice) within 48 h after SEB rechallenge. IFN‐γ was involved in the lethal syndrome as it could be prevented by injection of neutralizing anti‐IFN‐γ monoclonal antibody. We conclude that SEB‐reactive T cells made deficient for the production of IL‐2 by exposure to SEB in vivo are primed for IFN‐γ and IL‐10 production, and that IFN‐γ up‐regulation is involved in the shock syndrome occurring upon SEB rechallenge.
Co‐expression of B7‐1 and ICAM‐1 on tumors is required for rejection and the establishment of a memory response
Authors: Cavallo Federica , Martin‐Fontecha Alfonso , Bellone Matteo , Heltai Silvia , Gatti Evelina , Tornaghi Paola , Freschi Massimo , Forni Guido , Dellabona Paolo , Casorati Giulia
Published: March 2007

Although the transfection of B7‐1 cDNA into a few mouse tumor cell lines can induce anti‐tumor T cell immunity, its expression alone is ineffective in many other tumor cell lines tested. We were interested to study what factors limit B7‐1 co‐stimulatory activity, and decided to investigate whether B7‐1 requires the cooperation of ICAM‐1 to provide the minimal co‐stimulatory signal for establishing an efficient anti‐tumor immunity. We show that the transfection of B7‐1 cDNA into three ICAM‐1+ (plasmocytoma J558L, T lymphomas EL‐4 and RMA), but not into two ICAM‐1− tumor cell lines (adenocarcinoma TS/A and melanoma B16.F1), is sufficient to induce their complete rejection in syngeneic mice. The expression of ICAM‐1 is necessary for the rejection of the B7 expressing tumors, since the primary response elicited by B7‐1+ EL‐4 and RMA clones expressing reduced levels of ICAM‐1 is severely reduced. Furthermore, super‐transfection of ICAM‐1 cDNA into B7‐1+ adenocarcinoma and melanoma clones optimizes their primary rejection. Histologic examination of transfected tumors reveals that B7‐1 and ICAM‐1 exert a potent pro‐inflammatory activity. The intra‐tumor infiltration is composed of both eosinophils and lymphomono‐cytes, and is already massive 5 days after the tumor challenge. The primary rejection of the B7‐1+ ICAM‐1+ tumors depends critically on CD8+ T cells, natural killer cells and granulocytes, but is independent of CD4+ T cells. Remarkably, in addition to its effects on the early phases of the immune response, the co‐expression of ICAM‐1 and B7‐1 on tumors is also necessary for the efficient induction of a memory response. In fact, only the primary challenge with B7‐1+, ICAM‐1+ tumor cells protects the majority of the mice from a second injection of parental tumor cells. Collectively, our findings indicate that B7‐1 and ICAM‐1 are fundamental components for triggering the primary rejection of tumors and establishing a protective memory response. These findings may help to define new strategies for the rational application of co‐stimulation in tumor immunotherapy.
Homotypic aggregation of murine B lymphocytes is independent of CD23
Authors: Davey Edward J. , Bartlett William C. , Kikutani Hitoshi , Fujiwara Hiroshi , Kishimoto Tadamitsu , Conrad Daniel H. , Severinson Eva
Published: March 2007

CD23 is a low‐affinity receptor for IgE (FcϵRII). Functions attributed to CD23 not involving IgE suggest that it interacts with ligands other than IgE. CD21 has recently been described as a counter ligand for CD23. A number of lines of evidence have implicated CD23 as an adhesion molecule in human B cells. We have investigated the role of CD23 in homotypic B cell aggregation in the mouse, using lipopolysaccharide plus interleukin‐4‐induced aggregation as a model system. In this system high levels of aggregation are accompanied by a massive up‐regulation of CD23 expression. However, in contrast to what has been observed in human B cells, we find no evidence of a role for CD23 in homotypic adhesion of murine B cells.