bluuebunny/crossref_metadata_2025_split huggingface dataset:
Human IgG2 Antibodies against Epidermal Growth Factor Receptor Effectively Trigger Antibody-Dependent Cellular Cytotoxicity but, in Contrast to IgG1, Only by Cells of Myeloid Lineage
Authors: Schneider-Merck Tanja , Lammerts van Bueren Jeroen J. , Berger Sven , Rossen Kai , van Berkel Patrick H.C. , Derer Stefanie , Beyer Thomas , Lohse Stefan , Bleeker Wim K. , Peipp Matthias , Parren Paul W. H. I. , van de Winkel Jan G. J. , Valerius Thomas , Dechant Michael 
Published: December 2009

Abstract
Ab-dependent cellular cytotoxicity (ADCC) is usually considered an important mechanism of action for immunotherapy with human IgG1 but not IgG2 Abs. The epidermal growth factor receptor (EGF-R) Ab panitumumab represents the only human IgG2 Ab approved for immunotherapy and inhibition of EGF-R signaling has been described as its principal mechanism of action. In this study, we investigated effector mechanisms of panitumumab compared with zalutumumab, an EGF-R Ab of the human IgG1 isotype. Notably, panitumumab was as effective as zalutumumab in recruiting ADCC by myeloid effector cells (i.e., neutrophils and monocytes) in contrast to NK cell-mediated ADCC, which was only induced by the IgG1 Ab. Neutrophil-mediated tumor cell killing could be stimulated by myeloid growth factors and was triggered via FcγRIIa. Panitumumab-mediated ADCC was significantly affected by the functional FcγRIIa-R131H polymorphism and was induced more effectively by neutrophils from FcγRIIa-131H homozygous donors than from -131R individuals. This polymorphism did not affect neutrophil ADCC induced by the IgG1 Ab zalutumumab. The in vivo activity of both Abs was assessed in two animal models: a high-dose model, in which signaling inhibition is a dominant mechanism of action, and a low-dose model, in which effector cell recruitment plays a prominent role. Zalutumumab was more effective than panitumumab in the high-dose model, reflecting its stronger ability to induce EGF-R downmodulation and growth inhibition. In the low-dose model, zalutumumab and panitumumab similarly prevented tumor growth. Thus, our results identify myeloid cell-mediated ADCC as a potent and additional mechanism of action for EGF-R–directed immunotherapy.
Altered CD8+ T Cell Immunodominance after Vaccinia Virus Infection and the Naive Repertoire in Inbred and F1 Mice
Authors: Flesch Inge E. A. , Woo Wai-Ping , Wang Yang , Panchanathan Vijay , Wong Yik-Chun , La Gruta Nicole L. , Cukalac Tania , Tscharke David C. 
Published: December 2009

Abstract
Previous studies of CD8+ T cell immunodominance after primary virus infection of F1 mice compared with their inbred parents have generally concluded that no dramatic changes occur. In this study, we revisit this issue using vaccinia virus (VACV), which has a large genome, a recently defined immunodominance hierarchy in mice, and is a candidate vector for vaccines. We found that immunogenicity of VACV peptides defined using inbred mice was highly variable in F1 progeny: some peptides were equally immunogenic in F1 and inbred, whereas others elicited responses that were reduced by &gt;90% in F1 mice. Furthermore, the dominance of a peptide in the relevant inbred parent did not predict whether it would be poorly immunogenic in F1 mice. This result held using F1 hybrids of MHC-congenic mice, suggesting that MHC differences alone were responsible. It was also extended to foreign epitopes expressed by an rVACV vaccine. F1 mice were less able to mount responses to the poorly immunogenic peptides when used as a sole immunogen, ruling out immunodomination. In addition, conserved TCR Vβ usage between inbred and F1 mice did not always correlate with strong responses in F1 mice. However, direct estimation of naive precursor numbers showed that these were reduced in F1 compared with inbred mice for specificities that were poorly immunogenic in the hybrids. These data have implications for our understanding of the extent to which MHC diversity alters the range of epitopes that are immunogenic in outbred populations.
Cutting Edge: Limited Specialization of Dendritic Cell Subsets for MHC Class II-Associated Presentation of Viral Particles
Authors: Keller Susanne A. , Bauer Monika , Manolova Vania , Muntwiler Simone , Saudan Philippe , Bachmann Martin F. 
Published: December 2009

Abstract
Dendritic cells (DCs) are the most important APC. It was recently reported that there is a dichotomy for Ag presentation by DC subsets; exogenous Ags reach the MHC class I pathway, but not the MHC class II pathway, in CD8+ DCs, whereas CD8− DCs only process Ags for the MHC class II pathway. In this study, we used virus-like particles (VLPs) to show that CD8+ and CD8− DCs efficiently capture and process VLPs for presentation in association with MHC class II in vivo. In contrast, CD8+ DCs, but not CD8− DCs, cross presented VLP-derived peptides. This pattern was changed in an FcγR-dependent fashion in the presence of VLP-specific Abs, because under those conditions both DC subsets failed to efficiently cross present. Thus, the presentation of viral particles to CD4+ T cells is not restricted to distinct DC subsets, whereas the presentation of viral particles to CD8+ T cells is limited to CD8+ DCs.
A Minor Catalytic Activity of Src Family Kinases Is Sufficient for Maximal Activation of Mast Cells via the High-Affinity IgE Receptor
Authors: Poderycki Michael , Tomimori Yoshiaki , Ando Tomoaki , Xiao Wenbin , Maeda-Yamamoto Mari , Sauer Karsten , Kawakami Yuko , Kawakami Toshiaki 
Published: December 2009

Abstract
Src family kinases (SFK) are critical for initiating and regulating the response of mast cells activated by engagement of the high-affinity IgE receptor, FcεRI. Lyn is the predominant SFK in mast cells and has been ascribed both positive and negative roles in regulating mast cell activation. We analyzed the mast cell phenotype of WeeB, a recently described mouse mutant that expresses a Lyn protein with profoundly reduced catalytic activity. Surprisingly, we found that this residual activity is sufficient for wild-type levels of cytokine production and degranulation in bone marrow-derived mast cells after low-intensity stimulation with anti-IgE. High-intensity stimulation of lyn−/− bone marrow-derived mast cells with highly multivalent Ag resulted in enhanced cytokine production as previously reported, and WeeB cells displayed an intermediate phenotype. Under this latter condition, SFK inhibition using PP2 increased cytokine production in wild-type and WeeB but not lyn−/− cells, resulting in substantially higher levels in the PP2-treated WeeB than in lyn−/− cells. Restoration of wild-type and WeeB lyn alleles in lyn−/− cells generated activation phenotypes similar to those in nontransduced wild-type and WeeB cells, respectively, whereas a kinase-dead allele resulted in a phenotype similar to that of empty-vector–transduced cells. These data indicate that inhibition of Lyn and/or SFK activity can result in higher levels of mast cell activation than simple deletion of lyn and that only near-complete inhibition of Lyn can impair its positive regulatory functions. Furthermore, the data suggest that both positive and negative regulatory functions of Lyn are predominantly carried out by its catalytic activity and not an adaptor function.
Autoimmunity against Fibrinogen Mediates Inflammatory Arthritis in Mice
Authors: Ho Peggy P. , Lee Lowen Y. , Zhao Xiaoyan , Tomooka Beren H. , Paniagua Ricardo T. , Sharpe Orr , BenBarak Maya J. , Chandra Piyanka E. , Hueber Wolfgang , Steinman Lawrence , Robinson William H. 
Published: December 2009

Abstract
Rheumatoid arthritis (RA) is an autoimmune synovitis characterized by the presence of anticitrullinated protein Abs, although the exact targets and role of anticitrullinated protein autoimmunity in the pathogenesis of RA remain to be defined. Fibrinogen, which can be citrullinated, has recently emerged as a candidate autoantigen. To determine whether autoimmunity against fibrinogen can mediate inflammatory arthritis, we immunized a variety of common mouse strains with fibrinogen and found that DBA/1 and SJL mice developed an inflammatory and erosive arthritis. Mice with fibrinogen-induced arthritis (FIA) possess fibrinogen-reactive T cells that produce the proinflammatory cytokines IL-6, IL-17, TNF-α, and IFN-γ. FIA can be adoptively transferred with either plasma or fibrinogen-specific T cells from diseased mice. Mice with FIA possess rheumatoid factor, circulating immune complexes, and anticyclic citrullinated peptide Abs, all of which are characteristic of human RA. These observations demonstrate that fibrinogen is arthritogenic in mice and that the pathogenesis of FIA is mediated by both autoantibodies and fibrinogen-reactive T cells.
Requisite Role of the Cholinergic α7 Nicotinic Acetylcholine Receptor Pathway in Suppressing Gram-Negative Sepsis-Induced Acute Lung Inflammatory Injury
Authors: Su Xiao , Matthay Michael A. , Malik Asrar B. 
Published: December 2009

Abstract
Although activation of the α7 nicotinic acetylcholine receptor (α7 nAChR) modulates the response to sepsis, the role of this pathway in the development of sepsis-induced acute lung injury (ALI) is not known. In this study, we addressed the contribution of α7 nAChR in mediating endotoxin- and live Escherichia coli–induced ALI in mice. Because we found that α7 nAChR+ alveolar macrophages and neutrophils were present in bronchoalveolar lavage and injured lungs of mice, we tested whether acetylcholine released by lung vagal innervation stimulated these effector cells and thereby down-regulated proinflammatory chemokine/cytokine generation. Administration of α7 nAChR agonists reduced bronchoalveolar lavage MIP-2 production and transalveolar neutrophil migration and reduced mortality in E. coli pneumonia mice, whereas vagal denervation increased MIP-2 production and airway neutrophil accumulation and increased mortality. In addition, α7 nAChR−/− mice developed severe lung injury and had higher mortality compared with α7 nAChR+/+ mice. The immunomodulatory cholinergic α7 nAChR pathway of alveolar macrophages and neutrophils blocked LPS- and E. coli–induced ALI by reducing chemokine production and transalveolar neutrophil migration, suggesting that activation of α7 nAChR may be a promising strategy for treatment of sepsis-induced ALI.
Anti-CD3 Antibody Decreases Inflammation and Improves Outcome in a Murine Model of Pneumocystis Pneumonia
Authors: Bhagwat Samir P. , Wright Terry W. , Gigliotti Francis 
Published: December 2009

Abstract
The T cell–mediated immune response elicited by Pneumocystis plays a key role in pulmonary damage and dysfunction during Pneumocystis carinii pneumonia (PcP). Mice depleted of CD4+ and CD8+ T cells prior to infection are markedly protected from PcP-related respiratory deficit and death, despite progressive lung infection. However, the therapeutic effectiveness of Ab-mediated disruption of T cell function in mice already displaying clinical symptoms of disease has not been determined. Therefore, a murine model of PcP-related immune reconstitution inflammatory syndrome was used to assess whether Ab to the pan-T cell molecule CD3 is effective for reducing the severity of PcP when administered after the onset of disease. Mice that received anti-CD3 Ab exhibited a rapid and dramatic halt in the PcP-associated pulmonary function decline within 1 week after treatment, and a striking enhancement of survival rate compared with mice receiving the control Ab. Physiologic improvement in anti-CD3 treated mice was associated with a significant reduction in the number of CD4+ and CD8+ T cells recovered in lung lavage fluid. This effectiveness of anti-CD3 was noted whether the mice also received antibiotic therapy with trimethoprim-sulfamethoxazole. These data suggest that monoclonal Ab-mediated disruption of T cell function may represent a specific and effective adjunctive therapy to rapidly reverse the ongoing pathologic immune response occurring during active PcP. Thus, the anti-human CD3 monoclonal Ab OKT3, which is already in clinical use, has the potential to be developed as an adjunctive therapy for PcP.
Dynamics and Consequences of IL-21 Production in HIV-Infected Individuals: A Longitudinal and Cross-Sectional Study
Authors: Iannello Alexandre , Boulassel Mohamed-Rachid , Samarani Suzanne , Debbeche Olfa , Tremblay Cécile , Toma Emil , Routy Jean-Pierre , Ahmad Ali 
Published: December 2009

Abstract
IL-21 is a relatively newly discovered immune-enhancing cytokine that plays an essential role in controlling chronic viral infections. It is produced mainly by CD4+ T cells, which are also the main targets of HIV-1 and are often depleted in HIV-infected individuals. Therefore, we sought to determine the dynamics of IL-21 production and its potential consequences for the survival of CD4+ T cells and frequencies of HIV-specific CTL. For this purpose, we conducted a series of cross-sectional and longitudinal studies on different groups of HIV-infected patients and show in this study that the cytokine production is compromised early in the course of the infection. The serum cytokine concentrations correlate with CD4+ T cell counts in the infected persons. Among different groups of HIV-infected individuals, only elite controllers maintain normal production of the cytokine. Highly active antiretroviral therapy only partially restores the production of this cytokine. Interestingly, HIV infection of human CD4+ T cells inhibits cytokine production by decreasing the expression of c-Maf in virus-infected cells, not in uninfected bystander cells. We also show that the frequencies of IL-21–producing HIV-specific, but not human CMV-specific, Ag-experienced CD4+ T cells are decreased in HIV-infected viremic patients. Furthermore, we demonstrate in this study that recombinant human IL-21 prevents enhanced spontaneous ex vivo death of CD4+ T cells from HIV-infected patients. Together, our results suggest that serum IL-21 concentrations may serve as a useful biomarker for monitoring HIV disease progression and the cytokine may be considered for immunotherapy in HIV-infected patients.
The Host Defense Peptide Cathelicidin Is Required for NK Cell-Mediated Suppression of Tumor Growth
Authors: Büchau Amanda S. , Morizane Shin , Trowbridge Janet , Schauber Jürgen , Kotol Paul , Bui Jack D. , Gallo Richard L. 
Published: December 2009

AbstractTumor surveillance requires the interaction of multiple molecules and cells that participate in innate and the adaptive immunity. Cathelicidin was initially identified as an antimicrobial peptide, although it is now clear that it fulfills a variety of immune functions beyond microbial killing. Recent data have suggested contrasting roles for cathelicidin in tumor development. Because its role in tumor surveillance is not well understood, we investigated the requirement of cathelicidin in controlling transplantable tumors in mice. Cathelicidin was observed to be abundant in tumor-infiltrating NK1.1+ cells in mice. The importance of this finding was demonstrated by the fact that cathelicidin knockout mice (Camp−/−) permitted faster tumor growth than wild type controls in two different xenograft tumor mouse models (B16.F10 and RMA-S). Functional in vitro analyses found that NK cells derived from Camp−/− versus wild type mice showed impaired cytotoxic activity toward tumor targets. These findings could not be solely attributed to an observed perforin deficiency in freshly isolated Camp−/− NK cells, because this deficiency could be partially restored by IL-2 treatment, whereas cytotoxic activity was still defective in IL-2-activated Camp−/− NK cells. Thus, we demonstrate a previously unrecognized role of cathelicidin in NK cell antitumor function.
Dissemination of Mycobacteria to the Thymus Renders Newly Generated T Cells Tolerant to the Invading Pathogen
Authors: Nobrega Claudia , Roque Susana , Nunes-Alves Cláudio , Coelho Angela , Medeiros Irene , Castro António Gil , Appelberg Rui , Correia-Neves Margarida 
Published: December 2009

Abstract
The ability of the thymus to generate a population of T cells that is, for the most part, self-restricted and self-tolerant depends to a great extent on the Ags encountered during differentiation. We recently showed that mycobacteria disseminate to the thymus, which raised the questions of how mycobacteria within the thymus influence T cell differentiation and whether such an effect impacts host–pathogen interactions. Athymic nude mice were reconstituted with thymic grafts from Mycobacterium avium-infected or control noninfected donors. T cells generated from thymi of infected donors seemed generally normal, because they retained the ability to reconstitute the periphery and to respond to unspecific stimuli in vitro as well as to antigenic stimulation with third-party Ags, such as OVA, upon in vivo immunization. However, these cells were unable to mount a protective immune response against a challenge with M. avium. The observation that thymic infection interferes with T cell differentiation, generating T cells that are tolerant to pathogen-specific Ags, is of relevance to understand the immune response during chronic persistent infections. In addition, it has potential implications for the repertoire of T cells generated in patients with a mycobacterial infection recovering from severe lymphopenia, such as patients coinfected with HIV and receiving antiretroviral therapy.
Selective Mobilization of Cytotoxic Leukocytes by Epinephrine
Authors: Dimitrov Stoyan , Lange Tanja , Born Jan 
Published: December 2009

AbstractIt is well-known that acute stress, presumably as a first defense against pathogens, enhances PBMC counts by mobilizing these β2-adrenoceptor positive cells from the marginal pool. Yet, only select leukocyte subsets participate in this phenomenon of adrenergic leukocytosis and underlying mechanisms are obscure. In this study, we analyzed in human blood adhesion molecule and chemokine receptor profiles in 14 leukocyte subsets, and responsiveness of subsets to epinephrine in vivo and in vitro. Five subsets, namely, CCR7−CD45RA+CD8+ effector T cells, CD4−CD8− γ/δ T cells, CD3+CD56+ NKT-like cells, CD16+CD56dim cytotoxic NK cells, and CD14dimCD16+ proinflammatory monocytes showed a rapid and transient increase after infusion of epinephrine at physiological concentrations. These cells were characterized by a CD62L−CD11abrightCX3CRbright phenotype, whereby expression of both CD11a and CX3CR1 was strongly correlated with adrenergic leukocytosis in vivo (r = 0.86 and 0.78, p &lt; 0.005). The same subsets showed highest adherence to activated endothelium in vitro, which (except for proinflammatory monocytes) was reversed by epinephrine. We conclude that these five cytotoxic effector leukocyte subsets comprise the marginal pool by a CD11a/CX3CR1-mediated attachment to the endothelium. Epinephrine rapidly attenuates this attachment to allow demargination and release of the cells into the circulation that, because of their cytotoxic effector function, provide immediate protection from invading pathogens.
A Heat Shock Protein 70-Based Vaccine with Enhanced Immunogenicity for Clinical Use
Authors: Gong Jianlin , Zhang Yunfei , Durfee John , Weng Desheng , Liu Chunlei , Koido Shigeo , Song Baizheng , Apostolopoulos Vasso , Calderwood Stuart K. 
Published: December 2009

Abstract
In previous studies, we have shown that heat shock protein 70-peptide complexes (HSP70.PCs) derived from the fusion of dendritic cells (DCs) to tumor cells (HSP70.PC-F) possess superior properties compared with HSP70.PCs from tumor cells. HSP70.PC-F are more effective in stimulation of DC maturation and induction of CTL that are able to provide protection of mice against challenge with tumor cells. To develop an improved formulation of HSP70.PC-based tumor vaccine for patient use, we extracted HSP70.PC-F from DCs fused to patient-derived ovarian cancer cells or established human breast cancer cells and examined their properties as tumor vaccines. HSP70.PC-F induced T cells that expressed higher levels of IFN-γ and exhibited increased levels of killing of tumor cells, compared with those induced by HSP70.PC derived from tumor cells. Enhanced immunogenicity of HSP70.PC-F was associated with improved composition of the vaccine, including increased content of tumor Ags and their processed intermediates, and the detection of other heat shock proteins (HSPs) such as HSP90 and HSP110. The present study has therefore provided an alternative approach to preparation of HSP-based vaccines using DC/tumor fusion technology and gentle and rapid isolation of HSP peptide complexes.
Lysine Acetylation Regulates Bruton’s Tyrosine Kinase in B Cell Activation
Authors: Liu Zhijian , Mai Antonello , Sun Jian 
Published: December 2009

Abstract
Bruton’s tyrosine kinase (Btk) is essential for BCR signal transduction and has diverse functions in B cells. Although Btk has been extensively studied, the role of lysine acetylation in Btk regulation has not been reported. In this study, we show that BCR cross-linking induces histone lysine acetylation at the Btk promoter, correlating with marked recruitment of histone acetyltransferase E1A-associated 300-kDa protein (p300) to the locus. These effects enhance Btk promoter activity and increase the expression of Btk mRNA and protein. Consistent with these results, activated B cells display increased p300 expression and total histone acetyltransferase activity in vitro and in vivo, resulting in global histone acetylation. Interestingly, we found that BCR signaling induces Btk lysine acetylation mediated by p300. Moreover, lysine acetylation of Btk promotes its phosphorylation. Together, our results indicate a novel regulatory mechanism for Btk transcription and reveal a previously unrecognized posttranslational modification of the Btk protein and its association with phosphorylation in B cell activation.
Conserved Amino Acids within the Adenovirus 2 E3/19K Protein Differentially Affect Downregulation of MHC Class I and MICA/B Proteins
Authors: Sester Martina , Koebernick Katja , Owen Douglas , Ao Minghui , Bromberg Yana , May Ed , Stock Emily , Andrews Lawrence , Groh Veronika , Spies Thomas , Steinle Alexander , Menz Beatrice , Burgert Hans-Gerhard 
Published: December 2009

Abstract
Successful establishment and persistence of adenovirus (Ad) infections are facilitated by immunosubversive functions encoded in the early transcription unit 3 (E3). The E3/19K protein has a dual role, preventing cell surface transport of MHC class I/HLA class I (MHC-I/HLA-I) Ags and the MHC-I–like molecules (MHC-I chain-related chain A and B [MICA/B]), thereby inhibiting both recognition by CD8 T cells and NK cells. Although some crucial functional elements in E3/19K have been identified, a systematic analysis of the functional importance of individual amino acids is missing. We now have substituted alanine for each of 21 aas in the luminal domain of Ad2 E3/19K conserved among Ads and investigated the effects on HLA-I downregulation by coimmunoprecipitation, pulse-chase analysis, and/or flow cytometry. Potential structural alterations were monitored using conformation-dependent E3/19K-specific mAbs. The results revealed that only a small number of mutations abrogated HLA-I complex formation (e.g., substitutions W52, M87, and W96). Mutants M87 and W96 were particularly interesting as they exhibited only minimal structural changes suggesting that these amino acids make direct contacts with HLA-I. The considerable number of substitutions with little functional defects implied that E3/19K may have additional cellular target molecules. Indeed, when assessing MICA/B cell-surface expression we found that mutation of T14 and M82 selectively compromised MICA/B downregulation with essentially no effect on HLA-I modulation. In general, downregulation of HLA-I was more severely affected than that of MICA/B; for example, substitutions W52, M87, and W96 essentially abrogated HLA-I modulation while largely retaining the ability to sequester MICA/B. Thus, distinct conserved amino acids seem preferentially important for a particular functional activity of E3/19K.