bluuebunny/crossref_metadata_2025 huggingface dataset:
Selective Expression of a Novel Surface Molecule by Human Th2 Cells In Vivo
Authors: Nagata Kinya , Tanaka Kazuya , Ogawa Kazuyuki , Kemmotsu Kazumi , Imai Toshio , Yoshie Osamu , Abe Hiroyuki , Tada Kohtaro , Nakamura Masataka , Sugamura Kazuo , Takano Shoichi
Published: December 2022

The search for reliable marker molecules discriminating between human Th1 and Th2 cells identified a gene encoding a novel member of the G protein-coupled leukocyte chemoattractant receptor family, which is selectively expressed in Th2 but not Th1 lineage cells, thereby named CRTH2 (chemoattractant receptor-homologous molecule expressed on Th2 cells). Studies with anti-CRTH2 mAbs demonstrated that CRTH2 was expressed in a small population (0.4–6.5%) of CD4+ T cells in fresh PBMCs of healthy adults, but no remarkable expression was seen in B cells and NK cells. In some cases, CD8+ T cells (∼3.5%) expressed CRTH2. Phenotypes of CD4+ T cells expressing CRTH2 were CD45RA−, CD45RO+, and CD25+, similar to those of Ag-activated effector/memory T cells. Freshly isolated CRTH2+ CD4+ T cells produced Th2- but little or no Th1-type cytokines upon stimulation with PMA and ionomycin. In addition, an allergen-induced proliferative response in fresh PBMCs was significantly and selectively reduced by subtracting CRTH2+ cells. Together, these results indicate that CRTH2 is selectively expressed in vivo in an activated state of Th2 cells including allergen-responsive Th2 cells, suggesting its pivotal roles in ongoing Th2-type immune reactions.
Alterations in CD4-Binding Regions of the MHC Class II Molecule I-Ek Do Not Impede CD4+ T Cell Development
Authors: Yelon Deborah , Schaefer Katherine L. , Berg Leslie J.
Published: December 2022

The T cell coreceptors CD4 and CD8 enhance T cell responses to TCR signals by participating in complexes containing TCR, coreceptor, and MHC molecules. These ternary complexes are also hypothesized to play a seminal role during T cell development, although the precise timing, frequency, and consequences of TCR-coreceptor-MHC interactions during positive selection and lineage commitment remain unclear. To address these issues, we designed transgenic mice expressing mutant I-Ek molecules with reduced CD4-binding capability. These transgenic lines were crossed to three different lines of I-Ek-specific TCR transgenic mice, and the efficiency of production of CD4+ lineage cells in the doubly transgenic progeny was assessed. Surprisingly, replacing wild-type I-Ek molecules with these mutant molecules did not affect the production of CD4+CD8− thymocytes or CD4+ peripheral T cells expressing any of the three TCRs examined. These data, when considered together with other experiments addressing the role of coreceptor during development, suggest that not all MHC class II-specific thymocytes require optimal and simultaneous TCR-CD4-MHC interactions to mature. Alternatively, it is possible that these particular alterations of I-Ek do not disrupt the CD4-MHC interaction adequately, potentially indicating functional differences between I-A and I-E MHC class II molecules.
cAMP Up-Regulates Cell Surface Expression of Lymphocyte CXCR4: Implications for Chemotaxis and HIV-1 Infection
Authors: Cole Steve W. , Jamieson Beth D. , Zack Jerome A.
Published: December 2022

The chemokine receptor CXCR4 mediates lymphocyte chemotaxis in response to stromal cell-derived factor-1 (SDF-1) and functions as a coreceptor for T cell-tropic strains of HIV-1. We examined the role of the cAMP-protein kinase A (PKA) signaling pathway in regulating expression of CXCR4. In response to exogenous dibutyryl cAMP or cAMP-inducing ligands, cell surface expression of CXCR4 was increased by up to 10-fold on CD3/CD28-stimulated PBMC and by up to sixfold on unstimulated PBMC. cAMP did not alter receptor mRNA levels or affect the size of the total CXCR4 pool. However, cAMP did significantly reduce CXCR4 internalization rates and thereby increased the fraction of the total CXCR4 pool expressed on the cell surface. cAMP-induced increases in CXCR4 expression counteracted SDF-1-induced receptor internalization and enhanced both chemotactic response to SDF-1 and cellular vulnerability to HIV-1 infection. Thus, altered chemokine receptor expression may provide one mechanism by which cAMP-inducing ligands influence lymphocyte localization and HIV pathogenesis.
Profound Enhancement of T Cell Activation Mediated by the Interaction Between the TCR and the D3 Domain of CD4
Authors: Vignali Dario A. A. , Vignali Kate M.
Published: December 2022

CD4 plays an important role in the activation and development of CD4+ T cells. This is mediated via its bivalent interaction with MHC class II molecules and the TCR:CD3 complex through p56lck. Recent studies have implicated a third site of interaction between the membrane-proximal extracellular domains of CD4 and the TCR. Due to these multiple interactions, direct evidence for the functional importance of this extracellular association has remained elusive. Furthermore, the residues that mediate this interaction are unknown. In this study, we analyzed the function of 61 CD4 mutants. Alanine substitution of just 2 residues, either Q114/F182 or F182/F201, which are partially buried and located close to the D2/D3 interface, completely abrogated CD4 function. Direct evidence for the functional importance of TCR:CD4.D3 interaction was obtained using an anti-CD3fos:anti-CD4jun-bispecific Ab. Surprisingly, it induced strong T cell activation in hybridomas transfected with cytoplasmic-tailless CD4, despite the lack of association with either p56lck or MHC class II molecules. However, this effect was completely abrogated with the CD4 mutants Q114A/F182A or F182A/F201A. These data demonstrate that TCR:CD4.D3 interaction can have a profound effect on T cell activation and obviates the need for receptor oligomerization.
TNF Receptor p55 Plays a Pivotal Role in Murine Keratinocyte Apoptosis Induced by Ultraviolet B Irradiation
Authors: Zhuang Lihua , Wang Binghe , Shinder Gayle A. , Shivji Gulnar M. , Mak Tak W. , Sauder Daniel N.
Published: December 2022

Excess exposure of skin to ultraviolet B (UVB) results in the appearance of so-called sunburn cells. Although it has been demonstrated that sunburn cells represent apoptotic keratinocytes, the molecular mechanisms for UVB-induced apoptosis in keratinocytes have not been fully elucidated. The cytokine, TNF-α, has been shown to induce apoptosis in a variety of cell types. Since UVB induces keratinocytes to release TNF-α, we hypothesized that TNF-α is involved in UVB-induced apoptosis in keratinocytes. In order to confirm this hypothesis and to further delineate which type of TNF receptor signaling mediates the apoptosis pathway, we performed both in vivo and in vitro experiments using gene-targeted knockout mice lacking either the TNF p55 receptor or the TNF p75 receptor. In the in vivo study, wild-type and mutant mice were exposed to UVB, and apoptotic keratinocytes were detected by examining DNA fragmentation using in situ nick-end labeling. For the in vitro experiments, keratinocytes derived from the wild-type and mutant mice were irradiated with UVB, and the degree of apoptosis was determined by flow cytometry, nick-end labeling of DNA, and a DNA ladder assay. Both in vivo and in vitro studies demonstrated that the deletion of TNF receptor p55 could suppress UVB-induced apoptosis in keratinocytes. Our observations support the notion that TNF-α is involved in UVB-induced keratinocyte apoptosis, and demonstrate that p55 receptor signaling plays a pivotal role in this event.
Elevation of Mitochondrial Transmembrane Potential and Reactive Oxygen Intermediate Levels Are Early Events and Occur Independently from Activation of Caspases in Fas Signaling
Authors: Banki Katalin , Hutter Eliza , Gonchoroff Nick J. , Perl Andras
Published: December 2022

Stimulation of the CD95/Fas/Apo-1 receptor leads to apoptosis through activation of the caspase family of cysteine proteases and disruption of the mitochondrial transmembrane potential (Δψm). We show that, in Jurkat human T cells and peripheral blood lymphocytes, Fas-induced apoptosis is preceded by 1) an increase in reactive oxygen intermediates (ROI) and 2) an elevation of Δψm. These events are followed by externalization of phosphatidylserine (PS), disruption of Δψm, and cell death. The caspase inhibitor peptides, DEVD-CHO, Z-VAD.fmk, and Boc-Asp.fmk, blocked Fas-induced PS externalization, disruption of Δψm, and cell death, suggesting that these events are sequelae of caspase activation. By contrast, in the presence of caspase inhibitors, ROI levels and Δψm of Fas-stimulated cells remained elevated. Because ROI levels and Δψm are regulated by the supply of reducing equivalents from the pentose phosphate pathway (PPP), we studied the impact of transaldolase (TAL), a key enzyme of the PPP, on Fas signaling. Overexpression of TAL accelerated Fas-induced mitochondrial ROI production, Δψm elevation, activation of caspase-8 and caspase-3, proteolysis of poly(A)DP-ribose polymerase, and PS externalization. Additionally, suppression of TAL diminished these activities. Therefore, by controlling the balance between mitochondrial ROI production and metabolic supply of reducing equivalents through the PPP, TAL regulates susceptibility to Fas-induced apoptosis. Early increases in ROI levels and Δψm as well as the dominant effect of TAL expression on activation of caspase-8/Fas-associated death domain-like IL-1β-converting enzyme, the most upstream member of the caspase cascade, suggest a pivotal role for redox signaling at the initiation of Fas-mediated apoptosis.
Activation of the Signal Transducer Glycoprotein 130 by Both IL-6 and IL-11 Requires Two Distinct Binding Epitopes
Authors: Kurth Ingo , Horsten Ursula , Pflanz Stefan , Dahmen Heike , Küster Andrea , Grötzinger Joachim , Heinrich Peter C. , Müller-Newen Gerhard
Published: December 2022

The coordination and regulation of immune responses are primarily mediated by cytokines that bind to specific cell surface receptors. Glycoprotein 130 (gp130) belongs to the family of class I cytokine receptors and is the common signal-transducing receptor subunit shared by the so-called IL-6 type cytokines (IL-6, IL-11, ciliary neurotrophic factor, leukemia inhibitory factor, oncostatin M, and cardiotrophin-1). The inflammatory cytokines IL-6 and IL-11 induce gp130 homodimerization after binding to their specific α receptors, which leads to the activation of the Janus kinase/STAT signal transduction pathway. A molecular model of IL-6/IL-6R/gp130, which is based on the structure of the growth hormone/growth hormone receptor complex, allowed the selection of several amino acids located in the cytokine-binding module of gp130 for mutagenesis. The mutants were analyzed with regard to IL-6- or IL-11-induced STAT activation and ligand binding. It was found that Y190 and F191 are essential for the interaction of gp130 with IL-6 as well as IL-11, suggesting a common mode of recognition of helical cytokines by class I cytokine receptors. Furthermore, the requirement of the gp130 N-terminal Ig-like domain for ligand binding and signal transduction was demonstrated by the use of deletion mutants. Thus, besides the observed analogy to the growth hormone/growth hormone receptor complex, there is a substantial difference in the mechanism of receptor engagement by cytokines that signal via gp130.
AIDS Primary Central Nervous System Lymphoma: Molecular Analysis of the Expressed VH Genes and Possible Implications for Lymphomagenesis
Authors: Julien Sylvie , Radosavljevic Mirjana , Labouret Nathalie , Camilleri-Broet Sophie , Davi Frederic , Raphael Martine , Martin Thierry , Pasquali Jean-Louis
Published: December 2022

AIDS-associated primary central nervous system lymphomas are late events that have an extremely poor prognosis. Despite different hypotheses, the brain localization of these B cell lymphomas remains an enigma. To better define the cell origin of the lymphomas and the possible role of the B cell receptor (BCR) in the brain localization and/or in the oncogenic transformation, we analyzed the V region genes of the Ig heavy chain expressed by lymphoma cells in five randomly selected patients. After amplifying the rearranged VHDJH DNA by PCR, cloning, and sequencing of the amplified products, we observed that: 1) of the five lymphomas analyzed, four were clearly monoclonal; 2) there was no preferential use of one peculiar VH family or one peculiar segment of gene; 3) the mutation analysis showed that an Ag-driven process occurred in at least two cases, probably before the oncogenic event; and 4) there was no intraclonal variability, suggesting that the hypermutation mechanism is no longer efficient in these lymphoma B cells. Taken together, our results suggest that distinct Ags could be recognized by the BCR of the lymphoma cells in different patients and that, if the Ags are responsible for the brain localization of these B cells bearing mutated BCR, other factors must be involved in B cell transformations in primary central nervous system lymphoma.
Atypical VH-D-JH Rearrangements in Newborn Autoimmune MRL Mice
Authors: Klonowski Kimberly D. , Primiano Laura L. , Monestier Marc
Published: December 2022

Antinuclear Abs are the hallmark of the autoimmune disease systemic lupus erythematosus (SLE). The ability of self reactive autoantibodies to bind to DNA and nucleosomes is partly conferred by an increased number of arginine and asparagine residues in the heavy chain third complementarity determining region. This increased content of cationic residues is primarily the result of unusual VH-D-JH rearrangements, which include D-D fusions and D gene inversions. While self Ag-driven clonal expansion is a major contributor to the production of antinuclear Abs in lupus, we explore in this study the hypothesis that newly emerging B cells from autoimmune mice display more frequently these unusual VH-D-JH rearrangements. To this end, libraries of PCR-generated VH-D-JH junctions from MRL and C3H newborn livers were analyzed. When compared with the C3H controls, D and JH gene usage in MRL junctions suggests a greater frequency of secondary D-JH rearrangements in this strain. Furthermore, B cells from the autoimmune-prone MRL mice have significantly increased numbers of atypical VH-D-JH rearrangements (D-D fusions and D inversions). Therefore, B cells from MRL mice manifest intrinsic defects that could confer an increased propensity to produce unusual VH-D-JH rearrangements early in ontogeny.
Innate Immunity in Insects: The Role of Multiple, Endogenous Serum Lectins in the Recognition of Foreign Invaders in the Cockroach, Blaberus discoidalis
Authors: Wilson Raymond , Chen Changwei , Ratcliffe Norman A.
Published: December 2022

Unlike vertebrates, insects do not have an Ab-based nonself recognition system, and must rely totally on innate immunity to defend themselves from microbial invaders. The most likely candidates for recognizing foreign material in insects are the lectins, which have already been shown to be important in mammalian innate immunity. The hemolymph of the cockroach, Blaberus discoidalis, contains multiple lectins, designated BDL1, BDL2, BDL3, and GSL (β-1,3-glucan-specific lectin), two of which, namely BDL1 and GSL, have close similarities to acute phase reactants. These endogenous molecules, as well as Con A, wheat germ agglutinin, and Helix pomatia agglutinin, have been shown to induce an enhanced phagocytic response by B. discoidalis plasmatocytes. This effect is related to the carbohydrates presented on the surface of the microorganism and to the sugar specificities of the lectins. Thus, the mannose-specific lectins, BDL1 and Con A, both increase the phagocytosis of baker’s yeast and Escherichia coli, whereas the N-acetyl-d-glucosamine/N-acetyl-d-galactosamine-specific lectins, BDL2, wheat germ agglutinin, and H. pomatia agglutinin, induce the phagocytosis of Bacillus cereus and E. coli. GSL, specific for β-1,3-glucan, and the N-acetyl-d-galactosamine-specific BDL3, only enhance the phagocytosis of yeast and B. cereus, respectively. Phenylthiourea, an inhibitor of the prophenoloxidase system, caused either total, partial, or no inhibition of the lectin-induced increase in phagocytosis, indicating that this immune enhancement results, in some cases, from at least two closely linked mechanisms. These results show that the endogenous lectins in the cockroach hemolymph are capable of acting as nonself recognition molecules for a wide range of microorganisms, and thus obviate the necessity of Abs in these animals.
Mucosal DNA Vaccine Immunization Against Measles with a Highly AttenuatedShigella flexneriVector
Authors: Fennelly Glenn J. , Khan Shibber A. , Abadi Maria A. , Wild T. Fabian , Bloom Barry R.
Published: December 2022

An intranasal vaccine vector would elicit protective immunity at the respiratory mucosa, the portal of entry and the primary site for replication for measles virus (MV) and other respiratory viruses. In a murine model of pulmonary Shigella, we demonstrate here that a candidate-attenuated Shigella vaccine vector is safely tolerated in IFN-γ deficient mice at an inoculum that is 1 million-fold higher than the inoculum of the wild-type parent strain that would be lethal for greater than 90% of these mice. Also, following intranasal inoculation, the Δasd Shigella harboring a DNA MV vaccine plasmid induces a vigorous MV-specific Th1-type (both CD8+ CTL and IFN-γ) and, to a lesser degree, Th2-type responses among splenocytes in addition to low levels of IgG and IgA in the serum. Priming for MV-specific CTL responses was possible in mice that had prior infection with a wild-type Shigella of the same serotype. Remarkably, mice immunized by the intranasal route with attenuated Shigella harboring the DNA MV vaccine plasmid had a level of MV-specific CTL activity among splenocytes that was comparable with levels observed in mice immunized by the i.p. route with attenuated Salmonella typhi harboring the same DNA vaccine plasmid, despite the fact that Shigella remained localized to the lungs, yet Salmonella disseminated to the spleen following inoculation. Thus, Δasd Shigella represents a very useful vector for delivery of DNA vaccines to mucosal lymphoid tissues.
Role of Resident Peritoneal Macrophages and Mast Cells in Chemokine Production and Neutrophil Migration in Acute Inflammation: Evidence for an Inhibitory Loop Involving Endogenous IL-10
Authors: Ajuebor Maureen N. , Das Anuk M. , Virág László , Flower Roderick J. , Szabó Csaba , Perretti Mauro
Published: December 2022

The roles played by resident macrophages (Mφ) and mast cells (MCs) in polymorphonuclear leukocyte (PMN) accumulation and chemokine production within the mouse peritoneal cavity in response to administration of zymosan (0.2 and 1 mg), LPS (1 mg/kg), and thioglycolate (0.5 ml of a 3% suspension) were investigated. A marked reduction (>95%) in intact MC numbers was obtained by pretreatment with the MC activator compound 48/80, whereas resident Mφ were greatly diminished (>85%) by a 3-day treatment with liposomes encapsulating the cytotoxic drug dichloromethylene-bisphosphonate. No modulation of thioglycolate-induced inflammation was seen with either pretreatment. Removal of either MCs or Mφ attenuated LPS-induced PMN extravasation without affecting the levels of the chemokines murine monocyte chemoattractant protein-1 and KC measured in the lavage fluids. In contrast, MC depletion inhibited PMN accumulation and murine monocyte chemoattractant protein-1 and KC production in the zymosan peritonitis model. Removal of Mφ augmented the accumulation of PMN elicited by the latter stimulus. This was due to an inhibitory action of Mφ-derived IL-10 because there was 1) a time-dependent release of IL-10 in the zymosan exudates; 2) a reduction in IL-10 levels following Mφ, but not MC, depletion; and 3) an increased PMN influx and chemokine production in IL-10 knockout mice. In conclusion, we propose a stimulus-dependent role of resident MCs in chemokine production and the existence of a regulatory loop between endogenous IL-10 and the chemokine-mediated cellular component of acute inflammation.
Novel HLA-Cw8-Restricted T Cell Epitopes Derived from Tyrosinase-Related Protein-2 and gp100 Melanoma Antigens
Authors: Castelli Chiara , Tarsini Paolo , Mazzocchi Arabella , Rini Francesca , Rivoltini Licia , Ravagnani Fernando , Gallino Francesco , Belli Filiberto , Parmiani Giorgio
Published: December 2022

The identification of T cell epitopes presented by alternative HLA-B and -C alleles may provide a means to counteract the tumor escape mechanism based on the selection of tumor cells no longer susceptible to HLA-A-restricted T cell recognition. Several T cell clones and lines were obtained from T lymphocytes purified from melanoma-infiltrated or noninfiltrated lymph nodes of a patient who remained disease free 8 yr after surgery. Selected T cells recognized the autologous melanoma as evaluated by direct cytolysis and production of cytokines. These effectors were directed against the tyrosinase-related protein-2 (TRP-2) and gp100 melanoma epitopes restricted by HLA-Cw8. The nonamer and decamer peptides containing the sequence ANDPIFVVL (residues 387–395) of TRP-2 and the octamer, nonamer, and decamer peptides containing the sequence SNDGPTLI (residues 71–78) of gp100 reconstituted the epitope for TRP-2- and gp100-specific T cell lines and clones, respectively. However, only the nonameric form of TRP-2 and the nonameric and octameric forms of gp100 were able to induce peptide-specific T cells recognizing the autologous tumor in an HLA-class I-restricted fashion from PBMC of the melanoma patient studied. Together these data indicate that HLA-Cw8 can restrict the recognition of gp100 and TRP-2 epitopes by CTL, and that such peptides could stimulate a patient’s PBL, suggesting that these Ags could have contributed to a systemic immunity against melanoma.
Changes in the Fine Specificity of gp100(209–217)-Reactive T Cells in Patients Following Vaccination with a Peptide Modified at an HLA-A2.1 Anchor Residue
Authors: Clay Timothy M. , Custer Mary C. , McKee Mark D. , Parkhurst Maria , Robbins Paul F. , Kerstann Keith , Wunderlich John , Rosenberg Steven A. , Nishimura Michael I.
Published: December 2022

In a recent clinical trial, HLA-A2+ melanoma patients were vaccinated with a peptide derived from the melanoma Ag gp100, which had been modified at the second position (g9-209 2M) to enhance MHC binding affinity. Vaccination led to a significant increase in lymphocyte precursors in 10 of 11 patients but did not result in objective cancer responses. We observed that some postvaccination PBMC cultures were less reactive with tumor cells than they were with g9-209 peptide-pulsed T2 cells. In contrast, g9-209-reactive tumor-infiltrating lymphocyte cultures generally reacted equally with tumor cells and g9-209 peptide-pulsed T2 cells. To investigate this difference in T cell reactivity, T cell cloids derived from the PBMC of three patients vaccinated with g9-209 2M were compared with T cell cloids isolated from g9-209-reactive TIL cultures. All of the T cell cloids obtained from TIL reacted with HLA-A2+, gp100+ melanoma cell lines as well as with g9-209 and g9-209 2M peptide-pulsed targets. In contrast, only 3 of 20 PBMC-derived T cell cloids reacted with melanoma cell lines in addition to g9-209 and to g9-209 2M peptide-pulsed targets. Twelve of twenty PBMC-derived cloids reacted with g9-209 and g9-209 2M peptide-pulsed targets but not with melanoma cell lines. And 5 of 20 PBMC-derived cloids recognized only the g9-209 2M-modified peptide-pulsed targets. These results suggest that immunizing patients with the modified peptide affected the T cell repertoire by expanding an array of T cells with different fine specificities, only some of which recognized melanoma cells.
Direct Analysis of Viral-Specific CD8+ T Cells with Soluble HLA-A2/Tax11-19 Tetramer Complexes in Patients with Human T Cell Lymphotropic Virus-Associated Myelopathy
Authors: Bieganowska Katarzyna , Höllsberg Per , Buckle Guy J. , Lim Dong-Gyun , Greten Tim F. , Schneck Jonathan , Altman John D. , Jacobson Steven , Ledis Stephen L. , Hanchard Barrie , Chin Jonathan , Morgan Owen , Roth Patricia A. , Hafler David A.
Published: December 2022

Human T cell lymphotropic virus-I (HTLV-I)-associated myelopathy is a slowly progressive neurologic disease characterized by inflammatory infiltrates in the central nervous system accompanied by clonal expansion of HTLV-I-reactive CD8+ T-cells. In patients carrying the HLA-A2 allele, the immune response is primarily directed to the Tax11-19 peptide. The frequency, activation state, and TCR usage of HLA-A2/Tax11-19 binding T cells in patients with HTLV-I-associated myelopathy was determined using MHC class I tetramers loaded with the Tax11-19 peptide. Circulating Tax11-19-reactive T cells were found at very high frequencies, approaching 1:10 circulating CD8+ T cells. T cells binding HLA-A2/Tax11-19 consisted of heterogeneous populations expressing different chemokine receptors and the IL-2R β-chain but not the IL-2R α-chain. Additionally, Tax11-19-reactive CD8+ T cells used one predominant TCR Vβ-chain for the recognition of the HLA-A2/Tax11-19 complex. These data provide direct evidence for high frequencies of circulating Tax11-19-reactive CD8+ T cells in patients with HTLV-I-associated myelopathy.
Immune-Mediated Destruction of Melanocytes in Halo Nevi Is Associated with the Local Expansion of a Limited Number of T Cell Clones
Authors: Musette Philippe , Bachelez Hervé , Flageul Béatrice , Delarbre Christiane , Kourilsky Philippe , Dubertret Louis , Gachelin Gabriel
Published: December 2022

The β-chain repertoire of the T cells that infiltrate spontaneously regressing nevi (the halo nevus phenomenon) was studied. In addition to the infiltration of the halo nevi by cutaneous lymphocyte-associated Ag-positive lymphocytes, oligoclonal expansion of T cells was observed in all halo nevi of all patients. T cells using the same TCR β-chain were observed in distinct halo nevi of the same patient but not in his peripheral blood, demonstrating a local expansion of common clones that are most likely activated by the Ag(s) shared by independent halo nevi of the same patient.
Signs of Immaturity of Splenic Dendritic Cells from the Autoimmune Prone Biobreeding Rat: Consequences for the In Vitro Expansion of Regulator and Effector T Cells
Authors: Delemarre Frans G. A. , Simons Peter J. , de Heer Hendrik Jan , Drexhage Hemmo A.
Published: December 2022

From the biobreeding-diabetic prone (BB-DP) rat, an animal model for endocrine autoimmunity, phenotype and function of splenic dendritic cells (DC) were studied. Furthermore, the suppressive effect of peritoneal macrophages (pMφ) from the BB-DP rat in the MLR was investigated. Lower numbers of splenic DC were isolated from BB-DP rats than from control Wistar rats. In the preautoimmune phase, DC of the BB-DP rat had a lower surface MHC class II expression (and in preliminary data, a lower CD80 expression), ingested more bacteria, and had a lower stimulatory potency in the syngeneic (syn)MLR as compared with control DC. During disease development, the MHC class II expression further decreased, and a low stimulatory activity became evident in the allogeneic (allo)MLR. With regard to the expansion of suppressor/regulatory T cells, a lower percentage of RT6+ T cells but higher percentages of CD45RClow T cells were induced by BB-DP DC in synMLR, but not in alloMLR. An increase in the CD4/CD8 T cell ratio was observed in both the syn- and alloMLR due to a relative weak expansion of CD8+ T cells with DC of the BB-DP rat. Resident pMφ isolated from BB-DP or Wistar rats were equally effective in suppressing the DC-driven synMLR. In conclusion, splenic DC from the BB-DP rat have a lower accessory cell function already at young age, before the development of disease, and expanded different subsets of effector/suppressor T cells in vitro as compared with those from Wistar rats. The dysfunction of DC from BB-DP rats is likely to be caused by their relative immaturity as indicated by their low class II and costimulatory molecule expression and relatively high phagocytic activity.
Blocking OX-40/OX-40 Ligand Interaction In Vitro and In Vivo Leads to Decreased T Cell Function and Amelioration of Experimental Allergic Encephalomyelitis
Authors: Weinberg Andrew D. , Wegmann3 Keith W. , Funatake Castle , Whitham Ruth H.
Published: December 2022

The OX-40R is a member of the TNF receptor family and is expressed primarily on activated CD4+ T cells. When the OX-40R is engaged by the OX-40 ligand (OX-40L), a potent costimulatory signal occurs. We have identified a population of CD11b+ cells, isolated from the central nervous system (CNS) of mice with actively induced experimental allergic encephalomyelitis (EAE), that expresses OX-40L. Moreover, the expression of OX-40L was found to be associated with paralytic episodes of EAE and was reduced or absent at disease recovery. These CD11b+ cells also coexpressed B7 and MHC class II. Therefore, to address the relative contributions of OX-40R/OX-40L and CD28/B7 to the costimulation of myelin-specific T cells, blocking studies were performed using soluble OX-40R and/or soluble CTLA-4. CD11b+ cells isolated from the CNS of mice with actively induced EAE were able to present Ag to proteolipid protein 139–151-specific T cell lines in vitro. The addition of soluble OX-40R:Ig to CD11b+ brain microglia/macrophages inhibited T cell proliferation by 50–70%. The addition of CTLA-4:Ig inhibited T cell proliferation by 20–30%, and the combination inhibited T cell proliferation by 95%. In vivo administration of soluble OX-40R at the onset of actively induced or adoptively transferred EAE reduced ongoing signs of disease, and the mice recovered more quickly from acute disease. The data imply that OX-40L, expressed by CNS-derived APC, acts to provide an important costimulatory signal to EAE effector T cells found within the inflammatory lesions. Furthermore, the data suggest that agents designed to inhibit the OX-40L/OX-40R complex may be useful for treating autoimmune disease.
Cutting Edge: A Role for the Adaptor Protein LAT in Human NK Cell-Mediated Cytotoxicity
Authors: Jevremovic Dragan , Billadeau Daniel D. , Schoon Renee A. , Dick Christopher J. , Irvin Brenda J. , Zhang Weiguo , Samelson Lawrence E. , Abraham Robert T. , Leibson Paul J.
Published: December 2022

Stimulation of NK cell-mediated cytotoxicity involves the coupling of proximal Src and Syk family protein tyrosine kinases to downstream effectors. However, the mechanisms linking these second messenger pathways are incompletely understood. Here, we describe a key role for the LAT (p36) adaptor protein in human NK cell activation. LAT is tyrosine phosphorylated upon stimulation of NK cells through FcγRIII receptors and following direct contact with NK-sensitive target cells. This NK stimulation induces the association of LAT with several phosphotyrosine-containing proteins. In addition to the biochemical evidence showing LAT involvement in NK cell activation, a genetic model shows that LAT is required for FcR-dependent phosphorylation of phospholipase C-γ. Furthermore, overexpression of LAT in NK cells leads to increased Ab-dependent cell-mediated cytotoxicity and “natural cytotoxicity,” thus demonstrating a functional role for LAT in NK cells. These data suggest that LAT is an important adaptor protein for the regulation of human NK cell-mediated cytotoxicity.
Islet-Specific Th1, But Not Th2, Cells Secrete Multiple Chemokines and Promote Rapid Induction of Autoimmune Diabetes
Authors: Bradley Linda M. , Asensio Valérie C. , Schioetz Li-Karine , Harbertson Judith , Krahl Troy , Patstone Gail , Woolf Nigel , Campbell Iain L. , Sarvetnick Nora
Published: December 2022

Migration of CD4 cells into the pancreas represents a hallmark event in the development of insulin-dependent diabetes mellitus. Th1, but not Th2, cells are associated with pathogenesis leading to destruction of islet β-cells and disease onset. Lymphocyte extravasation from blood into tissue is regulated by multiple adhesion receptor/counter-receptor pairs and chemokines. To identify events that regulate entry of CD4 cells into the pancreas, we transferred Th1 or Th2 cells induced in vitro from islet-specific TCR transgenic CD4 cells into immunodeficient (NOD.scid) recipients. Although both subsets infiltrated the pancreas and elicited multiple adhesion receptors (peripheral lymph node addressin, mucosal addressin cell adhesion molecule-1, LFA-1, ICAM-1, and VCAM-1) on vascular endothelium, entry/accumulation of Th1 cells was more rapid than that of Th2 cells, and only Th1 cells induced diabetes. In vitro, Th1 cells were also distinguished from Th2 cells by the capacity to synthesize several chemokines that included lymphotactin, monocyte chemoattractant protein-1 (MCP-1), and macrophage inflammatory protein-1α, whereas both subsets produced macrophage inflammatory protein-1β. Some of these chemokines as well as RANTES, MCP-3, MCP-5, and cytokine-response gene-2 (CRG-2)/IFN-inducible protein-10 (IP-10) were associated with Th1, but not Th2, pancreatic infiltrates. The data demonstrate polarization of chemokine expression by Th1 vs Th2 cells, which, within the microenvironment of the pancreas, accounts for distinctive inflammatory infiltrates that determine whether insulin-producing β-cells are protected or destroyed.
Characterization of TCR Gene Rearrangements During Adult Murine T Cell Development
Authors: Livák Ferenc , Tourigny Michelle , Schatz David G. , Petrie Howard T.
Published: December 2022

Development of the αβ and γδ T cell lineages is dependent upon the rearrangement and expression of the TCRα and β or γ and δ genes, respectively. Although the timing and sequence of rearrangements of the TCRα and TCRβ loci in adult murine thymic precursors has been characterized, no similar information is available for the TCRγ and TCRδ loci. In this report, we show that approximately half of the total TCRδ alleles initiate rearrangements at the CD44highCD25+ stage, whereas the TCRβ locus is mainly in germline configuration. In the subsequent CD44lowCD25+ stage, most TCRδ alleles are fully recombined, whereas TCRβ rearrangements are only complete on 10–30% of alleles. These results indicate that rearrangement at the TCRδ locus can precede that of TCRβ locus recombination by one developmental stage. In addition, we find a bias toward productive rearrangements of both TCRδ and TCRγ genes among CD44highCD25+ thymocytes, suggesting that functional γδ TCR complexes can be formed before the rearrangement of TCRβ. These data support a model of lineage commitment in which sequential TCR gene rearrangements may influence αβ/γδ lineage decisions. Further, because TCR gene rearrangements are generally limited to T lineage cells, these analyses provide molecular evidence that irreversible commitment to the T lineage can occur as early as the CD44highCD25+ stage of development.
IL-15 Induces the Expression of Chemokines and Their Receptors in T Lymphocytes
Authors: Perera Liyanage P. , K. Goldman Carolyn , Waldmann Thomas A.
Published: December 2022

IL-15 is a T cell growth factor that shares many biological activities with IL-2 and uses the same β/γ polypeptides of the IL-2R complex for signal transduction. Accumulating evidence implicates an important role for this cytokine in the inflammatory response of the host. Consistent with such a role, IL-15 has been shown to be a chemoattractant for T lymphocytes, NK cells, and neutrophils. Extending these observations, we now show that IL-15 is a potent inducer of CC-, CXC-, and C-type chemokines in T lymphocytes. In addition, we demonstrate that IL-15 induces CC chemokine receptors, but not CXC chemokine receptors, in a dose-dependent manner. Thus, our findings suggest that the proinflammatory effects of IL-15 at least in part may be due to the induction of chemokines and their receptors in T cells. Furthermore, we demonstrate that IL-15 promotes entry and replication of macrophage-tropic HIV in T lymphocytes and suggest a plausible mechanism by which IL-15, a cytokine that is elevated in HIV-infected individuals, may promote the transition of HIV displaying the M-tropic phenotype primarily associated with the initial transmission into the T cell-tropic phenotype that predominates as the disease progresses.
Regulation of B Cell Receptor-Mediated MHC Class II Antigen Processing by FcγRIIB1
Authors: Wagle Neelam M. , Faassen Anne E. , Kim Julie H. , Pierce Susan K.
Published: December 2022

The processing and presentation of Ag by Ag-specific B cells is highly efficient due to the dual function of the B cell Ag receptor (BCR) in both signaling for enhanced processing and endocytosing bound Ag. The BCR for IgG (FcγRIIB1) is a potent negative coreceptor of the BCR that blocks Ag-induced B cell proliferation. Here we investigate the influence of the FcγRIIB1 on BCR-mediated Ag processing and show that coligating the FcγRIIB1 and the BCR negatively regulates both BCR signaling for enhanced Ag processing and BCR-mediated Ag internalization. Treatment of splenic B cells with F(ab′)2 anti-Ig significantly enhances APC function compared with the effect of whole anti-Ig; however, whole anti-Ig treatment is effective when binding to the FcγRIIB1 was blocked by a FcγRII-specific mAb. Processing and presentation of Ag covalently coupled to anti-Ig were significantly decreased compared with Ag coupled to F(ab′)2anti-Ig; however, the processing of the two Ag-Ab conjugates was similar in cells that did not express FcγRIIB1 and in splenic B cells treated with a FcγRII-specific mAb to block Fc binding. Internalization of monovalent Ag by B cells was reduced in the presence of whole anti-Ig as compared with F(ab′)2 anti-Ig, but the internalized Ag was correctly targeted to the class II peptide loading compartment. Taken together, these results indicate that the FcγRIIB1 is a negative regulator of the BCR-mediated Ag-processing function.
A Novel Role of IL-15 in the Development of Osteoclasts: Inability to Replace Its Activity with IL-2
Authors: Ogata Yoshiyasu , Kukita Akiko , Kukita Toshio , Komine Mitunori , Miyahara Akira , Miyazaki Sumio , Kohashi Osamu
Published: December 2022

IL-15 shares many activities with IL-2 on stimulating lymphocytes, hematopoietic progenitor cells, and macrophages. However, the role of IL-15 in osteoclastogenesis has not been elucidated. The recent finding of abundant IL-15 in rheumatoid arthritis synovial fluids suggested a possible role for this cytokine in the pathological destruction of bone and prompted us to determine whether IL-15 stimulates osteoclast formation. IL-15 stimulated the formation of multinucleated osteoclast-like cells in rat bone marrow cultures. In stroma-free cultures, IL-15 increased the number of mononuclear preosteoclast-like cells in the early stage of osteoclast formation. The stimulation was observed even after treatment with IL-15 for only 24 or 48 h of culture. Moreover, low IL-15 concentration (0.1 ng/ml) strongly increased the level of calcitonin receptor mRNA of mononuclear preosteoclast-like cells. Although IL-15 is known as a potent stimulator of TNF-α, its activity was not abolished by addition of anti-TNF-α Ab. Interestingly, IL-2 and IL-7, which utilize some IL-15R components, had no effect on osteoclast differentiation, but pretreatment with IL-2 or IL-7 of bone marrow cells before the addition of IL-15 inhibited the enhancing activity of IL-15. In summary, IL-15 has a novel activity to stimulate the differentiation of osteoclast progenitors into preosteoclasts, which cannot be replaced by IL-2 but may use components in common with IL-2R to mediate its effects.
A Tailless Fas-FADD Death-Effector Domain Chimera Is Sufficient to Execute Fas Function in T Cells But Not B Cells of MRL-lpr/lprMice
Authors: Kabra Nisha H. , Cado Dragana , Winoto Astar
Published: December 2022

The Fas receptor delivers signals crucial for lymphocyte apoptosis through its cytoplasmic death domain. Several Fas cytoplasmic-associated proteins have been reported and studied in cell lines. So far, only Fas-associated death domain protein (FADD), another death domain-containing molecule has been shown to be essential for Fas signals in vivo. FADD is thought to function by recruiting caspase-8 through its death-effector domain. To test whether FADD is sufficient to deliver Fas signals, we generated transgenic mice expressing a chimera comprised of the Fas extracellular domain and FADD death-effector domain. Expression of this protein in lymphocytes of Fas-deficient MRL-lpr/lpr mice completely diminishes their T cell but not their B cell abnormalities. These results suggest that FADD alone is sufficient for initiation of Fas signaling in primary T cells, but other pathways may operate in B cells.
Role of Innate and Adaptive Immunity in the Outcome of Primary Infection withChlamydia pneumoniae, as Analyzed in Genetically Modified Mice
Authors: Rottenberg Martín E. , Gigliotti Rothfuchs Antonio C. , Gigliotti Dulceaydee , Svanholm Cecilia , Bandholtz Lisa , Wigzell Hans
Published: December 2022

Infection with Chlamydia pneumoniae is a common cause of acute respiratory disease in man and is also associated with atherosclerotic cardiovascular disorder. Herein, we have compared bacterial load and immune parameters of C. pneumoniae-infected mice genomically lacking T cell coreceptors, cytokine receptors, or cytotoxic effector molecules. A protective role for CD8+ cells is shown by the enhanced severity of infection of CD8−/− or TAP-1−/−/β2-microglobulin −/− mice. CD8+ cells hindered a parasite growth-promoting role of CD4+ T cells, as indicated by the higher sensitivity to early infection of CD8−/− than CD4−/−/CD8−/− mice, which was further confirmed in experiments in which SCID mice were reconstituted with either CD4+ or CD4+ plus CD8+ T cells. Interestingly, CD4+ T cells played a dual role, detrimental early (14 and 24 days) after infection but protective at later time points (60 days after infection). The CD8+ T cell protection was perforin independent. The early deleterious role of CD4+ in the absence of CD8+ T cells was associated with enhanced IL-4 and IL-10 mRNA levels and delayed IFN-γ mRNA accumulation in lungs. In line with this, IFN-γR−/− (but not TNFRp55 −/−) mice showed dramatically increased susceptibility to C. pneumoniae, linked to reduced inducible nitric oxide synthase (iNOS) mRNA accumulation, but not to diminished levels of specific Abs. The increased susceptibility of iNOS−/− mice indicates a protective role for iNOS activity during infection with C. pneumoniae. The higher sensitivity of IFN-γR−/− mice to C. pneumoniae compared with that of SCID or recombination-activating gene-1−/− mice suggested a relevant protective role of IFN-γ-dependent innate mechanisms of protection.
Qualitative and Quantitative Requirements for CD4+ T Cell-Mediated Antiviral Protection
Authors: Maloy Kevin J. , Burkhart Christoph , Freer Giulia , Rülicke Thomas , Pircher Hanspeter , Kono Dwight H. , Theofilopoulos Argyrios N. , Ludewig Burkhard , Hoffmann-Rohrer Urs , Zinkernagel Rolf M. , Hengartner Hans
Published: December 2022

CD4+ Th cells deliver the cognate and cytokine signals that promote the production of protective virus-neutralizing IgG by specific B cells and are also able to mediate direct antiviral effector functions. To quantitatively and qualitatively analyze the antiviral functions of CD4+ Th cells, we generated transgenic mice (tg7) expressing an MHC class II (I-Ab)-restricted TCR specific for a peptide derived from the glycoprotein (G) of vesicular stomatitis virus (VSV). The elevated precursor frequency of naive VSV-specific Th cells in tg7 mice led to a markedly accelerated and enhanced class switching to virus-neutralizing IgG after immunization with inactivated VSV. Furthermore, in contrast to nontransgenic controls, tg7 mice rapidly cleared a recombinant vaccinia virus expressing the VSV-G (Vacc-IND-G) from peripheral organs. By adoptive transfer of naive tg7 CD4+ T cells into T cell-deficient recipients, we found that 105 transferred CD4+ T cells were sufficient to induce isotype switching after challenge with a suboptimal dose of inactivated VSV. In contrast, naive transgenic CD4+ T cells were unable to adoptively confer protection against peripheral infection with Vacc-IND-G. However, tg7 CD4+ T cells that had been primed in vitro with VSV-G peptide were able to adoptively transfer protection against Vacc-IND-G. These results demonstrate that the antiviral properties of CD4+ T cells are governed by the differentiation status of the CD4+ T cell and by the type of effector response required for virus elimination.
Experimental Murine Schistosomiasis in the Absence of B7 Costimulatory Molecules: Reversal of Elicited T Cell Cytokine Profile and Partial Inhibition of Egg Granuloma Formation
Authors: Hernandez Hector J. , Sharpe Arlene H. , Stadecker Miguel J.
Published: December 2022

The granulomatous inflammation in infection with the helminth Schistosoma mansoni represents a cellular hypersensitivity reaction mediated by, and dependent upon, MHC class II-restricted CD4+ Th cells sensitized to parasite egg Ags. The current work examines the role and significance of the B7:CD28/CTLA-4 pathway in providing the costimulation necessary for the activation of these pathogenic T cells. In vitro T cell responses in B7-1−/− mice, 7–8 wk postinfection, were no different from wild-type controls, but the absence of B7-2 molecules resulted in a decrease in egg Ag-induced proliferation with increased IFN-γ production. Both B7-1−/− and B7-2−/− mice exhibited intact granuloma formation. In contrast, CD4+ Th cells from B7-1/2 double-deficient mice displayed a dramatic loss of proliferative capacity upon stimulation with egg Ag. Most strikingly, these T cells secreted only IFN-γ, but not IL-4 and IL-10, a pattern entirely opposite to that displayed by wild-type controls. Despite these major differences in T cell reactivity, B7-1/2−/− mice had only a limited reduction of granuloma size and fibrosis, without appreciable difference in cellular composition. These results show that substantial granuloma formation can occur under conditions of limited T cell expansion and restricted Th1-type cytokine production. They also support the notion that the combined effect of B7 signaling is not as critical for Th1 cell activation as it is for the development of the Th2 dominant environment characteristic of the evolving schistosome infection in H-2b mice.
Bacterial Lipopolysaccharide Causes Rapid Shedding, Followed by Inhibition of mRNA Expression, of the IL-1 Type II Receptor, with Concomitant Up-Regulation of the Type I Receptor and Induction of Incompletely Spliced Transcripts
Authors: Penton-Rol Giselle , Orlando Simone , Polentarutti Nadia , Bernasconi Sergio , Muzio Marta , Introna Martino , Mantovani Alberto
Published: December 2022

The IL-1 type I receptor (IL-1RI) is part of a signaling complex together with the IL-1R accessory protein, whereas available information is consistent with a “decoy” model of function for the IL-1 type II receptor (IL-1RII). The present study was designed to investigate the effect of bacterial LPS on IL-1R in human monocytes. LPS causes rapid release of the IL-1RII, an effect blocked by a metalloprotease inhibitor. Subsequently, LPS-treated monocytes showed a drastic reduction of IL-1RII mRNA. In contrast, LPS induced IL-1RI and, to a lesser extent, IL-1AcP expression. LPS-induced augmented expression of the canonical 5-kb IL-1RI mRNA was accompanied by the appearance of 2.4-kb IL-1RI transcripts. The use of probes representative of different regions of the IL-1RI mRNA, as well as cDNA cloning, revealed that the 2.4-kb inducible band includes incompletely spliced, polyadenylated transcripts potentially encoding truncated versions of the receptor. The observation that the prototypic proinflammatory molecule LPS has divergent effects on IL-1Rs, with inhibition of IL-1RII and stimulation of IL-1RI and IL-1R accessory protein, is consistent with the view that these molecules subserve opposite functions in the pathophysiology of the IL-1 system. The rapid shedding of IL-1RII by monocytes early in recruitment may serve to buffer the systemic action of IL-1 leaking from sites of inflammation. This early event, followed by prolonged inhibition of IL-1RII expression and up-regulation of IL-1RI, may render monocytes more responsive to IL-1 at sites of inflammation.