bluuebunny/crossref_metadata_2025_split huggingface dataset:
Activation of Low Avidity CTL Specific for a Self Epitope Results in Tumor Rejection But Not Autoimmunity
Authors: Morgan David J. , Kreuwel Huub T. C. , Fleck Shonna , Levitsky Hyam I. , Pardoll Drew M. , Sherman Linda A. 
Published: January 2023

Abstract
To determine how self-tolerance can alter the ability of the immune system to respond against tumor-associated Ags that are also expressed by normal tissue, we designed experiments in which the same protein was expressed both as a tumor Ag and as a transgene product. Unlike conventional BALB/c mice that rejected renal carcinoma cells transfected with the influenza virus hemagglutinin (Renca-HA), transgenic mice that are tolerant of HA due to its expression as a self-Ag on pancreatic islet β cells, (Ins-HA mice) supported progressive growth of these tumor cells. However, when Ins-HA mice were immunized with a recombinant strain of vaccinia virus expressing the dominant H-2Kd peptide epitope of HA before receiving Renca-HA cells, they too were able to reject the tumor cells. Rejection of Renca-HA cells by immunized Ins-HA mice was found to be associated with the generation of CTL having much lower avidity for target cells presenting the KdHA epitope than CTL from immunized conventional BALB/c mice. Significantly, we show that self-tolerance to the HA Ag is quantitative rather then absolute, and that vaccination of Ins-HA mice can activate low avidity KdHA-specific CD8+ T cells that are able to reject tumor cells expressing high levels of HA, yet these mice remain tolerant of pancreatic islet β cells expressing HA.
Lack of Intraclonal Diversification in Ig Heavy and Light Chain V Region Genes Expressed by CD5+IgM+ Chronic Lymphocytic Leukemia B Cells: A Multiple Time Point Analysis
Authors: Schettino Edward W. , Cerutti Andrea , Chiorazzi Nicholas , Casali Paolo 
Published: January 2023

Abstract
To analyze the modalities of clonal expansion of chronic lymphocytic leukemia (CLL) cells, we sequenced at multiple time points the V(D)J genes expressed by CD5+IgM+CLL B cells in three patients. All three V(D)J gene sequences were found to be point mutated. The mutation frequency in the Ig VH (3.96 × 10−2 and 2.41 × 10−2 change/bp) and Vκ and Vλ (6.67 × 10−2 and 1.74 × 10−2 change/bp) genes of two CLLs (1.19 and 1.32, respectively) was similar, and higher than that in the corresponding gene segments of the third CLL (1.69; 3.4 × 10−3 and 6.67 × 10−3 change/bp). In all three CLLs, there was no preferential representation of nucleotide changes yielding amino acid replacement (R mutations), nor was there any preferential segregation of R mutations within the Ig V gene complementarity-determining regions. In all three CLLs, the somatic mutations were all identical in multiple Ig VHDJH transcripts at any given time point, and were all conserved at multiple time points throughout a 2-yr period. The lack of concentration of R mutations in the complementarity-determining regions and the lack of intraclonal heterogeneity suggest that Ag may no longer be able to play a significant role in the clonal expansion of these cells. This conclusion would be strengthened further by the germline configuration of the bcl-1 and bcl-2 proto-oncogenes that are translocated in neoplastic B cells that display significant traces of intraclonal diversification and Ag-dependent selection, such as B-prolymphocytic leukemia and low grade follicular non-Hodgkin lymphoma.
Distinct Patterns of Folding and Interactions with Calnexin and Calreticulin in Human Class I MHC Proteins with Altered N-Glycosylation
Authors: Zhang Qing , Salter Russell D. 
Published: January 2023

Abstract
Calnexin is a lectin-like chaperone that binds to class I MHC molecules soon after their synthesis, retaining unassembled heavy chains and also assisting their folding. Following association with β2-microglobulin (β2m) in the endoplasmic reticulum, a large proportion of human class I molecules release from calnexin, whereas mouse class I molecules do not. We asked whether addition of a second N-glycan to the human class I molecule A*0201 at position 176, a site present in mouse, would affect its binding to calnexin. The 176dg mutant with N-glycans at positions 86 and 176, when transfected into CIR cells, demonstrated increased binding to calnexin, detectable both before and after association with β2m, and reduced interaction with calreticulin and TAP relative to wild-type protein bearing a single N-glycan at position 86. Cell surface levels of the mutant were decreased only slightly relative to the wild type, suggesting that the protein is not misfolded or grossly altered structurally. A subpopulation of mutant molecules was retained in the endoplasmic reticulum, and surprisingly, these molecules reacted with w6/32, which recognizes an epitope present on transport-competent class I HLA complexes. Transfection into Daudi cells demonstrated that 176dg reacts with w6/32 in the absence of β2m, suggesting that the Ab epitope can be induced by binding of calnexin. These data may explain previously noted differences between mouse and human class I MHC proteins and demonstrate that the location of N-oligosaccharides within proteins can influence their folding and interactions with chaperones such as calnexin and calreticulin.
Control of Leishmania major by a Monoclonal αβ T Cell Repertoire
Authors: Reiner Steven L. , Fowell Deborah J. , Moskowitz Naomi H. , Swier Kevin , Brown Daniel R. , Brown Charles R. , Turck Christoph W. , Scott2 Phillip A. , Killeen Nigel , Locksley3 Richard M. 
Published: January 2023

Abstract
Little is known regarding the diversity of the host T cell response that is required to maintain immunologic control of microbial pathogens. Leishmania major persist as obligate intracellular parasites within macrophages of the mammalian host. Immunity is dependent upon activation of MHC class II-restricted T cells to an effector state capable of restricting growth and dissemination of the organisms. We generated α-β Leishmania-specific (ABLE) TCR transgenic mice with MHC class II-restricted T cells that recognized an immunodominant Leishmania Ag designated LACK. Naive T cells from ABLE mice proliferated in vitro after incubation with recombinant LACK or with Leishmania-parasitized macrophages and in vivo after injection into infected mice. Infected ABLE mice controlled Leishmania infection almost as well as wild-type mice despite a drastic reduction in the T cell repertoire. ABLE mice were crossed to mice with disruption of the TCR constant region α gene to create animals with a single αβ T cell repertoire. Although mice deficient in all αβ T cells (TCR-Cαo mice) failed to control L. major, mice with a monoclonal αβ T cell repertoire (ABLE TCR-Cαo mice) displayed substantial control. The immune system is capable of remarkable efficiency even when constrained to recognition of a single epitope from a complex organism.
TNF Receptor-Deficient Mice Reveal Divergent Roles for p55 and p75 in Several Models of Inflammation
Authors: Peschon Jacques J. , Torrance Dauphine S. , Stocking Kim L. , Glaccum Moira B. , Otten Carol , Willis Cynthia R. , Charrier Keith , Morrissey Philip J. , Ware Carol B. , Mohler Kendall M. 
Published: January 2023

Abstract
The pleiotropic activities of the potent proinflammatory cytokine TNF are mediated by two structurally related, but functionally distinct, receptors, p55 and p75, that are coexpressed on most cell types. The majority of biologic responses classically attributed to TNF are mediated by p55. In contrast, p75 has been proposed to function as both a TNF antagonist by neutralizing TNF and as a TNF agonist by facilitating the interaction between TNF and p55 at the cell surface. We have examined the roles of p55 and p75 in mediating and modulating the activity of TNF in vivo by generating and examining mice genetically deficient in these receptors. Selective deficits in several host defense and inflammatory responses are observed in mice lacking p55 or both p55 and p75, but not in mice lacking p75. In these models, the activity of p55 is not impaired by the absence of p75, arguing against a physiologic role for p75 as an essential element of p55-mediated signaling. In contrast, exacerbated pulmonary inflammation and dramatically increased endotoxin induced serum TNF levels in mice lacking p75 suggest a dominant role for p75 in suppressing TNF-mediated inflammatory responses. In summary, these data help clarify the biologic roles of p55 and p75 in mediating and modulating the biologic activity of TNF and provide genetic evidence for an antagonistic role of p75 in vivo.
Dynamic Regulation of α- and β-Chemokine Expression in the Central Nervous System During Mouse Hepatitis Virus-Induced Demyelinating Disease
Authors: Lane Thomas E. , Asensio Valérie C. , Yu Naichen , Paoletti Alyssa D. , Campbell Iain L. , Buchmeier Michael J. 
Published: January 2023

Abstract
Infection of C57BL/6 mice with the V5A13.1 strain of mouse hepatitis virus (MHV-V5A13.1) results in an acute encephalomyelitis and chronic demyelinating disease with features similar to the human demyelinating disease multiple sclerosis. Chemokines are a family of proinflammatory cytokines associated with inflammatory pathology in various diseases. The kinetics and histologic localization of chemokine production in the central nervous system of MHV-infected mice were examined to identify chemokines that contribute to inflammation and demyelination. Transcripts for the chemokines cytokine-response gene-2 (CRG-2), regulated on activation, normal T cell expressed and secreted (RANTES), macrophage-chemoattractant protein-1 and protein-3 (MCP-1, MCP-3), macrophage-inflammatory protein-1β (MIP-1β), and MIP-2 were detected in the brains of MHV-infected mice at 3 days postinfection (p.i.), and these transcripts were increased markedly in brains and spinal cords at day 7 p.i., which coincides with the occurrence of acute viral encephalomyelitis. By day 35 p.i., RANTES, CRG-2, and MIP-1β were detected in brains and spinal cords of mice with chronic demyelination. CRG-2 mRNA expression colocalized with viral RNA and was associated with demyelinating lesions. Astrocytes were the predominant cell type expressing CRG-2 mRNA. These observations suggest a role for chemokines, notably CRG-2, in the initiation and maintenance of an inflammatory response following infection with MHV, which is important in contributing to demyelination.
Gene Organization and Promoter Function for CC Chemokine Receptor 5 (CCR5)
Authors: Guignard Florence , Combadiere Christophe , Tiffany H. Lee , Murphy Philip M. 
Published: January 2023

Abstract
CC chemokine receptor 5 (CCR5) functions physiologically as a receptor for the leukocyte chemoattractants macrophage inflammatory protein-1α, macrophage inflammatory protein-1β, and RANTES, and functions pathologically as a key cell entry coreceptor for HIV-1. The factors that regulate CCR5 expression may be useful therapeutic targets for HIV-1 infection. To identify nuclear regulatory factors, we have located and functionally characterized the CCR5 gene promoter. The gene consists of two exons separated by a 1.9-kb intron. Exon 1 contains 43 bp of the 5′-untranslated region; exon 2 contains 11 bp of the 5′-untranslated region and the complete open reading frame. Primer extension analysis identified two adjacent transcriptional start points (tsp) that map to the first 2 bp found in the longest known CCR5 cDNA sequence. A TATA box is present 31 bp upstream from the first tsp. CCR5 mRNA was detected constitutively in both primary human myeloid and lymphoid cells by Northern blot hybridization. Consistent with this, transcription of a chloramphenicol acetyltransferase reporter gene was constitutively activated in both transiently transfected myeloid and lymphoid cell lines by the 80-bp gene fragment located immediately upstream of the tsp. Deletion analysis located a strong silencer element between nucleotides −244 and −80, and a strong enhancer element between −486 and −244. These results suggest that the gene region between −486 and −1 may regulate the expression of CCR5 in monocyte/macrophages and T lymphocytes.
Functional Roles of Fas and Bcl-2-Regulated Apoptosis of T Lymphocytes
Authors: Van Parijs Luk , Biuckians Andre , Abbas Abul K. 
Published: January 2023

AbstractApoptotic cell death is an important mechanism for maintaining homeostasis in the immune system and for regulating the fates of lymphocytes following encounters with self and foreign Ags. To study the physiologic roles of the proapoptotic Fas pathway and the antiapoptotic protein, Bcl-2, in T cell maturation and homeostasis, a TCR transgene has been bred into mice lacking functional Fas and mice that express Bcl-2 constitutively. In vitro, Fas-deficient T cells are resistant to activation-induced cell death, whereas Bcl-2-overexpressing T cells are resistant to death induced by withdrawal of growth factors. In vivo, Bcl-2-overexpressing mice accumulate T cells in the thymus and peripheral lymphoid tissues in the absence of Ag, but these cells are deleted normally after Ag administration. In contrast, Fas-deficient mature T cells are present in normal numbers in the absence of Ag, but are resistant to Ag-induced deletion. Both Fas-deficient and Bcl-2 overexpressing thymocytes are deleted when exposed to transgene-encoded circulating self Ag, indicating that the pathways of apoptosis controlled by these proteins are not critical for negative selection of developing thymocytes. Moreover, deficiency of Fas, but not Bcl-2 overexpression, results in the accumulation of autoreactive T cells in peripheral lymphoid tissues. These results demonstrate that Fas and Bcl-2 regulate different pathways of apoptosis that may serve distinct functions in lymphocyte homeostasis and in the maintenance of T cell tolerance.
Synergistic Activation of CD4+ T Cells by IL-16 and IL-2
Authors: Parada Nereida A. , Center David M. , Kornfeld Hardy , Rodriguez Wilma L. , Cook Jennifer , Vallen Margaret , Cruikshank William W. 
Published: January 2023

Abstract
IL-16, in a CD4-dependent manner, induces high affinity IL-2R (CD25) selectively on CD4+ T cells. Based on this observation, we determined the relative effects of IL-16 on IL-2Rα, β, and γ expression on CD4+ T cells and of IL-16/IL-2 cotreatment of resting human PBMC obtained from normal individuals on CD4+ T cell proliferation and cytokine production, in vitro. IL-16 increased CD4+ T cell IL-2Rα and β expression, but had no effect on expression of IL-2Rγ. There was marked synergy of thymidine uptake and expansion of CD4+ T cell numbers in the presence of IL-16 and IL-2 or IL-16 and IL-15 compared with the responses to any of the cytokines alone. By 4 wk, IL-16/IL-2-cotreated PBMC cultures were predominantly CD4+, CD25+ CD45RO T cells. Of the cytokines measured, IL-16 treatment alone was sufficient to induce synthesis of granulocyte-macrophage CSF by 2 wk. IL-16/IL-2 cotreatment did not appear to induce selective proliferation of any Th subset, as cytokines of both Th1 (e.g., IFN-γ) and Th2 (e.g., IL-5) types were synthesized by the expanded cell populations at 2 and 4 wk. These results suggest that IL-16 can prime CD4+ T cells for IL-2 responsiveness, and therefore may be a useful adjunct to IL-2 therapy for immune reconstitution in disease or therapeutic conditions resulting in CD4+ T cell depletion.
CD40 Ligand and Appropriate Cytokines Induce Switching to IgG, IgA, and IgE and Coordinated Germinal Center and Plasmacytoid Phenotypic Differentiation in a Human Monoclonal IgM+IgD+ B Cell Line
Authors: Cerutti Andrea , Zan Hong , Schaffer Andras , Bergsagel Leif , Harindranath Nagaradona , Max Edward E. , Casali Paolo 
Published: January 2023

AbstractB lymphocytes are induced to undergo Ig class switching and a complex phenotypic differentiation by the milieu of the germinal center. Partly as a result of the lack of a suitable in vitro B cell model, the relationship between these processes in the humans has never been formally established in vitro. We have identified a human monoclonal B cell line, CL-01, that expresses surface IgM and IgD and, upon induction with CD40 ligand, IL-4, and IL-10, switches to all seven downstream isotypes, showing typical DNA switch recombination preceded by germline transcription of targeted CH regions. In CL-01 cells, switch-inducing stimuli trigger concomitant changes in expression of surface IgD, CD23, CD38, and CD77 that parallel those reported in ex vivo isolated tonsillar centroblasts, centrocytes, and memory B cells. Eventually, in the presence of IL-6, CL-01 cells express CD56 and accumulate cytoplasmic IgG and IgA, both traits of plasmacytoid differentiation. Analysis of transcription and recombination of the Ig H locus in sorted CL-01 cells suggest that Ig class switching begins in centroblasts, it extends to all isotypes in centrocytes, and it is extinct in memory B cells. Thus, we have induced coordinated Ig class switching, progression through germinal center phenotypic stages, and differentiation to memory B cells and plasma cells at the level of a single B clonotype. Our data suggest that these processes are likely regulated by a common maturation program, the activation of which may require CD40 ligand, IL-4, IL-10, and IL-6 only.
Fetal Mouse NK Cell Clones Are Deficient in Ly49 Expression, Share a Common Broad Lytic Specificity, and Undergo Continuous and Extensive Diversification In Vitro
Authors: Manoussaka Maria S. , Smith Rachel J. , Conlin Victoria , Toomey Jennifer A. , Brooks Colin G. 
Published: January 2023

AbstractNK cells obtained by exposing mouse fetal thymocytes to appropriate combinations of IL-4, IL-2, and PMA are phenotypically indistinguishable from cultured adult splenic NK cells with the exception that they generally lack measurable expression of all of the inhibitory Ly49 molecules that can currently be detected with Abs (Ly49A, -C, -G, and -I) and of the activating molecule Ly49D. Despite this deficiency, fetal NK cells have a similar specificity to Ly49-expressing adult splenic NK cells. Individual fetal NK cell clones display an essentially invariant and broad specificity similar to that of polyclonal populations of fetal or adult NK cells, although significant differences in the fine specificity of clones can occasionally be detected. Most remarkably, cloned fetal NK cell lines display heterogeneous expression of a restricted set of surface molecules that includes 10A7, Ly6C, 3C2, CD8, certain isoforms of CD45, and also, occasionally, Ly49 molecules. This heterogeneity is not related to the cell cycle or activation status of the cells, and micromanipulation recloning demonstrates unambiguously that it is not due to a lack of a single cell origin. Diversity is generated rapidly and the capacity for diversification appears to persist indefinitely in vitro. The expression of individual variable Ags is independent and stochastic, resulting in fetal NK “clones” being potentially composed of hundreds of phenotypically distinct cells. We hypothesize that fetal NK cells behave as progenitor cells that are undergoing a process of rapid, extensive, and continuous diversification and that are individually capable of generating and regenerating a complex NK cell repertoire.
CD28 Receptor Endocytosis Is Targeted by Mutations That Disrupt Phosphatidylinositol 3-Kinase Binding and Costimulation
Authors: Céfaï Daniel , Schneider Helga , Matangkasombut Oranart , Kang Hyun , Brody Joshua , Rudd Christopher E. 
Published: January 2023

Abstract
Although the lipid kinase phosphatidylinositol 3-kinase (PI-3K) binds at high levels to the cytoplasmic tail of CD28, controversy exists regarding its role in CD28 costimulation. Potentially, the kinase could be linked to a signaling cascade or be needed indirectly in events such as receptor endocytosis. Indeed, little is known regarding both the fate of CD28 following receptor ligation and the events that control the process. In this study, we help to resolve this issue by providing evidence that PI-3K plays a role in regulating CD28 endocytosis. We show that ∼25 to 35% of wild-type CD28 becomes endocytosed following Ab binding (t1/2 = 10 min), followed by segregation into two pools; one pool is destined for degradation in lysosomal compartments and is blocked by chloroquine, and another pool that is recycled to the cell surface (t1/2 = 2.5 h). Recycling of CD28 could have an important impact on CD80/86-mediated costimulation by replenishing functionally active receptors on the cell surface. Several findings implicate PI-3K in the control of endocytosis. Modulation experiments indicate that CD28-PI-3K complexes are preferentially endocytosed, and mutations that alter PI-3K binding concordantly affect the efficacy of endocytosis. Importantly, mutations that inhibit receptor internalization also block cosignaling. Therefore, previous results documenting a requirement for PI-3K may be explained by a blockage of receptor internalization.
Identification of an IL-7-Associated Pre-Pro-B Cell Growth-Stimulating Factor (PPBSF). I. Production of the Non-IL-7 Component by Bone Marrow Stromal Cells from IL-7 Gene-Deleted Mice
Authors: McKenna Sean D. , Chen Fangqi , Lai Laijun , Goldschneider Irving 
Published: January 2023

AbstractMouse bone marrow (BM) stromal cell conditioned medium (CM) from our long-term lymphoid culture system selectively induces the in vitro proliferation and presumptive differentiation of pre-pro-B cells (B220+, HSA−, TdT− or TdT+, cμ−) from adult rat, mouse, and human BM. However, the responsible growth factor(s) has not yet been identified. Inasmuch as IL-7 is one of the cytokines most closely associated with early B-lineage development, we utilized BM adherent cells and stromal cell lines from IL-7 gene-deleted (−/−) mice in combination with rIL-7 and anti-IL-7 mAb to investigate its possible regulatory role in our culture system. The results show that, although rIL-7 and IL-7 (−/−) CM each can maintain the viability of freshly harvested pre-pro-B cells in vitro, neither induces them to proliferate and/or differentiate, even in the presence of recombinant stem cell factor (rSCF) and/or recombinant insulin-like growth factor (rIGF). The results also show that anti-IL-7 mAb fails to neutralize the pre-pro-B cell growth-stimulating activity in IL-7 (+/+) CM. Yet rIL-7 enables IL-7 (−/−) CM to induce proliferation of pre-pro-B cells, and to “prime” them to respond directly to monomeric IL-7. Furthermore, anti-IL-7 mAb adsorbs the pre-pro-B cell growth-stimulating activity from both IL-7 (+/+) CM and rIL-7-supplemented IL-7 (−/−) CM; but rIL-7 does not restore this activity. Lastly, both pre-pro-B cell growth-stimulatory activity and IL-7 are quantitatively recovered by ultrafiltration in the 50 to 100 kDa, rather than the 10 to 50 kDa, apparent molecular mass fraction. These results suggest that the pre-pro-B cell growth-stimulating activity in our culture system is the property of a self-associating complex of IL-7 and a second BM stromal cell-derived cofactor.