bluuebunny/crossref_metadata_2025_split huggingface dataset:
HLA-DQ polymorphisms are highly selective for peptide binding interactions.
Authors: Kwok W W , Nepom G T , Raymond F C 
Published: December 2022

Abstract
The impact of HLA-DQ allelic polymorphism on peptide binding interactions was investigated. MHC class II binding peptides from lambda repressor (lambda R), thyroid peroxidase (TPO), and a modified poly-alanine peptide (AKY) were used in two different binding assays, one with purified DQ molecules and another with cells that expressed DQ cell surface dimers. Class II heterodimers of different combinations of DQ alpha-chain and the DQ beta-chain independently influenced specific peptide interactions. Each of the peptides tested bound differentially to DQ alleles: TPO632-645 bound test to DQ2 molecules (DQA1*0501/DQB1*0201), lambda R12-24 bound best to DQ8 molecules (DQ3.2 or DQA1*0301/DQB1*0302), and AYK bound best to DQ1 (DQA*0102/DQB*0602) and DQ7 (DQ3.1 OR DQA1*0301/DQB1*0301). However, in each case in which either the DQ alpha- or DQ beta-chain was exchanged, major alterations or reversals of this pattern of interaction were observed. The interaction of lambda R with DQ8 was highly dependent on specific sequence polymorphisms at residue 57; an Ala--&gt;Asp substitution on the DQ beta-chain at the polymorphic codon 57 prevented peptide binding. However, Ala 57 alone was not sufficient to permit binding in other DQ allelic contexts. These studies demonstrate the critical role of specific DQ polymorphisms in establishing the nature of bound Ag and thereby influencing the potential immune repertoire. Analysis of the ability of DQ molecules to bind and present antigenic peptides should aid in understanding their role in immunity and in development of HLA-DQ-associated autoimmune disease.
Myeloma Ig heavy chain V region sequences reveal prior antigenic selection and marked somatic mutation but no intraclonal diversity.
Authors: Vescio R A , Cao J , Hong C H , Lee J C , Wu C H , Der Danielian M , Wu V , Newman R , Lichtenstein A K , Berenson J R 
Published: December 2022

Abstract
The lg VH region sequence in 48 patients with multiple myeloma (MM) was analyzed to characterize the malignant cell of origin. The sequences were obtained after amplification of bone marrow cDNA by using VH family-specific and CH primers, then compared with either directly sequenced patient germ-line or published VH gen sequences to assay for somatic mutation. Because somatic hypermutation of the VH gene occurs late in B cell development, its presence has been helpful in determining the cell of origin in other B cell malignancies. Overall, a median of 8.2% of the nucleotides had evidence of substitution within each VH gene sequence (range=2.7% to 16.5%), which is more prevalent than in any other reported tumor type. Strong evidence of prior antigenic selection pressure was also evident. The ratio of nucleotide substitutions that resulted in amino acid replacement was significantly higher in the complementarity-determining region than in the framework region (3.25 vs 1.56, respectively; p &lt; 0.00005). No VH gene intraclonal diversity was noted, despite sequencing multiple clones (3-16) from each patient, nor was there evidence of further VH gene somatic mutation over the course of three patients' disease. These findings strongly imply that the malignant clone in MM evolves from a cell late in B cell development.
Identification and localization of a developmental stage-specific promoter activity from the murine lambda 5 gene.
Authors: Yang J , Glozak M A , Blomberg B B 
Published: December 2022

Abstract
The lambda 5 protein is expressed in pre-B cells in association with VpreB and mu-heavy chains, and is critical for differentiation to the B cell stage. Pre-B cell-specific expression of the lambda 5 and VpreB genes is regulated at the level of transcription initiation. In this report, we have identified several DNase l-hypersensitive sites 2.5- to 6.0-kb downstream of the lambda 5 gene, which are present in the pre-B cell line 70Z/3, but not in the myeloma cell line j558L. These sites, however, were shown to have no transcriptional enhancer activity as measured by transient transfection. Enhancer activity was identified within a 361-bp fragment (-296 to +65, where +1 is the major 5' transcription initiation site) upstream of the mouse lambda 5 gene. This activity is orientation and position independent, and is also tissue and differentiation stage specific (active in pre-B but not B and T cells). Deletion constructs indicate that three adjacent areas (-210 to -169, -153 to -64, and -64 to -22) are all necessary for enhancer activity. Pre-B cell-specific promoter activity was shown to reside within the -219 to +109 fragment. Basal promoter activity resides within the -64 to +109 fragment, but is not tissue specific or stage specific. A negative element within the -101 to -64 region is active in all lymphoid cell lines tested and therefore cannot by itself be responsible for the tissue and stage specificity. The data indicate that the elements responsible for the enhancer activity (-210 to -22) are part of the lambda 5 gene promoter and likely confer the tissue and stage specificity via positive elements within the -210 to -22 region.
IL-12-induced protection against blood-stage Plasmodium chabaudi AS requires IFN-gamma and TNF-alpha and occurs via a nitric oxide-dependent mechanism.
Authors: Stevenson M M , Tam M F , Wolf S F , Sher A 
Published: December 2022

Abstract
The effects of IL-12 administration on the development of protective immunity to blood-stage Plasmodium chabaudi AS were analyzed. Treatment of susceptible A/J mice on the day of infection and for 5 days postinfection with various doses 0.025-0.3 microgram) of rIL-12 significantly decreased the peak parasitemia level, but only treatment with 0.1 microgram resulted in increased survival. Treatment of resistant B6 mice with 0.1 microgram of rIL-12 using the same regimen also significantly decreased the peak parasitemia level, but 40% of the animals died. Treatment of these mice with anti-IL-12 mAb resulted in a more severe course of infection, but survival was not significantly altered. The mechanism of IL-12-induced resistance was examined in A/J mice during infection. Compared with spleen cells from untreated mice, cells from IL-12-treated mice produced significantly higher levels of IFN-gamma spontaneously as well as in response to Con A or Ag stimulation on day 7 postinfection. Significantly higher levels of INF-gamma and TNF-alpha were found in the sera of IL-12-treated mice, which correlated with high levels of the nitric oxide (NO) metabolite, NO3-. Furthermore, CD4+T cell depletion was found to abrogate IL-12-induced resistance. Administration of neutralizing mAb against IFN-gamma or TNF-alpha to IL-12-treated mice showed that simultaneous depletion of both cytokines resulted in 100% mortality. The role of NO was investigated by administration of aminoguanidine, a selective inhibitor of cytokine-inducible nitric oxide synthase, to IL-12-treated mice. Significantly increased mortality was observed following treatment twice daily with 9 mg of aminoguanidine, but there was no effect on parasitemia. In conclusion, these results demonstrate that IL-12 regulates the development of resistance to P. chabaudi AS via a CD4+ Th1 response, which involves the cytokines IFN-gamma and TNF-alpha, and is in part NO dependent. Therefore, IL-12, given in the appropriate dose, may be useful in the induction of protective immunity to blood-state malaria.
Comparative studies of cytotoxicity and the release of TNF-alpha, nitric oxide, and eicosanoids of liver macrophages treated with lipopolysaccharide and liposome-encapsulated MTP-PE.
Authors: Dieter P , Ambs P , Fitzke E , Hidaka H , Hoffmann R , Schwende H 
Published: December 2022

Abstract
LPS and liposome-encapsulated MTP-PE induce liver macrophages cytotoxicity against tumor target cells and a release of TNF-alpha, nitric oxide, and eicosanoids but not a generation of superoxide anions. Neither agent elicits a formation of inositol phosphates, a change in intracellular free calcium, or a translation of protein kinase C-beta. Inhibition or down-regulation of protein kinase C does not inhibit the release of TNF-alpha and nitric oxide but inhibits the formation of prostanoids. In contrast to LPS, liposome -encapsulated MTP-PE induces an elevation of diacylglycerol mass and an enhanced expression of protein kinase C-delta. LPS, but not liposome-encapsulated MTP-PE, elicits an enhanced expression of cytosolic phospholipase A2 and a predominant formation of PGE2. Both agents elicit different responses when given to cells pretreated with one of the immunomodulators, with dexamethasone, or with PGE2. In contrast, to liposome-encapsulated MTP-PE, LPS induces only cytotoxicity when added to liver macrophages simultaneously or a maximum of 2 h before the addition of tumor target cells. The observed differences might reflect partly differences in the potencies of LPS and some liposome-encapsulated MTP-PE as immunomodulators.
Murine mast cells express two types of C1q receptors that are involved in the induction of chemotaxis and chemokinesis.
Authors: Ghebrehiwet B , Kew R R , Gruber B L , Marchese M J , Peerschke E I , Reid K B 
Published: December 2022

Abstract
Although previous studies have shown that different cells and cell lines of murine origin bind human C1q, suggesting that they display cell surface receptors for C1q, no information is available to indicate whether mouse or human mast cells express C1q receptors. This paper presents the first evidence to show that murine mast cells express specific receptors for C1q. Western blot analysis of cell membrane proteins prepared from a bone marrow-derived mouse cell line using two monospecific polyclonal Abs, one directed against the 60-kDa C1q receptor (C1q-R) that binds to the collagen-like stalk of C1q (cC1q-R) and the other directed against the 33-kDa molecule that binds to the globular "heads" of C1q (gC1q-R), show that both of these receptors are present on these cells. In addition, C1q can induce mast cell migration in a specific and dose-dependent manner. Interestingly, the C1q-induced migratory response was found to be biphasic; the first response peaked at a C1q concentration of 0.1 nM, whereas the second phase peaked at approximately 40 nM. Checkerboard analysis of the mast cell migratory response to C1q showed that the first phase was primarily due to chemotaxis and the second phase was attributable to chemokinesis. Preincubation of C1q with Abs specific for the collagen-like tail of the molecule abolished both its chemotactic and chemokinetic response, whereas heat inactivation of C1q (56 degrees C, 1 h) resulted in 85% abrogation of the chemotactic phase and 42% reduction in the chemokinetic phase. The observed mast cell migratory responses were mediated by cell surface C1q-R(s), as inclusion of a mixture of anti-C1q-R and anti-gC1q-R Abs with the cells inhibited their migratory response toward C1q. However, incubation of cells with various doses of C1q did not result in histamine release. Furthermore, engagement of mast cell C1q-Rs by the ligand C1q induced an antiproliferative response, as coculturing of mast cells with C1q resulted in a specific and dose-dependent decrease in DNA synthesis. These data suggest that C1q-Rs may play a significant role in mast cell function and regulation by providing an important signal through which mast cells can be recruited to inflammatory sites of increased C1q concentration.
Heterogeneous T cell responses to beta-lactam-modified self-structures are observed in penicillin-allergic individuals.
Authors: Brander C , Mauri-Hellweg D , Bettens F , Rolli H , Goldman M , Pichler W J 
Published: December 2022

Abstract
To investigate the role of T cells in drug allergy, we stimulated PBMC from penicillin-allergic patients with reactive penicillin G itself or penicillin G coupled with human serum albumin (BPO-HSA). T cell clones specific for penicillin G or BPO-HSA were established and their phenotype and reactivity to both forms of the beta-lactam were analyzed. T cell clones stimulated by penicillin G were CD4 and CD8 positive, whereas BPO-HSA stimulated the growth of CD4+ T cells. The penicillin G-specific clones were HLA class I or class II restricted and processing was not required as fixed APC could still present penicillin G. In contrast, BPO-HSA has to undergo processing to stimulate BPO-HSA-specific T cell clones. In addition to classical APC, activated MHC class II expressing T cells could also restimulate the penicillin G-specific clones, indicating that various cell types might serve as APC. Penicillin G and BPO-HSA-specific T cell clones produced a heterogeneous cytokine pattern as most clones produced high amounts of IL-2, IFN-gamma, TFN-alpha, and rather variable levels of IL-4 and IL-5. Since no Ag processing was required, penicillin G may stimulate T cells by binding directly to MHC molecules on the cell surface or to their embedded peptide. Alternatively, it may bind to soluble proteins like HSA, which are processed and subsequently presented in an immunogenic form. These different modes of presentation, which elicit a variety of immunological reactivities, may explain the great heterogeneity of the clinical pictures seen in penicillin allergy.
A proteoglycan (aggrecan)-specific T cell hybridoma induces arthritis in BALB/c mice.
Authors: Buzás E I , Brennan F R , Mikecz K , Garzó M , Negroiu G , Holló K , Cs-Szabó G , Pintye E , Glant T T 
Published: December 2022

Abstract
Aggrecan, the high buoyant density cartilage proteoglycan (PG), has been shown to induce progressive polyarthritis and ankylosing spondylitis in genetically susceptible BALB/c mice. To further characterize the nature of the autopathogenic effector T cells operating in these mice and to determine the region(s) of the PG molecule recognized by these T cells, we generated PG-specific T cell hybridomas from arthritic mice. One of the PG-specific T cell hybridomas (5/4E8), when injected into naive irradiated BALB/c mice, was capable of inducing clinical and histopathologic signs of arthritis. Massive swelling and redness of the paws dominated the clinical picture. A reactive synovial cell proliferation, the accumulation of hybridoma and inflammatory cells in the enlarged joint space, the loss of PG from the superficial layer of the articular cartilage, and the erosion of articular surface were identical histopathologic signs to those found either in primary or adoptive transfer of PG-induced arthritis. The PG-specific and arthritogenic T cell hybridoma (5/4E8) expressed TCR-alpha beta + (V beta 4), CD4+, and CD8- phenotypes and belonged to the Th1 subset, as the cells secreted IL-2 and IFN-gamma, but not IL-4 upon PG stimulation, and the response was MHC class II (I-Ad)-restricted. These observations provide direct evidence that PG-specific Th cells play crucial roles in autoimmune arthritic processes.
Unexpected presence of polyreactive catalytic antibodies in IgG from unimmunized donors and decreased levels in rheumatoid arthritis.
Authors: Kalaga R , Li L , O'Dell J R , Paul S 
Published: December 2022

Abstract
Polyclonal IgG from healthy humans and unimmunized mice was screened for peptide-methylcoumarinamide (peptide-MCA) hydrolyzing activity. The activity was detected in every IgG sample examined. Contaminant enzymes were precluded as an explanation, as the activity tracked exactly with the 150-kDa IgG peak separated by gel filtration in denaturing solvent (6 M guanidine hydrochloride) and with the 50-kDa Fab fragment peak produced by papain-digestion of the IgG. Patients with rheumatoid arthritis displayed a 3.2-fold reduced peptide-MCA hydrolyzing activity (mean) compared to healthy subjects. Control osteoarthritis patients showed no diminution in activity. A progressive decrease in the activity by 7.4-fold of the pre-immune levels was observed in mice over the course of hyperimmunization with SRBC, indicating that exogenous Ag challenge, like rheumatoid arthritis, is associated with decreased catalytic activity. Apparent Km values of the IgG for Pro-Phe-Arg-MCA were 0.39 to 0.53 mM, values approximately 3-orders of magnitude greater than observed previously for Ag-specific catalysis by Abs. The only common structural feature in peptide-MCA conjugates utilized by the Abs as substrates was the presence of Arg-MCA and Lys-MCA bonds. The IgG hydrolyzed Pro-Phe-Arg-Phe at the Arg-Phe peptide bond, showing that the activity is relevant to cleavage of peptide bonds in natural Ags. The universal occurrence of this polyreactive catalytic activity in unimmunized donors and its diminution in an autoimmune disease and nonspecific Ag challenge suggest that it may possess an important, but as yet unidentified, biologic role.
Molecular genetic analysis of X-linked hypogammaglobulinemia and isolated growth hormone deficiency.
Authors: Stewart D M , Notarangelo L D , Kurman C C , Staudt L M , Nelson D L 
Published: December 2022

Abstract
In 1980 the clinical syndrome of X-linked hypogammaglobulinemia and isolated growth hormone deficiency (XLA/GHD) was described. XLA/GHD patients have reduced serum levels of Ig and normal cell-mediated immunity, and thus resemble patients with Bruton's X-linked agammaglobulinemia (XLA). However, XLA/GHD patients also have isolated GHD. Mutations and deletions in the Bruton's tyrosine kinase gene (BTK) are responsible for Bruton's XLA. We investigated BTK gene expression in an XLA/GHD patient from the family originally described by Northern analysis, cDNA sequencing, and Western analysis of protein production using mAb to BTK. BTK mRNA was normal in size and abundance, and the mRNA sequence was normal over the coding region, except for a single silent mutation. BTK protein was present in normal amounts in PBMC of this patient. Thus, at the molecular level, XLA/GHD is a different disease entity from Bruton's XLA. These results suggest that undescribed genes critical for B cell development and growth hormone production exist on the X chromosome.
Ig domains 1 and 2 of murine CD22 constitute the ligand-binding domain and bind multiple sialylated ligands expressed on B and T cells.
Authors: Law C L , Aruffo A , Chandran K A , Doty R T , Clark E A 
Published: December 2022

Abstract
Baby hamster kidney cells transfected with murine CD22 (mCD22) mediate adhesion to B- and T-lineage cells. To further characterize mCD22-mediated cell adhesion, we generated a panel of recombinant globulins (Rg) consisting of different extracellular Ig-like (Ig) domains of mCD22. FACS analysis using these mCD22.Rgs revealed that ligands for mCD22 are expressed on both B and T cell lines and also normal B and T cells. In B-lineage cells, the expression of mCD22 ligands began on sIgM- pre-B cells in bone marrow. The ligand-binding site of mCD22 for ligands was mapped to Ig domains 1 and 2: mCD22.Rgs containing Ig domains 1 and 2 bound target cells and immunoprecipitated sets of glycoproteins similar to Rgs containing Ig domains 1 to 3 or all 7 CD22 Ig domains, whereas Rgs containing Ig domains 2 to 3 or 3 to 7 did not bind either B or T cells. Furthermore, B cells apparently expressed higher levels of mCD22 ligands than that of T cells, suggesting a potential competition for CD22 binding between ligands expressed on the same B cell and those expressed on another B cell or T cells. Immunoprecipitation experiments using the mCD22.Rgs identified mCD22 itself and the B cell-specific isoform of mCD45RA (B220) as two of the mCD22 ligands expressed on B cells. Thus, mCD22 may potentially regulate B cell activation through interactions with itself or mCD45RA/B220.
Ig VH hypermutation is absent in the germinal centers of aged mice.
Authors: Miller C , Kelsoe G 
Published: December 2022

Abstract
After injection with immunogenic conjugates of the hapten (4-hydroxy-3-nitrophenyl)acetyl (NP), two distinct B cell populations can be identified in the spleen during the primary response. One of these populations is specialized for Ab production; the other, the germinal centers (GCs), has been identified as the site of Ig somatic hypermutation. Ag-driven selection of GC B cells bearing mutated receptors with higher affinity leads to the affinity maturation of serum Ab and increased protective humoral immunity. Microdissection of GC B cell populations specific for NP and sequencing of the recovered Ig heavy chain variable region genes revealed that the somatic hypermutation process is absent in the GCs of aged C57BL/6 mice. However, selection for Ag appears to occur in the absence of hypermutation in the form of competition between unmutated clones of Ag-activated B lymphocytes. Thus, affinity maturation in these animals is limited to the affinities of Ab encoded by the germline.
Human B cell activation. Effect of T cell cytokines on the physicochemical binding requirements for achieving cell cycle progression via the membrane IgM signaling pathway.
Authors: Mongini P K , Highet P F , Inman J K 
Published: December 2022

Abstract
Given the range of mIg-binding affinities expressed by Ag-specific B cells, the ligand:receptor affinity threshold for achieving full B cell activation via the mIgM-mediated signaling pathway is quite high. Several recombinant, or semi-purified, cytokines were found to reduce the very high mIgM:ligand affinity threshold for induction of human B cell S phase entry by bivalent, affinity-diverse anti-IgM mAbs without notably affecting the lower affinity threshold for G1-related RNA synthesis. Two-stage culture experiments suggested that one major means by which IL-4, IL-2, and low m.w. B cell growth factor lower the affinity threshold for S phase entry is an indirect one, i.e., rescue of B cells whose mIg engagements with Ag are of sufficient affinity for achieving G1 entry, but of insufficient affinity for initiating the late-phase mIgM-mediated signals needed for the G1--&gt;S phase transition. IL-4 had additional effects in early G1. In contrast to the above cytokines, IFN-gamma, did not function as an independent cell cycle progression factor, but rather required the concomitant presence of mIgM-cross-linking ligand for enhancement. A greater potential of multivalent anti-IgM-dextran conjugates to trigger S phase entry in the absence of cytokines was found to reflect a greater potential for initiating mIgM signals during the late phase in B cell activation. The results indicate that progression of mIgM receptor-activated B cells past a G1--&gt;S phase restriction point is dependent upon continued signal transduction via either the mIgM receptor and/or a cytokine receptor signaling pathway. When mIgM-engaging ligands are ineffective at initiating late-phase signals, due to limited size and binding site valency and/or affinity, ancillary signal transduction through cytokine receptors becomes most relevant.