bluuebunny/crossref_metadata_2025 huggingface dataset:
The B cell response to autologous type II collagen: biased V gene repertoire with V gene sharing and epitope shift.
Authors: Mo J A , Holmdahl R
Published: December 2022

Collagen-induced arthritis is an autoimmune model disease induced in the DBA/1 mouse immunized with type II collagen (CII). Both T and B cells play a critical role for the induction of arthritis. Draining lymph nodes from CII-immunized mice contain high numbers of CII-specific B cells, which are isotype switched and V gene selected. In the present study we analyze the V region gene usage and epitope specificity of CII-reactive B cell hybridomas, randomly isolated from the primary and the secondary response in mice immunized with rat CII we make the following conclusions. 1) There are major epitopes in the native CII molecule to which the B cells preferentially respond. 2) B cells specific for the same epitope show a preferential pairing of certain VH/VK genes or a biased usage of individual VH (VHJ558 and VHX24) or VK genes (VK21). 3) The V genes are germ line encoded in the primary response and somatically mutated in the secondary response. Somatic mutations give the Abs cross-reactivity between CII epitopes, and epitope shift, i.e., another epitope within the CII molecule is recognized. 4) There is a sharing of certain V genes in B cell clones specific for different epitopes, indicating structural similarities of the different CII epitopes.
Mucosal addressin cell adhesion molecule-1: a structural and functional analysis demarcates the integrin binding motif.
Authors: Viney J L , Jones S , Chiu H H , Lagrimas B , Renz M E , Presta L G , Jackson D , Hillan K J , Lew S , Fong S
Published: December 2022

The leukocyte integrin receptor, alpha 4 beta 7, and the mucosal addressin cell adhesion molecule-1 (MAdCAM-1) are postulated to be important in regulating lymphocyte trafficking to normal intestine. Here we provide the first description of MAdCAM-1 expression in inflamed intestine. Using mouse models of experimentally induced colitis, we show a concordant increase in MAdCAM-1 expression associated with increased cellular infiltrates in areas of intestinal inflammation. To understand more of the molecular nature of the interactions between MAdCAM-1 and its leukocyte ligand, the alpha 4 beta 7 integrin receptor, we have analyzed the structural and functional properties of chimeric recombinant MAdCAM-1 proteins in vitro. Using site-directed mutagenesis and molecular modeling, we demarcate the alpha 4 beta 7 binding motif as three linear residues within the C-D loop in the first domain of MAdCAM-1. Mutation of residue L40, D41, or T42 in the first domain completely abrogates alpha 4 beta 7+ cell binding and cellular activation. Mutagenesis of other residues in the first domain do not impact these functions. We have modeled peptides based on the predicted structure of the alpha 4 beta 7 integrin binding motif on MAdCAM-1 and are able to show specific and selective blocking of cell binding. These observations suggest that the amino acid residues LDT on MAdCAM-1 play a role in the interaction with alpha 4 beta 7 in cell adherence and cell activation.
Induction of Th2 cytokines and control of collagen-induced arthritis by nondepleting anti-CD4 Abs.
Authors: Chu C Q , Londei M
Published: December 2022

CD4+ T cells play a key role in the development of cell-mediated autoimmune diseases, and their modulation has been used to prevent autoimmune diseases in animal models. The effect of the nondepleting anti-CD4 mAb (KT6) was investigated in collagen-induced arthritis (CIA) in DBA/1 mice and in adoptive transfer of CIA into SCID mice. KT6 (200 microg/dose/mouse) was administered systematically from the day of collagen type II (CII) immunization and continued by alternate-day injection until day 11. Only 20% of KT6-treated mice developed arthritis compared with 100% of the isotype control treated mice (p < 0.001). KT6 treatment in a similar regimen also abrogated the adoptive transfer of CIA into SCID mice. Serum levels of IgG2a anti-CII Abs in KT6-treated DBA/1 mice were significantly reduced (p < 0.001), while IgG1 anti-CII were not significantly changed (p > 0.05). Lymph node cells of mice treated in vivo with KT6 had a reduced production of IFN-gamma but increased IL-4 upon in vitro challenge with CII. Furthermore, KT6 could also reverse the profile of cytokine release of in vivo primed and pathogenic CII-specific T cells. These results demonstrate that in vivo modulation with nondepleting anti-CD4 Abs prevents CIA, likely by altering the functional profile of Th1 T cells to Th2. Furthermore, we demonstrate that this treatment can not only prevent, but more importantly also control pathogenic T cells by switching their cytokine production from a Th1 to a Th2-like profile. Our results thus provide compelling evidence of how treatment with nondepleting anti-CD4 may control an autoimmune process. They also indicate that this approach not only prevents, but also could control ongoing autoimmune diseases.
Deficient type I protein kinase A isozyme activity in systemic lupus erythematosus T lymphocytes: II. Abnormal isozyme kinetics.
Authors: Kammer G M , Khan I U , Kammer J A , Olorenshaw I , Mathis D
Published: December 2022

Systemic lupus erythematosus (SLE) T cells exhibit deficient type I protein kinase A (PKA-1) isozyme phosphotransferase activity, resulting in impaired phosphorylation of plasma membrane-associated proteins. To determine the mechanism of this isozyme deficiency, we studied 16 SLE subjects with a mean (+/-1 SD) SLE disease activity index of 16.7 +/- 8.8 and 16 normal controls. Immunoblotting of type I regulatory (RI) subunit protein in SLE and control T cells demonstrated no significant differences in the amount of protein. Analysis of isozyme kinetics in SLE T cells demonstrated a 2.2-fold increase in the Michaelis-Menten constant, a 2.5-fold increase in the apparent association constant for cAMP, a 3.8-fold decrease in the maximal velocity, and a reduction in the mean maximal binding of cAMP to the RI subunit compared with control T cells. Reduction of the Hill coefficient from 1.2 in normal T cells to 0.7 in SLE T cells indicated a loss of positive cooperativity between cAMP binding sites A and B. An increase in the apparent association constant for cAMP signifies relative resistance to cAMP, indicating that higher intracellular concentrations of cAMP are necessary to activate the isozyme. Because the R subunit of PKA is the only intracellular receptor for cAMP, the abnormal isozyme kinetics may account for the deficiency of PKA-I phosphotransferase activity and impaired PKA-I-catalyzed protein phosphorylation observed in SLE T cells. This disordered isozyme function may contribute to the altered signal transduction and observed cellular immune dysfunctions in SLE. Moreover, these altered isozyme kinetics raise the possibility of a structural defect(s) in the RI subunit.
Differential roles for IL-12 in the maintenance of immune responses in infectious versus autoimmune disease.
Authors: Seder R A , Kelsall B L , Jankovic D
Published: December 2022

IL-12 has been shown to be important in the generation of a functional Th1 response in animal models of both infectious and autoimmune disease. Furthermore, the role of IL-12 in the maintenance of the immune responses in these diseases is now emerging. Herein, we discuss the idea that memory responses for certain infections may be IL-12 independent, whereas memory responses for specific autoimmune diseases still require IL-12 to maintain a pathogenic response.
Distribution of IL-15 receptor alpha-chains on human peripheral blood mononuclear cells and effect of immunosuppressive drugs on receptor expression.
Authors: Chae D W , Nosaka Y , Strom T B , Maslinski W
Published: December 2022

IL-15, a newly described cytokine exerting IL-2-like in vitro activities, binds to and induces proliferation of cells co-expressing IL-15R alpha, IL-2R beta, and IL-2R gamma chains. To study the expression of human IL-15R alpha chains, we have utilized tagged human IL-15 protein and FACS analysis. In contrast to resting cells, mitogen-activated macrophages, NK cells, and CD4+ and CD8+ T cells express IL-15R alpha chains. Neither IL-2R alpha nor IL-2R beta chains are required for IL-15 binding. Dexamethasone, but not cyclosporine or rapamycin, blocks mitogen-induced IL-15R alpha expression. Dexamethasone-pretreated cells respond to IL-15 poorly, while the response to IL-2 is not affected. Thus, despite structural and functional similarities between IL-2R alpha and IL-15R alpha chains, the activation-triggered mechanisms of induction are different. Since IL-15R alpha chain is necessary and sufficient for IL-15 binding, regulation of IL-15R alpha expression may represent a new target for T cell-directed pharmacologic intervention.
Exposure to T helper 2 cytokines in vivo before encounter with antigen selects for T helper subsets via alterations in antigen-presenting cell function.
Authors: Cua D J , Coffman R L , Stohlman S A
Published: December 2022

The Th1 subset of CD4+ T cells mediate both delayed-type hypersensitivity (DTH) responses and experimental allergic encephalomyelitis (EAE). Th1 cells are induced by immunization of young adult female and older (> or = 10 wk of age) male SJL mice. By contrast, young adult (< or = 8 wk of age) male mice are characterized by the inability of immunization to induce either a DTH response or EAE, demonstrating a clear sex and age dependence to these Th1-mediated responses in SJL mice. T cell activation in age-matched female and male SJL mice was compared to understand the mechanism(s) of these differential responses. Here, we report that immunization of DTH responder female mice primes for Ag-specific secretion of IFN-gamma but not IL-4 and IL-10. In contrast, immunization of DTH nonresponder male mice primes Ag-specific T cells that secrete IL-4 and IL-10, but not IFN-gamma. Depletion of either IL-4 or IL-10 recovers DTH responsiveness in young adult male mice, demonstrating expansion of Th1 cells in these mice when Th2 cytokines are suppressed. The age- and sex-dependent inability to prime Th1 cells in young male mice is due to the functional absence of a macrophage APC population defined by co-expression of Mac-1 and Mac-3. To determine whether Th2 cytokines directly affect the APC's ability to support the priming of Th1 cells, Mac-3+ APC isolated from naive young male donors, which had been depleted of either IL-4 or IL-10, were transferred into DTH nonresponder males. Induction of DTH responses in these recipients demonstrates that in vivo suppression of Th2 cytokines enables the male-derived Mac-3+ APC to support priming of Th1 responses. These data indicate that, in addition to their regulatory roles in controlling preferential T cell subset expansion, exposure of APC to cytokines in vivo before the initial encounter with Ag may regulate induction of CD4+ T cell subsets.
The flt3 ligand promotes the survival of primitive hemopoietic progenitor cells with myeloid as well as B lymphoid potential. Suppression of apoptosis and counteraction by TNF-alpha and TGF-beta.
Authors: Veiby O P , Jacobsen F W , Cui L , Lyman S D , Jacobsen S E
Published: December 2022

The recently cloned fIt3 ligand (FL) potently enhances hemopoietic growth factor-induced growth of primitive hemopoietic progenitors. In agreement with previous reports, we found FL alone to be a weak mitogen for primitive Lin-Sca-1+ murine bone marrow progenitors. Using delayed addition of growth-promoting cytokines, we demonstrate that FL potently promotes the in vitro survival of Lin-Sca-1+ progenitors responsive to a potent myeloid growth factor combination (FL, stem cell factor (SCF), granulocyte CSF (G-CSF), and IL-1 alpha). Whereas no such progenitors survived in cultures supplemented with medium alone, 33% survived in FL compared with 75 and 13% in the presence of SCF and IL-1 alpha, respectively. These results were obtained when cells were plated individually, suggesting that the viability-promoting effect of FL is mediated directly on the progenitors. Whereas SCF was superior to FL in promoting the survival of FL-, SCF-, G-CSF-, and IL-1 alpha-stimulated Lin-Sca-1+ progenitors, FL was more efficient than SCF at promoting the survival of progenitors with a B cell potential, as measured by their ability to produce B220+ cells in response to delayed addition of FL, SCF, and IL-7. Seventy-one percent of the B220+ cell production could be recovered following 40-h incubation with FL compared with 2% in response to SCF. Analysis of day 12 spleen CFU content after 40-h preincubation of Lin-Sca-1+ cells in FL or SCF demonstrated that SCF maintained 64% of the day 12 spleen CFU, whereas only 16% survived in the presence of FL. Finally, there was no significant difference between the ability of FL and SCF to maintain the viability of long-term culture-initiating cells (25 and 32%, respectively). The ability of FL to promote the survival of Lin-Sca-1+ progenitor cells was reflected by the finding that FL also suppressed apoptosis. Finally, TGF-beta abrogated and TNF-alpha potently counteracted the survival-promoting effect of FL. Thus, FL promotes the survival of primitive hemopoietic progenitor cells, in particular those with an inherent B lymphoid potential.
CD95-dependent bystander lysis caused by CD4+ T helper 1 effectors.
Authors: Wang R , Rogers A M , Ratliff T L , Russell J H
Published: December 2022

CD95-dependent lysis of target cells by CD4+ cells raises important questions of specificity and its potential role in inflammation. Much of what we know about CD95L-dependent killing is in fact bystander killing because the T cells have been previously activated by pharmacologic reagents. In an effort to better understand its significance in a more physiologic setting, we have examined bystander lysis by Th1 cells stimulated by Ag and APC in a murine model system. We find that bystander lysis is readily stimulated by M phi APC but not some epithelial lines, even though they themselves are killed in a CD95-dependent process while serving as APC. Bystander activity requires close proximity between the T cell, the APC, and the bystander target because bystanders are not lysed during coculture in Transwells.
Differential binding avidities of human IgM for staphylococcal protein A derive from specific germ-line VH3 gene usage.
Authors: Hakoda M , Kamatani N , Hayashimoto-Kurumada S , Silverman G J , Yamanaka H , Terai C , Kashiwazaki S
Published: December 2022

Human IgM that express the variable region genes of the VH3 family bind staphylococcal protein A (SPA). We previously reported that the SPA-binding IgM can be divided into two groups based on the differential binding avidities for solid-phase SPA. To study the molecular basis for these differences, we cloned B cells from human blood by EBV transformation. The nucleotide sequences of the expressed Ig heavy chain genes were determined on 20 B cell clones that produce SPA-binding IgM. The germ-line VH3 gene usage in IgM with high avidities for SPA were distinct from the germ-line VH3 genes used in IgM with low avidities for SPA. There was no correlation in the usage of D or JH genes or in the usage of light chains in IgM according to the SPA binding avidity. These results suggest that the differential binding avidities for SPA are at least partly due to specific germ-line VH3 gene usage. An investigation of direct binding of SPA to the synthetic peptides corresponding to the portions of the variable regions of SPA-binding and non-SPA-binding IgM showed that the peptides corresponding to the VH3 family specific framework region 3 sequences had significant SPA binding capacities, while the peptides corresponding to the other subdomains and those corresponding to framework region 3 of the reported VH3 sequences from non-SPA-binding IgM showed little or no binding. It is of interest that the Ig-framework region 3 subdomain corresponds to the fourth hypervariable region, which in the TCR-beta chain has been implicated as a critical site for T cell superantigen binding.
IL-12 gene therapy protects mice in lethal Klebsiella pneumonia.
Authors: Greenberger M J , Kunkel S L , Strieter R M , Lukacs N W , Bramson J , Gauldie J , Graham F L , Hitt M , Danforth J M , Standiford T J
Published: December 2022

IL-12 is a proinflammatory cytokine that has recently been shown to have beneficial effects in the setting of acquired host immunity. To determine the role of IL-12 in innate immunity against Gram-negative bacterial organisms, CBA/J mice were challenged with 10(2) CFU of Klebsiella pneumoniae intratracheally (i.t.), resulting in the time-dependent expression of IL-12 mRNA (p35 and p40) and protein within the lung. Passive immunization of animals with anti-IL-12 serum i.p. at the time of K. pneumoniae inoculation resulted in a 12-fold increase in K. pneumoniae CFU in lung homogenates at 48 h, as compared with animals receiving control serum. In addition, treatment of Klebsiella-infected mice with anti-IL-12 Abs significantly decreased both short and long term survival. To assess the effect of compartmentalized IL-12 overexpression on outcome in Klebsiella pneumonia, animals were treated i.t. with 5 x 10(8) PFU of a nonreplicating adenoviral vector containing a human cytomegalovirus promoter and cDNAs coding for the p35 and p40 subunits of IL-12 inserted into the E1 and E3 domains (Ad5mIL-12), respectively. In vivo transfection with Ad5mIL-12 resulted in 45% long term survival in Klebsiella pneumonia, whereas no animals with Klebsiella pneumonia receiving control adenovirus survived. Moreover, treatment with anti-IFN-gamma Abs or soluble TNF receptor:Ig construct partially and completely attenuated survival benefits observed in animals receiving Ad5mIL-12, respectively. In conclusion, endogenous IL-12 is a critical component of antibacterial host defense, and the compartmentalized overexpression of IL-12 using recombinant adenoviral gene therapy represents a safe and effective approach to deliver IL-12 to the lung in the setting of murine Klebsiella pneumonia.
Protection against lethal influenza virus encephalitis by intranasally primed CD8+ memory T cells.
Authors: Stevenson P G , Hawke S , Bangham C R
Published: December 2022

The neurotropic influenza virus strain A/WSN (H1N1) caused a rapidly fatal encephalitis after intracerebral inoculation into naive mice. Intranasal immunization with the same virus (homotypic) completely protected mice against a subsequent intracerebral challenge with A/WSN; there was no clinical disease, and infectious virus could not be recovered from the brain. In vivo depletion of CD4+ or CD8+ T cell subsets did not affect homotypic protection, and the pups of immune mothers were also protected against a lethal intracerebral challenge with A/WSN, suggesting that the Ab produced by intranasal priming was sufficient to protect mice against later intracerebral infection. Intranasal immunization with the heterotypic influenza strain A/X31 (H3N2) did not generate protective Ab, but despite an acute illness, 80% of mice survived the subsequent intracerebral challenge. Immune protection was associated with CD8+ T cell infiltration throughout the brain substance, together with widespread up-regulation of intracerebral MHC class I and MHC class II expression. In vivo T cell subset depletion showed that heterotypic protection was dependent upon CD8+, but not CD4+, T cells. This model system demonstrates some of the mechanisms through which the immunity generated by an initial extracerebral virus infection may protect against later intracerebral virus replication.
Evidence that the Wiskott-Aldrich syndrome protein may be involved in lymphoid cell signaling pathways.
Authors: Cory G O , MacCarthy-Morrogh L , Banin S , Gout I , Brickell P M , Levinsky R J , Kinnon C , Lovering R C
Published: December 2022

Wiskott-Aldrich syndrome is an X-linked combined immunodeficiency affecting cells of several different hemopoietic lineages. The Wiskott-Aldrich syndrome protein (WASP), which has no homology with any other known protein families, is rich in proline motifs known to contribute to Src homology 3 binding sites. However, its function has not been determined. The Tec family of cytoplasmic tyrosine kinases, which include Btk (the X-linked agammaglobulinemia gene), Itk, and Tec, is thought to be involved in lymphoid cell signaling pathways. In this work, we show binding of WASP to the Src homology 3 domains of Btk, Itk, Tec, Grb2, and phospholipase C-gamma, which suggests a function for WASP in lymphoid cell signaling.
Beta1 integrin-mediated activation of focal adhesion kinase and its association with Fyn and Zap-70 in human NK cells.
Authors: Rabinowich H , Manciulea M , Herberman R B , Whiteside T L
Published: December 2022

Adhesive interactions mediated by cell surface receptors have been shown to induce signal transduction pathways that regulate changes in cellular function. We have reported recently that fibronectin (FN) receptors, alpha4beta1 and alpha5beta1 integrins, on NK cells transduce transmembrane signals leading to tyrosine phosphorylation of 60-, 70-, and 120-kDa proteins. In the current study, we have identified a 120-kDa phosphoprotein as the focal adhesion kinase (p125FAK), a structurally unique nonreceptor protein tyrosine kinase that localizes to focal adhesions. Activity of p125FAK was induced by adhesion of NK cells to plastic-immobilized FN, by cross-linking of cell surface-bound FN or FN fragments, FN120 or FN40, with anti-FN mAb, or by cross-linking of alpha4beta1 or alpha5beta1 integrins with alpha-chain-specific Abs. We also observed that enhanced in vitro kinase activity was associated with immunoprecipitates of alpha4beta1 or alpha5beta1 integrins from lysates of FN-adherent NK cells as compared with BSA-treated NK cells. In addition to p125FAK activity, FN-induced kinase activity was also found to be mediated by Fyn, Lyn, and Zap-70, as assessed by in vitro phosphorylation of the immunoprecipitated kinases in the presence of [gamma-32P]ATP. Clustering of FN receptors on NK cells by agonists such as immobilized FN or alpha4- or alpha5-specific Abs also induced association of Fyn and Zap-70 with p125FAK. Our observations indicate that activation and phosphorylation of p125FAK as well as Zap-70 and certain kinases of the src family play an important role in formation of active signaling complexes in response to triggering via beta1 integrins on NK cells. These results also suggest the existence of cross-talk or points of convergence between the beta1 integrin-mediated and other receptor-signaling pathways.
NK 1+ CD4- CD8- alphabeta T cells in the peritoneal cavity: specific T cell receptor-mediated cytotoxicity and selective IFN-gamma production against B cell leukemia and myeloma cells.
Authors: Sugie T , Kubota H , Sato M , Nakamura E , Imamura M , Minato N
Published: December 2022

NK1+ double negative (DN) alphabeta T cells were present in the peritoneal exudate cells (PEC) of both normal and athymic B6 mice, accounting for as much as 25% of the total T cells, while their numbers were far less in the PEC of BALB/c and (BALB/c x B6)F1 mice. IL-2-dependent clones established from the DN alphabeta T cell population in the PEC of IL-2 receptor alpha-chain transgenic B6 mice exhibited potent cytotoxicity against a series of B cell lineage leukemias and myelomas, such as CD5+BCL1 and MOPC, without affecting NK-susceptible targets. The cytotoxicity of the clones against BCL1 and MOPC was specifically inhibited by anti-CD3, anti-alphabetaTCR, or anti-relevant Vbeta (Vbeta8) Ab, but not by control Abs, indicating that it was mediated by the specific alphabetaTCR/CD3. Other BALB/c-derived target cells expressing both MHC class I and class II were not affected, and neither Ab against them affected the cytotoxicity, strongly suggesting that the cytotoxicity of NK1+ DN alphabeta T cell clones was independent of the particular MHC Ags. The clones produced IFN-gamma, but little IL-2 or IL-4, in response to anti-CD3 stimulation, to the susceptible, but not resistant, targets, and to IL-12. The clones exhibited TCRalpha (Valpha8) distinct from an invariant TCRalpha (Valpha14) reported to dominate in thymic NK1+ alphabeta T cells. The presence of DN alphabeta T cells with similar functional features in the normal PEC was confirmed by the short term stimulation in vitro. The present results along with other recent reports strongly suggested that, like the mainstream alphabeta T cells, the NK1+ DN alphabeta T cell population consisted of functionally heterogeneous subsets.
Immunoglobulin D(H) recombination signal sequence targeting: effect of D(H) coding and flanking regions and recombination partner.
Authors: VanDyk L F , Wise T W , Moore B B , Meek K
Published: December 2022

V(D)J recombination is targeted by recombination signal sequences (RSS) located immediately adjacent to immune receptor gene segments. While the RSS flanking D(H) segments appear to be equivalent, they are not randomly utilized. During D(H) to J(H) rearrangement, the 3' D(H) RSS is virtually exclusively utilized, suggesting that the 3' D(H) RSS could simply be a better target for the recombinase. However, when we examined V(H) to D(H) (without J(H)) rearrangements, we found that the preference for D(H) RSS use changes, so that the 5' D(H) RSS are preferred. This suggests that the 3' D(H) RSS are not simply superior targets for the V(D)J recombinase, but instead that certain 12/23-bp spacer RSS combinations work better together to target recombination than do others. We have analyzed a series of artificial recombination substrates to delineate cis sequences that affect D(H) RSS selection. Our data suggest that coding sequences adjacent to the D(H) RSS, flanking sequences outside the D(H) gene segment itself, and recombination partner all affect D(H) RSS targeting.
Intestinal transport and catabolism of IgE: a major blood-independent pathway of IgE dissemination during a Trichinella spiralis infection of rats.
Authors: Negrão-Corrêa D , Adams L S , Bell R G
Published: December 2022

Previous work has shown that Trichinella spiralis-infected rats transport IgE from plasma to intestinal tissue and fluids. In this study we quantitate IgE transport to the gut and circulation during T. spiralis infection in rats. Total IgE levels in intestinal fluid from infected rats were elevated by 4 days post-infection (dpi), but were not elevated in serum and lymph until 7 dpi. IgE levels in intestinal fluid ranged from 1 to 6 microg between 10 and 21 dpi, and serum and lymph IgE levels ranged from 100 to 200 ng/ml. Immunoprecipitation of intestinal fluid and enterocyte lysate at 11 dpi showed a protein of 190 kDa that was recognized by mouse anti-rat IgE-MARE-1 in Western blots. This protein was removed from intestinal wash samples with anti-IgE (A2)-Sepharose. The half-life of intact IgE in the intestinal lumen of rats 10 days after infection was 3.25 min. In serum, the half-life of IgE was 5 h. Analysis of IgE production and consumption in 10-day T. spiralis infected rats showed that about 4.67 microg IgE/day entered the serum, while 2570.00 microg IgE/day entered the intestinal lumen. The IgE present in serum 10 days after T. spiralis infection originated in the gut and/or associated lymphoid tissue and was transported to the circulation via thoracic duct lymph. However, most IgE produced in the intestine was transported to the gut lumen at a rate that exceeded transport to plasma by a factor of several-hundredfold.
Regulation by IL-5 of expression of functional platelet-activating factor receptors on human eosinophils.
Authors: Kishimoto S , Shimadzu W , Izumi T , Shimizu T , Fukuda T , Makino S , Sugiura T , Waku K
Published: December 2022

Platelet-activating factor (PAF) and IL-5 are both important mediators of various allergic reactions, although the relationship between these mediators in allergic responses has not yet been fully elucidated. In this study, we investigated the effects of human rIL-5 on the expression of the PAF receptor (PAF-R) on eosinophils from healthy human volunteers. The specific binding of [3H]WEB 2086, a specific ligand for PAF-R, to eosinophils treated with 5 ng/ml of IL-5 for 12 h was significantly higher than that to untreated cells. The Bmax value for IL-5-treated eosinophils was 1.8-fold higher than that for untreated cells, while the Kd values remained unchanged. This clearly indicates that surface expression of PAF-R on eosinophils is enhanced by IL-5. The enhancement was first observed at 6 h and reached a plateau at 12 to 18 h. The effect of IL-5 was abolished in the presence of cycloheximide or actinomycin D. When the relative amount of PAF-R mRNA was determined by reverse transcription PCR, the message was found to be increased through activation of transcription of transcript 1 on exposure to IL-5. Furthermore, we found that the PAF-induced increase in intracellular calcium ion concentration in eosinophils was markedly augmented by exposure to IL-5 for 12 h. Several lines of data suggest that the enhanced expression of PAF-R on eosinophils due to IL-5 is the cause of the augmented response to PAF. These findings will be of value for understanding the mechanisms of selective infiltration and activation of eosinophils in allergic diseases in which PAF and IL-5 are crucially involved.
Enhanced HIV-1 activity in bone marrow can lead to myelopoietic suppression partially contributed by gag p24.
Authors: Rameshwar P , Denny T N , Gascón P
Published: December 2022

Similar to other lymphoid organs, the bone marrow (BM) is a potential reservoir for HIV-1. Although hematologic abnormalities are common in AIDS patients, the mechanisms by which HIV-1 contributes to these abnormalities are poorly understood. Hemapoietic suppression can be mediated by HIV-1 and some of its associated proteins. We have previously reported that AIDS peripheral blood sera inhibit normal CFU-granulocyte macrophage (GM). In this study, we have found that sera obtained from AIDS BM patients are more inhibitory to CFU-GM than those from peripheral blood (p < 0.05). To determine a candidate suppressor factor, we studied the role of p24 and found that it exerts varying degrees of suppression to CFU-GM, but minimal inhibition on erythroid colonies. We have found that the suppressive levels of p24 in in vitro assays are similar to the average circulating levels in AIDS patients. We have also observed that most of the inhibition caused by p24 is mediated by soluble factor(s) produced by the BM stroma. Cross-linking studies with membrane proteins from normal BM stroma and CD34+ cells indicated a putative 26-kDa p24 receptor, indicating that p24 binds to a receptor present on normal BM cells. These results implicate another HIV-1 protein, p24, in hemapoietic suppression and add another plausible mechanism by which HIV-1 contributes to BM failure in AIDS. Furthermore, these findings suggest a potential risk for similar in vivo suppression in the early phase of HIV-1 infection when viremia is elevated, and also in long-term survivors who have low, although persistent, HIV-1 replication.
In vivo functions mediated by the p41 isoform of the MHC class II-associated invariant chain.
Authors: Takaesu N T , Lower J A , Yelon D , Robertson E J , Bikoff E K
Published: December 2022

We used a "hit and run" gene targeting strategy to generate mice expressing only the p41 isoform of the conserved invariant (Ii) chain associated with MHC class II molecules. In contrast to mutants expressing only p31 Ii chain, a small proportion of A(alpha)b A(beta)b molecules produced by these animals have reduced mobilities in SDS-PAGE and appear incompletely processed. Nonetheless, class II surface expression, peptide occupancy, CD4+ T cell maturation, and proliferative responses toward intact protein Ags are efficiently reconstituted. Moreover, spleen cells exclusively expressing p41 or p31 alone display equivalent dose-response curves in Ag presentation assays. Similar conclusions were reached analyzing mutants expressing two independent MHC haplotypes. Overall, these results demonstrate that Ii chain functional activities as a class II-specific chaperone are largely shared by p31 and p41 isoforms in the intact animal. Mutant mouse strains producing only p31 or p41 under control of endogenous regulatory elements responsible for constitutive and inducible Ii chain expression should prove useful for dissecting the contributions of these isoforms to diverse CD4+ T cell responses in vivo, such as those responsible for Ab production, inflammatory responses, autoimmune diseases, and protection against infectious agents.
Mice with a targeted deletion of the IgE gene have increased worm burdens and reduced granulomatous inflammation following primary infection with Schistosoma mansoni.
Authors: King C L , Xianli J , Malhotra I , Liu S , Mahmoud A A , Oettgen H C
Published: December 2022

Although IgE has been considered to play an essential role in host defense against parasitic helminth infections such as Schistosoma mansoni, in vivo evidence of a protective function of IgE in infected mice is lacking. In the present study, mice with a null mutation of the C epsilon gene, and thus incapable of making IgE (IgE deficient), were infected by S. mansoni cercariae percutaneously. In two independent experiments, IgE-deficient mice were significantly more susceptible to primary infection, developing worm burdens twofold greater than those of wild-type mice (p < 0.001). In contrast, resistance to challenge infection following three immunizations with irradiated cercariae was similar in the two groups. The percentage of reduction in worm burdens in immunized IgE-deficient animals compared with unimmunized mice was 50%; immunized wild-type mice had a reduction of 55% compared with the baseline parasite count. Levels of parasite-specific IgG1 were more than twofold lower in IgE-deficient mice after primary infection (p = 0.005), whereas no significant difference was observed in the IgG1 response of animals previously immunized with irradiated cercariae. IgE-deficient animals also developed significantly smaller granulomas (by 37-40%) around schistosome eggs deposited in their livers compared with wild-type animals (p < 0.001). The spleens of IgE-deficient mice contained significantly more Ag-specific IL-4-secreting cells following primary infection. These data show that IgE participates in parasite elimination in primary infection with S. mansoni and in the generation of humoral immunity and cytokine responses to the parasite.
MRC OX-2 defines a novel T cell costimulatory pathway.
Authors: Borriello F , Lederer J , Scott S , Sharpe A H
Published: December 2022

T cell activation requires the engagement of the TCR as well as a second, costimulatory signal. In this study, we demonstrate that MRC OX-2 (OX-2) mediates a previously unrecognized T cell costimulatory signal leading to enhanced T cell proliferation. One extensively studied costimulatory pathway, the B7/CD28 pathway, delivers its signal when CD28 is engaged by either of two ligands, B7-1 or B7-2, expressed on APC. Recent data have suggested that an additional ligand may exist in this pathway. This possibility prompted us to search previously cloned genes with both structural and expression characteristics similar to B7-1 and B7-2. Our search yielded OX-2, a rat lymphocyte activation marker, as a promising candidate gene. We now report that Chinese hamster ovary cell transfectants expressing the OX-2 protein can costimulate murine CD4+ T cells to proliferate in an Ag-independent fashion using anti-CD3, as well as an Ag-dependent fashion using peptide. In contrast to B7-1-mediated costimulation, OX-2 does not result in detectable levels of IL-2, IL-4, or IFN-gamma. In addition, OX-2 transfectants do not bind the soluble receptor reagents of the B7/CD28 pathway (CD28-Ig and CTLA4Ig). Furthermore, OX-2 costimulation is not inhibited by CTLA4Ig, as is B7-1-mediated costimulation, but is readily inhibited with an anti-OX-2 mAb. Thus, OX-2 is a T cell costimulatory ligand that acts through a non-B7/CD28 pathway, which leads to functionally distinct consequences, as reflected by the resulting cytokine profile.
Corticosteroids inhibit lymphocyte binding to endothelium and intercellular adhesion: an additional mechanism for their anti-inflammatory and immunosuppressive effect.
Authors: Pitzalis C , Pipitone N , Bajocchi G , Hall M , Goulding N , Lee A , Kingsley G , Lanchbury J , Panayi G
Published: December 2022

Glucocorticosteroids (GCS) are potent anti-inflammatory and immunosuppressive agents widely used in the treatment of many medical conditions, but their mechanism of action is not yet fully understood. Some of the anti-inflammatory effects of GCS have been attributed to the synthesis of lipocortins, whereas the immunosuppressive effects are thought to be mediated through the inhibition of several immune functions through a down-regulation of cytokine gene expression. Another important mechanism of action of GCS may relate to their ability to interfere with the phenomena of adhesion and migration of inflammatory cells. In this study, the direct effects of GCS on lymphocyte adhesion capacity in vitro were investigated. We demonstrate that GCS inhibit lymphocyte adhesion to endothelium through the down-modulation of lymphocyte adhesion molecules. We also provide evidence that GCS inhibit cell aggregate formation induced by TCR ligation, which directly correlates with the down-modulation of LFA-1 and CD2, but not LFA-3 or ICAM-1. Such down-modulation was paralleled by a decrease in the steady state mRNA level of LFA-1 and CD2 gene products, which suggests a direct GCS control of the expression of these genes. Finally, we show that GCS effects are mediated through the GCS receptor, since they can be completely reversed by the GCS-R antagonist RU-486. This study supports the concept that some of the immunosuppressive and anti-inflammatory effects of GCS are likely to be exerted by the inhibition of adhesion-dependent lymphocyte functions.
Differential infection of CD34+ cell-derived dendritic cells and monocytes with lymphocyte-tropic and monocyte-tropic HIV-1 strains.
Authors: Warren M K , Rose W L , Cone J L , Rice W G , Turpin J A
Published: December 2022

Monocytes and dendritic cells are infected by HIV-1 and subsequently produce virions that initiate further rounds of infection. Current methods for the isolation and study of dendritic cells are hampered by the low frequency of these cells and contamination with other cell types. A two-step culture method was devised to generate large numbers of either dendritic cells or monocytes from fetal liver CD34+ progenitors. CD34+ cells were first expanded with the growth factors granulocyte-macrophage CSF and stem cell factor to generate a population of intermediate progenitor cells with a relatively immature phenotype. To induce specific differentiation to dendritic cells, the cultures were switched to serum-free medium with the growth factors granulocyte-macrophage CSF, stem cell factor, TNF-alpha, and IL-4. The cells became highly positive for HLA class II Ags and the dendritic cell marker CD1a. Culture of the intermediate progenitors in serum-containing medium with macrophage CSF resulted in differentiation to adherent monocytes expressing high levels of CD14 with low CD1a expression. The intermediate progenitors were permissive for HIV infection by both monocyte- and lymphocyte-tropic strains. In contrast, differentiation to monocytes or dendritic cells resulted in restricted viral tropism. Dendritic cells efficiently replicated the lymphocyte-tropic virus HIV-1MN, but not the monocyte-tropic virus HIV-1ADA. As expected, monocytes only supported replication of HIV-1ADA. This two-step culture method allows for the production of large numbers of monocytes or dendritic cells from a common precursor pool for studying the development of tropism-associated events.
A newly recognized pathway for the negative regulation of mast cell-dependent hypersensitivity and inflammation mediated by an endogenous cell surface receptor of the gp49 family.
Authors: Katz H R , Austen K F
Published: December 2022

Mast cells are constitutively present at the portals between self and nonself, and contain a large and diverse complement of proinflammatory mediators. These characteristics suggest that the activation of mast cells must be carefully regulated in vivo. Regulation of pathologic and physiologic mast cell activation has been traditionally associated simply with the presence or absence of an activating signal. We examine here evidence supporting a new paradigm: mast cell homeostasis may result from inhibition of activation mediated by receptors on the surface of mast cells, typified by a member of the gp49 family.
Correlation of tolerogenicity of a viral antigen with its immunogenicity.
Authors: Bachmann M F , Fehr T , Freer G , Hengartner H , Zinkernagel R M
Published: December 2022

Induction of B cell tolerance or activation was analyzed with vesicular stomatitis virus (VSV) glycoprotein (G) expressed as a neo-self Ag. A membrane form of VSV-G expressed in all tissues, including the bone marrow, induced unresponsiveness at both the Th and B cell level, whereas a soluble form of VSV-G expressed peripherally in liver and kidney did not tolerize B cells and only reversibly anergized Th cells. Interestingly, a similar correlation was found for activation of mature lymphocytes. When mature normal spleen cells were transferred into the two transgenic mouse lines, the membrane form of VSV-G was strongly immunogenic for both Th and B cells, and high VSV-G-specific IgG Ab titers were induced in these transgenic mice. In contrast, spleen cells transferred into mice expressing the soluble form of VSV-G were not activated, and no VSV-G specific Abs were induced. These results indicate that highly immunogenic Ags are strongly tolerogenic for both immature B and T cells.
NK1.1+ CD4+ T cells lose NK1.1 expression upon in vitro activation.
Authors: Chen H , Huang H , Paul W E
Published: December 2022

NK1.1+ CD4+ T cells produce IL-4 promptly in vivo upon injection of anti-CD3 and may play a role in initiating Th2 cell-mediated immunity. To characterize their in vitro activation properties, NK1.1+ CD4+ T cells were obtained in high purity from spleens of normal C57BL/6 mice, where they represent 2 to 5% of CD4+ T cells, or from MHC-class II I-Ab gene knockout mice, where they constitute 42% of CD4+ T cells. Activation of NK1.1+ CD4+ T cells from either source with plate-bound anti-CD3 resulted in loss of expression of NK1.1 as determined both by flow cytometric analysis and by reverse transcriptase-PCR analysis. A portion of these cells also lost CD4 expression. Both the CD4+ and CD4- activated cells retained the over-representation of V beta8 and V alpha14 chains and expressed the intermediate levels of the TCR-CD3 complex that is characteristic of resting NK1.1+ CD4+ T cells. The anti-NK1.1 mAb used for cell sorting was not the cause of NK1.1 or CD4 disappearance, since the sorted cells remain both NK1.1+ and CD4+ when cultured in the absence of anti-CD3 or in the presence of anti-CD3 and cyclosporin A. Furthermore, NK1.1+ CD4+ T cells that were not treated with anti-NK1.1 Ab also lost NK1.1 expression after activation. Populations of activated CD4+ and CD4- cells (derived from NK1.1+ CD4+ T cells) produced both IL-4 and IFN-gamma upon restimulation with plate-bound anti-CD3.
Diurnal rhythmicity of human cytokine production: a dynamic disequilibrium in T helper cell type 1/T helper cell type 2 balance?
Authors: Petrovsky N , Harrison L C
Published: December 2022

Diurnal rhythmicity is a characteristic of neuroendocrine pathways but is less understood in relation to immune function. We asked whether cellular (type 1) or humoral (type 2) immune responses or type 1/type 2 balance exhibit diurnal rhythmicity in healthy humans, and, if so, whether this is related to plasma levels of cortisol or melatonin, two hormones with immunomodulatory actions. LPS- or tetanus-stimulated human whole blood IFN-gamma and IL-10 production, and the IFN-gamma/IL10 ratio exhibited significant diurnal rhythmicity. The IFN-gamma/IL-10 ratio peaked during the early morning and correlated negatively with plasma cortisol and positively with plasma melatonin. IFN-gamma and, to a lesser extent, IL-10 production was sensitive to inhibition by exogenous cortisone; the IFN-gamma/IL-10 ratio decreased by >70% after the administration of oral cortisone acetate (25 mg). Our findings support the concept that plasma cortisol and possibly melatonin regulate diurnal variation in the IFN-gamma/IL-10 ratio. As IFN-gamma and IL-10 have opposing effects on cellular immunity, changes in their balance would be anticipated to impose diurnal rhythmicity on cellular immunity. This implies that the nature of an immune response, e.g., to vaccination, may be modified by the time of day of Ag presentation and could be therapeutically manipulated by the administration of cortisol or melatonin.
Indirect suppression of IL-7-responsive B cell precursors by vasoactive intestinal peptide.
Authors: Shimozato T , Kincade P W
Published: December 2022

Bone marrow is supplied with nerves and neuropeptides that influence a variety of cellular responses. This study represents an initial evaluation of vasoactive intestinal peptide (VIP) as a possible regulator of B lineage lymphocyte formation. As little as 10(-10) M concentrations of VIP inhibited the IL-7-driven clonal proliferation of pre-B cells in semisolid agar cultures. The response was blocked by a VIP antagonist and augmented by the ectoenzyme inhibitor, phosphoramidon. Suspensions of highly enriched B lineage precursors were unaffected by VIP unless they were cocultured with macrophage-like cells and conditioned medium from VIP-treated macrophages contained inhibitory activity. Neutralizing Abs were used to determine that IFN-alpha is at least one substance that is elicited by exposure of macrophages to VIP. These findings suggest that a neuropeptide can potentially modulate lymphopoiesis through a regulatory circuit that involves macrophages and IFN-alpha. They also raise the possibility that VIP can participate in antiviral defense.
IL-6 induction of protein-DNA complexes via a novel regulatory region of the inducible nitric oxide synthase gene promoter: role of octamer binding proteins.
Authors: Sawada T , Falk L A , Rao P , Murphy W J , Pluznik D H
Published: December 2022

Macrophage inducible nitric oxide synthase (iNOS) catalyzes the synthesis of NO. IL-6-stimulated macrophage differentiation of murine myeloid M1 cells is accompanied by iNOS gene induction and steady-state mRNA expression. Two regions within the iNOS promoter mediate transcriptional responsiveness to LPS and IFN-gamma. Region I contains several essential transcription factor binding motifs and promotes responsiveness to LPS, whereas region II potentiates the LPS response by IFN-gamma. Because region I possesses basal promoter activity and directly mediates iNOS gene activation, we attempted to identify the trans-acting factors involved in IL-6-stimulated induction of the murine iNOS gene through this region. Using an electrophoretic mobility shift assay and methylation interference, we show that IL-6 induced reciprocal changes in the binding activity of POU family members to the candidate nonconsensus octamer sequence of region I that correlated, temporally, with iNOS steady-state mRNA expression. Although DNA-protein binding activity of IL-6-stimulated whole-cell extracts also interacted with a radiolabeled canonical octamer motif, such DNA-protein complexes were not eliminated in competition assays using consensus nuclear factor kappaB or IL-6 oligonucleotides. Specifically, our studies show that octamer binding protein-1-related protein binding activity decreased, while binding of octamer binding protein-2-related proteins increased during differentiation. Mutation of the octamer motif disrupted both binding of the IL-6-induced protein-DNA interactions and transcriptional activation through region I, revealing that this motif is absolutely essential for IL-6 induction of iNOS. Thus, differential activation of octamer binding transcriptional modulators from the POU family may be a novel mechanism of IL-6-mediated iNOS gene regulation.