bluuebunny/crossref_metadata_2025_split huggingface dataset:
Involvement of a metalloprotease in spontaneous and phorbol ester-induced release of natural killer cell-associated Fc gamma RIII (CD16-II).
Authors: Harrison D , Phillips J H , Lanier L L 
Published: December 2022

Abstract
Two genes encode the CD16 low affinity IgG FcR. CD16-I (Fc gamma RIII-1) is expressed on PMN as a phosphatidylinositol-glycan anchored glycoprotein. CD16-II (Fc gamma RIII-2) is expressed on NK cells and macrophages as a transmembrane glycoprotein associated with CD3 zeta or Fc epsilon RI-gamma. NK cells spontaneously release soluble CD16-II from the cell surface and this is enhanced by activation with phorbol ester. In this study, we demonstrate that a metalloprotease is involved in the spontaneous and PMA-induced release of CD16-II from NK cells. 1,10-phenanthroline, an inhibitor of Zn(2+)-dependent metalloproteases, efficiently inhibits CD16-II release. 1,7-phenanthroline, an inactive analogue that doesn't chelate Zn2+ or other divalent metal cations, and inhibitors of serine proteases do not affect spontaneous or PMA-induced release of CD16-II. Murine P815 mastocytoma cells transfected with human CD16-II cDNA shed membrane CD16, and 1,10-phenanthroline inhibits this process. P815 transfectants expressing CD16-II molecules with truncated cytoplasmic domains also release soluble receptors, indicating that the cytoplasmic segment of CD16-II is not required for interaction with the protease or the cytoskeleton. By contrast, 1,10-phenanthroline does not inhibit PMA-induced release of CD16-I glycoprotein from PMN, indicating a different mechanism of release for this phosphatidylinositol-glycan anchored molecule. Prior studies have demonstrated that NK cells are activated via the inositol phosphate pathway after engagement of CD16-II by immune complexes or Ig-coated tumor cell targets. A membrane metalloprotease with substrate specificity for CD16-II that is activated by PKC stimulation may provide a mechanism for releasing the immune complex or target from the effector cells and halting signal transduction.
Role of pertussis toxin-sensitive G proteins in stimulus-dependent human eosinophil degranulation.
Authors: Kita H , Abu-Ghazaleh R I , Gleich G J , Abraham R T 
Published: December 2022

Abstract
Stimulation of human normodense eosinophils with immobilized secretory IgA (sIgA) or IgG, or with the soluble stimulus, FMLP, triggers the exocytotic release of the granule protein, eosinophil-derived neurotoxin (EDN). In this report, we demonstrate that these stimuli also provoke an increase in phospholipase C-mediated phosphoinositide breakdown in eosinophils. Pretreatment of eosinophils with pertussis toxin (PTX) for 2 h irreversibly abolished the increases in phospholipase C activity and EDN release induced by immobilized sIgA or FMLP. In contrast, PTX treatment only transiently inhibited eosinophil activation induced by immobilized IgG. Maximal inhibition of IgG-stimulated phosphoinositide hydrolysis and EDN release occurred after 2 h of PTX pretreatment with PTX, followed by a gradual recovery of cellular responsiveness to immobilized IgG as the duration of PTX pretreatment was extended to 16 h. Activated PTX catalyzed the in vitro ADP-ribosylation of 41- and 44-kDa proteins in eosinophil membranes. A 2-h pretreatment of intact cells with PTX markedly reduced the pools of unmodified 41- and 44-kDa substrates available for subsequent ADP-ribosylation in vitro, suggesting that both proteins were substrates for PTX in intact eosinophils. Continuous exposure of eosinophils to PTX for times ranging from 2 to 15 h resulted in the gradual reappearance of unmodified 44-kDa protein, whereas the levels of unmodified 41-kDa protein were persistently reduced in PTX-treated cells. The time course of the decline and reappearance of unmodified 44-kDa substrate in PTX-treated eosinophils closely paralleled the changes in the responsiveness of these cells to immobilized IgG. These results suggest that the receptors for sIgA, FMLP, or IgG transduce activating signals for eosinophil degranulation through differential coupling to at least two PTX-sensitive G proteins.
Glucocorticoids inhibit cytokine-mediated eosinophil survival.
Authors: Wallen N , Kita H , Weiler D , Gleich G J 
Published: December 2022

Abstract
Glucocorticoids characteristically induce eosinopenia in vivo and are effective for treating allergic and other eosinophilic disorders. We studied the effect of glucocorticoids on cytokine-induced survival of human eosinophils in vitro. Eosinophils were purified from normal or mildly atopic volunteers by Percoll density gradient and incubated for 4 days in the presence of cytokine plus steroid. Cell viabilities were determined by staining cells with fluorescein diacetate and propidium iodide. In the absence of glucocorticoids, human rIL-5 enhanced eosinophil survival in a dose-dependent manner, from 22 fM for a minimal effect to 2200 fM for maximal effect. When eosinophils were cultured with a submaximal concentration of rIL-5 (220 fM), dexamethasone, methylprednisolone, and hydrocortisone inhibited eosinophil survival in a dose-dependent manner. Inhibition was time-dependent and required at least 2 days' exposure of eosinophils to dexamethasone. Dexamethasone, methylprednisolone, and hydrocortisone at 1000 nM inhibited survival by 88 +/- 2, 66 +/- 9 and 37 +/- 7%. In contrast, estradiol and testosterone (1000 nM) had no effect on eosinophil survival. When eosinophils were incubated with varying concentrations of human rIL-5 and 1000 nM dexamethasone, survival inhibition was reduced at higher concentrations of human rIL-5, and completely abolished by human rIL-5 23,000 fM. Human recombinant granulocyte-macrophage CSF, human rIL-3, and human rIFN-gamma also enhanced eosinophil survival in a dose-dependent manner and dexamethasone (1000 nM) strongly inhibited cell survival when submaximal concentrations of these cytokines were used. The effects of dexamethasone were reversed by higher concentrations of granulocyte-macrophage CSF (10 U/ml) and IL-3 (3 ng/ml). However, even 1000 U/ml IFN-gamma did not overcome dexamethasone inhibition, indicating a difference between the mechanism of eosinophil survival induced by IFN-gamma and other cytokines. These results suggest that glucocorticoids exert a direct, inhibitory effect on eosinophil survival, which may be important in the treatment of allergic and other eosinophilic disorders. Antagonism of this effect by higher amounts of cytokine may be a mechanism for glucocorticoid resistance.
Influenza A virus infection of macrophages. Enhanced tumor necrosis factor-alpha (TNF-alpha) gene expression and lipopolysaccharide-triggered TNF-alpha release.
Authors: Gong J H , Sprenger H , Hinder F , Bender A , Schmidt A , Horch S , Nain M , Gemsa D 
Published: December 2022

Abstract
We have previously shown that infection of macrophages by influenza A virus is capable of priming for a high TNF-alpha production in response to LPS. The present study was designed to examine in more detail TNF-alpha gene expression and TNF-alpha protein release of virus-infected, murine PU5-1.8 macrophages in the presence or absence of low and by itself rather inefficient concentrations of LPS (10 ng/ml). Although influenza A virus infection alone induced a massive TNF-alpha mRNA accumulation, translation into the bioactive TNF-alpha protein was low as intra- and extracellularly determined by bioassay, specific ELISA and Western blot. However, when LPS was added simultaneously or up to 4 h after infection, a high TNF-alpha production was initiated. The virus-induced TNF-alpha mRNA accumulation appeared to be due to both transcriptional and post-transcriptional changes: an enhanced TNF-alpha gene transcription as determined by nuclear run-on transcription assay and a markedly prolonged half-life of TNF-alpha mRNA as shown in actinomycin D-treated macrophages. These findings imply that influenza A virus may 1) either directly or indirectly stimulate TNF-alpha gene transcription activators or may interfere with labile transcription repressor proteins and 2) may stabilize TNF-alpha mRNA by delaying its degradation. Both mechanisms, taken together, prime influenza A virus-infected macrophages for a high TNF-alpha release in response to LPS which, as clinical cases show, may adversely affect patients with combined influenza A virus and bacterial infections.
Abrogation of tolerance to a chronic viral infection.
Authors: Jamieson B D , Somasundaram T , Ahmed R 
Published: December 2022

Abstract
This study documents failure of peripheral tolerance mechanisms in a chronic viral infection and shows that T cell tolerance to a viral Ag seen as self from fetal life can be broken despite the presence of this Ag in extrathymic tissues. Congenital infection of mice with lymphocytic choriomeningitis virus (LCMV) results in T cell tolerance to the virus. Such mice become carriers for life harboring virus in many tissues including the thymus and exhibit no LCMV-specific CTL responses. Our previous studies have documented the curing of this congenitally acquired chronic infection after adoptive transfer of CD8+ T cells from LCMV-immune mice and the presence of host-derived, LCMV-specific CTL in these "cured" carriers. In this study we have examined the mechanism by which these carriers acquired T cell competence and show that these CTL differentiated from the bone marrow after elimination of viral Ag from the thymus. These results demonstrate that even when a chronic infection has been established in utero, the adult thymus retains the ability to restore immunocompetence to the host and to provide protection against reinfection. Surprisingly, these LCMV specific CTL were acquired at a time when infectious virus and intracellular viral Ag, although cleared from the thymus, were readily detectable in organs such as the kidney, testes, and brain. In fact, active viral replication in peripheral tissues was ongoing when these mice acquired new virus-specific T cells. These results show that clearance of virus form the thymus was sufficient to abrogate tolerance to a congenitally acquired chronic infection and that Ag in peripheral tissues did not tolerize newly developing T cells. These findings suggest that mechanisms that operate on immature cells within the thymus to silence self-reactive T cells are effective in induction of tolerance to viruses, but mechanisms of tolerizing mature T cells are likely to breakdown. This has implications for virus-induced autoimmunity and for treatment of chronic infections.
The Leishmania donovani lipophosphoglycan T lymphocyte-reactive component is a tightly associated protein complex.
Authors: Jardim A , Tolson D L , Turco S J , Pearson T W , Olafson R W 
Published: December 2022

Abstract
Lymphocytes from mice immunized with Leishmania donovani (LPG) were specifically stimulated to proliferate in vitro by purified LPG or its delipidated congener, phosphoglycan. The response was dose dependent and required prior immunization with either LPG or phosphoglycan. Proliferation was eliminated by specific depletion of Thy-1+ cells with antisera and C and the proliferating T cell subset was shown to be CD4+CD8-. Tests of various LPG fragments indicated that the T cell stimulation was associated with the core structure of LPG rather than the lipid or phosphoglycan repeat structure. However, amino acid analysis of LPG and active LPG fragments, after acid hydrolysis, showed the presence of amino acids in peptide linkage. Specific hydrolysis of the glycosidic linkages in LPG with trifluoromethanesulfonic acid provided polypeptide material reactive with two mAb previously believed to be LPG carbohydrate core specific. The protein was separated from LPG by reverse phase chromatography and shown to be a complex of proteins with common epitopes recognized by the two mAb. The dominant species isolated from LPG was a set of small, approximately 11,000 Mr, molecules. Subsequent T cell proliferation studies showed that the lymphocyte stimulation was associated with the protein component of LPG and not the glycan.
The cellular location of a foreign B cell epitope expressed by recombinant bacteria determines its T cell-independent or T cell-dependent characteristics.
Authors: Leclerc C , Charbit A , Martineau P , Deriaud E , Hofnung M 
Published: December 2022

Abstract
We have targeted two foreign B cell antigenic determinants to different locations in the Escherichia coli cell to examine what effect this had on antibody responses elicited by the recombinant bacteria. The two epitopes were the 132-145 peptide from the PreS2 region of hepatitis B virus and the C3 neutralization epitope of poliovirus type 1. They were each expressed in two forms either on the surface, as part of the outer-membrane protein LamB, or soluble in the periplasm, as part of the periplasmic protein MalE. When live bacteria expressing the foreign epitope at the cell surface were used for immunization of mice, they induced T cell-independent antibody responses characterized by a rapid induction of IgM and IgG antibodies. In contrast, when the same foreign epitope was inserted into the MalE protein, the antibody response was only detectable after 3 wk, belonged only to the IgG class and was strictly T cell dependent. This study has therefore identified two major pathways by which epitopes expressed by bacterial cells can stimulate specific antibody responses. The first pathway is mediated by direct activation of B cells by bacterial cell-surface Ag and does not require T cell help. The second pathway is T cell dependent and concerns Ag that can be released from the bacteria in a soluble form. We have also studied the effect of the exact position of the B cell antigenic determinant within the LamB protein and with respect to the outer membrane by comparing the immunogenicity of the PreS epitope inserted at three different permissive sites of LamB. The data indicated that to obtain an antibody response with intact bacteria, the epitope must be protruding sufficiently from the outside of the outer membrane. In contrast, when semipurified hybrid proteins were used as immunogen, the exact position of the B cell antigenic determinant within solubilized LamB protein does not influence its immunogenicity.
Immunogenicity of human T cell leukemia virus type-I (HTLV-I) antigens for cytotoxic T lymphocytes in the rat system.
Authors: Tanaka Y , Isobe A , Masuda M , Tozawa H , Koyanagi Y , Yamamoto N , Shida H 
Published: December 2022

Abstract
We showed previously that WKA (rat MHC, RT-1k) and DA (RT-1a) rat CTL specific for human T cell leukemia virus type-I (HTLV-I) recognized the gag and pX gene-encoded Ag. In the present study, we explored HTLV-I Ag recognized by CTL from other MHC genotype (RT-1l) rats, LEW and F344, and examined whether HTLV-I Ag expressed by recombinant vaccinia viruses (rVV) could prime WKA and LEW rats for HTLV-I-specific CTL. Upon priming in vivo and repetitive stimulation in vitro with HTLV-I+ syngeneic T cells, HTLV-I-specific CD8+ CTL were demonstrated in LEW and F344 rat spleen cell cultures. Interestingly, these CTL were directed against HTLV-I env and pX gene products. Immunization of LEW and WKA rats with the env and gag gene-expressing rVV, respectively, resulted in generation of HTLV-I-specific CD8+ CTL. However, a pX-gene expressing rVV failed to prime either rat strain. In addition, HTLV-I-specific CD8+ CTL from F1 hybrid (WKA x LEW) rats generated by immunization and restimulation with HTLV-I+ syngeneic T cells showed gag and pX Ag specificity on WKA rat cells and env and pX Ag specificity on LEW rat cells. These results suggest that immunogenicity of HTLV-I gag and env Ag in induction of HTLV-I-specific CTL varies depending on MHC, and that the pX Ag expressed by rVV is not a potent immunogen for rats.
B cell response to T helper cell subsets. II. Both the stage of T cell differentiation and the cytokines secreted determine the extent and nature of helper activity.
Authors: Croft M , Swain S L 
Published: December 2022

Abstract
Helper activity of several murine CD4+ T cell subsets was examined. Effector Th, derived from naive cells after 4 days of in vitro stimulation with alloantigen, when generated in the presence of IL-4, secreted high levels of IL-4, IL-5, and IL-6, and low levels of IL-2 and IFN-gamma, and induced the secretion of all Ig isotypes particularly IgM, IgG1, IgA, and IgE from resting allogeneic B cells. Effectors generated with IL-6 secreted IL-2, IL-4, IL-5, IL-6, and IFN-gamma, and induced similar levels of total Ig, 25 to 35 micrograms/ml, but with IgM, IgG3, IgG1, and IgG2a isotypes predominating. Helper activity of these Th was significantly greater than that of effectors generated with IL-2 (10-15 micrograms/ml Ig) and of 24-h-activated naive and memory cells (2-4 micrograms/ml), both of which induced mainly IgM. Unlike other isotypes, IgE was induced only by effector Th generated with IL-4. Blocking studies showed that secretion of all isotypes in response to IL-6-primed effectors was dependent on IL-2, IL-5, and IL-6. IL-4 was required for optimal IgM, IgG1, and IgA secretion, but limited secretion of IgG2a, whereas IFN-gamma was required for optimal IgG2a secretion, and limited IgM, IgG1, and IgA. In contrast, secretion of all isotypes in response to IL-4-primed effectors was dependent on IL-5, although IL-4 and IFN-gamma were also essential for IgE and IgG2a, respectively. Addition of exogenous IL-5 to B cell cultures driven by IL-6-primed effectors did not obviate the requirement for IL-2, IL-4, and IL-6, suggesting that interaction of IL-4-primed effectors with B cells was qualitatively different from that of IL-6-primed effectors, driving B cells to a stage requiring only IL-5 for differentiation. Addition of exogenous factors to IL-2-primed effector Th, particularly IL-4 in the presence of anti-IFN-gamma, resulted in levels of Ig, including IgE, comparable to those induced with other effectors. These results show that functionally distinct Th cell subsets can be generated rapidly in vitro, under the influence of distinct cytokines, which vary dramatically in their levels of help for resting B cells. The cytokines involved in responses to distinct Th cells differ depending on the quality of interaction with the B cell, and the extent of help is strongly determined by the quantity and nature of cytokines secreted by the T cells.
Bovine afferent lymph veiled cells differ from blood monocytes in phenotype and accessory function.
Authors: McKeever D J , MacHugh N D , Goddeeris B M , Awino E , Morrison W I 
Published: December 2022

Abstract
Veiled cells have been prepared from bovine afferent lymph and their surface phenotype has been compared with that of blood monocytes using a panel of mAb that define bovine leukocyte Ag. It has been observed that the expression of CD1c and a putative bovine CD45R Ag is restricted within these populations to afferent lymph veiled cells (ALVC), whereas CD11b is expressed only on monocytes. The CD11a and CD11c specificities and an additional Ag defined by mAb 1LA24 (p110/75) are expressed by both cell types, although CD11a and p110/75 are found only on subpopulations of ALVC. In a comparison of accessory function, we have found that ALVC are considerably superior to blood monocytes both as stimulators in mixed leukocyte cultures and as presenters of soluble Ag to primed T cells. This superiority appears to be associated with an increased capacity to form clusters with responding lymphocytes. In addition, we have established that the capacity of ALVC to present soluble Ag to Ag-specific T cell clones resides almost exclusively in a subpopulation defined by the phenotype p110/75+ CD11a-.
Novel function for intestinal intraepithelial lymphocytes. Murine CD3+, gamma/delta TCR+ T cells produce IFN-gamma and IL-5.
Authors: Taguchi T , Aicher W K , Fujihashi K , Yamamoto M , McGhee J R , Bluestone J A , Kiyono H 
Published: December 2022

Abstract
Intestinal intraepithelial lymphocytes (IEL) from mice are greater than 80% CD3+ T cells and could be separated into four subsets according to expression of CD4 and CD8. In our studies designed to assess the functions of IEL, namely, cytokine production, it was important to initially characterize the various subsets of T cells that reside in IEL. The major subset was CD4-, CD8+ (75% of CD3+ T cells), which contained approximately 45 to 65% gamma/delta TCR+ and 35 to 45% alpha/beta TCR+ T cells. Approximately 7.5% of IEL T cells were CD4-, CD8- (double negative) and gamma/delta+ population. On the other hand, CD4+, CD8+ (double positive) and CD4+, CD8- fractions represented 10% and 7.5% of CD3+ T cells, respectively, which were all alpha/beta TCR+. Inasmuch as CD3+, CD4-, CD8+ T cells are a major subset of IEL which contain both gamma/delta TCR or alpha/beta TCR-bearing cells, the present study was focused on the capability of this subset of IEL T cells to produce the cytokines IFN-gamma and IL-5. Both gamma/delta TCR+ and alpha/beta TCR+ IEL spontaneously produced IFN-gamma and IL-5, although higher frequencies of cytokine spot-forming cells were associated with the alpha/beta TCR+ subset. Approximately 30% of CD8+, gamma/delta TCR+ cells produced both cytokines, whereas approximately 90% of alpha/beta TCR+ T cells produced either IFN-gamma or IL-5. Both gamma/delta TCR+ and alpha/beta TCR+ IEL possessed large quantities of cytokine-specific mRNA, clearly showing that these IEL were programmed for cytokine production. When IEL were activated with anti-gamma/delta or anti-CD8 antibodies, higher numbers of IFN-gamma and IL-5 spot-forming cells were noted. The present study has provided direct evidence that a major function of IEL involves cytokine production, and this is the first evidence that gamma/delta TCR+ cells in IEL possess the capability of producing both IL-5 and IFN-gamma.
Biochemical analysis of the immune B cell defect in xid mice.
Authors: Lindsberg M L , Brunswick M , Yamada H , Lees A , Inman J , June C H , Mond J J 
Published: December 2022

Abstract
Previous studies have shown that B cells from xid immune defective CBA/N mice that are unresponsive do not proliferate after stimulation with unconjugated anti-Ig. The experiments in this manuscript demonstrate that dextran-anti-Ig conjugates, which induce extensive and prolonged sIg cross-linking, are able to stimulate proliferation of xid B cells. The ability of these conjugates to stimulate proliferation of xid B cells is not related to their ability to stimulate higher levels of PIP2 breakdown. Thus, high concentrations of unconjugated anti-Ig antibody, which are nonmitogenic for xid B cells, stimulate higher levels of PIP2 breakdown and of calcium transients than lower concentrations of dextran-conjugated anti-Ig, which are mitogenic. Although unconjugated anti-Ig does not provide a fully competent signal to stimulate proliferation of xid B cells, it induces a sufficiently stimulatory signal to enable them to enter DNA synthesis in the presence of the protein kinase C activator, indolactam. This suggests that the extent or duration of activation of protein kinase C by anti-Ig may be limiting in xid B cells. To examine whether another recently described pathway of B cell activation is defective in these mice, we studied the induction of early anti-Ig-mediated tyrosine kinase activity in xid B cells. Both unconjugated and dextran-conjugated anti-Ig antibody stimulated comparable but not identical patterns of tyrosine phosphorylation. These data taken together with other findings that the combination of phorbol ester and calcium ionophore stimulates high levels of proliferation in xid B cells suggests that the immune defect of xid B cells may be distal to surface Ig-mediated activation of tyrosine kinase and of PIP2 breakdown but proximal to PKC activation. Alternatively, the xid immune defect may not result from abnormalities in the early signal transduction pathways, but rather from more distal and/or as yet undefined pathways leading to B cell activation.