bluuebunny/crossref_metadata_2025_split huggingface dataset:
CD45 monoclonal antibodies inhibit TCR-mediated calcium signals, calmodulin-kinase IV/Gr activation, and oncoprotein 18 phosphorylation.
Authors: Shivnan E , Clayton L , Allridge L , Keating K E , Gullberg M , Alexander D R 
Published: December 2022

Abstract
The effects of a pan-CD45 mAb (CD45.2) on TCR-mediated signaling pathways were investigated in Jurkat T cells. The simultaneous addition of CD45 mAb with an activating OKT3 mAb had little effect on TCR-stimulated signals. However, when Jurkat cells were exposed to the CD45 mAb for 10 to 20 min before the addition of OKT3, a partial uncoupling of the TCR from intracellular signals was observed. The maximal increase in intracellular calcium was inhibited 47 +/- 10% (n = 11, range 33-67%), whereas no inhibition of inositol trisphosphate production was detected. The transient TCR-mediated activation of the Ca2+/calmodulin-activated kinase IV/Gr was also inhibited by the CD45 mAb, and this was reflected in a 50 to 60% inhibition in the TCR-stimulated generation of the p21 and p23 phosphoisomers of oncoprotein 18, a Ca2+/calmodulin-activated kinase IV/Gr substrate recently implicated in cell cycle regulatory events. Oncoprotein 18 is also a substrate for mitogen- activated protein kinase, but no inhibition by the CD45 mAb of TCR-triggered mitogen-activated protein kinase activation was observed. The CD45 mAb was therefore selective in causing the uncoupling of the TCR from calcium signals and calcium-regulated events without promoting a general inhibition of all TCR-mediated signals. Confocal microscopy revealed that binding of the CD45 mAb caused patching of CD45 molecules at the cell surface and, unexpectedly, a marked redistribution of intracellular CD45. However, no change was observed in the total level of CD45 expressed at the cell surface. Aggregation of CD45 at the cell surface may result in its sequestration from its tyrosine kinase substrates, with a consequent selective uncoupling of the TCR from intracellular signaling pathways.
Suppression of murine allergic contact dermatitis by CTLA4Ig. Tolerance induction of Th2 responses requires additional blockade of CD40-ligand.
Authors: Tang A , Judge T A , Nickoloff B J , Turka L A 
Published: December 2022

Abstract
Blockade of costimulation through the B7-CD28 pathway by CTLA4Ig can lead to Ag-specific T cell tolerance. Most models studied to date involve a Th1-dependent response. To investigate whether the tolerizing effects of CTLA4Ig might vary depending upon the cytokine nature of the immune response, we studied its effects on contact hypersensitivity (CHS) in response to two allergens. In BALB/c mice, both 2,4-dinitrofluorobenzene (DNFB) and FITC induce CHS. However, the DNFB response is Th1-predominant, while the FITC response is Th2 predominant. CTLA4Ig treatment during primary sensitization induced long-lasting unresponsiveness to DNFB, with 88% and 76% inhibition of primary (first challenge) and secondary (re-sensitization and re-challenge) CHS, respectively. In contrast, CTLA4Ig inhibited primary CHS to FITC by over 82% but had little effect on secondary CHS. Consistent with its effects on CHS, the suppressive effect of CTLA4Ig on Th2 cells was short-lived in FITC-sensitized mice, while Th1-like cytokine-secreting cells remained reduced in DNFB-sensitized mice, even when the animals were rechallenged with DNFB. The addition of anti-CD40L Ab to CTLA4Ig was able to induce long-lasting unresponsiveness to FITC, indicating the ability of cells mounting this Th2 response to receive costimulatory signals through either pathway. In conclusion, CHS can be mediated by both Th1 and Th2 cells, and the ability of CTLA4Ig to lead to long-standing nonresponsiveness in this model depends on the nature (i.e., cytokine profile) of the immune response.
Epitope mapping by mass spectrometry: determination of an epitope on HIV-1 IIIB p26 recognized by a monoclonal antibody.
Authors: Parker C E , Papac D I , Trojak S K , Tomer K B 
Published: December 2022

Abstract
Matrix-assisted laser desorption mass spectrometry in combination with proteolytic protection assays has been used to identify the functional epitope on HIV-1 IIIB p26 recognized by a mAb. In this procedure, the intact protein is affinity bound to an immobilized mAb under physiologic conditions. A combination of proteolytic enzymatic cleavages was then performed to remove unprotected residues. Protected residues were identified by matrix-assisted laser desorption mass spectrometry based on their m.w. With this approach, an 11-residue sequence was identified as the most tightly affinity-bound fragment. in addition, two less tightly bound segments were observed. These latter two residues may contain elements of a discontinuous epitope or may be residues involved in a wider contact area. The combination of matrix-assisted laser desorption and proteolytic epitope footprinting has been applied to the determination of the epitope on a recombinant protein recognized by a mAb but should be equally applicable to the definition of an epitope on a native protein in its natural folded conformation.
Stimulation of phosphatidylinositol turnover is a key event for Fas-dependent, activation-induced apoptosis in human T lymphocytes.
Authors: Izquierdo M , Ruiz-Ruiz M C , López-Rivas A 
Published: December 2022

Abstract
We have analyzed the requirements for activation-induced apoptosis in Jurkat T cells expressing the heterologous human muscarinic type 1 receptor (HM1R; J-HM1-2.2 cells) that is coupled to phosphatidylinositol turnover through a protein tyrosine kinase-independent, G protein-regulated mechanism. Triggering of HM1R with the agonist carbachol is sufficient to induce apoptosis in J-HM1-2.2 cells. Apoptosis is also induced in J-HM1-2.2 cells by triggering of the TCR. Calcium influx, intracellular Ca2+ increase, calcineurin function, and de novo protein synthesis are necessary for receptor-controlled apoptosis. However, blocking protein kinase C with a specific inhibitor does not abrogate receptor-induced apoptosis. Furthermore, HM1R-induced apoptosis is inhibited by blocking Fas ligand/Fas interaction with an antagonist anti-Fas Ab, and Fas ligand mRNA and protein are expressed in J-HM1-2.2 cells stimulated through the HM1R. Therefore, protein tyrosine kinase activation is not an absolute requirement for receptor-controlled Fas ligand expression. Taken together, the results demonstrate that stimulation of phosphatidylinositol turnover can induce apoptosis through a Fas-dependent mechanism that requires calcineurin stimulation, but not protein kinase C activation.
Selection and binding of peptides to human transporters associated with antigen processing and rat cim-a and -b.
Authors: Wang P , Gyllner G , Kvist S 
Published: December 2022

Abstract
Cytotoxic T lymphocytes recognize antigenic peptides presented by MHC class I molecules. The peptides are generated in the cytosol by proteasomes, and probably also other proteases, and are then translocated into the endoplasmic reticulum (ER) lumen. The transporters associated with Ag processing (TAP) are key molecules for transporting peptides from the cytosol to the lumen of the ER. Using semipermeabilized cells, TAP-dependent peptide translocation was demonstrated, and the selectivity of peptide translocation was based on the carboxyl-terminal amino acid of peptides. We have examined peptide binding proteins in the ER membrane and the selection of peptides for binding to TAP by using a panel of peptides of different sequences and carboxyl-termini as well as peptides containing D amino acids. Peptides bound to TAP molecules in the absence of ATP. The presence of ATP induced binding of peptides to two additional membrane proteins (58 and 43 kDa). The selection of peptides by TAP molecules was based on peptide sequence and the carboxyl-terminal amino acid. Peptides containing D amino acid did not bind to TAP molecules. Rat cim-a and -b selected peptides differently, and selection was not only dependent on the carboxyl-terminal residue of the peptide, but included an influence of the peptide sequence. The different off-rates after peptide binding to TAP, indicated a dual binding step of peptide to TAP. ATP regulated the off-rate of peptides at a high affinity binding step. Our results demonstrate that the binding of peptides to TAP molecules is specific and most likely involves a multiple step pathway.
A synthetic peptide derived from the tumor-associated protein mdm2 can stimulate autoreactive, high avidity cytotoxic T lymphocytes that recognize naturally processed protein.
Authors: Dahl A M , Beverley P C , Stauss H J 
Published: December 2022

Abstract
Studies in melanoma patients have shown that unaltered self proteins can function as targets for tumor-reactive CTL. Here, we have investigated in a murine model whether autoreactive CTL can be found against the widely expressed proteins cyclin D1, mdm2, and p53, which are frequently overexpressed in transformed cells. Sixteen MHC class I binding peptides were identified in these proteins, and seven of them consistently stimulated primary CTL in vitro. Avidity measurements revealed that the avidity of peptide-induced CTL differed by &gt;1000-fold. The highest avidity CTL were induced by a peptide derived from mdm2. These CTL recognized target cells expressing mdm2 endogenously, while CTL generated against the remaining peptides were of lower avidity and did not recognize cells expressing relevant proteins endogenously. Generation of high avidity anti-mdm2 CTL required several cycles of peptide stimulation, suggesting that the CTL precursor frequency was low. The data show the normal T cell repertoire contains small numbers of potentially autoreactive CTL. Expansion of these CTL may lead to beneficial autoimmunity against tumors, but, equally, it may be the basis of detrimental autoimmune diseases.
T cell vasoactive intestinal peptide receptor subtype expression differs between granulomas and spleen of schistosome-infected mice.
Authors: Metwali A , Elliott D , Blum A M , Li J , Sandor M , Weinstock J V 
Published: December 2022

Abstract
Granulomas form in the liver and intestines of mice infected with the parasite Schistosoma mansoni. Vasoactive intestinal peptide (VIP) is a neurokine that can modulate aspects of the immune response by acting through receptors within the granuloma. Cloned are two novel VIP receptor (VIPR) mRNAs (VIPR1 and VIPR2) that also bind a second neurokine called pituitary adenylated cyclase-activating polypeptide (PACAP). The objective of this study was to determine if granulomas express either VIPR1 or VIPR2. Using a radioligand-binding assay, it was established that PACAP is as effective as VIP at displacing radiolabeled VIP from splenocytes and granuloma cells, and that most if not all VIPRs in the spleen and granulomas bind PACAP. PCR amplification of reverse transcribed RNA determined that granulomas express both VIPR1 and VIPR2 mRNAs. Gel electrophoresis and nucleotide sequencing confirmed the authenticity of the PCR products. Also, both receptor subtypes were amplified from several granuloma CD4+ T cell lines; yet reverse transcribed RNA from T cell-depleted, dispersed granuloma cells had only VIPR1 RNA. It is notable that reverse transcriptase-PCR detected only VIPR1 in the thymus and spleen, which are organs rich in T lymphocytes. Thus, the granulomas and spleens from mice with schistosomiasis contain cells that display authentic VIP/PACAP receptors. Moreover, these data suggest that T cells in different compartments vary in VIPR subtype expression. VIPR1 and VIPR2 may have different physiologic roles in inflammation.
B cell lymphoma-2 transfected P815 cells resist reactive nitrogen intermediate-mediated macrophage-dependent cytotoxicity.
Authors: Albina J E , Martin B A , Henry W L , Louis C A , Reichner J S 
Published: December 2022

Abstract
Activated murine peritoneal macrophage cytotoxicity against P815 tumor cells has been shown to be mediated by the reactive nitrogen intermediates (RNI) produced by macrophages from L-arginine through nitric oxide (NO) synthase. Previous results from this laboratory indicated that NO-dependent killing of P815 fulfilled the criteria for apoptotic death. Work by others, in turn, demonstrated that the product of the bcl-2 gene confers protection against various inducers of apoptosis, including reactive oxygen intermediates. Experiments were performed to determine whether Bcl-2 could equally protect sensitive cells from RNI-dependent apoptosis within the context of a relevant biologic system such as the delivery of such RNI by activated macrophages. Results demonstrated that transfection of P815 cells with the human bcl-2 gene confers immunity from RNI-dependent, macrophage-mediated cytotoxicity. In contrast with wild-type or mock-transfected P815 cells, which do not contain detectable Bcl-2, bcl-2-transfected cells showed minimal DNA fragmentation and cell membrane failure when cocultured with activated macrophages. Additional findings indicate that Bcl-2 affords the transfected cells almost complete resistance to the DNA-fragmenting effects of chemically generated NO or H202 and partial protection from their cytolytic effects. These findings are consistent with the hypothesis that tumor cells expressing bcl-2 may escape destruction by macrophage-dependent immune surveillance mechanisms.
IFN-alpha beta reconstitutes the deficiency in lipid A-activated AKR macrophages for nitric oxide synthase.
Authors: Jiang H , Rummage J A , Zhou A , Chen Z , Herriot M J , Stewart C A , Kolosov M , Leu R W 
Published: December 2022

Abstract
AKR mouse peritoneal macrophages (PM) were previously found to have a defect in their response to lipid A for nitric oxide (NO)-mediated tumor cytotoxicity, which was related to a lower level of C1q synthesis and reconstituted by exogenous IFN-gamma or C1q. We used AKR-PM as a model to further define the role of IFN-alpha beta in modulation of induction of macrophage nitric oxide synthase (NOS) in response to lipid A. Studies have revealed that AKR-PM produced a significantly lower level of IFN-alpha beta than responsive C3H-PM in response to lipid A. AKR-PM failed to increase NOS mRNA synthesis and NO generation when exposed to lipid A, although they had normal levels of TNF-alpha bioactivity and mRNA expression. This partial deficiency of AKR-PM to lipid A stimulation was reconstituted completely by exogenous IFN-alpha beta for both synthesis of NOS mRNA and release of NO. The failure of AKR-PM to produce NOS to lipid A stimulation appears to be related to reduced secretion of IFN-alpha beta and the resultant failure to express TNF-alpha type II receptor (TNF-RII) mRNA, which in turn decreases TNF-alpha binding to its receptor for autocrine induction of NOS. Insufficient synthesis and secretion of endogenous IFN-alpha beta may be the primary reason for AKR-PM refractoriness to induction of NOS in response to lipid A. furthermore, the close correlation between lack of IFN-alpha beta secretion and decreased TNF-RII mRNA synthesis may implicate a critical role for IFN-alpha beta in the upregulation of macrophage TNF-RII receptor expression for autocrine induction of NOS during lipid A stimulation.
Human monocytes are unable to bind to or phagocytize IgA and IgG immune complexes formed with influenza virus in vitro.
Authors: Scott C B , Ratcliffe D R , Cramer E B 
Published: December 2022

Abstract
An in vitro model system was used to investigate how human monocytes recognize influenza A/WSN(H1N1)-infected epithelial cells, and the role that anti-influenza IgA and IgG Abs play in this interaction. Pretreatment of the monocytes with neuraminidase or F(ab')2 fragments of a mAb against the Ca1 epitope on the hemagglutinin (HA) molecule inhibited monocyte adherence to the infected cells. This suggested that monocytes bound to the sialic acid binding site on the HA molecule and not to other viral or epithelial cell Ags. In the presence of neutralizing concentrations of intact Abs (human serum IgA, secretory IgA, IgG, or mouse anti-HA mAb), monocytes were unable to bind to influenza-infected epithelium or to phagocytize the IgA or IgG immune complexes formed with influenza virus, even though they could use these same Abs to attach to or phagocytize inert particles. Under conditions of Ag excess and low concentrations of Ab, monocytes bound primarily to the viral HA molecule, but showed some recognition of the viral immune complexes. This dual binding did not increase monocyte adherence to the infected epithelium above that observed with virus alone. These findings indicate that neutralizing concentrations of IgA or IgG Abs, the predominant Abs found in the upper and lower respiratory tract, respectively, do not augment and can prevent monocyte recognition of influenza virus. This suggests that in vivo monocytes must use a non-Fc-mediated mechanism to adhere to and phagocytize these immune complexes.
Heat shock protein 65 induces CD62e, CD106, and CD54 on cultured human endothelial cells and increases their adhesiveness for monocytes and granulocytes.
Authors: Verdegaal M E , Zegveld S T , van Furth R 
Published: December 2022

Abstract
Expression of members of the heat shock protein 60 (hsp60) family in tissues has been reported to coincide with leukocyte infiltration, but it is not known whether these proteins are directly involved in the extravasation of leukocytes. Extravasation of leukocytes requires their adhesion to endothelial cells (EC) via an interaction between adhesion molecules expressed on both cell types. The aim of the present study was to investigate the effect of recombinant mycobacterial hsp65 on the adhesive characteristics of EC for monocytes and granulocytes. Incubation of EC with hsp65 induces a concentration- and time-dependent increase in adhesiveness of these EC for monocytes and granulocytes. The effect was maximal after incubation of EC with hsp65 for 4 to 6 h. In addition, incubation of EC with hsp65 induced the expression of endothelial CD62E (E-selectin), CD106 (vascular cell adhesion molecule-1) and CD54 (intercellular adhesion molecule-1). The increased adhesion of granulocytes to hsp65-stimulated EC was inhibited completely by blocking Ab against CD62E. mAb against endothelial CD62E, CD106, or CD54 or against the monocyte adhesion molecules CD14 or CD49d (very late Ag-4) did not inhibit the increased adhesion of monocytes to hsp65-stimulated EC; however, mAb against the monocyte adhesion molecule CD18 (beta2-integrin) inhibited monocyte adhesion to hsp65-stimulated EC to the same extent as monocyte adhesion to nonstimulated EC. Hsp65 did not exert its effect in an autocrine or paracrine fashion via the endogenous production of IL-1, TNF-alpha, or other factors or via contaminating LPS. Together these results indicate that hsp65 can play an important role in the adhesion of monocytes and granulocytes to EC at sites of inflammation via modulation of the adhesive characteristics of EC and thus may facilitate extravasation of these phagocytes.
5-Lipoxygenase metabolism in alveolar macrophages from subjects infected with the human immunodeficiency virus.
Authors: Coffey M J , Phare S M , Kazanjian P H , Peters-Golden M 
Published: December 2022

Abstract
Pulmonary infection represents a major source of morbidity and mortality in AIDS. One important component of pulmonary host defense is the elaboration by resident alveolar macrophages (AM) of proinflammatory leukotrienes (LT) and other 5-lipoxygenase (5-LO) metabolites of arachidonic acid (AA). In this study, we compared the 5-LO metabolic capacity of AM isolated from normal controls with two groups of HIV-infected subjects: (1) patients with low CD4 counts undergoing diagnostic evaluation for pulmonary indications, and (2) volunteers without pulmonary complaints stratified into normal (&gt; 500) and low (&lt; 200) CD4 count groups. Compared with AM from control subjects, AM from HIV-infected subjects with normal and low CD4 counts demonstrated a marked reduction in LT synthesis. This reduced metabolic capacity could not be attributed to in vivo activation because there was no increase in lavage fluid LTB4 levels. However, there was a reduction (approximately twofold) in 5-LO protein expression in both the normal and the low CD4 subsets. 5-LO-activating protein (FLAP) expression was unchanged in cells from the normal CD4 HIV group, but was decreased threefold in the two groups with low CD4 counts. These observations indicate that there is a graded defect in the 5-LO metabolic capacity of AM from HIV-infected subjects, with decreased expression of only 5-LO in the normal CD4 group, and decreased expression of both 5-LO and FLAP in the low CD4 group. This defect would be expected to compound the immunosuppression seen in these subjects.
Defective monocyte costimulation for IFN-gamma production in familial disseminated Mycobacterium avium complex infection: abnormal IL-12 regulation.
Authors: Frucht D M , Holland S M 
Published: December 2022

Abstract
We have described previously a family in which several members have disseminated Mycobacterium avium complex infection. PBMC from affected members produced abnormally low amounts of IFN-gamma upon stimulation with PHA. Using PHA-stimulated allogeneic cocultures of highly purified monocytes and T cells from familial patients and normal subjects, we have now demonstrated that familial patient monocytes are defective in accessory cell function for IFN-gamma production. Familial patient monocytes did not inhibit IFN-gamma production by normal cells, nor did inhibition of PG synthesis restore normal IFN-gamma production by familial patient cells. Familial patient cells responded to the addition of exogenous IL-12 by increasing IFN-gamma production, while addition of exogenous anti-IL-12 had an insignificant effect on their IFN-gamma production. IL-12 was undetectable in PHA-stimulated cocultures of familial patient monocytes with familial or normal T cells. In addition, IL-12 production by adherent cells from patients and their unaffected mothers was abnormally low following stimulation with fixed Staphylococcus aureus Cowan I strain. However, normal amounts of IL-12 were detected when adherent familial patient cells were stimulated with S. aureus Cowan I strain and IFN-gamma, suggesting abnormal regulation of IL-12 production by familial monocytes. This is the first report of defective IL-12 production associated with increased susceptibility to an infectious disease, a finding that supports the critical role of this cytokine in host defense.
Analysis of central B cell tolerance in autoimmune-prone MRL/lpr mice bearing autoantibody transgenes.
Authors: Rubio C F , Kench J , Russell D M , Yawger R , Nemazee D 
Published: December 2022

Abstract
The effect of the autoimmune prone MRL/lpr (H-2k) genetic background on central B cell tolerance was studied in mice bearing 3-83 (anti-H-2Kk) Ig heavy and light chain transgenes. B cells bearing the dominant, transgene-encoded anti-H-2Kk specificity were tolerized appropriately on the MRL/lpr genetic background. Nevertheless, mice developed disease traits characteristic of the MRL/lpr strain, including lymphadenopathy and elevated levels of IgG dsDNA autoantibodies. Two transgenic lines were examined in this analysis: 3-83 mu delta, which expresses IgM and IgD forms of the 3-83 Ab, and Tol 1, which expresses only the IgM form of 3-83. The results obtained differed somewhat between the two transgenic lines. Crosses using 3-83 mu(delta) mice never demonstrated any defects in B cell self-tolerance to H-2Kk. Similarly, no Kk autoantibody production was seen in Tol 1 mice that were backcrossed onto the MRL/lpr genetic background and maintained in a specific pathogen-free facility. However, a subset of Tol 1/MRL/lpr mice that were housed in a conventional mouse facility demonstrated significant transgene-derived anti-Kk autoantibodies. Overall, these results suggest that there is no general defect in central B cell tolerance in MRL/lpr mice, despite their defect in the fas gene. These findings suggest similarities between the MRL/lpr T and B cell systems, because both fail to manifest clear central tolerance defects, but they nevertheless promote hyperplasia and autoimmunity in the peripheral immune system.