bluuebunny/crossref_metadata_2025_split huggingface dataset:
V-region-mediated binding of human Ig by protein A.
Authors: Ibrahim S , Seppälä I , Mäkelä O 
Published: December 2022

Abstract
The Fab-mediated "alternative" binding of Ig by staphylococcal protein A is a marker of a set of VH genes (a subset of family VH3 in man). We typed 115 monoclonal human Ig as alternative binders or nonbinders. The proportion of binders varied depending on the isotype, 35% in IgM but only 11-13% in IgA1 and IgG3. It was 28% among lambda-chain-bearing but 16% among kappa-bearing monoclonal Ig. Independent estimates of the proportions bound were obtained by studying polyclonal Ig of 10 healthy adults. The proportions bound were close to those observed in the study of monoclonal Ig (the means were IgM 32%, IgA1 13%, IgA2 24%, IgG3 14%). A higher proportion of infant than adult Ig was bound by protein A. Also, the proportion was less isotype-dependent in infants than in adults. At the age of 4 mo, 47% of IgM was bound (mean of 10 children), the values of other isotypes were: IgA1 35%, IgA2 39%, and IgG3 38%. At the age of 14 mo the proportion of alternative binders had decreased but was still far from adult values. We propose that ontogenically early ("virgin") B cells, besides being rich in IgM and lambda-chain producers, are rich in producers of alternative binders. A subsequent selection reduces the proportion of these B cells so that in ontogenically most developed B cell populations, e.g., those producing IgA1 kappa, such cells make up only about 10% of the total.
Characterization of the insulin A-chain major immunogenic determinant presented by MHC class II I-Ad molecules.
Authors: Williams D B , Ferguson J , Gariepy J , McKay D , Teng Y T , Iwasaki S , Hozumi N 
Published: December 2022

Abstract
Data are presented which demonstrate the minimal insulin peptide required to activate a large group of insulin-specific T hybrids following presentation by either live or fixed APC, is the N-terminal insulin-A(1-13) peptide. Functional activation and competition assays using both live and fixed APC with 19 synthesized variants of the N-terminal bovine insulin A-chain molecule permitted classification of peptide residues into MHC agretope and T cell epitope regions. Our findings indicate insulin A-chain peptide occupies the Ag binding groove of class II MHC in an extended conformation as a result of intracellular reduction of A-loop disulfide bonds. Insulin A-chain Cys7 and Cys11 residues represent two independent T cell epitopes N- and C-terminal to the A-loop region. Data are presented that demonstrate the unique residues associated with several insulin isoform molecules contribute to the peptide agretope region. Our findings may suggest peptide agretopes may subtly modify the peptide/MHC conformation presented to TCR.
Cytotoxic T cells from ovarian malignant tumors can recognize polymorphic epithelial mucin core peptides.
Authors: Ioannides C G , Fisk B , Jerome K R , Irimura T , Wharton J T , Finn O J 
Published: December 2022

Abstract
CTL isolated from tumor infiltrating lymphocytes/tumor associated lymphocytes (TAL) infiltrating ovarian tumors have been demonstrated to mediate lysis of tumor targets after in vitro culture. These effector cells are of particular interest as cellular probes to detect and define human tumor Ag and epitopes that stimulate cellular immunity to human tumors. Polymorphic epithelial mucin (PEM) core peptides are potential candidates as tumor specific Ag because of their preferential expression on epithelial tumors. We report here that ovarian CTL-TAL can recognize mucin (Muc-1) core peptide of PEM. Several ovarian CTL-TAL lines were developed that recognized in a non-MHC restricted fashion an Muc-1+ ovarian tumor, but not Muc-1-tumor. To define the specificity of these CTL-TAL and exclude cross-reactivity with other potential Ag, cytotoxicity experiments were performed using as targets EBV-transformed cell lines with an expression construct containing the Muc.1 cDNA. These ovarian CTL-TAL lysed mucin core-peptide transfected cells but not targets transfected with an expression construct containing a mucin frame-shift mutant cDNA as control. In addition, targets pulsed with short synthetic peptides composed of amino acids 1-14 of the Muc 1 core peptide repeat were also lysed by the same CTL-TAL. This lysis was inhibited by the mAb SM3 that recognize an epitope on the mucin core peptide. These results, which are a demonstration of a specific Ag recognized by ovarian CTL-TAL, may be of interest for specific immunotherapy of ovarian cancer.
Antigen-reactive gamma delta T cells in human leishmaniasis.
Authors: Russo D M , Armitage R J , Barral-Netto M , Barral A , Grabstein K H , Reed S G 
Published: December 2022

Abstract
The importance of Ag-specific gamma delta T lymphocytes in human immune responses to pathogenic organisms is unknown. In the present study the expression of gamma delta TCR on T lymphocytes from patients with cutaneous, mucosal, or visceral leishmaniasis was examined. All of these patient groups had elevated levels of gamma delta T cells in peripheral blood. Patients' gamma delta T cells included CD8+ as well as null cells. The percentage of T cells expressing gamma delta TCR was increased significantly by stimulation in vitro with certain parasite Ag. T-cell lines generated by stimulation with promastigote lysates of Leishmania amazonensis or L. braziliensis typically contained 25 to 60% gamma delta T cells. In contrast, two immunodominant surface Ag of L. amazonensis, gp63 and gp42, did not expand gamma delta T cells from infected patients, although both Ag elicited strong alpha beta T-cell responses. gamma delta T cells isolated from a Leishmania-specific T-cell line responded to stimulation with promastigote lysate. Of particular interest, gamma delta T cells from PBMC of a patient with mucosal leishmaniasis responded to stimulation with a recombinant 70 kDa heat shock protein of L. chagasi. This study demonstrated that several clinical forms of leishmaniasis induced elevated numbers of gamma delta T cells that responded specifically to Leishmania Ag in vitro. Therefore, this component of the T-cell response to Leishmania may impact the outcome of clinical disease.
Inhibition of DNA repair with aphidicolin enhances sensitivity of targets to tumor necrosis factor.
Authors: Gera J F , Fady C , Gardner A , Jacoby F J , Briskin K B , Lichtenstein A 
Published: December 2022

Abstract
To test whether DNA injury contributes to TNF-induced cytotoxicity, we attempted to enhance DNA injury by inhibiting its repair and then assessing effects on cytotoxicity. DNA repair, assayed as unscheduled DNA synthesis, was first detected in TNF-sensitive targets by 2-3 h of incubation with TNF. Targets resistant to TNF cytotoxicity did not demonstrate significant repair replication. Repair preceded the detection of TNF-induced DNA injury, which was subsequently demonstrated by a double-stranded DNA fragmentation assay, sedimentation of DNA in neutral and alkaline sucrose gradients, and gel electrophoresis of extracted DNA. This suggested that early during exposure to TNF, DNA repair proceeds more rapidly than strand breakage. To inhibit repair, nontoxic concentrations of aphidicolin (inhibitor of DNA polymerase-alpha) and dideoxythymidine (inhibitor of DNA polymerase-beta and gamma) were used. Aphidicolin inhibited repair and consistently sensitized to TNF cytotoxicity, decreasing the ID50 for TNF at least 10- to 50-fold. In contrast, dideoxythymidine had no effect on repair or cytotoxicity. Deoxycytidine, which competitively inhibits binding of aphidicolin to DNA polymerase, blocked the sensitization in a concentration-dependent fashion. In targets sensitized with aphidicolin, TNF-induced strand breakage was accelerated, being detected by 4 h of culture in the sucrose gradient assay. Sensitization to TNF was not due to a heightened activation of poly (ADP-ribose) polymerase. These results indicate that TNF-induced strand breakage participates in TNF-induced cytotoxicity and that the level of DNA repair plays a role in determining relative sensitivity of targets.
Modulation of rat mast cell reactivity by IL-1 beta. Divergent effects on nitric oxide and platelet-activating factor release.
Authors: Hogaboam C M , Befus A D , Wallace J L 
Published: December 2022

Abstract
Release of inflammatory mediators by mast cells can be modulated by certain cytokines and by nitric oxide. An in vitro platelet aggregation bioassay was used to assess the effects of interleukin-1 beta (IL-1 beta) on the release of platelet-activating factor and nitric oxide from resting or ionophore-activated peritoneal mast cells (PMC) from rat. PMC spontaneously released a substance that inhibits thrombin-stimulated platelet aggregation. The activity of this substance is abolished by addition of hemoglobin to the platelet suspension and augmented by preincubation of the PMC with L-arginine, suggesting that it is nitric oxide. Within minutes, IL-1 beta concentration-dependently (1 pg/ml-100 ng/ml) enhanced the release from activated PMC of nitric oxide, as measured by its ability to inhibit thrombin-induced platelet aggregation, and as confirmed with a biochemical assay for nitrite. This action of IL-1 beta was inhibited by pretreatment of PMC with a calmodulin antagonist (calmidazolium), an IL-1 receptor antagonist, or either of two nitric oxide synthase inhibitors (L-NAME and LY-83583). IL-1 beta also inhibited the release of platelet-activating factor from PMC through a nitric-oxide-dependent mechanism. These results demonstrate that IL-1 beta is a potent and rapid-acting modulator of mast cell reactivity, stimulating nitric oxide release while inhibiting the production of platelet-activating factor.
Co-clustering of beta 1 integrins, cytoskeletal proteins, and tyrosine-phosphorylated substrates during integrin-mediated leukocyte aggregation.
Authors: Sánchez-Mateos P , Campanero M R , Balboa M A , Sánchez-Madrid F 
Published: December 2022

Abstract
The involvement of the VLA-4 integrin in an alternative leukocyte homotypic adhesion mechanism that is LFA-1/ICAM-1 independent, has been previously reported. We describe here the localization of beta 1 and alpha 4 integrin subunits at sites of cell-cell contact, on both beta 1- and alpha 4-induced aggregates of B lymphoblastoid Ramos cells. Moreover, the distribution of different VLA-alpha subunits was also examined on beta 1-induced cell aggregates of alpha 2- and alpha 4-transfected K-562 cells. Both alpha 2 and alpha 4 integrin subunits were mainly localized at sites of intercellular boundaries, suggesting a possible role for these integrins in leukocyte intercellular adhesion. The fibronectin receptor alpha 5 subunit was either diffuse throughout the plasma membrane, or displayed some accumulation at sites of cell-cell contact. Even though homotypic aggregation of U-937 cells was induced with the anti-alpha 5 P1D6 mAb, the alpha 5 subunit showed only partial redistribution to regions of cell-cell contact, compared with the complete redistribution of the alpha 4 subunit in the alpha 4-induced aggregates. The reorganization of the actin-cytoskeleton was observed at sites of intercellular boundaries in both the anti-beta 1- and anti-alpha 4-induced cell aggregates. Hence, F-actin and the cytoskeletal protein talin co-localized with beta 1 and alpha 4 integrin clusters at sites of cell-cell contact. Signal transduction during VLA-mediated homotypic cell adhesion has also been investigated. We found co-localization of beta 1 and alpha 4 subunits with tyrosine-phosphorylated proteins at cell-cell contact regions during cell aggregation. These data indicate that VLA integrin-mediated leukocyte aggregation results in clustering of beta 1-integrins at sites of cell-cell contact, together with co-localization of cytoskeletal proteins. These results also suggest that protein tyrosine phosphorylation is an important signal transduction mechanism when VLA integrins participate in intercellular contacts.
Splenic uptake of immune complexes in man is complement-dependent.
Authors: Davies K A , Erlendsson K , Beynon H L , Peters A M , Steinsson K , Valdimarsson H , Walport M J 
Published: December 2022

Abstract
We have examined the effects of hereditary homozygous C2 deficiency on the processing of radiolabeled soluble immune complexes (IC). A patient with C2 deficiency was studied before and after treatment with fresh frozen plasma (FFP). Hepatitis B surface Ag (HBsAg):anti-HBsAg immune complexes were prepared in vitro using Ag radiolabeled with 123I, and injected intravenously. Dynamic and static gamma-scintigraphy was performed to delineate the sites and kinetics of complex clearance. The patient was initially studied when her C2 level and CH50 were zero, and again 1 wk later after treatment with 12 units of FFP, which normalized these parameters. Before treatment there was rapid uptake of complexes by the liver (t90% [time for 90% uptake] = 13.6 min) and rapid clearance from the circulation (t1/2 = 6.8 min). No splenic uptake was detected, and there was no binding of complexes to erythrocyte CR1. Between 30 and 60 min there was release of 11% of the tracer from the liver. In the second study, performed after normalization of classical pathway complement activity, the t1/2 of IC clearance increased to 9.8 min, and t90% was 27 min. Twenty percent of injected complexes now localized to the spleen, and there was no longer any release of complexes between 30 and 60 min. The kinetics of IC processing and the sites of uptake in this posttherapy study were closely similar to two normal subjects studied in parallel, with a maximum of 72% of injected complexes binding to erythrocytes. These observations indicate that the uptake of immune complexes in the spleen in humans is complement-dependent, and suggest that the observed predisposition to SLE in patients with complement deficiency may be related to abnormal processing of immune complexes.
Characterization of MHC class I restricted cytotoxic T cell responses to tax in HTLV-1 infected patients with neurologic disease.
Authors: Koenig S , Woods R M , Brewah Y A , Newell A J , Jones G M , Boone E , Adelsberger J W , Baseler M W , Robinson S M , Jacobson S 
Published: December 2022

Abstract
To understand the nature of the cytotoxic T cell response generated in human T lymphotropic virus type 1 (HTLV-1)-infected patients with HTLV-1-associated myelopathy/tropical spastic paraparesis, we cloned CTL from the peripheral blood and cerebrospinal fluid from patients with neurologic diseases and demonstrated the presence of HLA-A2, A3, and B14 restricted responses to the HTLV-1 p40x (tax) protein. We identified the minimal amino acid residues within the epitopes required for binding and recognition by HLA-A2- and B14-restricted CTL, identified the critical residues within the peptide sequence defining the HLA-A2-restricted response, and demonstrated that CTL can lyse T cells infected with HTLV-1. This study shows that the CTL response to HTLV-1 tax in patients with neurologic diseases is heterogenous in nature and is not confined to patients of a single HLA haplotype or to a specific region of the tax protein.
Specific antibody production to a recall or a neoantigen by SCID mice reconstituted with human peripheral blood lymphocytes.
Authors: Nonoyama S , Smith F O , Ochs H D 
Published: December 2022

Abstract
To explore the extent of immune reconstitution of SCID mice by human peripheral blood lymphocytes (hu-PBL-SCID mice), we studied the production of immunoglobulin isotypes and specific antibody (Ab) by the engrafted human cells. Human IgG was detectable in 94% of hu-PBL-SCID mice. IgE synthesis by hu-PBL-SCID mice correlated with the IgE levels observed in human donors. All SCID mice receiving PBL obtained from human donors previously immunized with the T-cell-dependent Ag, bacteriophage phi x 174 (phage), produced phage neutralizing antibody. Quantity and quality (Ig isotypes) of phage-specific Ab produced by hu-PBL-SCID mice correlated with that observed in the donor serum. Human B cells alone failed to engraft, and T cells were required for the production of Ig and anti-phage Ab. Phage-specific Ab production occurred without direct Ag exposure of the hu-PBL-SCID mice, suggesting that the specific Ab production was induced directly by polyclonal activation of the engrafted human cells. Intravenous phage injections given 4 wk after cell transfer failed to further increase the anti-phage Ab titer. Phage neutralizing Ab production could not be boosted if spleen cells obtained from hu-PBL-SCID mice were cultured in the presence of Ag. However, hu-PBL-SCID mice produced increased amounts of anti-phage Ab, providing they were injected with phage at the time of cell transfer. Injection of phage at the time of cell transfer, but not 4 wk later, to mice receiving PBL from nonimmunized donors induced production of minute amounts of anti-phage Ab. We conclude that human peripheral blood lymphocytes transferred into SCID mice become maximally stimulated presumably by xenogeneic murine Ag, resulting in polyclonal expansion of the graft and spontaneous production of Ab to Ag the human donor was previously exposed to, and in loss of responses to subsequent Ag exposure. Ab production to neoantigen, however, can be induced and that to recall Ag can be modified if PBL are exposed to Ag at the time of cell transfer.
A subset of mouse monoclonal antibodies cross-reactive with cytoskeletal proteins and group A streptococcal M proteins recognizes N-acetyl-beta-D-glucosamine.
Authors: Shikhman A R , Greenspan N S , Cunningham M W 
Published: December 2022

Abstract
It is well known that antibodies to N-acetyl-beta-D-glucosamine (GlcNAc) cross-react with cardiac valves, skin, and other host tissues. However, molecular targets of these antibodies have not been identified. For this reason, anti-streptococcal mAb cross-reactive with group A streptococci and heart proteins were studied for their reactivity with GlcNAc, the immunodominant epitope of group A streptococcal carbohydrate. Characterization of the mAb that recognized GlcNAc revealed that each mAb had its own unique antigen-binding profile and pattern of immunofluorescence on rat heart cells. In the ELISA and Western blot these mAb reacted with cytoskeletal and heart proteins such as actin, keratin, myosin, and vimentin, as well as with streptococcal recombinant M5 and M6 proteins. Binding of the mAb to cytoskeletal proteins was inhibited by GlcNAc conjugated with BSA in a dose-dependent manner, and the mAb preferentially reacted with high-density GlcNAc-BSA conjugates. Antigenic determinants on the proteins recognized by the mAb were resistant to sodium periodate and N-acetylglucosaminidase treatment, suggesting reactivity with peptide and not carbohydrate structures. On reaction of the mAb with a panel of synthetic streptococcal, viral, and myosin peptides, one of the mAb, 49.8.9, was found to react most strongly with a synthetic peptide sequence synthesized from the coxsackievirus B3 capsid protein VP1, which shows homology with and cross-reacts with sequences in the streptococcal M6 protein and human cardiac myosin. This most interesting mAb, previously shown to neutralize coxsackie viruses, recognized the amino acid sequence RRKLEFF, which may mimic the GlcNAc epitope. The data collected show that we have identified a new group of multireactive autoantibodies that recognize GlcNAc and cytoskeletal proteins, as well as defined peptide epitopes.
Xenogeneic thyroid-stimulating hormone-like activity of the human natural anti-Gal antibody. Interaction of anti-Gal with porcine thyrocytes and with recombinant human thyroid-stimulating hormone receptors expressed on mouse cells.
Authors: Winand R J , Anaraki F , Etienne-Decerf J , Galili U 
Published: December 2022

Abstract
Anti-Gal is a natural polyclonal antibody that constitutes 1% of circulating IgG in all humans and that interacts specifically with the mammalian carbohydrate epitope Gal alpha 1-3Gal beta 1-4GlcNAc-R (termed the alpha-galactosyl epitope). This epitope is abundant on thyrocytes, as well as, on other cells of nonprimate mammals, prosimians and New World monkeys, but its expression is diminished in Old World monkey, ape, and human tissues. We hypothesized that anti-Gal may bind in vitro to alpha-galactosyl epitopes on xenogeneic TSH receptors (TSHR) and mimic the effect of TSH on xenogeneic thyrocytes. Assays performed with porcine thyrocytes have indicated that anti-Gal can mimic in vitro TSH effects in stimulation for cAMP synthesis, 125I uptake, and cell proliferation. Furthermore, depletion of anti-Gal from serum of patients with Graves' disease resulted in elimination of a large proportion of the thyroid stimulating immunoglobulin activity and half of the thyroglobulin binding inhibiting Ig activity, when the sera were assayed with porcine thyrocytes. The effect of anti-Gal binding to alpha-galactosyl epitopes on TSHR was further demonstrated by the antibody-mediated stimulation for cAMP synthesis in mouse 3T3 cells (cells expressing alpha-galactosyl epitopes), which were transfected with recombinant human TSHR. CHO cells (cells lacking alpha-galactosyl epitopes), transfected with recombinant human TSHR were not stimulated by anti-Gal. It is, therefore, suggested that in studies on antibodies in Graves' disease sera, the effect of anti-Gal may be excluded by using target cells that are devoid of alpha-galactosyl epitopes. Alternatively, anti-Gal could be removed from the tested sera, before the assay with xenogeneic thyrocytes.
Immune functions of tumor necrosis factor. I. Tumor necrosis factor induces apoptosis of mouse thymocytes and can also stimulate or inhibit IL-6-induced proliferation depending on the concentration of mitogenic costimulation.
Authors: Hernández-Caselles T , Stutman O 
Published: December 2022

Abstract
Murine rTNF produces at least three effects on mouse thymocytes in vitro: 1) Is a modest co-stimulator of proliferation with low PHA-P doses. 2) Has a bi-directional interaction with rIL-6-depending on PHA concentration: at low PHA (5 to 10 micrograms/ml) TNF augments and at high PHA (20 to 30 micrograms/ml) inhibits IL-6-induced proliferation. A comparable bidirectional PHA dose-dependent TNF interaction was seen with IL-1 beta, whereas only inhibition at high PHA with IL-2 and only augmentation at low PHA with IL-4 were seen. 3) TNF induces direct thymocyte apoptosis (a property not shared by IL-1 beta, IL-2, IL-4, IL-6 and IL-7). Of the cytokines studied, only IL-7 reduced TNF apoptosis. Thymocyte apoptosis by TNF showed the same species specificity as costimulation (i.e., human TNF had no effect) and was not inhibited by CY. The thymocyte CD4-CD8 phenotype after 72-h cultures showed that TNF decreased mainly double negative (DN) and single positive (SP) subsets, whereas IL-6 with low or high PHA increased DN and SP, especially the SP CD8+ subset. The regulatory and apoptotic effects of TNF were seen only with thymocytes and not with peripheral splenic or lymph node T cells. Four mAb to mouse TNF (2E2, XT22, 1C6, and 1OD9) could abrogate TNF costimulation and the TNF effects on IL-6-induced thymocyte proliferation, at both augmenting and inhibitory PHA conditions. However, only the two antibodies that also neutralize TNF lytic activity (2E2, XT22) could inhibit TNF-mediated apoptosis, implying two different but neighboring functional domains in the TNF molecule mediating apoptosis/lysis and costimulation. Our studies show that TNF might have unique and complex regulatory effects on growth and death of thymocyte populations in adult mice quite different from its effects on T cells in periphery.