19 research outputs found
The Natural Human-igg Anti-f(ab')(2) Antibody Recognizes A Conformational Igg1 Hinge Epitope
No full textNatural IgG anti-F(ab')(2) Abs are part of the physiologic immune repertoire and have important immunoregulatory functions. Although previous work suggested that some of these Abs recognize epitopes located in the constant region of the F(ab')(2) molecule, an exact epitope mapping has not been performed. We found that the anti-F(ab')(2) Ab binds strongly to F(ab')(2) but only weakly to Fab fragments. Fab fragments are lacking the core and lower hinge region. In our experiments, we show that the IgG anti-F(ab')(2) Ab binds strongly to a synthetic double chain peptide (225-237/225'-237') comprising the core and lower hinge region of the human IgG1 molecule. In contrast, it binds only weakly to the same peptide in monomeric form (225-237) or to a short double chain hinge peptide (225-232/225'-232'). The double chain peptides comprise a cyclic region between the two cystine bridges and an exocyclic region. Previous nuclear magnetic resonance analyses showed that the cyclic portion of the short double chain hinge peptide adopts the same conformation as that found in the intact IgG1 molecule. The dichroic properties of the short and long double chain hinge peptides indicate that they have identical conformations in their cyclic regions, but have different conformations in their exocyclic regions. The conformational differences in the exocyclic regions explain the binding of the Ab to the long double chain hinge peptide and the lack of binding to the short one. The circular dichroism spectrum of the monomeric hinge peptide, which is not recognized by the Ab, is consistent with the absence of an ordered peptide structure. These findings lead us to conclude that the IgG anti-F(ab')(2) Ab recognizes a conformational IgG1 hinge epitope
Effects of different electrical discharge machining strategies on the fatigue life of tool steel for molds and dies
No full textRecognition of HLA-DR1/DRB1 *0101 molecules presenting HLA-A2 derived peptides by a human recombinant antibody, Fab-5 A1
No full textThe cAMP response element binding protein is involved in hydra regeneration
No full textHydra provides an interesting developmental model system where pattern formation processes are easily accessible to experimentation during regeneration. Previous studies have shown that the neuropeptide head activator affects cellular growth and head-specific cellular differentiation during head regeneration and budding. In order to investigate the signal transduction pathway and the regulatory genes involved in these processes, we measured cAMP levels after head activator treatment and found that head activator leads to an increase in cAMP levels at concentrations where effects on nerve cell determination and differentiation are observed (10(-11) to 10(-9) M). Moreover, exposure of intact hydra to a permeable form of cAMP stimulates nerve-cell differentiation and thus mimicks the effect of endogenous head activator. Band-shift assays were performed to detect changes in hydra nuclear protein binding activity during regeneration or after head activator treatment. We found that the cAMP response element (CRE) promotes a specific and strong DNA-binding activity which is dramatically enhanced and modified during early regeneration or after HA treatment. We also identified a surprisingly highly conserved hydra gene encoding the cAMP Response Element Binding protein, which is involved in this CRE-binding activity. Initiation of regeneration upon wounding provokes an endogenous release of HA which leads to the final differentiation of determined nerve cells. We propose that the nerve-cell differentiation observed within the first 4-8 hours of regeneration relies on the agonist effect of head activator on the cAMP pathway, which would in turn modulate the CRE-binding activity of the hydra CREB protein and thus regulate the transcriptional activity of genes involved in regeneration processes
Shifts in Eastern German Production Structure Under Market Forces
No full textThe paper is organized into three major sections. The first section considers agricultural production prior to German reunification in 1990. It looks at the agricultural production structure in the region prior to the division of Germany in 1945 as well as the patterns which arose under the communist government. The second section starts with the 1989 situation and then discusses the initial adjustments seen as market forces are introduced -- 1990 and 1991. The third section builds upon this base to speculate on how the production structure will unfold in the future.International Relations/Trade,
Antibodies to steroids from a small human naive IgM library
No full textAbstractHuman antibodies specific for digoxigenin, estradiol, testosterone and progesterone have been isolated from a small combinatorial IgM repertoire (4×107) of single chain antibodies (scFv). The affinities of both the anti-estradiol and anti-progesterone scFv were approximately 108 M−1. Naive IgM genes appeared to be highly represented, since only the heavy chain variable domain of the anti estradiol antibody contained differences to corresponding germline sequences. The light chain variable domain of the progesterone receptor was also identical to a germline sequence, showing that it is possible for completely naive antibodies to bind steroids with affinities comparable to those obtained after a secondary immune response
Suppression of anti-erythrocyte autoantibody-producing B cells by a physiological IgG-anti-F(ab')2 antibody and escape from suppression by tumour transformation; a model relevant for the pathogenesis of autoimmune haemolytic anaemia
No full textSUMMARY
We showed previously that broadly reactive IgG anti-immunoglobulin autoantibodies produced by rats during the immune response suppress the B cell response. We report here on the effect of a similar human antibody on self-reactive human B cells. IgG anti-F(ab')2 was added to cultures of anti-erythrocyte autoantibody-producing B cells derived from healthy donors. A dose-dependent suppression of the antibody response was obtained (maximum at 1.3 ng IgG/106 cells). This effect was competitively inhibited by F(ab')2γ. Autoimmune haemolytic anaemia can be caused by chronic monoclonal B cell proliferation. To reproduce this condition in vitro we immortalized B cells with Epstein-Barr virus (EBV) and raised a B cell population with anti-erythrocyte autoantibody activity. These cells were electrically fused with CB-F7 tumour cells and an IgGl cold-reactive anti-erythrocyte autoantibody-producing B cell line was established. Surprisingly, the tumour cells were not suppressed by IgG anti-F(ab')2. It is known that anti-immunoglobulins selectively suppress antigen-receptor (AgR)-occupied B cells by a Fcγ-receptor (FeyRemediated mechanism. To occupy their AgR, we preincubated the tumour cells with anti-AgR antibody. In spite of this, their susceptibility to suppression was not restored. As shown by rabbit IgG-sensitized ox erythrocyte (EA)-rosetting, this refractoriness was not due to a loss of FcγR. Our experiments delineate a mechanism of peripheral B cell suppression to autoantigens, and show a way of escape from control relevant for the pathogenesis of autoimmune haemolytic anaemia.</jats:p
Construction and Functional Evaluation of a Single-Chain Antibody Fusion Protein With Fibrin Targeting and Thrombin Inhibition After Activation by Factor Xa
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