Biomedical subjects

H Schulze-Koops

Publications and source records attributed to H Schulze-Koops.

43 records · Page 3Linked to original sources

PubMed1994

Purification and analytical characterization of an anti-CD4 monoclonal antibody for human therapy.

A purification process for the monoclonal anti-CD4 antibody MAX.16H5 was developed on an analytical scale using (NH4)2SO4 precipitation, anion-exchange chromatography on MonoQ or Q-Sepharose, hydrophobic interaction chromatography on phenyl-Sepharose and gel filtration chromatography on Superdex 200. The purification schedule was scaled up and gram amounts of MAX.16H5 were produced on corresponding BioPilot columns. Studies of the identity, purity and possible contamination by a broad range of methods showed that the product was highly purified and free from contaminants such as mouse DNA, viruses, pyrogens and irritants. Overall, the analytical data confirm that the monoclonal antibody MAX.16H5 prepared by this protocol is suitable for human therapy.

Animals↗

PubMed1994

Engagement of the CD4 receptor inhibits the interleukin-2-dependent proliferation of human T cells transformed by Herpesvirus saimiri.

Infection with Herpesvirus saimiri, a tumor virus of non-human primates, transformed human CD4+ T cell clones to permanent interleukin (IL)-2-dependent growth without need for restimulation with antigen and accessory cells. The IL-2-dependent proliferation of these cells was dramatically inhibited by soluble anti-CD4 whole antibodies, F(ab')2 and Fab fragments, and also by gp 120 of human immunodeficiency virus. The inhibition was not due to cell death and could be overcome by high concentrations of exogenous IL-2. Cell surface expression of CD4, and to a lesser degree the density of the IL-2 receptor alpha chain, were reduced upon anti-CD4 treatment. After long lasting (> 12 h) incubation with anti-CD4, abundance and activity of CD4-bound p56lck were diminished while the free fraction of p56lck remained unchanged. Since IL-2 binding to its receptor activated only the CD4-bound fraction of p56lck, the IL-2-induced p56lck activity was diminished after long-term CD4 ligation. Taken together, our results suggest a cross talk between CD4- and IL-2 receptor-mediated signaling via p56lck.

Antibodies, Monoclonal↗

PubMed1993

Human CD4 modulation in vivo induced by antibody treatment.

Clinical improvement after treatment with anti-CD4 antibodies has been documented in patients suffering from rheumatoid arthritis. This observation has stimulated the interest in effects induced by the in vivo application of anti-CD4 antibodies. Here, we have investigated features of CD4 modulation during and after anti-CD4 therapy with the monoclonal anti-body MAX.16H5. Depletion of circulating helper T cells was accompanied by modulation of the CD4 molecule down to 30% of the initial antigen density 1 hr after antibody infusion. However, despite the reappearance of CD4+ cells in the circulation CD4 remained down-modulated for up to 28 days without a significant residual anti-CD4 binding. Depletion of CD4+ cells as well as CD4 modulation were observed to a similar extent both in responders and non-responders to anti-CD4 therapy. Modulation of CD4 was more effective in vivo than in vitro with a mean reduction of CD4 density down to 46% in vitro. It was induced in varying degrees by all anti-CD4 antibodies investigated except for OKT4 and required viable monocytes in the case of MAX.16H5 and most of the anti-CD4 antibodies investigated. Supernatants from LPS-activated monocytes or the addition of monocytes that were freeze-fractioned or fixed monocytes did not substitute for this requirement. The effect was Fc-receptor dependent since F(ab)2 fragments of MAX.16H5 did not induce CD4 modulation. No significant co-modulation was found for a variety of T-cell surface antigens including CD2, CD3, CD8, CD45R, CD45RO, CD25, CDw29, and HLA-DR. In order to test functional effects, the influence of CD4 modulation on the increase of free cytosolic Ca2+ concentration ([Ca2+]i) stimulated via the T-cell receptor complex by an anti-CD3 antibody was studied. A significant inhibition was observed upon direct binding of anti-CD4 to its ligand. However, a diminished CD4 density alone as induced by in vivo modulation did not reduce, but rather enhanced the T cell receptor-mediated mobilization of [Ca2+]i in T cells of the patients. Taken together, no evidence was found that CD4 modulation per se could explain the beneficial effects of anti-CD4 therapy.

Adjuvants, Immunologic↗

PubMed1993

Outer membrane protein YadA of enteropathogenic yersiniae mediates specific binding to cellular but not plasma fibronectin.

The binding of bacteria or bacterial products to host proteins of tissue extracellular matrix may be a mechanism of tissue adherence. We investigated interactions of the plasmid-encoded outer membrane protein YadA, which confers pathogenic functions on enteropathogenic yersiniae, with fibronectin. Attachment of YadA-positive and YadA-negative recombinant Yersinia enterocolitica strains to cartilage-derived human cellular fibronectin and human plasma fibronectin in the solid phase revealed that YadA mediates binding of yersiniae to cellular fibronectin in a saturable, concentration-dependent manner. The interaction could be inhibited by an anti-YadA-specific anti-serum. An anti-beta 1-integrin antibody and the synthetic peptide G-R-G-D-S-P, representing the binding site for alpha 5 beta 1-integrin on fibronectin, did not block attachment of YadA-positive yersiniae to cellular fibronectin, indicating a binding site for YadA on cellular fibronectin independent of the R-G-D-S-containing site. By contrast, YadA failed to mediate binding to plasma fibronectin immobilized on nitrocellulose or plastic surfaces. These observations provide evidence for the hypothesis that the binding region for YadA in cellular fibronectin is not present in plasma fibronectin. This study is the first report on differential binding of bacteria to splicing variants of fibronectin. Further experiments might answer the question whether binding of YadA to cellular fibronectin contributes to the pathogenesis of yersiniae, both to the initial adhesion of the bacteria to the matrices of the host and to the arthritogenic potential of enteropathogenic yersiniae.

Adhesins, Bacterial↗

PubMed1992

Plasmid-encoded outer membrane protein YadA mediates specific binding of enteropathogenic yersiniae to various types of collagen.

The plasmid-encoded outer membrane protein YadA of enteropathogenic yersiniae is associated with pathogenicity. Recently, collagen binding of YadA-positive yersiniae was reported without detailed characterization (L. Emödy, J. Heesemann, H. Wolf-Watz, M. Skurnik, G. Kapperud, P. O'Toole, and T. Wadström, J. Bacteriol. 171:6674-6679, 1989). To elucidate the nature of collagen binding to YadA, we used a recombinant Yersinia strain expressing the cloned YadA gene. Direct binding of YadA-positive yersiniae to collagens was demonstrated in affinity blot experiments on nitrocellulose filters. A spectrum of collagen types in a wide concentration range were tested for their ability to block binding of 125I-labeled collagen type II to YadA-positive yersiniae. The results indicate a specific binding site(s) for YadA in collagen types I, II, III, IV, V, and XI. In contrast, collagen type VI did not bind to YadA. To characterize the binding site(s) more precisely, isolated collagen chains and cyanogen bromide fragments were investigated. These studies revealed that binding of YadA to collagen type I is confined to the alpha 1(I) chain, whereas the binding site within collagen type XI is localized in the alpha 3(XI) chain. alpha 2(I), alpha 1(XI), and alpha 2(XI) did not bind to YadA. Most interestingly, in the alpha 1(II) chain the specific binding site for YadA resides in the cyanogen bromide fragment CB10. The latter might indicate a binding site that does not depend on conformation. Based on these findings, further fragmentation and the synthesis of peptides may allow definition of the peptide sequence(s) relevant for YadA binding.

Bacterial Adhesion↗

PubMed1992

[Treatment of autoimmune diseases and graft rejection with anti-CD4 antibodies].

Based on the experience that T helper lymphocytes play an important part in the initiation and maintenance of various autoimmune diseases and also in graft rejection, novel therapeutic approaches have been developed and are under investigation. They are aimed at selective inhibition of T cells whose activation is unwanted. Useful tools for this purpose are monoclonal antibodies to cell surface molecules which are restricted to certain cell populations. In this review the concept of treatment with antibodies to CD4-a surface molecule characteristic of T helper lymphocytes-is discussed. Encouraged by experimental experiences obtained during the past years, a series of case reports were published and clinical pilot studies have been performed, the preliminary results of which are now becoming available. Anti-CD4 therapy appears to be a promising approach. Short-lasting effects can be separated from long-lived effects. The latter are not easy to explain, although hypotheses have been developed still requiring more detailed experimental confirmation.

Animals↗

PubMedDate not supplied

What we have learned from trials of immunomodulatory agents in rheumatoid arthritis: Future directions.

In recent years substantial progress has been made in understanding the mechanisms of inflammation and autoimmunity. In an attempt to interfere with selected stages of the immune response, a variety of biological agents has been designed that specifically targets elements of the immune system. In rheumatoid arthritis (RA), a number of open-labeled clinical trials with immunomodulatory agents, such as monoclonal antibodies or recombinant proteins, has provided encouraging initial clinical results. However, with the recent exceptions of biologics inhibiting the activity of proinflammatory cytokines, randomized, controlled studies have largely failed to demonstrate a significant benefit of these agents over placebo. Nevertheless, the clinical trials have provided an excellent opportunity to test the consequences of interfering with specific interactions involved in immunity. Moreover, from the results and experiences from these studies new therapeutic strategies are constantly emerging. Some new approaches, including the application of agents that target a diverse array of substances such as cytokines, chemokines, enzymes, cell surface molecules involved in adhesion or signaling, and nitric oxide, are currently tested in animal models of human rheumatic diseases. In this article, trials of immunomodulatory agents in RA are reviewed, with an emphasis on what we have learned so far and what we have yet to learn. We will discuss recent advantages in the understanding of the pathogenesis of the disease and delineate new therapeutic approaches for chronic arthritis.

Journal Article↗