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Biomedical subjects

G Möller

Publications and source records attributed to G Möller.

At least 73 records · Page 4Linked to original sources
PubMed1993

Macrophage depletion decreases IgG anti-DNA in cultures from (NZB x NZW)F1 spleen cells by eliminating the main source of IL-6.

We have studied the role of macrophages in the production of IgG anti-DNA autoantibodies by (NZB x NZW)F1 mice (B/W). One of the main features of the systemic lupus erythematosus (SLE)-like disease that affects these mice, is the presence of circulating IgG autoantibodies and immune complexes, which lead to renal failure and death by the age of 8-9 months. IgG autoantibodies are produced without in vitro stimulation by total spleen cells from these mice when they reach the age of 6 months. We have demonstrated that IL-6 increases the production of IgG autoantibodies in cultures of splenic purified B cells from the old B/W mice. The aim of this study was to show the involvement of macrophages in the production of IL-6 and consequently in the production of IgG anti-DNA antibodies in vitro. We show that elimination of the macrophages by different treatments led to reduction of the content of IL-6 in the supernatants as well as of IgG anti-DNA autoantibodies. Addition of fresh, splenic or peritoneal macrophages restored the production of autoantibodies in macrophage-depleted cultures from old B/W mice. There were no differences in the capacity of IL-6 production between macrophages from old or young B/W mice, but an important difference was observed between peritoneal and splenic macrophages, where the former produced much higher levels of IL-6, and consequently were more potent inducers of IgG autoantibodies. The present results reinforce the role of macrophages and IL-6 in the production of IgG anti-DNA autoantibodies in B/W mice. The implications of these results in the pathogenesis of the disease are discussed.

Animals↗
PubMed1993

Membrane-incorporated surrogate receptors increase antigen presentation by resting B cells, but not by LPS-activated blasts.

Palmitate-conjugated monoclonal antibodies specific to ovalbumin were inserted into the cell membrane of normal resting B cells and LPS-activated blasts. These two decorated B cells were tested for their ability to act as antigen-presenting cells for ovalbumin-specific I-Ad-restricted T-cell hybridomas. It was found that the antibody-decorated resting B cells presented antigen more efficiently than non-decorated controls. However, no increment was observed when decorated LPS blasts were compared with non-decorated blasts. This is explained by the fact that the inserted antibodies quickly disappeared from the cell membrane of LPS blasts, while they were retained for a long period in the membrane of resting B cells.

Animals↗
PubMed1993

Commitment to lymphokine profile during primary in vitro stimulation.

We have shown previously that different conditions in primary in vitro SEB stimulation of resting CD4+ T cells, could induce selectively production of either IFN gamma or IL4 and IL10. The present investigation shows that the priming conditions also decide which lymphokines will be produced during restimulations. The cells that had been induced to produce mainly IFN gamma during the primary SEB stimulation, or during stimulation with IL4 and IL10, synthesized the same lymphokines at restimulation, regardless of stimuli and were unaffected by exogenous IL4. Thus, at an early stage of primary SEB stimulation, cells became committed to produce a certain pattern of lymphokines which remained throughout the period of in vitro culture testing.

Animals↗
PubMed1993

B cells carrying surrogate receptors in their membranes process and present antigen to specific murine T cells.

A palmitate-conjugate derivative of ovalbumin which can be inserted into the membrane of B cells has been prepared. The ability of these cells to act as antigen-presenting cells for specific T lymphocytes obtained from immunized mice was tested. It was found that the conjugates were more efficiently processed and presented than the naive form of the antigen. Palmitate-conjugated antibodies specific to ovalbumin were also inserted into the cell membrane of normal B lymphocytes. These cells were pulsed with the antigen and tested as antigen-presenting cells for T cells obtained from immunized mice. The antibody-decorated B cells presented ovalbumin more efficiently than non-decorated controls. Whether antibody-decorated, antigen-pulsed B cells could prime T cells in vivo was investigated. Some priming activity was found.

Animals↗
PubMed1993

Partial biochemical characterization and purification of IgG2b inducing factor as a new cytokine from synovial fluid of patients with rheumatoid arthritis.

Rheumatoid arthritis synovial fluid (RA-SF) contains a novel biological activity, which selectively induces IgG2b antibody production in lipopolysaccharide (LPS)-activated mouse spleen cells in vitro and in vivo. Our previous studies have shown that this activity is not functionally identical to other well-known cytokines and interleukins. In this study we demonstrate the partial purification and biochemical characterization of the IgG2b inducing activity in RA-SF. Biochemical characterization revealed that the IgG2b inducing activity in RA-SF has the following properties: it is a protein, sensitive to pH > 11 and < 4, which is precipitated by 50% of saturated ammonium sulphate and has a molecular weight of 50-70 kDa; it binds to Cibacron-blue and heparin and its activity is not mediated by immunoglobulins or immune complexes, which are present in RA-SF. Biochemical characteristics of the IgG2b inducing activity also differ from other cytokines and interleukins. The term IgG2b inducing factor is proposed for this novel activity.

Arthritis, Rheumatoid↗
PubMed1992

Control of glycoprotein synthesis. Characterization of (1-->4)-N-acetyl-beta-D-glucosaminyltransferases acting on the alpha-D-(1-->3)- and alpha-D-(1-->6)-linked arms of N-linked oligosaccharides.

Hen oviduct membranes contain at least three N-acetyl-beta-D-glucosaminyltransferases (GlcNAc-T) that attach a beta GlcNAc residue in (1-4)-linkage to a D-Man p residue of the N-linked oligosaccharide core, i.e., (1-->4)-beta-D-GlcNAc-T III which adds a "bisecting" GlcNAc group to form the beta-D-GlcpNAc-(1-->4)-beta-D-Man p-(1-->4)-D-GlcNAc moiety; (1-->2)-beta-D-GlcNAc-T IV which adds a GlcNAc group to the (1-->3)-alpha-D-Man arm to form the beta-D-GlcpNAc-(1-->4)-[beta-D- GlcpNAc-(1-->2)]-alpha-D-Man p-(1-->3)-beta-D-Man p-(1-->4)-D-GlcpNAc component; and (1-->4)-beta-D-GlcNAc-T VI which adds a GlcNAc group to the alpha-D-Man p residue of beta-D-GlcpNAc-(1-->6)-[beta-D-GlcpNAc- (1-->2)]-alpha-D-Man p-R to form beta-D-GlcpNAc-(1-->6)-[beta-D-GlcpNAc-(1-->4)]-[beta-D-GlcpNAc- (1-->2)]-alpha-D-Man p-R. We now report a novel (1-->4)-beta-D-GlcNAc-T activity (GlcNAc-T VI') in hen oviduct membranes that transfers GlcNAc to beta-D-GlcpNAc-(1-->2)-alpha-D-Man p-(1-->6)-beta-D-Man p-R to form beta-D-GlcpNAc-(1-->4)-[beta-D-GlcpNAc-(1-->2)]-alpha-D-Man p-(1-->6)- beta-D-Man p-R. The structure of the enzyme product was confirmed by 1H NMR spectroscopy, FAB-mass spectrometry and methylation analysis. Previous work with GlcNAc-T IV was carried out with biantennary substrates; we now show that hen oviduct membrane GlcNAc-T IV can also transfer GlcNAc to monoantennary beta-D-GlcpNAc-(1-->2)-alpha-D-Manp-(1-->3)-beta-D-Man p-R to form beta-D-GlcpNAc-(1-->4)-[beta-D-GlcpNAc-(1-->2)]-alpha-D-Man p- (1-->3)-beta-D-Man p-R. The findings that GlcNAc-T VI' and IV have similar kinetic characteristics and that hen oviduct membranes can convert methyl beta-D-GlcpNAc-(1-->2)-alpha-D-Man p to methyl beta-D-GlcpNAc-(1-->4)-[beta-D-GlcpNAc-(1-->2)]-alpha-D-Man p suggest that these two activities may be due to the same enzyme. The R-group of the beta-D-GlcpNAc-(1-->2)-alpha-D-Man p-(1-->6)-beta-D-Man p (or Glcp)-R substrate has an important influence on GlcNAc-T VI' enzyme activity.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

Control of glycoprotein synthesis: substrate specificity of rat liver UDP-GlcNAc:Man alpha 3R beta 2-N-acetylglucosaminyltransferase I using synthetic substrate analogues.

UDP-GlcNAc: Man alpha 3R beta 2-N-acetylglucosaminyltransferase I (GlcNAc-T I; EC 2.4.1.101) is the key enzyme in the synthesis of complex and hybrid N-glycans. Rat liver GlcNAc-T I has been purified more than 25,000-fold (M(r) 42,000). The Vmax for the pure enzyme with [Man alpha 6(Man alpha 3)Man alpha 6](Man alpha 3)Man beta 4GlcNAc beta 4GlcNAc beta-Asn as substrate was 4.6 mumol min-1 mg-1. Structural analysis of the enzyme product by proton nuclear magnetic resonance spectroscopy proved that the enzyme adds an N-acetylglucosamine (GlcNAc) residue in beta 1-2 linkage to the Man alpha 3Man beta-terminus of the substrate. Several derivatives of Man alpha 6(Man alpha 3)Man beta-R, a substrate for the enzyme, were synthesized and tested as substrates and inhibitors. An unsubstituted equatorial 4-hydroxyl and an axial 2-hydroxyl on the beta-linked mannose of Man alpha 6(Man alpha 3)Man beta-R are essential for GlcNAc-T I activity. Elimination of the 4-hydroxyl of the alpha 3-linked mannose (Man) of the substrate increases the KM 20-fold. Modifications on the alpha 6-linked mannose or on the core structure affect mainly the KM and to a lesser degree the Vmax, e.g., substitutions of the Man alpha 6 residue at the 2-position by GlcNAc or at the 3- and 6-positions by mannose lower the KM, whereas various other substitutions at the 3-position increase the KM slightly. Man alpha 6(Man alpha 3)4-O-methyl-Man beta 4GlcNAc was found to be a weak inhibitor of GlcNAc-T I.

Animals↗
PubMed1992

Age-dependent responsiveness to interleukin-6 in B lymphocytes from a systemic lupus erythematosus-prone (NZB x NZW)F1 hybrid.

The cellular mechanisms for the production of IgG anti-DNA antibodies were studied. Culture of T and B cells from old (NZB x NZW)F1 mice led to the production of IgG anti-DNA antibodies. We found that direct cell contact was partly necessary for the production of IgG anti-DNA antibodies. Fixation of the T cells showed that lymphokines were largely responsible for the antibody synthesis. Antibodies to mouse interleukin-6 (IL-6) inhibited the production of these antibodies in the T-B cell coculture. Human IL-6 could induce small "resting" B cells from the old (NZB x NZW)F1 mice to produce IgG anti-DNA antibodies in a dose-dependent fashion. The response was inhibited by an anti-human IL-6 monoclonal antibody. Large or small B cells from young (B/W)F1 mice or Balb/c mice were not induced by IL-6 to antibody production. Therefore, the capacity of the B/W mice to produce the IgG anti-DNA antibodies correlated with the ability of the B cells to respond to IL-6 and with the age at which the mice begin to have signs of the disease.

Animals↗
PubMed1992

Hospital care versus home care for rehabilitation after hip replacement.

A pilot study was done to assess the feasibility of reducing the hospital stays of patients with total hip replacement (THR). The length of hospital stay for these patients depends largely on how rehabilitation, mostly physical therapy, is organized. This study shows that not more than a half hour per postoperative day was devoted to care services and rehabilitation activities. It is feasible and less expensive to reduce substantially hospital stay by planned physical therapy in the patient's home. These results have prompted a randomized controlled clinical trial to assess hospital versus home rehabilitation.

Aged↗
PubMed1992

Qualitative shift of lymphokine production in response to stimulation, as a consequence of preactivation in vivo or in vitro.

Lymphokine production, analysed at the single cell level, was compared in resting and primed T-cell populations. Cells were preactivated in vitro by repeated mitogen stimulations, or isolated as large, low density cells naturally activated in vivo, from normal spleens of unimmunized animals. A similar qualitative shift in the pattern of lymphokines synthesized after restimulation was found as a result of in vivo and in vitro preactivation of cells. Repeated stimulations in vitro resulted in a qualitative shift in the lymphokines produced in response to activation, from a dominance of IL-2 during the first and second culture, to a dominance of IL-4 and IL-5 in the later stimulations. In vivo activation lead to a similar separation of lymphokine production as primarily IL-2 was made by small resting cells, while large cells preferentially produced IL-4 and IL-5. IFN-gamma was produced by both small and large cells. Preactivation in vitro lead to a more rapid appearance of lymphokines during restimulation. In contrast, the in vivo naturally activated cells responded with a slow onset of lymphokine production when stimulated in vitro.

Animals↗
PubMed1992

Primary stimulation of CD4+ cells in the presence of IL-4 or IFN-gamma alters the frequencies of cytokine-producing cells at restimulation.

The induction of specific effector functions in naive T cells may be directed by accessory signals during activation. These could be elicited through binding to cell surface molecules or through factors secreted by antigen-presenting cells or other simultaneously activated cells. We have investigated the influence of CD8+ cells and of exogenously added cytokines (interleukin (IL)-2, IL-4 and interferon (IFN)-gamma) on the cytokine production in splenic CD4+ T cells. IL-2, IL-4, IL-5 and IFN-gamma production in CD4+ cells was measured at the single cell level during primary mitogen stimulation in vitro in the presence or absence of factors or CD8+ cells. On day 5 the cells were restimulated with mitogen alone and analysed to evaluate the short-term development of cytokine-producing cells in such cultures. Preactivation in the presence of either exogenous IL-4 or IFN-gamma led to an increased production of IL-4 and IFN-gamma respectively at restimulation, and the effects of both IL-4 and IFN-gamma were augmented by IL-2. After preactivation in the presence of IL-2 and IL-4, every third CD4+ cell could be induced to produce IL-4. Exogenous IL-4 or IFN-gamma further decreased each other's production. Depletion of CD8+ cells before activation resulted in a slight increase of IL-4-producing cells, indicating that simultaneous activation of CD8+ cells will influence lymphokine production in CD4+ cells. The results suggest that the pattern of lymphokines induced in naive cells may be influenced by factors secreted by preactivated CD4+ and CD8+ cells, and that naive cells are preferentially 'recruited' to produce similar cytokines.

Animals↗
PubMed1992

Control of O-glycan synthesis: specificity and inhibition of O-glycan core 1 UDP-galactose:N-acetylgalactosamine-alpha-R beta 3-galactosyltransferase from rat liver.

The specificity of glycosyltransferases is a major control factor in the biosynthesis of O-glycans. The enzyme that synthesizes O-glycan core 1, i.e., UDP-galactose:N-acetylgalactosamine-alpha-R beta 3-galactosyltransferase (beta 3-Gal-T; EC 2.4.1.122), was partially purified from rat liver. The enzyme preparation, free of pyrophosphatases, beta 4-galactosyltransferase, beta-galactosidase, and N-acetylglucosaminyltransferase I, was used to study the specificity and inhibition of the beta 3-Gal-T. beta 3-Gal-T activity is sensitive to changes in the R-group of the GalNAc alpha-R acceptor substrate and is stimulated when the R-group is a peptide or an aromatic group. Derivatives of GalNAc alpha-benzyl were synthesized and tested as potential substrates and inhibitors. Removal or substitution of the 3-hydroxyl or removal of the 4-hydroxyl of GalNAc abolished beta 3-Gal-T activity. Compounds with modifications of the 3- or 4-hydroxyl of GalNAc alpha-benzyl did not show significant inhibition. Removal or substitution of the 6-hydroxyl of GalNAc reduced activity slightly and these derivatives acted as competitive substrates. derivatives with epoxide groups attached to the 6-position of GalNAc acted as substrates and not as inhibitors, with the exception of the photosensitive 6-O-(4,4-azo)pentyl-GalNAc alpha-benzyl, which inhibited Gal incorporation into GalNAc alpha-benzyl. The results indicate that the enzyme does not require the 6-hydroxyl of GalNAc, but needs the 3- and the axial 4-hydroxyl as essential requirements for binding and activity. In the usual biochemical O-glycan pathway, core 2 (GlcNAc beta 6[Gal beta 3] GalNAc alpha-) is formed from core 1 (Gal beta 3GalNAc-R). We have now demonstrated an alternate pathway that may be of importance in human tissues.

Animals↗
PubMed1992

Increasing the efficiency of lipid-conjugated antibodies incorporation into the membrane of antigen presenting B cells.

We have introduced some modifications in the technique called "cell decoration" in order to increase the amount of lipid-conjugated antibodies which can be incorporated into the membrane of B cells. As shown by FACS analysis, we have obtained an approximately 4-fold increment in the amount of specific antibodies incorporated into the cell membrane. The procedure, which consists of successive changes of the medium that contains the lipid-conjugated antibodies, avoided changes on parameters that interfere with cell viability. The proposed modification resulted in an approximately 2-fold enhancement of the ability of decorated B cells to act as antigen presenting cells for specific T hybridomas.

Animals↗
PubMed1991

T and B cell collaboration: induction of motility in small, resting B cells by interleukin 4.

In this report we investigate if IL 4 can work as a chemoattractant factor by inducing locomotion in B cells. We found that murine recombinant IL 4 (rIL 4) induced motile morphology and migration through polycarbonate micropore filters of murine, splenic B cells at an optimal concentration of 3 ng/ml. Kinetic studies revealed optimal migration at 8-16 h, although a significant response could be detected already after 1 h. Flow cytometric studies confirmed that the migrated cells were indeed B cells. We also compared the activity of small, dense B cells and large, low-density B cells, based on Percoll gradient separation. We found no difference in IL 4-induced motility among the two groups. Furthermore, we looked at B cells activated in vitro by preculture in lipopolysaccharide (LPS) or IL 4. Our data indicate that both LPS and IL 4 can increase the general capacity for motility in B cells after preculture for 24 h. T and B cell collaboration requires close cell-cell contacts in order for T cell help to be administered to the B cell. One way of enhancing such cell contacts could be through directional cell migration induced by helper factors (chemotaxis). We suggest that IL 4 can play a role as a chemoattractant factor that enhances cell contacts between T helper cells and B cells.

Animals↗
PubMed1991

Differential regulation of lymphokine production in mitogen-stimulated murine spleen cells.

Activation of murine spleen cells in vitro with soluble anti-CD3 monoclonal antibody and phorbol 12-myristate 13-acetate (PMA) induced an initial production of interleukin 2 (IL2), interferon-gamma (IFN-gamma), IL4 and IL5, followed by a refractory state during which the T cells did not produce lymphokines when stimulated with some common mitogens. The refractory state was long-lasting, depended on the presence of anti-CD3 and PMA but could be reverted by incubation in fresh medium. Pokeweed mitogen (PWM) differed from other mitogens tested, since stimulation by PWM and PMA induced lymphokine production and proliferation also in the refractory cells. Furthermore, PWM stimulation selectively induced IL4 and IFN-gamma production but not IL2 and IL5, as detected by intracellular cytokine-specific immunofluorescence and in situ hybridization for mRNA. The results indicate differential regulation of lymphokine production in primary lymphocytes.

Animals↗
PubMed1991

Helper interleukins are produced by both CD4 and CD8 splenic T cells after mitogen stimulation.

We have earlier described (Cardell, S. and Sander, B., Eur. J. Immunol. 1990. 20:389) mitogen-induced production of interleukin (IL)2, IL4 and IL5 mRNA by murine spleen cells, analyzed by in situ hybridization. In the present study we have investigated the potential of CD8 T cells to produce these interleukins, normally associated with the helper function of CD4 T cells. When concanavalin A (Con A)-activated spleen cells were restimulated with Con A and phorbol 12-myristate 13-acetate (PMA), higher levels of IL2, IL4 and IL5 mRNA were induced, as detected both by increased frequencies of positive cells, and by more mRNA per cell. Four-to-six-day Con A blasts were enriched for CD4+ or CD8+ T cells, and restimulated with Con A and PMA. Both CD4 and CD8 cells were found to produce all three kinds of mRNA when restimulated. The frequencies of IL2 mRNA-containing CD8 cells were half of those found for CD4 cells (3.5% as compared to 7%). On the average 1% of the CD8 cells were induced to produce IL4 and IL5 mRNA, while 9% and 3% of the activated CD4 cells contained IL4 and IL5 mRNA, respectively. CD4 and CD8 cells displayed different sensitivities to the reagents when tested alone. Con A induced the synthesis of IL4 and IL5 in CD4 cells, but not CD8 cells, independently of PMA. PMA alone induced extensive thymidine incorporation in CD8 cells, but not in CD4 cells, in the absence of detectable lymphokine mRNA. The results suggest that some CD8 cells have the capacity to give help in immune responses, by secretion of IL2, IL4 and IL5.

Animals↗
PubMed1991

Interferon-gamma and growth factor production by murine T cells derived from three different lymphoid tissues.

Various antigen-presenting cells and the environment in different lymphoid tissues have been suggested to influence the type of lymphokine produced by T cells. We have investigated the mitogen-induced proliferation, interferon-gamma (IFN-gamma) and growth factor production by cells isolated from spleen, mesenteric and peripheral (axillary, brachial and inguinal) lymph nodes (LN). We found that stimulation with concanavalin A or staphylococcus enterotoxin B induced IFN-gamma synthesis in spleen cells but not in LN cells. Proliferation and growth factor production were comparable in the three cell populations. The addition of the phorbol ester phorbol 12-myristate 13-acetate (PMA), which is commonly used as a substitute for accessory cells, did not influence the IFN-gamma synthesis by LN cells. The growth factor production was, on the other hand, elevated by the addition of PMA. A high number of IFN-gamma-producing peripheral LN cells were obtained if they were stimulated in the presence of splenic adherent cells. The growth factor synthesis was marginally affected by the presence of these cells. Thus, splenic adherent cells provide a co-stimulatory signal to the T cell necessary for IFN-gamma synthesis.

Animals↗