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Biomedical subjects

G Möller

Publications and source records attributed to G Möller.

At least 91 records · Page 5Linked to original sources
PubMed1991

Antigen processing and presentation by small and large B cells.

We have investigated the ability of different cells from non-immunized mice of the BALB/c strain to present antigen to two ovalbumin-specific I-Ad-restricted T hybridomas. Lipopolysaccharide-activated B-cell blasts were found to be the most efficient antigen-presenting cells. Purified small and dense splenic B cells also stimulated the hybridomas, although not to the same extent as the activated blasts, but comparable to non-fractionated spleen cells. Glutaraldehyde-treated B cells failed to present antigen, whereas F(ab')2 anti-mouse IgM-treated B cells exhibited markedly increased ability to present antigen. Using flow cytometry, we further purified the resting B cells by sorting the small lymphocytes to ensure that the ability of these cells to activate the hybridomas was not due to contamination with large non-resting B cells. The sorted small B cells retained the ability of antigen presentation. Their resting state was confirmed by the fact that they did not incorporate [3H]-thymidine as shown by autoradiographic analysis.

Animals↗
PubMed1991

Membrane-incorporated immunoglobulin receptors increase the antigen-presenting ability of B cells.

Monoclonal antibodies specific for ovalbumin were conjugated to palmitate and inserted into the membrane of normal spleen B cells. Their presence in the membrane, as well as their ability to bind ovalbumin, was established by immunofluorescence. The so called anti-ovalbumin-'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 B cells presented antigen more efficiently than non-decorated B cells.

Animals↗
PubMed1991

The influence of T cells on the immunoglobulin repertoire and the affinity maturation of the immune response against dextran B512 in C57BL/6 mice.

A collection of hybridomas from C57BL/6 mice producing antibodies to dextran B512 was analysed and found to reflect the immune response in vivo with regard to immunoglobulin class expression, T cell dependency and antibody affinity. IgM-, IgG-3, and IgG-2b, and IgA-producing hybridomas were found. IgG3-producing hybridomas were obtained from nude mice, indicating T cell independent IgG3 synthesis. All monoclonal antibodies were of kappa light chain. A major anti-dextran idiotype was expressed in many monoclonals. Secondary immune responses to dextran were also suppressed at the hybridoma cell level. However, hybridomas from secondary responses produced antibodies expressing the major idiotype, suggesting that anti-idiotype mediated suppression was not responsible for the reduced secondary response. Most monoclonals belonged to the VHJ558 family, but the IgG3-producing hybridomas showed a preferential use of genes from the VHX24 family. All monoclonals were directed against internal structures of the dextran molecule. The affinity for dextran of the IgG antibodies produced in secondary immune responses was drastically increased, even when the mice were immunized with thymus-independent forms of dextran, indicating that T helper cells need not be involved in affinity maturation of the immune response.

Animals↗
PubMed1991

The immunoglobulin receptors on B cells bind antigen, focus activation signals to them and initiate antigen-presentation.

We do not agree with the analysis of Langman and Cohn on the function of Ig receptors. We have reviewed the available literature regarding anti-Ig activation of B cells and found it contradictory and unconvincing. We have presented experimental evidence on the inability of Ig receptors on B cells to mediate activation or tolerogenic signals. We suggest that the Ig receptors serve to focus antigen to specific B cells so the B cells can be activated by TI antigens or helper T cells. The Ig molecules also bind foreign antigen and thereby initiate internalization and antigen processing. The processed peptides are exported to the membrane, where they associate with MHC class II antigens, thus transforming B cells into efficient antigen-presenting cells.

Animals↗
PubMed1991

The effects of interleukins 4 and 5 on the differentiation of B cells from (NZB x NZW)F1 mice.

We describe here that IL-4 and IL-5 together can induce the production of high amounts of IgG1 polyclonal antibodies by B cells from old (NZB x NZW)F1 mice even in the absence of LPS. The effect was less marked in young mice from the same strain or in normal Balb/c mice. The cells sensitive to the treatment with the interleukins were the large B cells. Old mice had higher proportions of such cells than young mice or normal Balb/c mice. Synthesis of anti-DNA antibodies of the IgM class was induced. Although IL-4 plus IL-5 induced a strong polyclonal IgG1 production, there were no IgG1 anti-DNA antibodies.

Animals↗
PubMed1990

Control of mucin synthesis: the peptide portion of synthetic O-glycopeptide substrates influences the activity of O-glycan core 1 UDPgalactose:N-acetyl-alpha-galactosaminyl-R beta 3-galactosyltransferase.

Synthetic O-glycopeptides containing one or two GalNAc residues attached to Ser or Thr were used as substrates to investigate the effect of peptide structure on the activity of crude preparations of UDP-Gal:GalNAc alpha-R beta 3-Gal-transferase from pig stomach and pig and rat colonic mucosa and of a partially purified enzyme preparation from rat liver. High-performance liquid chromatography used to separate enzyme products revealed that uncharged glycopeptides with an acetyl group at the amino-terminal end and a tertiary butyl or an amide group at the carboxy-terminal end were resistant to proteolysis in crude preparations. The activity of beta 3-Gal-transferase varied with the sequence and length of the peptide portion of the substrate, the presence of protecting groups, the attachment site of GalNAc, and the number of GalNAc residues in the substrate. The presence and position of Pro had little effect on enzyme activity; ionizing groups near the GalNAc unit interfered with enzyme activity. Since the GalNAc-Thr moieties in many of these O-glycopeptides have been shown to assume similar rigid conformations, the variation in enzyme activity indicates that the beta 3-Gal-transferase recognizes both the peptide and carbohydrate moieties of the substrate. Rat and pig colonic mucosal homogenates contain beta 3- and beta 6-GlcNAc-transferases that synthesize respectively O-glycan core 3 (GlcNAc beta 3GalNAc alpha-R) and core 4 [GlcNAc beta 6(GlcNAc beta 3)GalNAc alpha-R]. These enzymes also showed variations in activity with different peptide structures; these effects did not parallel those observed with beta 3-Gal-transferase.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1990

Simultaneous production of interleukin 2, interleukin 4 and interferon-gamma by activated human blood lymphocytes.

The production of interleukin 2 (IL 2), IL 4 and interferon-gamma (IFN-gamma) by in vitro activated unselected human blood mononuclear cells was studied at a single-cell level. Individual lymphokine-synthesizing cells were identified by intracellular immunofluorescent staining using cytokine-specific monoclonal or polyclonal antibodies. Cultures from adult blood donors revealed a biphasic kinetic production pattern for IL 2 and IFN-gamma with peaks occurring 4-6 and 24-30 h after initiation of the cultures. Approximately 20%-40% of the lymphocytes produced IL 2 and IFN-gamma. In contrast, only 1%-3% of the lymphocytes synthesized IL 4 with maximal frequency after 6 h of culture. CD4+ as well as CD8+ T cells contributed to the synthesis of all three lymphokines studied. CD4+CD45R- T cells were the major producers of IL 2 and IL 4, while CD8+CD45R- T cells were the most common phenotype of IFN-gamma-synthesizing cells. By performing two-color immunofluorescence studies we observed that among IL 4-producing cells every second one made simultaneously IL 2 and every fourth one made IFN-gamma. Mononuclear cells from umbilical cord blood could be stimulated to make IL 2 to the same extent as cells from adult blood donors. No IL 4 production and a strikingly reduced frequency of IFN-gamma producers were noted in cell cultures from neonates. IL 2, IL 4 and IFN-gamma accumulated in the Golgi system, which resulted in a characteristic morphology of the staining, eliminating problems with evaluation of background signals.

Adult↗
PubMed1990

Structural and functional differentiation of the embryonic chick pineal organ in vivo and in vitro. A scanning electron-microscopic and radioimmunoassay study.

The development of sensory structures in the pineal organ of the chick was examined by means of scanning electron microscopy from embryonic day 10 through day 12 post-hatching. At embryonic day 10, the wall of the tubules within the pineal primordium is composed of cells with unspecialized luminal surface. Differentiation of sensory structures starts at embryonic day 12 when pinealocytes and supporting cells can be distinguished. Pinealocytes are recognized by virtue of an inner segment only rarely endowed with a cilium, whereas supporting cells exhibit numerous short microvilli. Further differentiation of the sensory apparatus is achieved by development of an oval-shaped, biconcave swelling at the tip of the cilium, 1 x 2 microns in size, and a collar of long microvilli at the base of the inner segment. Membrane specializations of sensory cilia, however, were not detected. Since during embryonic life new tubules and follicles are continuously formed, all stages of differentiation of sensory structures are found in the chick pineal organ during the second half of the incubation period and the first two weeks after hatching. In 200-microns-thick Vibratome sections of chick-embryo pineal organs cultured in medium BM 86 Wissler for periods up to 13 days the cytodifferentiation parallels the development in vivo. Using an organ-culture system the 24-h release of melatonin into the culture medium was measured by means of radioimmunoassay after solid-phase extraction. At embryonic day 10, the 24-h secretion of melatonin was at the lower range of detection of the RIA (5 pg). The rapid increase in 24-h secretion in melatonin until hatching (approximately 50 micrograms) is approximated by an exponential curve.

Animals↗
PubMed1990

Serum antibody and cellular immune response in mice to dextran B512.

Serum antibodies to dextran started to appear 3 days after immunization of C57BL/6 mice. Synthesis of IgM antibodies was followed by IgG3 and IgGA. Other immunoglobulin classes (IgG1, IgG2b, and IgG2a) were very low or absent. The immune response to dextran was also thymus independent with regard to IgG3 and IgA synthesis as demonstrated by the use of nu/nu mice. CBA and C57BL/6 mice were high responders to dextran with regard to IgM synthesis. C57BL/6 mice produced high levels of IgG3 and IgA antibodies, whereas CBA, A/J, and A.TL only synthesized IgM antibodies. A/J and A.TL strains were most frequently low responders with regard to IgM synthesis and CBA/N mice were completely nonresponders with regard to all immunoglobulin classes. The ability to produce anti-dextran antibodies increased with age in high responder strains. This was most pronounced for IgG3 and IgA antibodies, which reached adult levels 3 months after birth. The affinity of anti-dextran antibodies was high and homogeneous in antisera from C57BL/6 mice. Preimmune matural antibodies and antibodies from immunized low responder strains had a low and variable affinity for dextran.

Aging↗
PubMed1990

Frequencies of interleukin-5 mRNA-producing cells in healthy individuals and in immunoglobulin-deficient patients, measured by in situ hybridization.

Interleukin-5 (IL-5) has previously been demonstrated to enhance immunoglobulin synthesis, especially IgA. Thus, it could be hypothesized that a defect production of IL-5 may cause immunoglobulin deficiency. We have analysed the frequency of IL-5 mRNA-producing cells in healthy adults and in patients with common variable immunodeficiency or selective IgA deficiency. Unstimulated lymphocytes were rarely found to synthesize IL-5 as measured by in situ hybridization. However, pokeweed mitogen and several other activating ligands induced the synthesis of IL-5 mRNA in peripheral blood and spleen lymphocyte cultures. After pokeweed mitogen activation, the number of IL-5 mRNA-producing cells most often peaked on day 3 with a maximal frequency of around 1-2% of mononuclear cells. In a kinetic study we were unable to detect any peak frequency differences between healthy controls (mean 0.44%) and 20 patients (mean 0.58%). Thus, although IL-5 has been reported to be an important regulator of IgA synthesis, a defect production does not seem to be the underlying mechanism in human immunoglobulin deficiency.

Adult↗
PubMed1990

Thymus-independent B-cell activation: passively incorporated membrane antibodies serve to focus the antigen but cannot transmit activation signals.

We have activated B cells with membrane-incorporated monoclonal antibodies against the hapten trinitrophenyl (TNP) using various concentrations of the polyclonal activator lipopolysaccharide (LPS) haptenated with TNP. We found that anti-TNP-decorated B cells were polyclonally activated by 1000-fold lower concentrations of TNP-LPS than untreated B cells or B cells decorated with antibodies of other specificities. In order to test whether the passively incorporated anti-TNP monoclonals could mediate activation signals or only served to focus the polyclonal activator TNP-LPS to the B cells, we compared the response of anti-TNP-decorated B cells from normal C3H/He mice and from the LPS-unresponsive strain C3H/HeJ. We found that B cells from C3H/HeJ mice could not be activated to polyclonal antibody synthesis, in contrast to B cells from the LPS-responsive strain C3H/He. Thus, contrary to what was previously suggested, the incorporated anti-TNP antibodies could not mediate activation signals, but only served to passively bind and concentrate TNP-LPS to the membrane of the B cells, thereby increasing the concentration of the polyclonal B-cell activator LPS to the B cells.

Animals↗
PubMed1990

Screening trace elements and electrolytes in serum by inductively-coupled plasma emission spectrometry.

This rapid, accurate procedure for trace elements and electrolytes in serum requires little sample preparation: to 1 mL of serum a single reagent is added that contains trichloroacetic and hydrochloric acids for protein precipitation, hydroxylamine sulfate for iron reduction, and yttrium as the internal standard. After centrifugation, the supernates are directly analyzed for Na, K, Mg, Ca, Pi, Fe, Cu, and Zn by inductively-coupled plasma emission spectrometry. The CVs were respectively 7.9%, 8.4%, 8.6%, 10.0%, 9.0%, 9.4%, 9.0%, and 9.0% for five assays of National Institute of Standards and Technology Standard Reference Material (SRM) no. 1598, Bovine Serum. Analytical recoveries ranged from 92% to 107% for both SRM 1598 and commercial control serum.

Blood Chemical Analysis↗
PubMed1989

Characterization of individual tumor necrosis factor alpha-and beta-producing cells after polyclonal T cell activation.

Mononuclear cells from human blood were stimulated to tumor necrosis factor alpha (TNF alpha) or beta (TNF beta) production by the T cell mitogens anti-CD3 antibody (OKT3) or staphylococcal enterotoxin A (SEA). The cells were then fixed and subsequently permeabilized in suspension by the detergent saponin in order to enable TNF alpha- or TNF beta-specific antibodies to enter the cells and interact with cytoplasmic TNF in producer cells. A characteristic morphology of the staining pattern of the two cytokines was noted, with a local accumulation in the cytoplasm in a perinuclear position reflecting the presence of TNF alpha or -beta in the Golgi system. TNF alpha-producing cells appeared 2-3 h after activation of the cultures and increased up to 6 h. The majority of these early TNF alpha-producing cells were monocytes as judged by two-color staining and morphology, but a small fraction of CD4- and CD8-positive T cells was found up to 72 h. TNF beta production started later and peaked 18 or 48 h after OKT3 or SEA stimulation, respectively. The number of TNF beta-producing cells was much larger than that of TNF alpha-producing cells, and approximately 90% of them were CD4-positive T cells. The remaining TNF beta production occurred in CD8-positive T cells and in B cells. Almost every second CD4-positive T cell made TNF beta at the peak of the SEA-induced synthesis. The cytotoxic activity found in the supernatants correlated well with the number of TNF-producing cells found in the cultures. Cells from fresh blood or unstimulated cultures showed no or very few TNF-producing cells.

Antigens, CD↗
PubMed1989

Trypsin does not reconstitute responsiveness to lipopolysaccharide in the strain C3H/HeJ, but is a B-cell mitogen-like lipopolysaccharide, stimulating a different subpopulation.

The effect of trypsin on mouse spleen cells and enriched B cells, added alone or together with lipopolysaccharide (LPS), was investigated. With trypsin, proliferation in serum free spleen cell cultures was 2-6 times greater than the background using cells from LPS responder strains, and 2-4 times the background with cells from the C3H/HeJ strain. Trypsin also induced the formation of a low number of IgM plaque forming cells (PFC). When added together with LPS, trypsin increased the proliferation caused by LPS alone by 10-50% with cells from LPS responder strains and by 50-100% with cells from the LPS non-responder strain C3H/HeJ. Trypsin enhanced proliferation in cultures maximally stimulated by LPS. The increased proliferation obtained when trypsin was added to LPS-stimulation of cells from the C3H/HeJ strain, was therefore not interpreted as a reconstitution of the LPS response. We conclude that trypsin has a moderate mitogenic effect on mouse B cells, stimulating the cells to proliferate and secrete IgM. The mechanism of action is unknown, but is different and independent from the action of LPS.

Animals↗
PubMed1989

Detection of individual interleukin 4- and gamma interferon-producing murine spleen cells after activation with T-cell mitogens.

Murine spleen cells were activated with concanavalin A (Con A), pokeweed mitogen (PWM), or phorbol myristate acetate (PMA) and the calcium ionophore A23187. Cells producing gamma interferon (IFN-gamma) or interleukin 4 (IL-4) could be detected by lymphokine-specific monoclonal antibodies and indirect immunofluorescence. The frequency and kinetics of the lymphokine-producing cells were examined and were approximately the same after stimulation with Con A or PMA and A23187. Thirty hours after activation, 3-9% of the cells produced IFN-gamma. There were few IL-4-producing cells, and the maximal frequency was 1 out of 400 spleen cells 48 h after activation. When the cells were activated with PWM, the frequency of IFN-gamma-producing cells was still high 72 h after culture. The majority of the IFN-gamma-producing cells were CD8+ and expressed receptors for IL-2.

Animals↗