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Biomedical subjects

G Gaudernack

Publications and source records attributed to G Gaudernack.

At least 127 records · Page 7Linked to original sources
PubMed1987

Effect of UVA and PUVA on alloactivating and antigen-presenting capacity of human epidermal Langerhans cells.

Human epidermal cell suspensions (EC), obtained with a suction blister technique and enzyme digestion, were irradiated with various doses of UVA with (PUVA) or without previous incubation with 8-methoxypsoralen (8-MOP). EC were then cocultured with allogeneic T cells or pulsed with the soluble antigen purified protein derivative of tuberculin (PPD) for 90 min before being cocultured with autologous T cells. While low doses of UVA induced a small but significant increase in the PPD-specific T-cell response, both PUVA and higher doses of UVA induced dose-dependent reductions. The allogeneic T-cell responses were reduced with PUVA, as well as with UVA, in a dose-dependent fashion. PUVA was far more effective than UVA in reducing both allogeneic and antigen-specific T-cell responses. There were no differences between numbers of DR-positive cells in EC before, immediately after or 24 h after PUVA or UVA radiation, and quantitative determination of EC HLA-DR molecules using an indirect radioimmunoassay (RIA) technique did not reveal any difference between PUVA-treated and non-irradiated cells.

Cells, Cultured↗
PubMed1986

Isolation of pure functionally active CD8+ T cells. Positive selection with monoclonal antibodies directly conjugated to monosized magnetic microspheres.

A monoclonal antibody of the IgM isotype, ITI-5C2, which binds with high affinity to CD8 molecules, was directly conjugated to the monosized magnetic microspheres M-450. This permits selective removal of the CD8+ T cell subset (T8) from peripheral blood mononuclear cell suspensions in a rapid one-step procedure. With a low ratio of microspheres to cells (2:1), functionally active T8 cells can be recovered. In vitro experiments involving such positively selected T8 cells or recombinations of isolated T8 and T4 subsets, demonstrate that the presence of M-450 microspheres coated with ITI-5C2 do not interfere with the immunological functions of the positively selected cells. The method has possible application in the isolation of all cell populations where high avidity mAbs of appropriate specificity are available.

Antibodies, Monoclonal↗
PubMed1986

The role of the CD8-positive subset of T cells in proliferative responses to soluble antigens. I. Studies of healthy subjects, type 1 diabetics, and coeliac disease patients.

Using magnetic monosized polymer particles (M 450) coated with a monoclonal mouse IgM anti-CD8 (ITI 5C2) antibody, we were able to selectively remove and isolate functionally active CD8+ T cells from human peripheral blood mononuclear cells. Isolated CD8+ cells did not respond by proliferation to soluble antigens, but proliferated in response to phytohaemagglutinin. However, in the presence of CD4+ T cells, CD8+ cells were able to mount a substantial proliferation when stimulated with soluble antigens. Depletion of CD8+ cells decreased rather than increased the T-cell responses to the antigens glyc-gli, Coxsackie B4, and mumps in healthy individuals. We therefore found no indication of involvement of functionally-active CD8+ suppressor cells in vitro. The T-cell responsiveness to these antigens has previously been shown to be influenced by HLA-DR-associated restriction elements, but the tendency for decreased responsiveness to these antigens by CD8 depletion seemed independent of the DR type of the cell donors. As in healthy subjects, CD8 depletion resulted in a decreased responsiveness to the gluten antigen glyc-gli in untreated and treated coeliac disease patients and to Coxsackie B4 and mumps antigens in Type 1 diabetics.

Antigens, Viral↗
PubMed1986

Positive selection of activated T cells of the T8 (CD8) sub-type by immunomagnetic separation.

By conjugating a monoclonal IgM antibody of CD8-specificity to magnetite-containing polymer particles, we have developed a rapid and simple one-step procedure for positive selection of T8 cells. The method ensured good yield and viability of pure T8 cells. The positively selected T8-fraction from MLC activated T cells retained their cytolytic capacity and gave a moderate proliferative response. Most of the proliferative response occurred in the negatively selected T4 population which showed only a marginal cytotoxic activity against PHA blasts as target cells. Transferrin receptor expression, as measured in a direct radiobinding assay, could also be demonstrated both among pure T4 and T8 cells upon MLC-activation.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1986

HLA class I and II typing using cells positively selected from blood by immunomagnetic isolation--a fast and reliable technique.

This paper describes a new cell isolation and HLA typing technique, which permits cell separation and HLA class I or class II typing to be performed in 70 min. Magnetic monodisperse microspheres (Dynabeads TM) were coated with monoclonal antibodies (MAbs) specific for the CD8 T cell antigen or for HLA class II monomorphic epitopes. They could then be used to obtain HLA class I or class II positive cells directly from ACD blood in approximately 15 min by the use of magnetic separation. The cells (attached to the microspheres) were subsequently used in microcytotoxic HLA typing (total incubation time of 55 min) using acridin orange/ethidiumbromide to stain viable (yellow) and dead (red) cells. It was found that this immunomagnetic (IM) HLA typing technique was specific, has a sensitivity superior to that observed for conventional microcytotoxicity assays and gave low background staining. IM HLA-ABC typing of 50 healthy donors and 10 patients and IM HLA-DR typing of 25 healthy donors and 30 patients gave results corresponding well with that obtained independently by conventional HLA typing (concordancy rates 92-100%). Furthermore, the IM HLA typing technique permitted reliable HLA class II typing of blood cells from six patients where conventional HLA class II typing was impossible. The IM HLA typing technique also enables HLA class I and II typing to be quickly and reliably performed on cells from ACD blood of cadaveric donors.

Antibodies, Monoclonal↗
PubMed1986

Suppressive effect of monocytes in vitro in patients with carcinoma of the uterine cervix.

The adherent cell fraction (AdC) of human peripheral blood mononuclear cells (PBM) contains two cell types of opposing function in vitro. Dendritic cells (DC) act as antigen-presenting cells (APC) in vitro, while monocytes (Mo) have a suppressive effect on antigen activation of T cells. In this report we show that patients with cervical carcinoma have a significantly increased number of suppressive Mo compared with healthy controls. The T cell response to Herpes Simplex Virus (HSV-1) and PPD was about the same in the two groups, but after removal of Mo by adherence a significantly higher T cell response was seen among the patients with advanced stage (Figo stage IIb-IVa) compared with patients in early stage (Figo stage Ia-IIa) and healthy controls. These observations indicate that patients with cervical carcinoma have an increased number of T cells reactive with HSV, and normal DC function. The relative suppression expressed on a per Mo basis was the same in all groups, which indicates that the increased suppression in the patients was caused by an increased number of Mo, and not by changes in their activation state.

Adenocarcinoma↗
PubMed1986

The role of the CD8-positive subset of T cells in proliferative responses to soluble antigens. II. CD8-positive cells are not responsible for DR-associated differences in responsiveness to mumps and Coxsackie B4.

The role of CD8 (T8, Leu 2)-positive T lymphocytes in the proliferative T-lymphocyte response to mumps and Coxsackie B4 viral antigens in vitro was investigated. The frequency among enriched T-lymphocyte blasts of antigen-reactive T lymphocytes (ARTL) restricted by different DR-associated elements was investigated, using antigenic restimulation with allogeneic antigen-presenting cells in a limiting dilution assay. A decreased frequency of DR3-restricted and an increased frequency of DR4-restricted mumps and Coxsackie B4 ARTL were seen in the limiting dilution assay, whether or not HLA class I determinants were shared in the antigenic restimulation. Removal of CD8-positive cells did not increase the primary in vitro responsiveness to mumps and Coxsackie B4 viral antigens, and did not change the DR-associated differences in the frequency of ARTL seen in the limiting dilution assay.

Antigen-Presenting Cells↗
PubMed1985

Thromboplastin (tissue factor) in plasma membranes of human monocytes.

The synthesis of thromboplastin, a potent trigger of blood coagulation, can be induced in human peripheral blood monocytes. Indirect evidence suggests that newly synthesized thromboplastin becomes in part available on the cell surface. We have attempted to study the localization and availability of thromboplastin more directly by isolating plasma membranes from isolated human peripheral blood monocytes. The specific activities of the plasma membrane markers increased 16-22-fold in these preparations with a recovery of about 15%. The contamination by mitochondria, lysosomes, nuclei and endoplasmic reticulum was low as estimated by marker enzymes and electron microscopy. In both unstimulated and stimulated monocytes thromboplastin was largely recovered in this plasma membrane fraction, providing direct evidence for its membrane localization. Phospholipase C (E.C. 3.1.4.3) is a potent inactivator of thromboplastin through its hydrolysis of the phospholipids necessary for thromboplastin activity [Otnaess, Prydz, Bjørklid & Berre (1972) Eur. J. Biochem. 27, 238-243]. About 70% of the total membrane thromboplastin activity was inactivated when whole cells were treated with phospholipase C and the membranes subsequently isolated. Following stimulation to induce thromboplastin synthesis, the plasma membranes showed a shift in their relative content of phosphatidylcholine and phosphatidylethanolamine consistent with a transmethylation process.

Cell Membrane↗
PubMed1985

Identification, at the genomic level, of an HLA-DR restriction element for cloned antigen-specific T4 cells.

Two T4 cell clones (TLC) specific for antigenic epitopes on Chlamydia trachomatis were studied. Using a panel of allogeneic antigen-presenting cells (APC), both TLC were found to be restricted by HLA class II elements closely associated with, but not identical to the DRw5S specificity, as determined by highly selected alloantisera, a monoclonal antibody (mAb), 109d6, and confirmed on the DNA level by determination of restriction fragment length polymorphisms (RFLP) with a DR beta probe. Furthermore, HLA-DR-specific mAb, including 109d6, but not other HLA class II- or class I-specific antibodies inhibited the two TLC, strongly suggesting that the restriction element is expressed by a DR molecule. Using digestion with Hind III restriction enzyme and a DR beta probe, we found a complete concordance between the appearance of a 9.3 kilobase band and the ability of allogeneic APC to restimulate the T cell clones. Thus, the restriction element for these T cell clones appear to be expressed by DR molecules, but can, at present, only be detected at the genomic level.

Antibodies, Monoclonal↗
PubMed1985

Enriched Langerhans cells express more HLA-DR determinants than blood-derived adherent cells (monocytes and dendritic cells).

When used as antigen-presenting cells, enriched Langerhans cells (LC) are known to induce a stronger proliferative T-cell response towards antigens than blood-derived adherent cells (a mixture of monocytes and dendritic cells). To study the mechanism behind this difference in accessory cell function, we have compared the quantitative expression of HLA-DR molecules on LC and adherent cells (AdC), using a radioimmunoassay system. The amount of HLA-DR determinants was calculated to be 50-100 times higher on LC than on AdC.

Antigen-Presenting Cells↗
PubMed1985

Dendritic cells and monocytes as accessory cells in T-cell responses in man. I. Phenotypic analysis of dendritic cells and monocytes.

A method is described for simple and rapid preparation of human dendritic cells (DC) and monocytes (Mo) from peripheral blood. The phenotype of enriched DC and Mo was determined and compared by means of a panel of monoclonal antibodies (Mab's). The distribution and quantitative expression of HLA class II molecules encoded by the subloci DP, DQ, and DR were the same on the two cell types. During in vitro culture a rapid decrease of class II antigens on Mo was observed, whereas the expression of class II antigens on DC was relatively stable. The absence of monocyte markers on DC may indicate that this cell type does not belong to the monocyte/macrophage cell lineage. The phenotypic analysis shows that peripheral blood DC also lack differentiation antigens expressed by epidermal Langerhans cells (OKT6) and lymph node follicular dendritic reticulum cells (DRC-1). The relationship between peripheral blood DC and tissue-localized DC thus remains unsolved. With relatively high numbers of DC now available, production of DC lineage-specific Mab's may be approached.

Antibodies, Monoclonal↗
PubMed1985

Dendritic cells and monocytes as accessory cells in T-cell responses in man. II. Function as antigen-presenting cells.

The main antigen-presenting cells (APC) of human blood are reported to be the dendritic cells (DC), whereas monocytes (Mo) are only weakly or not at all capable of inducing T-cell immune responses to the soluble antigen purified protein derivative (PPD). In contrast, we found Mo to have a suppressive effect on the APC function of DC in vitro. Removal of Mo by adherence resulted in an increased APC activity, even though Mo produce more interleukin 1 (Il-1) than DC. Furthermore, addition of the prostaglandin synthesis inhibitor indomethacin gave rise to increased Il-1 production, HLA-class II expression, and a stronger antigen-specific T-cell response to PPD. Taken together, our studies indicate that the superior accessory cell function of DC compared with Mo in in vitro cultures may, at least partly, be attributed to the prostaglandin E2 production by Mo and more stable expression of HLA-class II molecules on DC.

Animals↗
PubMed1985

Relative efficiency of human Langerhans' cells and blood derived dendritic cells as antigen-presenting cells.

T4 cells recognize antigens together with HLA class II molecules in the membrane of antigen-presenting cells (APC). The magnitude of the induced T cell response is in part dependent upon the APC's amount of MHC-class II molecules. Langerhans' dendritic cells (LC) express 50-100 times more HLA-DR molecules than monocytes (Mo) and blood derived dendritic cells (DC). We report here that LC are more efficient APC than DC from the same donor, indicating that the APC capacity of dendritic cells isolated from different organs is correlated to their expression of HLA class II gene products.

Antigen-Presenting Cells↗
PubMed1985

Tissue thromboplastin generation in circulating mononuclear phagocytes and development of coagulation disorders during E. coli endotoxinaemia in pigs.

Tissue thromboplastin generation in monocytes was studied during various stages of Escherichia coli endotoxinaemia in pigs. The pigs were monitored in halothane anaesthesia and mechanically ventilated. Blood was sampled from the superior caval vein before and during endotoxin infusion and up to 6 hours after its start. Monnuclear leukocytes were harvested with Lymphoprep separation and monocyte counts were made, using TRITC-labelled sheep erythrocytes, acridine orange and a fluorescence microscope. Thromboplastin was quantified in a two-stage assay by incubating the test sample together with purified factor X, factor VII and Ca++. The generated factor Xa was thereafter assayed. There was statistically significant increase of tissue thromboplastin activity in monocytes after endotoxin infusion. Maximum level was reached at the end of the infusion and was maintained throughout the observation period. Decrease occurred in platelets, leukocytes, antithrombin III, fibrinogen and clotting factors V, VII and VIII, and clotting time was prolonged. These findings indicated significant disseminated intravascular coagulation. The endotoxin-stimulated monocytes with their elevated tissue thrombo-plastin activity thus may play an important part in development of the DIC which so often follows septicemia.

Animals↗
PubMed1984

Antigen-specific T cell clones restricted by DR, DRw53 (MT), or DP (SB) Class II HLA molecules. Inhibition studies with monoclonal HLA-specific antibodies.

T lymphocyte clones (TLCs) specific for Chlamydia trachomatis were obtained after limiting dilution of activated T cells from a single donor, BS (HLA-A3; B7,15; DR1, 4; DRw53; DPw4). Most of the proliferative TLCs obtained apparently used restriction elements on DR1 or DR4 molecules, expressed in the antigen-presenting cells (APC). The restriction pattern of two TLCs, however, closely followed the DRw53 specificity, while one TLC seemed to be restricted by elements on DPw4 molecules. A panel of murine monoclonal antibodies (Mabs) was employed to further dissect the restriction specificities. The proliferative capacity of some of the TLCs was studied with and without Mabs directed against different HLA molecules, using non-T cells, monocytes, and peripheral blood dendritic cells as APC. Two Mabs, 7.2 and D-54, which seem to detect monomorphic determinants on HLA-DR, inhibited both DR- and DRw53-restricted TLCs. One Mab, 109d6 which reacts with DRw53 determinants, selectively inhibited the DRw53-restricted TLCs. The DP-restricted TLC was not inhibited significantly by any tested Mabs, including two Mabs with putative specificity for monomorphic determinants on the DP molecule.

Antibodies, Monoclonal↗
PubMed1984

Humoral immunity and output of first-stage larvae of Elaphostrongylus rangiferi (Nematoda, Metastrongyloidea) by infected reindeer, Rangifer tarandus tarandus.

The use of an indirect immunofluorescence technique demonstrated that serum from reindeer, Rangifer tarandus tarandus, infected with Elaphostrongylus rangiferi (Nematoda, Metastrongyloidea) contained antibodies directed against antigen(s) on the cuticle of the parasites first-stage larvae (L1). Output of L1 from the male reindeer was low in the period June to August, but increased to a higher level during the rutting season (September to October). The titre of specific antibody showed an inverse pattern. In the female reindeer, larval output remained high throughout the sampling period from January to July. During this period antibody titre was low. A relationship between stress (rutting season or calving period), immunity and larval output is suggested.

Animals↗
PubMed1983

Stress causes reduced natural killer activity in mice.

The natural killer (NK) activity of spleen cells from C57B1/10 mice subjected to standardized stress conditions was reduced when compared with that of untreated controls. Both the total number of nucleated spleen cells and their cytotoxic activity against an NK-sensitive target were reduced. The reduction appeared after induction of stress, and the NK activity was reduced throughout an 8-day stress period.

Animals↗