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Biomedical subjects

H Northoff

Publications and source records attributed to H Northoff.

At least 91 records · Page 5Linked to original sources
PubMed1992

In vitro desensitization to lipopolysaccharide suppresses tumour necrosis factor, interleukin-1 and interleukin-6 gene expression in a similar fashion.

Like blood monocytes, the human monocytic cell line Mono Mac 6 can be stimulated by lipopolysaccharide (LPS) at 1 microgram/ml to produce high levels of cytokines. When Mono Mac 6 cells are stimulated for 4-6 hr at 1 x 10(6)/ml, supernatants contain tumour necrosis factor (TNF) at an average of 60 U/ml and interleukin-6 (IL-6) at an average of 1000 U/ml. IL-1 is not detected in the supernatant, but after three freeze-thaw cycles cell-associated IL-1 can be detected (100 U/ml) and with similar amounts of IL-alpha and -beta. Preculture of Mono Mac 6 cells with LPS at 10 ng/ml for 3 days results in cells refractory to subsequent stimulation by LPS at 1 microgram/ml. In the refractory desensitized cells, production of all three cytokines is down-regulated, with a more than 10-fold reduction in protein production. For all three cytokines, this desensitization appears to be regulated at the transcript level, with a strong reduction in specific mRNA as detected by Northern blot analysis. Furthermore, Mono Mac 6 cells can be stimulated by Staphylococcus aureus (LPS contamination less than 10 pg/ml) to produce cytokines. This type of stimulus is unable to overcome desensitization, in that the secretion of TNF in LPS-precultured Mono Mac 6 cells was 10- to 100-fold lower than in Mono Mac 6 cells without LPS preculture. These data show that desensitization in Mono Mac 6 cells affects all three cytokines tested and that it extends to other activating signals, such as staphylococci.

Antigens, Bacterial↗
PubMed1991

Studies on the interaction between interleukin 6 and human malignant nonhematopoietic cell lines.

We have previously reported on stimulation of clonal growth of cell lines from human solid tumors by recombinant human interleukin 3, recombinant human granulocyte-macrophage colony-stimulating factor, and recombinant human granulocyte colony-stimulating factor (W. E. Berdel et al., Blood, 73: 80-83, 1989; Exp. Hematol., 16: 510, 1988). Within an extensive screening program of hematopoietic growth factor activity on malignant cells, the effects of recombinant human interleukin 6 (rhIL-6) were tested on the growth (tritiated thymidine uptake and human tumor cloning assay) of 26 different human cell lines derived from a wide range of solid tumors (head and neck, 4; lung, 1; pancreatic, 1; gastric, 1; colorectal, 3; renal, 3; bladder, 1; prostate, 1; breast, 2; ovary, 2; choriocarcinoma, 1; sarcoma, 2; glioblastoma, 2; neuroblastoma, 2). rhIL-6 (dose range up to 10(4) IU/ml) caused no reproducible enhancement or inhibition of tritiated thymidine uptake by tumor cell lines from nonhematopoietic origin. Furthermore, 19 of the tumor cell lines were clonogenic in a capillary modification of the human tumor cloning assay. No reproducible stimulation of clonal growth by rhIL-6 was observed in any of the cells tested. Particularly, there was no sensitivity of those cell lines for rhIL-6, which were previously shown to be sensitive for recombinant human interleukin 3 and recombinant human granulocyte-macrophage colony-stimulating factor in this assay. On the other hand, there were no significant growth-inhibitory effects of rhIL-6 on the cell lines tested in this study. Further experiments showed no influence of neutralizing monoclonal anti-hIL-6 antibody on the growth of 3 kidney carcinoma cell lines, making autocrine growth-modulating loops for IL-6 in these lines unlikely. In conclusion, no major interactions between hIL-6 and the growth of the human malignant cell lines from nonhematopoietic origin tested were detected in this study.

Antibodies↗
PubMed1991

Sia-b1 and I antigens recognized by Mycoplasma pneumoniae-induced human cold agglutinins.

Postinfection cold agglutinins (CAs) with anti-Sia-b1 (i.e., anti-Sialo-branched) specificity frequently occurring together with anti-I CAs recognize antigenic determinants that are present on Oh red cells and are partially destroyed by endo-beta-galactosidase on the red cell surface. They differ markedly from the monoclonal anti-Sia-b1 FI CA, which recognizes an epitope not expressed on Oh cells, and resistant to the enzyme. On the other side, Sia-b1 determinants reacting with postinfection CAs share the characteristics of I determinants, with the exception that Sia-b1 determinants require sialyl groups as an immunodominant component. Five sera containing coexisting anti-Sia-b1 and anti-I CAs were tested against Oh and enzyme-treated group O red cells. The results are consistent with a postinfection autoimmune response against a sialo-type 2 structure common for Sia-b1 and I determinants, which could serve as a receptor for Mycoplasma pneumoniae.

Agglutinins↗
PubMed1991

Immunologic mediators as parameters of the reaction to strenuous exercise.

Both the unspecific and the specific branch of the immune system are triggered and governed by contact and by a set of cytokines, including interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor (TNF). These mediators, which are produced by activated macrophages and other cells, have also multiple (pleiotropic) effects on different cells and organs. While TNF and IL-1 have strongly proinflammatory effects and seem to play a critical role in clinical situations such as septic shock, IL-6 has more restorative effects by being the main inducer of the acute phase response of the liver. The monokines also induce fever and release of ACTH in the brain. Strenuous exercise leads to a significant elevation of cytokines in the serum thereby eliciting an acute phase response. Analysis of systemic cytokines in the serum of marathon runners by the 7TD1 cell line assay revealed that the observed activity is very likely IL-6.

Acute-Phase Reaction↗
PubMed1991

Cytokine response by human monocytes to Clostridium difficile toxin A and toxin B.

Clostridium difficile toxins A and B isolated from strain VPI 10463 were tested for induction of cytokine release by human monocytes. Toxin B at 10(-12) M activated human monocytes as measured by release of interleukin-1 (IL-1), tumor necrosis factor (TNF), or IL-6. These effects of toxin B were heat labile (51 degrees C, 30 min). Toxin B was as effective as bacterial lipopolysaccharides in inducing IL-1 beta but less effective in inducing TNF or IL-6. Toxin B and lipopolysaccharides were synergistic in induction of IL-1 beta, TNF, and IL-6. The toxin A preparation used was 1,000-fold less active than toxin B. Apart from the difference in activity, the two toxins showed identical patterns of reaction and there was no synergism between them. A short pulse with toxin B was sufficient to trigger IL-1 release. Toxin B was also extremely toxic for monocytes. The toxicity and the induced proinflammatory monokines (IL-1 and TNF) may contribute to the pathogenic mechanisms of C. difficile infection and pseudomembranous colitis.

Bacterial Proteins↗
PubMed1991

[Preliminary results of the DGTI Workshop for evaluating the reactivity of monoclonal anti-D].

Within a working group of the German transfusion society, a workshop was conducted to evaluate the reactivity of monoclonal anti-D supernatants. During this evaluation 10,000 samples were tested, including 325 Du-samples, with 3-5 IgM type antibodies and 3-4 IgG type antibodies, which were selected to also find 'D-variants'. In general, the reactivity with D+ red blood cells was good, and specific in respect to D negative samples. Some samples have been found to have a different pattern of reactivity than the monoclonal antibodies used. Dependent on the method and on the antibody, in some studies up to 100% of Du samples could be detected by anti-D of the IgM type. Some data indicate that the reaction with Du samples is not dependent on titer. In addition, in separate studies the data show a correlation of reactivity in respect to the Rh-phenotype (CcDuee greater than ccDuEe).

Antibodies, Monoclonal↗
PubMed1990

Anti-lipopolysaccharide-immunoglobulin (IgG-anti-LPS) therapy in intensive care patients following surgery from infectious disease.

In 18 intensive care patients the effect of a IgG-Anti-Lipopolysaccharide (Anti-LPS), was investigated in a randomized study following surgery after bacterial infections, mostly peritonitis. Fresh frozen plasma was administered during the first 5 postoperative days, containing either more than 65 micrograms/ml Anti-LPS in the therapy group or less than 12.5 micrograms/ml in the control group. The serum level of Anti-LPS was monitored. Clinical and chemical parameters were recorded to evaluate infectious complications and outcome of the patients. The mortality in the treatment group was not different from the control group with 30% (3 out of 10) and 25% (2 out of 8), respectively. No beneficial effect was observed either from the administration of Anti-LPS or from endogenously produced Anti-LPS on any clinical parameter in our patients.

Adult↗
PubMed1989

Inhibition of endotoxin-induced activation of human monocytes by human lipoproteins.

Toxicity of lipopolysaccharide (LPS) (endotoxin) is, to a large extent, mediated by the activation of monocytes/macrophages and subsequent release of monokines, such as interleukin-1 (IL-1) and tumor necrosis factor alpha (TNF-alpha). It is known that LPS binds readily to serum lipoproteins and that LPS-lipoprotein complexes are less toxic than unbound LPS. Here we present data analyzing the impact of the LPS-serum interaction at the cellular level. By measuring IL-1 TNF-alpha, and IL-6, the interaction of different LPSs or lipid A with human serum could be shown to prevent the activation of human monocytes. The amounts of LPS inactivated by normal human serum did not exceed 10 ng/ml. The LPS-inactivating capacity of serum was shown to be a function of the lipoproteins. Other serum components, such as naturally occurring anti-LPS immunoglobulin G, complement, or nutritive lipids, had no significant influence in our system. Our experiments suggest that serum lipoproteins control endotoxin-induced monocyte activation and monokine release.

Antibodies, Bacterial↗
PubMed1989

Lipopolysaccharide-free conditions in primary astrocyte cultures allow growth and isolation of microglial cells.

Primary rat astrocyte cultures were used to isolate a macrophage population that does not adhere to the confluent glial cells. The cells multiplied vigorously in coculture with astrocytes during the 14 d culture period, provided that functionally active lipopolysaccharide (LPS) was either absent or present in very low concentrations. Based on morphological, immunocytochemical, and pharmacological data, it was concluded that the isolated cells were microglia, the resident macrophages of the brain. The findings characterized them as a distinct cell population that shares features both of peritoneal macrophages and of astroglial cells. Like peritoneal macrophages, the isolated cells were able to phagocytize as shown by their ingestion of latex beads and uptake of L-leucyl methylester. Furthermore, they were immunocytochemically stainable by a specific monoclonal antibody (ED 1) against a macrophage-specific antigen (Dijkstra et al., 1985). They also synthesized prostaglandin E2 (PGE2) and secreted interleukin 1 (IL-1) upon stimulation with LPS. Upon stimulation with the ionophore A23187, PGD2, the predominant prostaglandin of the brain, was the major PG metabolite released by these cells. In contrast to peritoneal macrophages, microglial cells were able to multiply. Proliferation of microglial cells in coculture with astrocytes was suppressed when 2 ng LPS/ml or higher concentrations were added to astroglial culture media. These astrocyte cultures, which contained approximately 1% microglia, were used to investigate the influence of LPS on prostaglandin and IL-1 secretion in order to compare astroglial and microglial features. Increasing LPS concentrations induced increased PGE2 secretion, whereas PGD2 secretion was essentially unaffected by LPS. The critical influence of LPS contaminations in most of the commercially available animal sera used for astrocyte cultures on cellular composition in general and on metabolism of hormones and growth factors in particular is discussed.

Animals↗
PubMed1988

Cell-free-synthesized interleukin-6 (BSF-2/IFN-beta 2) exhibits hepatocyte-stimulating activity.

Secretory products of cultured human blood monocytes contain a hepatocyte-stimulating factor which is able to induce the acute-phase proteins alpha 2-macroglobulin and fibrinogen in rat liver cells. Total RNA was isolated from unstimulated and lipopolysaccharide-stimulated human monocytes and translated in a reticulocyte lysate. The capability of the cell-free synthesized proteins to induce the acute-phase proteins alpha 2-macroglobulin and fibrinogen was assayed in rat hepatocyte primary cultures and in the rat hepatoma cell line Fao. The products translated from the mRNA of lipopolysaccharide-stimulated human monocytes induced mRNAs for alpha 2-macroglobulin and fibrinogen and therefore contain hepatocyte-stimulating factor. The translation products of unstimulated monocytes had no effect. A cDNA containing the coding sequence for interleukin-6 (B-cell stimulatory factor 2, interferon-beta 2/26-kDa protein, interleukin HP1) derived from human T-cells cloned into the transcription vector pGEM4 was transcribed in vitro. Translation of the isolated RNA in a reticulocyte lysate led to the synthesis of a protein of about 25 kDa. This cell-free synthesized interleukin-6 exhibited hepatocyte-stimulating activity measured by the induction of beta-fibrinogen mRNA in Fao cells. Using an antibody against interleukin-6, two proteins of 22 kDa and 23 kDa were immunoprecipitated from the culture medium of lipopolysaccharide-stimulated human monocytes. These two proteins were not synthesized by unstimulated monocytes. When total RNA from unstimulated human monocytes and lipopolysaccharide-stimulated human monocytes and lymphocytes was subjected to Northern analysis and hybridized with the interleukin-6 cDNA, a strong hybridization signal corresponding to an RNA of about 1300 bases was detected only in the RNA from lipopolysaccharide-stimulated human monocytes, indicating that human monocytes express the interleukin-6 gene after stimulation. The data presented in this paper strongly suggest that hepatocyte-stimulating factor from human monocytes and interleukin-6 from T-cells are identical.

Animals↗
PubMed1988

Induction of alpha 1-acid glycoprotein by recombinant human interleukin-1 in rat hepatoma cells.

The induction of alpha 1-acid glycoprotein mRNA by recombinant murine interleukin-1, recombinant human interleukin-1 alpha, and recombinant human interleukin-1 beta has been studied in the rat hepatoma cell line Fao. Whereas the stimulatory capacities of recombinant human interleukin-1 alpha and recombinant murine interleukin-1 were almost identical, the concentrations of recombinant human interleukin-1 beta needed for half-maximal induction of alpha 1-acid glycoprotein mRNA were lower by three orders of magnitude. A 60-fold increase in alpha 1-acid glycoprotein mRNA levels was observed 18 h after the addition of recombinant interleukin-1 beta. In parallel albumin mRNA levels decreased to about 30%. The alpha 1-acid glycoprotein mRNA induction was strictly dependent on the presence of dexamethasone. For a full stimulation dexamethasone concentrations of greater than 10(-7) M were needed, whereas concentrations of less than 10(-12) M were ineffective. The increase in alpha 1-acid glycoprotein mRNA after recombinant human interleukin-1 beta was followed by a 36-fold stimulation in alpha 1-acid glycoprotein synthesis and secretion. When protein synthesis was blocked by either cycloheximide, puromycin, or emetine, the induction of alpha 1-acid glycoprotein mRNA by recombinant human interleukin-1 beta was impaired suggesting the involvement of a short-lived protein in the induction of alpha 1-acid glycoprotein mRNA.

Animals↗
PubMed1988

Carbimazole-induced immune haemolytic anaemia: role of drug-red blood cell complexes for immunization.

We report on a patient who developed acute intravascular immune haemolysis while receiving carbimazole. Serological studies revealed a strongly (3+) and a discretely positive (1+) direct antiglobulin test due to C3d and IgG respectively, and a very weak IgG autoantibody in the eluates. Serum from the patient contained specific carbimazole-dependent red blood cell (RBC) antibodies which reacted with all normal human RBC in the presence of free carbimazole as well as with RBC coated with the drug either in vitro or in vivo, although carbimazole itself is not detectable in plasma after oral administration. The results provide direct evidence for the sequence of the drug-RBC-antibody interaction and show that the RBC (and not plasma proteins) function as 'carrier-like' macromolecules in the immune response.

Aged↗
PubMed1987

Recombinant human B cell stimulatory factor 2 (BSF-2/IFN-beta 2) regulates beta-fibrinogen and albumin mRNA levels in Fao-9 cells.

Conditioned medium from human monocytes contains a partially characterized hepatocyte-stimulating factor that simultaneously elevates the mRNA levels of the acute-phase protein beta-fibrinogen and decreases albumin mRNA in rat hepatoma cells. We demonstrate that recombinant human B-cell stimulatory factor 2, which is identical to interferon-beta 2/26 kDa protein and interleukin-HP1, exhibits the same activity as hepatocyte-stimulating factor. Furthermore, a specific antibody against B-cell stimulatory factor 2 was able to inhibit hepatocyte-stimulating factor in conditioned medium from human monocytes. Our data show that hepatocyte-stimulating factor and B-cell stimulatory factor 2 are functionally and immunologically related proteins.

Albumins↗
PubMed1987

The inflammation mediators interleukin 1 and hepatocyte-stimulating factor are differently regulated in human monocytes.

Human peripheral monocytes can be induced by bacterial lipopolysaccharide to produce the inflammatory mediators interleukin 1 (IL 1) and hepatocyte-stimulating (HS) activity. IL1 and HS activities were separated by gel permeation chromatography. It is also shown that the two monokines are differently regulated. Evidence for this stems from the finding that monocytes cultured for 24 h lose their ability to produce IL1 in response to lipopolysaccharide, while synthesis of HS activity remains essentially unaffected.

Dose-Response Relationship, Drug↗