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I Hilgert

Publications and source records attributed to I Hilgert.

At least 73 records · Page 4Linked to original sources
PubMed1981

Different efficiency of mercurascan in allograft survival prolongation in male and female mice.

The efficiency of mercurascan on prolongation of skin allograft survival was found to depend on the sex of experimental animals. Long-term treatment of the recipients by MSC in the mouse strain combination B10--B10.LP (donor X recipient, difference in non-H-2 loci) was more efficient in females than in males. The immunosuppressive effect of MSC was weak. MSC had no effect on the survival time of skin or heart allografts in a strain combination with limited H-2 differences [B10.D2--M(504)]. The effect of MSC on the cell membrane was followed in vitro by measurement of the rate of H-2 antigen redistribution on lymphoid cells of animals treated in vivo by MSC. The rate of redistribution on lymphoid cells from MSC-treated females was decreased; no effect was observed in the case of cells from treated males.

Animals↗
PubMed1980

Lentil lectin effectively induces allotransplantation tolerance in mice.

The interaction of lectins with carbohydrate receptors on the plasma membrane of eukaryotic cells results in a wide variety of biological effects. One effect which has been extensively studied is the stimulation of lymphocytes to blastogenesis and proliferation. High doses of concanavalin A (Con A) and phytohaemagglutinin (PHA) have been shown to activate in vitro regulatory cells capable of suppressing proliferation of other cells in the culture. However, Con A and PHA treatment were used effectively to prolong the survival of skin and heart allografts before it was recognised that some lectins have an activatory effect on suppressor cells in vitro. A possible explanation of these tolerogenic effects is the activation of specific suppressor cells. In this letter we have compared systematically various lectins differing in their carbohydrate specificity and mitogenicity in relation to their ability to induce prolonged skin allograft survival in mice with the aim of selecting the most effective lectin tratment schedule. Some preliminary results of this study have been mentioned in a recent review.

Animals↗
PubMed1980

Isolation, characterization and biological activities of verotetrone from a mutant strain of Streptomyces aureofaciens.

A new metabolite denoted as verotetrone was isolated from the mycelium of the mutant strain Streptomyces aureofaciens NMG-2. Interpretations of physical data concerning verotetrone and its triacetate and, the determination of its degradation product indicate that verotetrone belongs to pretetramide-type metabolites. Verotetrone exhibits neither antibacterial nor antifungal activity. In vitro it inhibits the synthesis of nucleic acids as well as proteins in Ehrlich ascites carcinoma cells. Both verotetrone and its triacetate interfere in vivo with the metabolism of tumour and lymphoid cells, exhibiting antitumour or immunosuppressive activity. This activity, which is more intense with verotetrone than with its triacetate, is detectable in a dose which is already toxic in some animals.

Animals↗
PubMed1980

The regulatory role of I-J subregion in neonatal tolerance induction to H-2D alloantigens.

The mechanism of neonatally induced transplantation tolerance was studied in two mouse strain combinations involving differences at the D region of the H-2 complex only or at the same D region plus I-J subregion (including I-E, I-C, S and G regions). In the strain combination with the H-2D difference only, cells from tolerant mice proliferated markedly in the MLR assay when incubated with antigens tolerated in vivo, whereas the MLR reactions were negative in the combination with D plus I-J region disparities. In the latter combination cells from tolerant mice also did not respond to third-party antigens and their incubation with the tolerated antigens led to the suppression of cell proliferation. This non-specific suppression was absent in cells from tolerant mice in the strain combination, which differed in I-C, S, G and D alloantigens. Specific suppressor cells, which inhibited the development of cytotoxic cells, were demonstrated in tolerant mice of both strain combinations. The results show that, in additon to the specific suppressor cells induced by H-2K or H-2D alloantigens, nonspecific suppressor cells induced by the I-J region disparity that may regulate the resultant activity against H-2D (and probably also H-2K) alloantigens are involved in transplantation tolerance.

Animals↗
PubMed1980

Partial purification and separation of H-2 antigens by free-flow preparative electrophoresis.

The membrane fraction of murine spleen cells was solubilized by autolysis in 0.25% potassium cholate and 3M potassium chloride, and the solubilized membrane components were fractionated by ultrafiltration and preparative free-flow electrophoresis. This procedure yielded partially purified fractions with enriched specific antigenic activities. The H-2Ka and H-2Da antigens were found to possess distinctly different electrophoretic mobilities.

Animals↗
PubMed1979

Induction of suppressor cell mechanism in antilymphocyte serum-induced skin allograft tolerance in mice.

In the B10.D2 leads to B10.D2(M504) strain combination (H-2D incompatibility), 20--40% of skin allografts survive for more than 100 days in ALS-treated recipients. Allograft tolerance in ALS-treated recipients could not be abolished by adoptively transferred normal or immune syngeneic spleen cells, but it could be adoptively transferred by spleen or lymph node cells to sublethally irradiated syngeneic mice. The suppressive activity of transferred cell population markedly declined after treatment with anti Thy-1.2 serum and complement. Cells with suppressor activity could be demonstrated by adoptive transfers as early as 5 days after skin grafting and ALS treatment. The results showed that the long-term allograft-promoting effect of ALS was caused not only by a decrease in the graft-rejection cell potential of the recipients (as demonstrated by other authors earlier) but also by the activation of a T cell-mediated suppressor mechanism.

Animals↗
PubMed1978

Evidence of suppresssor cell-mechanism of allograft tolerance induced by spleen extract and hydrocortisone.

The mechanism of allograft tolerance in mice induced by cell-free spleen extract in combination with hydrocortisone was investigated. HC potentiated tolerance induction when given after the spleen extract. When HC was given before, or during the first 2 weeks of antigenic treatment, it counteracted rather than potentiated the tolerance-inducing effect. Spleen or lymph node cells transferred from tolerant donors to untreated or sublethally irradiated syngeneic recipients suppressed the recipients' response to the particular alloantigens. The suppressive activity of lymphoid cells from tolerant donors was abolished when before their transfer the subpopulation of T cells was eliminated by means of anti Thy-1.2 serum and complement. This finding suggests that suppressor T cells may be involved in tolerance induced by spleen extract and hydrocortisone.

Animals↗
PubMed1977

The involvement of a suppressor mechanism in neonatally induced allograft tolerance in mice.

The possible involvement of a suppressor cell mechanism in neonatally induced allograft tolerance was tested in two different mouse-strain combinations. In an H-2 incompatible donor-recipient combination presented by the congeneic strains B10.D2 and B10.D2(M504), adoptive transfer of tolerance with 5 X 10(7) spleen cells to syngeneic sublethally (400 R) irradiated recipients was successful resulting in a markedly prolonged test graft survival or even take. The result of tests for negative tolerance (which should be suceptible to abolition by means of cells from normally reactive donors) did not indicate that neonatally induced tolerance across the given barrier rested on this principle. The suppressor mechanism seemed to be involved in neonatally induced allograft tolerance also in the other strain combination (B10-40NX).

Animals↗
PubMed1977

Effect of mercurascan and tetracycline on ischaemia-altered immunogenicity of liver extract alloantigens in mice.

The action of Mercurascan and Tetracycline on ischaemic liver in mice was investigated. The effect was reflected in different immunogenicity (in allotrasplantation reaction) of liver extracts 1 mg. membrane fraction) derived from treated and normal organs in the donor--recipient strain combination B10--B10.LP. In the recipients treated with a single administration of extract from ischaemic liver the survival time of skin grafts was shortened as compared to the untreated control group and the control group given normal liver extract. Immunogenicity of the liver extracts from Mercurascan- or Tetracycline-treated mice was diminished.

Animals↗
PubMed1977

Antitumour and immunosuppressive activity of hydroxyanthraquinones and their glucosides.

Both isomeric monohydroxyanthraquinones (1a, b), three dihydroxyanthraquinones (alizarin 1c, chrysazin 1d, and anthraflavin 1e) and corresponding acetylated (2) and free (3) beta-D-glucosides were screened for antitumour and immunosuppressive activity. Furthermore, four O-acetyl and O-benzyl derivatives of alizarin (5a--d) were tested. Antitumour activity was judged by the inhibition of growth of syngeneic tumours in the treated recipients and immunosuppressive activity by the effect on tumour growth or on skin graft survival in pretreated allogeneic recipients; as standard of reference served the activity of certain cancerostatic or immunosuppressive drugs used in clinical practice. 1-Hydroxyanthraquinone (1a), alizarin (1c), chrysazin (1d), acetylated glucoside of 2-hydroxyanthraquinone (2b), 2-benzylalizarin (5c), and 1-acetyl-2-benzylalizarin (5d) were found to exhibit antitumour activity. Distinct immunosuppressive activity was detected in alizarin (1c), acetylated glucoside of 1-hydroxyanthraquinone (2a), acetylated glucoside of 2-hydroxyanthraquinone (2b), acetylated glucoside of chrysazin (2d), 2-acetylalizarin (5a), and 1-acetyl-2-benzylalizarin (5d). The group of hydroxyanthraquinone glucodises (3a--3d) exhibited neither antitumour nor immunosuppressive activity.

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