Gebhard Schumann

Modulation of myelopoiesis by different bacterial cell-wall components: Induction of colony-stimulating activity (by pure preparations, low-molecular-weight degradation products and a synthetic low-molecular analog of bacterial cell-wall components) in vitro

Abstract Chemically pure preparations of three structurally unrelated components of the cell wall of gram-negative bacteria (BCWC), lipid A, outer-membrane lipoprotein, and murein, were tested for lymphocyte mitogenicity and the ability to induce colony-stimulating activity (CSA) in various serum-free tissue-culture systems. All three components were B-cell mitogens and induced CSA in spleen-cell cultures. However, in lymphnode-cell cultures the concentrations of these agents required for either mitogenicity or CSA induction differed markedly. Moreover, in contrast to thymidine incorporation, CSA induction was not influenced by pre-irradiation of the cells. Conversely, after removal of phagocytic cells with the iron-magnet technique, CSA was no longer inducible by BCWC, while lymphocyte proliferation was barely impaired. All three BCWC readily induced CSA release in cultures of adherent peritoneal cells without influencing the release of a cytoplasmic enzyme. BCWC-dependent CSA release from adherent peritoneal cells was not influenced by pretratment of the cultures with anti-immunoglobulin, but completely suppressed by preincubation with anti-macrophage-1.2 alloantiserum and complement. CSA induction in macrophage cultures was also achieved with a low-molecular-weight synthetic muramyldipeptide and degradation products of lipoprotein. The results suggest that the induction of CSA is not directly related to the mitogenic, immunogenic, or antigenic properties of the BCWC, but that BCWC-mediated CSA production is caused by a direct “hormone-like” interaction of the agents with mature macrophages.

Induction of tumouricidal leucocytes by the intranasal application of MTP-PE, a lipophilic muramyl peptide

SummarySingle intransal applications of MTP-PE, a lipophilic muramyl peptide, induce tumouricidal and tumouristatic leucocytes in the lungs of rats. In ex vivo assays the tumouristatic activity was detectable for 8 days after drug administration. By separation of the effector cells on Ficoll-Hypaque gradients, it was shown that both neutrophils and macrophages are responsible for this activity. Using the B16/BL6 melanoma system in mice, there was a high survival rate after repeated intranasal applications of MTP-PE

Mitogen induction of murine C-type viruses: II. Effect of B-lymphocyte mitogens

Abstract Various B-lymphocyte mitogens have been examined for their capacity to induce C-type virus in mouse spleen cells. Lipopolysaccharide (LPS) Escherichia coli , LPS Salmonella abortus equi , lipid A and tuberculin (purified protein derivative, PPD) were all inductive. 5-Bromo-2′-deoxyuridine amplified virus induction but not mitogenicity of LPS and PPD, when tested in BALB c and nu nu cells. Antibody against reverse transcriptase from Rauscher leukemia virus inhibited the enzyme of LPS- and PPD-induced viruses. Preexposure of cells to 500 R blocked virus induction. Spleen cells of C3H HeJ mice known to be resistant to the mitogenic action of LPS could not be induced by this agent but could still be induced by PPD.

New developments in drugs enhancing the immune response: activation of lymphocytes and accessory cells by muramyl-dipeptides

Recently, stimulation of host defence mechanisms has become a major goal of pharmacotherapeutic research. Immunopotentiating compounds exert their effects in different ways. On the one hand, they may enhance non-specific effector mechanisms operative in the resistance of infectious agents and to neoplastic cells. On the other hand, they may non-specifically increase specific immune responses elicited by the recognition of antigenic determinants. Of course, the two mechanisms operative in the resistance to infectious agents and to neoplastic cells. On may be mediated by the pharmacological activation of common target cells, that is macrophages and other accessory cells, such as polymorphonuclear leucocytes.

Mitogen induction of murine C-type viruses. III. Effect of culture conditions, age, and genotype.

Abstract Various parameters affecting the induction of endogenous C-type virus from mouse spleen cell cultures by lipopolysaccharide (LPS), a B-lymphocyte mitogen, have been examined. Virus induction and mitogenicity, as measured by stimulation of intracellular DNA synthesis, showed very similar dose-response patterns suggesting that they are linked phenomena. 5-Bromo-2′-deoxyuridine (BrdU) enhances the virus induction by LPS in a dose-dependent way with an optimum concentration of 5 μg/ml. When the cell concentration was varied, optimal conditions for virus release were found to be between 2 × 106 and 5 × 106 cells/ml. Age dependence of virus induction was examined by comparing the effects of LPS and BrdU in cultures from old and young BALB/c mice. Cells from old mice released more virus in response to LPS than those from young mice, but additional BrdU treatment caused no enhancement of virus release. The mitogenic effect of LPS was found to be very similar in cultures from old and young mice. Spleen cultures from several strains of mice showed differing response patterns. While BALB/c, C57BL/6, and AKR cultures all released virus in response to LPS, additional BrdU treatment enhanced virus release from BALB/c and C57BL/6 but not from AKR cells. Cultures of 129/J mice are stimulated to divide by LPS but they could not be induced to release virus by this drug alone or in combination with additional BrdU. These results suggest that in B lymphocytes stimulated by LPS expression of endogenous viral genes is a function of age as well as genotype unlike their mitogenic response to LPS.

Concanavalin A promotes bromodeoxyuridine induction of endogenous C-type virus in B cells

Abstract Spleen lymphocytes stimulated in vitro by concanavalin A, aT-cell mitogen, in the presence of bromodeoxyuridine, release C-type viruses. Since spleen cultures are noninducible by other T-cell mitogens in contrast to several inducing B-cell mitogens, we have analyzed the subpopulation of cells releasing virus following concanavalin A stimulation. In one approach lymphocyte suspensions were enriched for B or T cells by treatment with anti-Thy 1.2 plus complement or by nylon wool filtration, respectively. Mitogen-triggered virus release in these two enriched, as well as in reconstituted populations, was then measured. In a second line of investigation, increasing doses of X irradiation were used to preferentially block B- but not T-cell proliferation. Mitogen-stimulated virus release was also determined in these irradiated cultures. These methods independently demonstrated that the presence of both B and T cells was necessary for virus induction by concanavalin A in the presence of bromodeoxyuridine. Results of these experiments suggested that concanavalin A/bromodeoxyuridine-induced virus release occurred in a B-cell- through T-cell-dependent stimulation.

Tuberculin Shock in Mice: Relationship Between Systemic Reactions to Tuberculin and Endotoxin and Lack of Correlation Between Tuberculin Shock and Cellular Immunity to Tuberculin:

Summary Systemic reactivity to tuberculin was regularly induced after two injections of living BCG. In contrast, only a small proportion of mice was fatally shocked with PPD after a single iv or ip inoculation of mycobacteria. Single treatments with high doses of bacteria given either ip or into the foot pads together with Freunds adjuvant caused anaphylaxis rather than delayed tuberculin shock upon challenge with PPD. With regard to the conditions of induction and the time of occurrence there was a strict correlation between systemic hypersensitivity to PPD and sensitivity to endotoxin. In the period of increased sensitivity to endotoxin, PPD shock and endotoxin shock had an identical symptomatology. On the other hand, there was a complete lack of correlation between systemic tuberculin reactivity and manifestations of cell-mediated immunity such as skin reactivity, in vitro transformation of lymphocytes and inhibition of the migration of peritoneal exudate cells. These facts, as well as the demonstration of a small but decisive endotoxin activity in the PPD preparations used in this study, corroborate the view that systemic tuberculin reactivity is fundamentally a nonimmunological phenomenon.

Evidence supporting a physiological role for endogenous C-type virus in the immune system.

The discovery that sequences coding for C-type viruses were endogenous to the genome of a variety of vertebrates raised several important questions. Principal among these were the relationship of endogenous viruses to oncogenic C-type viruses and their putative function during normal differentiation and development of their host cells. Recently a possible link between endogenous virus expression and the development of spontaneous leukemia has been proposed by the work of Hartley and Rowe with AKR mice [1]. Reasons for the retention and expression of these viruses in normal cells, however, have been lacking.

Induction of tumouricidal macrophages by MTP-PE: its enhancement by a factor produced spontaneously by tumour cells.

Tumouricidal activity of rat alveolar macrophages is induced by MTP-PE in vitro. This tumouricidal activity is enhanced by a factor (tumour cell derived immunostimulating factor, TCIF) contained in tumour cell culture supernatants. TCIF is not species specific, since culture supernatants of rat MADB-200 as well as mouse B16 or Meth A tumour cells showed similar effects on rat alveolar macrophages. TCIF is not produced in cultures of normal cells, e.g. rat embryo cells. TCIF produced by MADB-200 tumour cells is relatively heat-stable and dialyzable. It is destroyed by treatment at pH 2 for 24 hrs. These results suggest that TCIF can participate in macrophage activation and could be of potential therapeutic value.

BIOLOGICAL EFFECTS OF AN ANTISERUM DIRECTED AGAINST ENDOGENOUS XENOTROPIC C-TYPE VIRUS

Publisher Summary This chapter discusses the biological effects of an antiserum directed against endogenous xenotropic C-type virus. Genetic information for C-type viruses is found in the cellular DNA of many vertebrate species. These endogenous viral sequences are inherited in the germ line in a Mendelian fashion. In an experiment described in the chapter, rabbit serum selected for its cytotoxicity on virally infected rabbit SIRC cells was found to have two biologically important effects. Anti-B/X serum suppresses the humoral immune response against SRBC and colony formation by pluripotent precursor cells present in bone marrow. The cytotoxic, immunosuppressive, and CFU-S suppressing activities of a single batch of anti-B/X serum are correlated. This batch showed complement-dependent cytotoxicity on virus-infected SIRC cells at a titer of 1:625, while it had no effect on infected SIRC cells. It was found that when included in Mishell–Dutton cultures, this serum suppressed the immune response against SRBC. At a final dilution of 1:1600, more than 50% suppression was still observed. When the immunosuppressive property of this serum batch was tested in vivo , half maximal suppression was observed near a dilution of 1:64-1:256.