Biomedical subjects

M Strath

Publications and source records attributed to M Strath.

26 records · Page 2Linked to original sources

PubMed1985

Identification of a lymphokine that stimulates eosinophil differentiation in vitro. Its relationship to interleukin 3, and functional properties of eosinophils produced in cultures.

Factors stimulating eosinophil differentiation in vitro have been studied by means of a liquid bone marrow culture system in which the number of eosinophils is estimated directly by morphology or indirectly by assay for eosinophil peroxidase. The results show that eosinophil colonies are not formed in agar, emphasizing the importance of the liquid culture system. Three types of evidence identify a novel lymphokine, eosinophil-differentiating factor (EDF). (a) Coordinate analysis of lymphokine activity in media conditioned by a panel of parasite antigen and another panel of alloantigen-reactive T cell clones indicates that EDF is distinct from interleukin 2 (IL-2), IL-3, and bone marrow proliferation activity (BMPA). (b) A T hybrid (NIMP-TH1) produces EDF but no IL-2, IL-3, interferon, or colony-stimulating factor. (c) Gel filtration of conditioned media (CM) indicates that NIMP-TH1 and a T clone (NIMP-T2) produce EDF (Mr 46,000). NIMP-T2 also produced IL-3 (Mr 26,000) but this was easily separated from EDF. IL-3 is also shown to have eosinophil differentiation activity (EDA) but this represents a very small proportion of the EDA in T2-CM. Fractionation of WEHI-3-CM indicates that EDA from this source has a similar elution profile to IL-3 (Mr 35-36,000). Furthermore, a comparison of the relative activities in purified IL-3 and WEHI-3-CM indicates that all the EDA can be attributed to the IL-3 in the latter. EDF is shown to stimulate production of eosinophils in long-term bone marrow cultures; the kinetics of eosinophil production suggests that EDF is acting on committed precursors in the bone marrow. The transient nature of eosinophil production suggests that precursors from multipotential stem cells are not produced. The eosinophils produced in these cultures are morphologically normal and functional in that they lysed sheep red blood cells coated with IgG1, IgG2a, and IgG2b, but not with IgM, IgA, or IgE. In addition, they were capable of adhering to and killing Schistosoma mansoni schistosomula.

Animals↗

PubMed1985

Production and functional properties of eosinophils from bone marrow cultures.

Bone marrow cultures have been established from mice infected with Mesocestoides corti and undergoing parasitic eosinophilia. In the absence of added conditioned medium, eosinophil differentiation ceases, and eosinophils are undetectable by 7 days, whereas neutrophil production continues over several weeks as with normal bone marrow. Eosinophil production can be induced by adding pokeweed mitogen-stimulated spleen supernatants (MSSS) or specific antigen-stimulated spleen supernatants (ASSS) produced from-spleen cells of M. corti-infected mice. In contrast to the continuous production of neutrophils, eosinophil production is transient, suggesting that there is no continued production of eosinophil progenitor cells in these cultures. More eosinophils are produced when MSSS is added at the initiation of cultures, compared to after a delay of 2 weeks, and establishing the cultures at 33 degrees C does not appear to enhance eosinophil production. The eosinophils produced are shown to express the eosinophil differentiation antigen defined by monoclonal antibody NIMP-R13, they produce eosinophil peroxidase in similar amounts to eosinophils taken from mice. They show normal phagocytic activity of antibody-coated erythrocytes and lyse red cells coated with antibodies of IgG1, IgG2a, IgG2b, but not IgM isotypes.

Animals↗

PubMed1985

Isolation of specific antigen-reactive T-cell clones from nude (nu/nu) mice infected with Mesocestoides corti.

Infection of nude mice with Mesocestoides corti results in spleen enlargement, with a decrease in percentage positive, but overall increase in Thy-1 positive cells. A low frequency of both parasite antigen-specific and alloantigen-reactive T-cell clones were isolated from the spleen, mesenteric lymph nodes, peritoneal exudate and Peyer's patches. The T-cell clones from spleen were found to express the antigens Thy-1, Lyt-1 and Lyt-2; furthermore, after stimulation with antigen in the absence of exogenous T cell growth factor (IL-2), they produced normal levels of haemopoietic growth factor (IL-3), bone marrow proliferation activity and eosinophil differentiation activity. A higher proportion produced IL-2 compared to clones from normal mice. The isolation of antigen-specific T-cell clones showing normal T-cell characteristics from young nude mice adds weight to suggestions that exposure to antigen results in significant extra-thymic T-cell maturation.

Animals↗

PubMed1985

The production of lymphokines by primary alloreactive T-cell clones: a co-ordinate analysis of 233 clones in seven lymphokine assays.

A total of 233 primary alloreactive T-cell clones have been tested for the production of interleukin-2 (IL-2), interleukin-3 (IL-3), immune(gamma) interferon (IFN) and granulocyte-macrophage colony-stimulating factor (CSF-2), B-cell growth factor I and II (BCGFI, BCGFII), and eosinophil differentiation factor (EDF). EDF was assayed by means of the eosinophil differentiation assay (EDA). Two principal correlations were observed: IL-3 was shown to be the major lymphokine detected in the bone marrow proliferation assay (BMPA) used to detect CSF-2, and there was a high correlation between the EDA and BCGFII. Subsequent work has suggested that this latter correlation is because a single factor is responsible for both activities. Apart from these two exceptions, and low level correlations probably due to the fact that different assays detect more than one lymphokine, there was no evidence for co-ordinate expression of lymphokines. There was a large variation in amounts of individual lymphokines produced. More clones produced multiple lymphokines than would be expected from independent control. Taken together, this pattern of regulation is consistent with the hypothesis that antigen stimulation of T cells results in the activation of all the lymphokine genes, but the amount of each produced is determined by secondary controlling mechanisms.

Animals↗

PubMed1984

Differentiation antigens on mouse eosinophils and neutrophils identified by monoclonal antibodies.

A panel of hybridomas secreting monoclonal antibodies (mAb) reacting with antigens on mouse eosinophils and neutrophils has been selected. It is shown that four mAb bind preferentially to eosinophils, recognizing antigens expressed between 5 and 25 times more densely on these cells than on neutrophils. One mAb reacts preferentially with neutrophils, binding an antigen about 12 times more common on these cells than on eosinophils. Four mAb are shown to react with both eosinophils and neutrophils, and also macrophages. These mAb confirm the presence of different differentiation antigens on both eosinophils and neutrophils, and show that the myeloid series express antigens not expressed on lymphocytes.

Animals↗

PubMed1983

Mouse immunoglobulin isotypes mediating cytotoxicity of target cells by eosinophils and neutrophils.

The cytotoxic activity of mouse eosinophils and neutrophils in the presence of antibodies of different isotypes has been studied. Mouse monoclonal anti-hapten antibodies of all the known mouse immunoglobulin isotypes have been used to coat hapten-coupled, 51Cr-labelled target cells. Two different target cells have been used, sheep red cells, as a model for intracellular killing, and BW cell line cells, as a model for extracellular killing. It is shown that both eosinophils and neutrophils lyse sheep red cells coated with IgG1, IgG2a and IgG2b and to a lesser extent IgG3. No killing is detected when sheep red cells are coated with IgM, IgA or IgD. Neutrophils, but not eosinophils are shown to lyse IgE-coated sheep red cells. When tested against BW cells, neutrophils have been found to induce high levels of 51Cr release in the presence of IgG1, IgG2a, IgG2b and IgE, but not when IgG3, IgM, IgA or IgD were used. In contrast, no killing of BW cells by eosinophils could be detected with any of the different antibody isotypes tested. However, it is shown that eosinophils are able to kill IgG-coated BW cells when hapten coupling is increased to maximum levels or when complement is added into the system, emphasizing our previous results showing that eosinophils require much higher levels of ligands than neutrophils to be effective. To test the possibility that eosinophils have a weak IgE receptor, complement was added to IgE-coated BW cells by means of a monoclonal IgM anti-Thy-1 antibody but no cytotoxicity was detected. It cannot be completely excluded that eosinophils have IgE blocking a putative IgE receptor.

Animals↗

PubMed1981

IgG and complement receptors on purified mouse eosinophils and neutrophils.

Mouse eosinophil and neutrophil receptors for IgG and complement have been examined by means of rosette formation, phagocytosis and 51Cr release assays, using mouse monoclonal antibodies and complement-coated sheep erythrocytes. Mouse eosinophils and neutrophils form a high number of rosettes in the presence of mouse complement but eosinophils show a higher requirement for complement molecules. Both types of granulocyte phagocytose complement-coated sheep erythrocytes very actively, although low levels of 51Cr release are obtained. Eosinophils and neutrophils show higher activity in the presence of IgG2b than in the presence of IgG1, and while both cell types are similarly active when the former antibody is used, neutrophils are the more active when IgG1 is used. However, it remains uncertain whether this is a result of the higher binding obtained with the IgG2b monoclonal antibody. Both cell types behave similarly at high antibody concentrations but neutrophils are the more active at high antibody dilutions. The 51Cr release assay is shown to be superior to the rosette assay at it allows comparisons between eosinophils and neutrophils at high antibody concentrations. A time course study indicates that highest values of phagocytosis of opsonized red cells are obtained after 5 minutes rather than the half to one hour incubation periods normally used.

Animals↗

PubMedDate not supplied

Antimalarial activity of rifampicin in vitro and in rodent models.

The antimalarial activity of rifampicin, a specific inhibitor of bacterial ribonucleic acid (RNA) polymerase, was confirmed with Plasmodium falciparum in vitro and with P. chabaudi in vivo. The viability of ring forms of P. falciparum, measured by [3H]hypoxanthine and [14C]isoleucine uptake, was significantly reduced within 5 h of exposure to 2.5 microM rifampicin, the 50% inhibitory concentration. Streptolydigin and tagetitoxin, other specific inhibitors of bacterial RNA polymerase, were much less effective as antimalarials. A rifampicin-tolerant sub-line of P. falciparum was selected in vitro. When released from drug pressure, the tolerant line showed appreciably greater rates of incorporation of precursors and growth than the parent line, but over a period of months these characteristics gradually reverted. Rifampicin was effective against a chloroquine-resistant line of P. falciparum and the rifampicin-tolerant line had increased chloroquine sensitivity. Treatment of patent parasitaemias of P. chabaudi in mice with more than 100 mg/kg rifampicin twice daily significantly reduced the parasitaemia within 24 h and parasites were barely detectable on blood films by the fourth day. Recrudescence occurred on release of drug pressure.

Aminoglycosides↗