Biomedical subjects

M Strath

Publications and source records attributed to M Strath.

12 recordsLinked to original sources

PubMed1992

Infection of IL5 transgenic mice with Mesocestoides corti induces very high levels of IL5 but depressed production of eosinophils.

Transgenic mice expressing interleukin 5 (IL5) have been demonstrated to show a lifelong high level eosinophilia. These mice were produced using a construct in which the dominant control region (DCR) of the human CD2 gene was ligated to a 10-kb fragment containing the mouse IL5 gene. The construct allows the expression of the IL5 gene under the control of its own promoter, but the DCR ensures constitutive expression by all T cells. Infection of these transgenic mice with Mesocestoides corti, which is itself a potent inducer of eosinophilia, increases serum IL5 to very high levels. This demonstrates that the transgenes retain inducibility, which is a feature of the endogenous gene. However, despite the high levels of IL5, the numbers of eosinophils in the blood, marrow, and spleen decrease during the period 1-4 weeks after infection. Furthermore, there is a decrease in eosinophil precursors, as assessed by the capacity of bone marrow to produce eosinophils in culture. After this decrease eosinophils return to their previous high levels, although the levels of IL5 remain high. These results suggest that a control mechanism is operating to limit the numbers of eosinophils produced. This control appears to act at the level of the precursor production and may not be directly related to the high levels of IL5.

Animals↗

PubMed1991

Structure-function analysis of interleukin-5 utilizing mouse/human chimeric molecules.

Interleukin-5 (IL5) is a T cell derived glycoprotein that stimulates eosinophil production and activation. In the mouse, but apparently not in the human, it is active on B cells. The murine and human IL5 polypeptides exhibit 70% sequence similarity and yet display distinct species-specific activity. Whilst mouse and human IL5 are equally active in human cell assays, human IL5 is 100-fold less active than murine IL5 in mouse cell assays. Two restriction sites were utilized to divide the human and mouse sequences into three fragments. Hybrid molecules consisting of all combinations of these fragments were constructed and expressed. In the human cell assays [using bone marrow or the erythroleukaemic cell line (TF-1)] all the hybrid proteins generated activity comparable to that of the human and mouse IL5. This implies that replacing different domains does not result in detrimental effects to the tertiary structure of the molecule. In the mouse cell assays [using bone marrow or the pro-B cell line (B13)] the hybrids clearly identified the importance of residues in the C terminus for biological activity. The changing of only eight residues in this region of human IL5, to those of mouse IL5, resulted in the hybrid producing biological activity comparable to mouse IL5. In addition, competition binding assays showed that this region probably interacts with the receptor.

Amino Acid Sequence↗

PubMed1991

Analysis of interleukin 5 receptors on murine eosinophils: a comparison with receptors on B13 cells.

The interleukin 5 receptor (IL-5R) on murine eosinophils and a mouse B cell line (B13) was investigated using iodinated murine IL-5 produced in the baculovirus system. Electrophoretic analysis of this recombinant protein identified a range of bands Mr 26,000 to 32,000 resulting from differential glycosylation. The specific activity and binding kinetics of the iodinated IL-5 (125I-IL-5) were essentially identical to unlabeled material. Both high-affinity (Kd approximately 50 pM) and low-affinity (Kd approximately 1 nM) receptor populations were identified on murine eosinophils. Approximately 50 high-affinity receptors and 10,000 low-affinity receptors were present. This was compared with approximately 2,000 high-affinity (Kd approximately 80 pM) and about 8,000 low-affinity (Kd approximately 3 nM) sites on B13 cells. An antibody that inhibits IL-5 binding to, and proliferation of, B13 cells (R52.120) was also shown to inhibit eosinophil proliferation, suggesting that eosinophils and B cells bear the equivalent IL-5 binding proteins.

Animals↗

PubMed1990

Eosinophilia in transgenic mice expressing interleukin 5.

Experiments in vitro suggest that although interleukin 5 (IL-5) stimulates the late stages of eosinophil differentiation, other cytokines are required for the generation of eosinophil progenitor cells. In this study transgenic mice constitutively expressing the IL-5 gene were established using a genomic fragment of the IL-5 gene coupled to the dominant control region from the gene encoding human CD2. Four independent eosinophilic transgenic lines have thus far been established, two of which with 8 and 49 transgene copies, are described in detail. These mice appeared macroscopically normal apart from splenomegaly. Eosinophils were at least 65- and 265-fold higher in blood from transgenics, relative to normal littermates, and approximately two- or sevenfold more numerous relative to blood from mice infected with the helminth Mesocestoides corti. Much more modest increases in blood neutrophil, lymphocyte, and monocyte numbers were noted in transgenics, relative to normal littermates (less than threefold). Thus IL-5 in vivo is relatively specific for the eosinophil lineage. Large numbers of eosinophils were present in spleen, bone marrow, and peritoneal exudate, and were highest in the line with the greatest transgene copy number. Eosinophilia was also noted in histological sections of transgenic lungs, Peyer's patches, mesenteric lymph nodes, and gut lamina propria but not in other tissues examined. IL-5 was detected in the sera of transgenics at levels comparable to those seen in sera from parasite-infected animals. IL-3 and granulocyte/macrophage colony-stimulating factor (GM-CSF) were not found. IL-5 mRNA was detected in transgenic thymus, Peyer's patches, and superficial lymph nodes, but not in heart, liver, brain, or skeletal muscle or in any tissues from nontransgenics. Bone marrow from transgenic mice was rich in IL-5-dependent eosinophil precursors. These data indicate that induction of the IL-5 gene is sufficient for production of eosinophilia, and that IL-5 can induce the full pathway of eosinophil differentiation. IL-5 may therefore not be restricted in action to the later stages of eosinophil differentiation, as suggested by earlier in vitro studies.

Animals↗

PubMed1988

Isolation, structure and expression of cDNA and genomic clones for murine eosinophil differentiation factor. Comparison with other eosinophilopoietic lymphokines and identity with interleukin-5.

Eosinophil differentiation factor (EDF) is a recently described regulator affecting eosinophil growth and activation. cDNA clones for murine EDF were isolated by direct expression from libraries prepared from the T cell hybrid NIMP-TH1. The longest cDNA clone obtained was 1534 bp in length encoding a polypeptide of 133 amino acids. Two variant cDNAs suggesting alternative RNA processing events were detected. The EDF gene was cloned from a genomic lambda library and a region of 6727 bp encompassing the gene was sequenced. The gene contains three introns 829, 1875 and 79 bases in length and has numerous repetitive sequences. A common, possible regulatory element, including a conserved decamer, lies adjacent to the TATA boxes of the EDF and granulocyte-macrophage colony-stimulating factor (GM-CSF) genes and similar sequences are present in some other lymphokine genes. Recombinant EDF produced in monkey COS cells strongly stimulated the eosinophil lineage and also showed B-cell-growth factor II (BCGFII) activity whereas recombinant murine interleukin-3 and GM-CSF showed much broader activity towards the different myeloid lineages, were less active on eosinophils and had no BCGFII activity. The BCGFII activity of recombinant EDF together with a comparison of the BCGFII (interleukin-5) cDNA sequence with that of the EDF cDNA establishes that these two activities are the properties of a single polypeptide.

Animals↗

PubMed1987

Schistosoma mansoni: evidence that immunity in vaccinated and chronically infected CBA/Ca mice is sensitive to treatment with a monoclonal antibody that depletes cutaneous effector cells.

Naive mice, mice vaccinated 4 weeks previously with radiation-attenuated cercariae of Schistosoma mansoni and mice infected 16 weeks previously with normal S. mansoni cercariae were treated with a rat monoclonal antibody (NIMP-R14), that has been reported elsewhere to recognize neutrophils selectively. The establishment of a primary schistosome population in naive mice was not affected by the administration of this reagent. In contrast, immune-dependent challenge elimination was reduced in both vaccinated and chronically infected mice following treatment with NIMP-R14. Maximal suppression of resistance in both vaccinated (67% mean reduction) and chronically infected (44% mean reduction) mice was achieved when NIMP-R14 was injected intraperitoneally on the day of challenge. The monoclonal was markedly less effective when administered on or after day 3. Analysis of the blood leucocyte profiles of vaccinated/NIMP-R14 treated mice showed that the monoclonal totally abrogated neutrophils from the peripheral circulation between days 1 and 6. Histological examination of the skin site of challenge revealed, however, that NIMP-R14 treatment had reduced the number of eosinophils and macrophages as well as neutrophils in the cutaneous tissues of vaccinated mice. The reaction site thus more closely resembled that of naive/challenged mice than that of untreated vaccinated/challenged mice. Although we have not been able to identify a specific effector cell from these studies, we have demonstrated clearly that a skin-located cellular effector mechanism contributes to immune resistance in both murine models.

Animals↗

PubMed1986

Detection of eosinophil differentiation factor and its relationship to eosinophilia in Mesocestoides corti-infected mice.

Eosinophil differentiation activity has been identified using a simple assay to detect eosinophil differentiation in vitro. Two factors were involved in this activity: eosinophil differentiation factor (EDF, Mr 32-64K) and IL-3 (Mr 19-44K). In this paper it is shown that eosinophil differentiation activity (EDA) can be detected in the serum of mice undergoing eosinophilia induced by Mesocestoides corti. This serum activity is shown to follow the ability of spleen cells to produce EDF after stimulation with parasite antigen or pokeweed mitogen. The activity in mitogen stimulated spleen supernatant (MSSS) and serum has a mean Mr of 38K (range 26K-58K). IL-3 is detectable in MSSS but not in serum. The appearance of the EDA is accompanied by an increase in eosinophil precursors in the bone marrow. These reach a peak at about eight to 16 days. A significant blood eosinophilia was detected by 16 days, reaching a peak at 24 days, although blood levels are a poor indicator of the number of eosinophils reaching the tissues. Eosinophils were present in large numbers in the spleen by 14 days and in the peritoneal exudate by 21 days. At peak levels, 5 X 10(7) eosinophils could be recovered from the peritoneal exudate.

Animals↗

PubMed1985

Detection of eosinophils using an eosinophil peroxidase assay. Its use as an assay for eosinophil differentiation factors.

A colorimetric assay for peroxidase has been applied to the detection of eosinophils in bone marrow cultures and tissue cell suspensions. The substrate solution consists of 0.1 mM o-phenylenediamine in 0.05 M Tris-HCl buffer pH 8.0 containing 0.1% Triton and 1 mM hydrogen peroxide. The method is shown to be an easy and reproducible method of detecting eosinophils, with insignificant interference from neutrophils.

Amitrole↗

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↗