SufC hydrolyzes ATP and interacts with SufB from Thermotoga maritima.

Genetic experiments in bacteria have shown the suf operon is involved in iron homeostasis and the oxidative stress response. The sufB and sufC genes that always occur together in bacteria are also found in plants, and even the malaria parasite, associated with the plastid organelle. Although the suf operon is believed to encode an iron-dependent ABC-transporter there is no direct evidence. By immunolocalization we show here that SufB and SufC are associated with the membrane of Escherichia coli. We also present kinetic studies with a recombinant version of SufC from Thermotoga maritima that shows it is an ATPase and that it interacts with SufB in vitro.

Antimalarial activity in vitro of the glyoxalase I inhibitor diester, S-p-bromobenzylglutathione diethyl ester.

S-p-Bromobenzylglutathione diethyl ester induced toxicity in the malarial parasite Plasmodium falciparum in infected human red blood cells in culture. The median inhibitory concentration, IC50, was 4.77 +/- 0.12 microM (N = 10) for incorporation of [3H]hypoxanthine in nucleotide synthesis and 5.20 +/- 0.1 microM (N = 10) for incorporation of [14C]isoleucine into protein. The prospective mechanism of action is inhibition of glyoxalase I by the de-esterified metabolite, S-p-bromobenzylglutathione, and accumulation of the cytotoxic substrate methylglyoxal.

Respective role of polymorphonuclear leukocytes and their integrins (CD-11/18) in the local or systemic toxicity of lipopolysaccharide.

The role of neutrophils (PMNs) and leukocyte integrins was investigated in two models of lipopolysaccharide (LPS)-induced toxicity: the systemic lethality assay in D-galactosamine-sensitized mice and the local reaction elicited by intradermal injection of LPS and tumor necrosis factor (TNF) at 24-h intervals. In the local reaction, depletion of PMNs with an anti-PMN monoclonal antibody (mAb) and mAbs against CD-11a (or LFA1) and CD-11b (or CR3) completely prevented the hemorrhagic necrosis. Evaluation of histological sections and myeloperoxidase levels suggested different mechanism of protection because PMNs were abundant in anti-CD-11- and absent in anti-PMN-treated mice. In the systemic assay, depletion of PMNs ensured 100% survival, whereas after administration of anti-CD-11a or b mAb, the percentages of survivors were 6 and 59%, respectively. One hour after LPS injection, the serum TNF-alpha level was higher in PMN-depleted mice than in controls. These studies provide evidence that neutrophils are essential for the expression of local or systemic LPS-induced injury, whereas the requirement for their leukocytic integrins is obvious only in the local reaction.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.