Th2-induced airway mucus production is dependent on IL-4Ralpha, but not on eosinophils.
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Mucus hyperproduction in asthma results from airway inflammation and contributes to clinical symptoms, airway obstruction, and mortality. In human asthmatics and in animal models, excess mucus production correlates with airway eosinophilia. We previously described a system in which TCR transgenic CD4 Th2 cells generated in vitro were transferred into recipient mice and activated in the respiratory tract with inhaled Ag. Th2 cells stimulated airway eosinophilia and a marked increase in mucus production, while mice that received Th1 cells exhibited airway inflammation without eosinophilia or mucus. Mucus could be induced by IL-4-/- Th2 cells at comparable levels to mucus induced by IL-4+/+ Th2 cells. In the current studies we dissect further the mechanisms of Th2-induced mucus production. When IL-4-/- Th2 cells are transferred into IL-4Ralpha-/- mice, mucus is not induced, and BAL eosinophilia is absent. These data suggest that in the absence of IL-4, IL-13 may be critical for Th2-induced mucus production and eosinophilia. To determine whether eosinophils are important in mucus production, IL-5-/- Th2 cells were transferred into IL-5-/- recipients. Eosinophilia was abolished, yet mucus staining in the epithelium persisted. These studies show definitively that IL-5, eosinophils, or mast cells are not essential, but signaling through IL-4Ralpha is critically important in Th2 cell stimulation of mucus production. (+info)
The beta2-adrenergic agonist salbutamol is a potent suppressor of established collagen-induced arthritis: mechanisms of action.
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The therapeutic potential of salbutamol, a beta2-adrenergic agonist, was explored in collagen-induced arthritis. This study was based on a report that salbutamol, by elevating intracellular cAMP, inhibits IL-12 production by macrophages and dendritic cells, thus preventing Th1 development. Ten-week-old male DBA/1 mice were immunized by intradermal injection of type II collagen in CFA. Arthritis developed 15-30 days later and the mice were treated after onset of disease with salbutamol, 200 microgram i.p. After 10 days, the mice were sacrificed, and the hind paws were evaluated histologically. Salbutamol, 200 microgram daily or every other day, had a profound therapeutic effect on the clinical progression of arthritis, as assessed by clinical score and paw thickness. The therapeutic effect was dose dependent. Daily administration of 200 microgram of salbutamol offered the best protection against joint damage, as assessed by histology. In vitro, salbutamol reduced IL-12 and TNF-alpha release by peritoneal macrophages in a dose-dependent manner, as well as TNF release by synovial cells from arthritic mice. Ex vivo, draining lymph node cells of the salbutamol-treated arthritic mice showed a diminished CII-specific IFN-gamma production and proliferation. In vivo, salbutamol specifically blocked mast cell degranulation in joint tissues. In conclusion, salbutamol has important effects on the immunoinflammatory response and a significant therapeutic action in collagen-induced arthritis. (+info)
The effect of processing on inflammatory markers in induced sputum.
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The effects of the mucolytic agent, dithioerythritol (DTE), and the temperature at which sputum processing is conducted on cellular and biochemical markers in induced sputum was assessed. Samples from healthy and atopic asthmatic subjects were treated with either DTE or phosphate-buffered saline (PBS) at 22 or 37 degrees C and compared for cell counts and concentrations of histamine, tryptase, eosinophil cationic protein (ECP), free interleukin (IL)-8, immunoglobulin (Ig)A, IL-8/IgA complexes and secretory component (SC). In addition, the influence of DTE on in vitro mediator release from blood eosinophils, basophils and bronchoalveolar lavage (BAL) mast cells was studied. Processing with DTE improved cytospin quality and increased the cell yield and measurable ECP, tryptase, IgA and SC, but reduced levels of histamine in PBS-treated samples and had no effect on IL-8. Cell counts or mediator levels were similar when sputum was processed at 22 or 37 degrees C, even though DTE induced blood basophils and BAL mast cells to release histamine at 37 degrees C. In spiking experiments, recovery of added ECP, tryptase, total IL-8 and histamine from sputum was similar in DTE- and PBS-processed sputum, but reduced for free IL-8 in PBS-treated samples. In conclusion, dithioerythritol improves cell and mediator recovery without causing cell activation when sputum processing is conducted at room temperature. The extent of recovery depends on the mediator studied. (+info)
Reciprocal effects of interleukin-4 and interferon-gamma on immunoglobulin E-mediated mast cell degranulation: a role for nitric oxide but not peroxynitrite or cyclic guanosine monophosphate.
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We report that cultured rat peritoneal cells spontaneously synthesize nitric oxide and this is associated with active suppression of mast cell secretory function. Addition of interleukin-4 (IL-4) or the nitric oxide synthase inhibitor N-monomethyl-l-arginine to peritoneal cells inhibited nitric oxide synthesis and enhanced anti-IgE-mediated mast cell degranulation, measured as serotonin release. Interferon-gamma (IFN-gamma) completely overcame the enhancement of serotonin release and suppression of nitrite production induced by IL-4. Over several experiments, with or without IL-4 and/or IFN-gamma, serotonin release correlated inversely with nitrite production. On a cell-for-cell basis, non-mast cells produced approximately 30 times more nitrite than mast cells in peritoneal cell populations, with or without IFN-gamma stimulation. The nitric oxide donor S-nitrosoglutathione inhibited anti-IgE-induced serotonin release from purified mast cells, whereas 8-bromo-cyclic GMP, the guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, superoxide dismutase and the peroxynitrite scavenger uric acid, were without effect. We conclude that IL-4 and IFN-gamma reciprocally regulate mast cell secretory responsiveness via control of nitric oxide synthesis by accessory cells; the nitric oxide effect on mast cells is direct but does not involve cyclic GMP or peroxynitrite. (+info)
Reactivity of the immunoglobulin E in bovine gelatin-sensitive children to gelatins from various animals.
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It has been reported that most children who showed anaphylaxis to measles, mumps and rubella vaccines containing bovine gelatin as a stabilizer have anti-bovine gelatin IgE. The present study was designed to investigate the reactivity of IgE in bovine gelatin-sensitive children to gelatins from various animals, and the antigenic cross-reactivity between the gelatins. Serum samples taken from 10 children who showed anaphylaxis to vaccines containing bovine gelatin were used in this study. The level of anti-bovine gelatin IgE in these serum samples ranged from 11.0 to 251 Ua/ml. The IgE in most of the children reacted to kangaroo and mouse gelatins, to which they had had little or no exposure as a food or a vaccine stabilizer. The IgE binding to kangaroo and mouse gelatins was completely inhibited by bovine gelatin, whereas reciprocal inhibition was not complete, indicating that antigenic cross-reactivity is present between the mammalian gelatins. Only one child had strong IgE reactivity to fish gelatins, and this reactivity was not inhibited by bovine gelatin, indicating that no antigenic cross-reactivity exists between bovine and fish gelatins. Most of the children who displayed sensitivity to bovine gelatin showed IgE reactivity to other mammalian gelatins. This reactivity may be due primarily to the antigenic cross-reactivity between mammalian gelatins. (+info)
Surface and gene expression of immunoglobulin E receptors on mast cells and mast-cell numbers in interleukin-4-gene knockout mice.
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We quantified immunoglobulin E (IgE) on peritoneal mast cells of interleukin-4 (IL-4)-gene knockout (-/-) mice and wild-type (+/+) controls using a cytofluorometric method, and examined the expression of IgE receptors, estimated by quantifying the total binding of IgE on the mast cells of IL-4 (-/-) mice. The mast cells of IL-4 (+/+) mice, identified and measured using microscope fluorometry, had a fluorescence intensity five to six times higher than that of non-mast cells, while the mast cells obtained from IL-4 (-/-) mice had fluorescence intensities within the range of those of non-mast cells. Two weeks after an infection with Nippostrongylus brasiliensis, the fluorescence intensity of the mast cells of IL-4 (+/+) mice increased to a level about twice as high as that before immunization. However, no significant increase after infection was observed in IL-4 (-/-) mice. Furthermore, the mast cells of IL-4 (-/-) mice did not bind IgE when incubated with IgE at concentrations that saturated IgE receptors on the mast cells of wild-type controls, thereby indicating that the expression of IgE receptors on mast cells was impaired in the IL-4-deficient mice. Using a reverse transcription-polymerase chain reaction, we found gene expression of all three subunits (alpha-, beta- and gamma-chains) of the IgE receptor in IL-4 (-/-) like that in IL-4 (+/+) mice. The results thus suggest that the binding of IgE may be essential to induce the translation of mRNA to IgE-receptor proteins. We also observed that there were about twice as many peritoneal mast cells in the IL-4 (-/-) mice as there were in the IL-4 (+/+) mice, in both immunized and non-immunized animals. This was unexpected in view of previous findings suggesting that IL-4, in concert with stem cell factor and IL-3, stimulates the proliferation and differentiation of mast cells in vitro. (+info)
Inhibition of mast cell-dependent anaphylaxis by sodium salicylate.
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Sodium salicylate (NaSal) is a commonly used agent with a wide pharmacological spectrum. The objective of the present study was to investigate the effect of NaSal on anaphylaxis. NaSal (10-1 and 1 mm) significantly inhibited systemic anaphylaxis induced by compound 48/80 in rats. NaSal also significantly inhibited local anaphylaxis activated by anti-dinitrophenyl (DNP) immunoglobulin E (IgE). NaSal (10-1 and 1 mm) significantly inhibited histamine release from rat peritoneal mast cells (RPMC) activated by compound 48/80 or anti-DNP IgE. Northern-blot analysis demonstrated that a significantly reduced level of the mRNA of L-histidine decarboxylase was expressed in mast cells treated with NaSal, compared with that without NaSal. NaSal (10-2 and 10-1 mm) had a significant inhibitory effect on anti-DNP IgE-induced tumour necrosis factor-alpha secretion from RPMC. The level of cyclic AMP in RPMC, when NaSal (1 mm) was added, transiently and significantly increased about sixfold compared with that of basal cells. These results suggest a possible use of NaSal in managing mast cell-dependent anaphylaxis. (+info)
Linker for activation of T cells (LAT), a novel immunohistochemical marker for T cells, NK cells, mast cells, and megakaryocytes: evaluation in normal and pathological conditions.
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LAT (linker for activation of T cells) is an integral membrane protein of 36-38 kd that plays an important role in T cell activation. Using a rabbit polyclonal antibody generated against the cytosolic portion of LAT, we investigated the immunohistochemical expression of LAT in normal and pathological hematolymphoid tissues. LAT reacts with human T cells in paraffin sections, including decalcified bone marrow trephines. LAT appears early in T cells at the thymocyte stage and before TdT expression in embryos, and is expressed in peripheral lymphoid tissues, without restriction to any T cell subpopulations. In addition to T cells, natural killer (NK) cells (evaluated with flow cytometry), megakaryocytes and mast cells are also LAT-positive, whereas B cells and other myeloid and monocytic derived cells are negative. Tested on a total of 264 paraffin-embedded tissue biopsies, LAT reacted with the great majority (96.8%) of T/NK-cell neoplasms, covering the full range of T cell maturation. Although antibodies to both LAT and CD3 had a similarly high sensitivity in the staining of T/NK-cell lymphomas, when used in conjunction, they successfully identified a higher number of cases (98.4%). Atypical megakaryocytes from different hematological disorders, as well as mast cells in mastocytosis were also LAT-positive, but all neoplasms of B cell origin, Hodgkin's lymphomas, and several nonlymphoid malignancies were negative. These data indicate that the anti-LAT antibody may be of value to diagnostic histopathologists for the identification of T cell neoplasms. (+info)