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Biomedical subjects

G J Gleich

Publications and source records attributed to G J Gleich.

At least 199 records · Page 11Linked to original sources
PubMed1992

Platelet activation in the lung after antigen challenge in a model of allergic asthma.

The purpose of this study was to investigate whether platelets are activated and release their products in the human lung after antigen challenge. Using subsegmental antigen challenge as a model of asthma, bronchoalveolar lavage fluids from ragweed-allergic asthmatic subjects were assayed for the alpha granule products, platelet factor 4 (PF4) and beta-thromboglobulin (beta-TG), prior to challenge (baseline) and at 5 min and 19 h after challenge with ragweed antigen. Airway segments challenged with normal saline were used as controls. Five minutes after antigen challenge, levels of platelet products in BAL fluid were not elevated from baseline or normal saline control levels. However, 19 h after antigen challenge, a 10-fold increase in platelet products in BAL fluids was found. The mean PF4 levels increased from baseline and saline control values of less than 1.0 to 7.2 ng/ml (p less than 0.05) 19 h after antigen challenge. beta-TG increased from baseline and control levels of less than 1.0 to 6.6 ng/ml (p less than 0.05). Elevations in PF4 and beta-TG were highly correlated with each other (r = 0.98, p less than 0.0001). Levels of platelet products during the 19-h response correlated with albumin, with kinins, with the prostaglandins 6-keto-PGF1 alpha, PGE2, and PGF2 alpha, and with the eosinophil-derived proteins, eosinophil-derived neurotoxin and eosinophil peroxidase. We conclude that platelet activation in the lung is a feature of the late inflammatory response to antigen challenge and that platelets may play an important role in allergic inflammation and asthma.

Adult↗
PubMed1992

The effect of T-cell depletion on enhanced basophil histamine release after in vitro incubation with live influenza A virus.

A number of mechanisms participate in virus-induced asthma. Previously, we described enhanced basophil histamine release (HR) during an experimentally induced rhinovirus infection and after in vitro incubation of peripheral blood mononuclear cells (PBMC) with influenza virus. This study extends our previous observations and examines the effect of influenza A virus on basophil leukotriene C4 (LTC4) release as well as the effect of T-cell depletion on virus-enhanced basophil HR. PBMC were isolated from ragweed-allergic subjects and incubated with live influenza A virus or control medium (allantoic fluid). After incubation with influenza A, ragweed antigen (AgE) stimulated LTC4 and HR were enhanced (P less than 0.05). To further define the role of T cells in virus-enhanced basophil secretion, PBMC were isolated and divided into two aliquots. In one aliquot, T cells were removed by magnetic bead separation of mouse monoclonal anti-CD3-coated lymphocytes. T-cell-depleted and nontreated PBMC suspensions were incubated with influenza A or control medium, collected, and challenged with AgE to release histamine. Basophil HR was enhanced in the virus-treated group of PBMC that had not undergone T-cell depletion. In contrast, virus incubation did not enhance HR in the T-cell-depleted fraction. Finally, preliminary analysis of the supernate from virus-treated leukocytes indicates the presence of interferon-gamma. These findings suggest that T cells, and their cytokine products, play an integral role in the process by which viruses enhance basophil HR.

Adult↗
PubMed1992

Eosinophil activation and function in health and disease.

The emerging picture regarding the role of eosinophils in the immune response appears to be the following: IL-3 [in humans, (251)], and/or IL-1 [in the mouse system, (253)], then IL-5 and GM-CSF [which are secreted from activated T-cells at the inflammation sites or even from activated mast cells (346-348)] induce differentiation and proliferation of eosinophils in bone marrow. Other factors, such as PAF (303-309), C5a, soluble parasite products (259-261), or even IL-5 (139), serve as chemoattractants for eosinophils to the sites of allergic inflammation, usually around mucosal surfaces. Eosinophil survival and state of activation is enhanced by IL-5 (139). Eosinophils degranulate, thus releasing their toxic granule proteins by cross-linking Ig receptors, the most potent of which is sIgA, and the degranulation is enhanced by IL-5, IL-3, GM-CSF, and other factors or parasite products. Eosinophil degranulation can also be induced by complement, as well as PAF. The interplay of all these different mediators, and their effects on eosinophil function, is an integral part of the eosinophil's involvement in different disease conditions. Eosinophils appear to be involved in the pathophysiology of different diseases, in part, by releasing their toxic granule contents in tissues and causing tissue damage.

Animals↗
PubMed1992

Refractory periorbital edema in a 29-year-old man.

A 29-year-old man developed periorbital edema which was initially diagnosed as angioedema. Further clinical investigation by orbital CT and orbital biopsy showed this to be orbital pseudotumor. Immunofluorescence staining for major basic protein clearly demonstrated tissue eosinophilia and extracellular major basic protein deposition. Orbital pseudotumor can mimic angioedema or allergic rhinoconjunctivitis and should be familiar to allergists and primary care physicians. The demonstration of striking extracellular major basic protein in biopsy specimen implicates a role for eosinophils in the pathogenesis of this disease.

Adult↗
PubMed1992

Tissue eosinophilia and eosinophil degranulation in syndromes associated with fibrosis.

Eosinophilia has long been associated with endomyocardial fibrosis, but the involvement of the eosinophilia in fibrosis of other organs is unclear. To investigate this question, the authors tested whether tissue eosinophilia and eosinophil degranulation are present in syndromes associated with fibrosis. The authors used an indirect immunofluorescent technique to localize eosinophil granule major basic protein (MBP) in formalin-fixed, paraffin-embedded tissue specimens from 50 patients. Thirty-four specimens were obtained from patients with inflammatory fibrosis: 12 with idiopathic retroperitoneal fibrosis, seven with sclerosing mediastinitis, four with sclerosing cholangitis, and 11 with pulmonary fibrosis. The remaining 16 specimens were obtained from patients with noninflammatory fibrous proliferations: four with keloids, six with scars, three with Dupuytren's contracture and three with dense stromal fibrosis of the breast. Eosinophil infiltration and/or extracellular MBP deposition were observed in 28 of the 34 specimens (82%) from patients with inflammatory fibrosis, including 11 of the 12 cases of retroperitoneal fibrosis, five of the seven cases of sclerosing mediastinitis, all four cases of sclerosing cholangitis, and 8 of the 11 cases of pulmonary fibrosis. In contrast, eosinophil infiltration and MBP deposition were not observed in specimens from the 16 patients with noninflammatory fibrous proliferation (P less than 0.001). These results indicate that eosinophil infiltration and release of a granule protein, namely MBP, commonly occur in inflammatory fibrotic lesions.

Adult↗
PubMed1991

Role of pertussis toxin-sensitive G proteins in stimulus-dependent human eosinophil degranulation.

Stimulation of human normodense eosinophils with immobilized secretory IgA (sIgA) or IgG, or with the soluble stimulus, FMLP, triggers the exocytotic release of the granule protein, eosinophil-derived neurotoxin (EDN). In this report, we demonstrate that these stimuli also provoke an increase in phospholipase C-mediated phosphoinositide breakdown in eosinophils. Pretreatment of eosinophils with pertussis toxin (PTX) for 2 h irreversibly abolished the increases in phospholipase C activity and EDN release induced by immobilized sIgA or FMLP. In contrast, PTX treatment only transiently inhibited eosinophil activation induced by immobilized IgG. Maximal inhibition of IgG-stimulated phosphoinositide hydrolysis and EDN release occurred after 2 h of PTX pretreatment with PTX, followed by a gradual recovery of cellular responsiveness to immobilized IgG as the duration of PTX pretreatment was extended to 16 h. Activated PTX catalyzed the in vitro ADP-ribosylation of 41- and 44-kDa proteins in eosinophil membranes. A 2-h pretreatment of intact cells with PTX markedly reduced the pools of unmodified 41- and 44-kDa substrates available for subsequent ADP-ribosylation in vitro, suggesting that both proteins were substrates for PTX in intact eosinophils. Continuous exposure of eosinophils to PTX for times ranging from 2 to 15 h resulted in the gradual reappearance of unmodified 44-kDa protein, whereas the levels of unmodified 41-kDa protein were persistently reduced in PTX-treated cells. The time course of the decline and reappearance of unmodified 44-kDa substrate in PTX-treated eosinophils closely paralleled the changes in the responsiveness of these cells to immobilized IgG. These results suggest that the receptors for sIgA, FMLP, or IgG transduce activating signals for eosinophil degranulation through differential coupling to at least two PTX-sensitive G proteins.

1-Methyl-3-isobutylxanthine↗
PubMed1991

Glucocorticoids inhibit cytokine-mediated eosinophil survival.

Glucocorticoids characteristically induce eosinopenia in vivo and are effective for treating allergic and other eosinophilic disorders. We studied the effect of glucocorticoids on cytokine-induced survival of human eosinophils in vitro. Eosinophils were purified from normal or mildly atopic volunteers by Percoll density gradient and incubated for 4 days in the presence of cytokine plus steroid. Cell viabilities were determined by staining cells with fluorescein diacetate and propidium iodide. In the absence of glucocorticoids, human rIL-5 enhanced eosinophil survival in a dose-dependent manner, from 22 fM for a minimal effect to 2200 fM for maximal effect. When eosinophils were cultured with a submaximal concentration of rIL-5 (220 fM), dexamethasone, methylprednisolone, and hydrocortisone inhibited eosinophil survival in a dose-dependent manner. Inhibition was time-dependent and required at least 2 days' exposure of eosinophils to dexamethasone. Dexamethasone, methylprednisolone, and hydrocortisone at 1000 nM inhibited survival by 88 +/- 2, 66 +/- 9 and 37 +/- 7%. In contrast, estradiol and testosterone (1000 nM) had no effect on eosinophil survival. When eosinophils were incubated with varying concentrations of human rIL-5 and 1000 nM dexamethasone, survival inhibition was reduced at higher concentrations of human rIL-5, and completely abolished by human rIL-5 23,000 fM. Human recombinant granulocyte-macrophage CSF, human rIL-3, and human rIFN-gamma also enhanced eosinophil survival in a dose-dependent manner and dexamethasone (1000 nM) strongly inhibited cell survival when submaximal concentrations of these cytokines were used. The effects of dexamethasone were reversed by higher concentrations of granulocyte-macrophage CSF (10 U/ml) and IL-3 (3 ng/ml). However, even 1000 U/ml IFN-gamma did not overcome dexamethasone inhibition, indicating a difference between the mechanism of eosinophil survival induced by IFN-gamma and other cytokines. These results suggest that glucocorticoids exert a direct, inhibitory effect on eosinophil survival, which may be important in the treatment of allergic and other eosinophilic disorders. Antagonism of this effect by higher amounts of cytokine may be a mechanism for glucocorticoid resistance.

Cell Survival↗
PubMed1991

Administration of interleukin-2 (IL-2) results in increased plasma concentrations of IL-5 and eosinophilia in patients with cancer.

Peripheral eosinophilia is almost invariably observed during the course of interleukin-2 (IL-2) therapy and is frequently accompanied by the development of a capillary leak syndrome characterized by edema, weight gain, and oliguria. We studied five patients with advanced malignancy treated with IL-2. Eosinophilia was not present initially but developed in all patients late in the course of therapy, with counts ranging from 2,328/mm3 to 15,958/mm3. In all patients, there was a temporal relationship between the infusion of IL-2 and the appearance of elevated plasma concentrations of IL-5, a growth factor for eosinophils. Granulocyte-macrophage colony-stimulating factor was not detectable in plasma. IL-4 and gamma-interferon plasma levels were variably elevated. Plasma concentrations of major basic protein, a toxic eosinophil granule protein, began increasing before eosinophil counts increased. By the time of the third IL-2 infusion, high concentrations of major basic protein were present in all five patients (up to 5,600 ng/mL) and skin biopsies showed major basic protein deposition in the dermis. Four patients developed significant capillary leak syndrome and all of these patients showed markedly elevated major basic protein levels. The lowest peak plasma concentration of major basic protein (1,751 ng/mL) was observed in the one patient who did not develop edema and weight gain. These results suggest that IL-2 induces IL-5 leading to marked peripheral eosinophilia and extravascular eosinophil degranulation. The release of toxic eosinophil products at extravascular sites and in the circulation may contribute to the pathogenesis of the capillary leak syndrome complicating IL-2 therapy.

Aged↗
PubMed1991

Granulocyte/macrophage colony-stimulating factor and interleukin 3 release from human peripheral blood eosinophils and neutrophils.

Human peripheral blood eosinophils released eosinophil survival-enhancing activity when stimulated with the calcium ionophore, ionomycin. The release of activity was detected as early as 3 h after stimulation and was inhibited by an immunomodulating agent, cyclosporin A. The survival-enhancing activity was completely abolished by treatment with anti-interleukin 3 (IL-3) and anti-granulocyte/macrophage colony-stimulating factor (GM-CSF) monoclonal antibodies. Moreover, IL-3 and GM-CSF were measurable in ionomycin-stimulated eosinophil supernatants by immunoassay. Eosinophils produced approximately one-half as much IL-3 and one-fifth as much GM-CSF as ionomycin-stimulated mononuclear cells. Neutrophils also produced IL-3 and GM-CSF, but the amounts were less than those produced by eosinophils. These observations suggest a novel role for eosinophils in pathophysiology of allergic inflammation and host defense mechanisms.

Cell Survival↗
PubMed1991

Regulation of Ig-induced eosinophil degranulation by adenosine 3',5'-cyclic monophosphate.

We have investigated the effects of cAMP on Ig-induced human eosinophil activation. Stimulation of human normodense eosinophils with IgG- or secretory IgA (sIgA)-coated Sepharose beads induced cellular degranulation, as measured by the release of the granule protein, eosinophil-derived neurotoxin (EDN). Pretreatment with cAMP analogs (N6,O2,-dibutyryl adenosine-3,':5' cyclic monophosphate; 8-bromoadenosine 3':5' cyclic monophosphate; or N6-benzoyladenosine 3':5' cyclic monophosphate) or cAMP phosphodiesterase-inhibitors (theophylline or isobutylmethyl xanthine (IBMX] strongly inhibited Ig-induced human eosinophil degranulation. The beta-adrenoceptor agonists, isoproterenol and salbutamol, induced relatively low level increases in intracellular cAMP, and weakly suppressed EDN release induced by IgG-coated beads. However, cellular pretreatment with IBMX synergistically enhanced the inhibitory effects of isoproterenol or salbutamol on both IgG and sIgA-induced eosinophil degranulation. Similarly, PGE2 treatment increased intracellular cAMP concentrations in eosinophils and correspondingly inhibited the Ig-dependent cellular degranulation response: co-incubation with IBMX further enhanced both effects of PGE2. Finally, cholera toxin, which irreversibly activates the stimulatory guanine nucleotide-binding protein linked to adenylyl cyclase, strongly inhibited the release of EDN from IgG- or sIgA-stimulated eosinophils. The time-dependent accumulation of cAMP in cholera toxin-treated cells closely paralleled the time courses of inhibition of IgG- and sIgA-induced EDN release after toxin exposure. These data indicate that the cAMP-dependent signal transduction mechanism in eosinophils exerts a negative modulatory effect on the cellular degranulation responses induced by sIgA or IgG. The inhibitory effects of cAMP on eosinophil activation may provide an important physiologic and a clinically relevant therapeutic mechanism for limiting the release of eosinophil-derived cytotoxic proteins during certain allergic or inflammatory responses in vivo.

1-Methyl-3-isobutylxanthine↗
PubMed1991

Eosinophil and neutrophil degranulation in ophthalmic lesions of Wegener's granulomatosis.

Although eosinophils and neutrophils have been identified in orbital and corneoscleral tissues in some patients with Wegener's granulomatosis, their role in the pathogenesis of the disorder is not completely understood. Nine specimens from six patients with Wegener's granulomatosis and autopsy controls from patients without ophthalmic disease were evaluated with indirect immunofluorescence for eosinophil granule major basic protein and neutrophil elastase. Extracellular deposition of both major basic protein and elastase was identified in orbital tissues from all the patients with Wegener's granulomatosis. Two of the specimens were from enucleated eyes with corneoscleral disease; extracellular deposition of eosinophil major basic protein was identified in one eye, and extracellular neutrophil elastase was deposited in both eyes in lesional areas. None of the control tissues showed major basic protein or elastase deposition. These findings suggest that both eosinophils and neutrophils participate in the pathogenesis of the orbital and corneoscleral manifestations of Wegener's granulomatosis.

Blood Proteins↗
PubMed1991

Eosinophil infiltration and degranulation in Helicobacter pylori-associated chronic gastritis.

Eosinophil granules contain cationic proteins, including the major basic protein, which are toxic to mammalian tissue. While eosinophils have been observed to comprise part of the inflammatory reaction in acute Helicobacter pylori gastritis, the role of the eosinophil in the pathogenesis of chronic gastritis is unknown. We evaluated whether eosinophil infiltration and degranulation are associated with chronic gastritis and H. pylori infection. We studied eight patients with chronic H. pylori antral gastritis, three with chronic antral gastritis in the absence of H. pylori, 11 healthy age-matched volunteers without antral gastritis, and eight patients with H. pylori-negative chronic specific gastritis (three Crohn's antral gastritis and five Ménétrier's disease). Serial sections were stained with hematoxylin and eosin, with Giemsa, and by a specific indirect immunofluorescence technique for eosinophil granule major basic protein. Specimens were graded independently by three observers and scores of 0-3 were given for eosinophil infiltration and degranulation (0 = none to 3 = confluent infiltration and/or degranulation). In H. pylori antral gastritis, significantly greater eosinophil infiltration and degranulation were found compared to the normal group, Ménétrier's disease, and chronic H. pylori-negative gastritis. There was no significant difference between gastric Crohn's disease and H. pylori gastritis. The severity of chronic gastritis was significantly correlated with the eosinophil score. Eosinophil degranulation did not appear to be greater at or near sites of bacterial colonization in the H. pylori gastritis specimens. The results suggest that eosinophil infiltration and degranulation may be associated with H. pylori gastritis. We postulate that the release of toxic cationic proteins from eosinophils contributes to the inflammatory changes present in H. pylori gastritis.

Cell Degranulation↗
PubMed1991

Association of immunoreactive eosinophil major basic protein with placental septa and cysts.

A protein that is immunochemically indistinguishable from the major basic protein of the eosinophil granule is present at elevated concentrations in the plasma of pregnant women. Major basic protein has been localized to placental trophoblasts known as X cells. Because X cells are located in placental septa and septal cysts, we tested whether the numbers of these structures are correlated with plasma levels of major basic protein. Data analysis revealed strong positive correlations between maternal plasma major basic protein concentrations and the number of placental septa, septal cysts, and subchorial cysts and the presence of subchorial fibrin deposits. No significant correlation was found between plasma major basic protein levels and other variables examined, such as placental weight. Thus major basic protein is a specific marker for septa and cysts, presumably because it is an X-cell product. The study of major basic protein may aid in delineating the function and ontogeny of X cells, as well as their role in fibrin deposition and in septa and cyst formation.

Blood Proteins↗
PubMed1991

Evidence of ongoing mast cell and eosinophil degranulation in symptomatic asthma airway.

To assess whether mast cell and eosinophil (EOS) degranulation occurs in the airway of subjects with moderately symptomatic asthma, we have measured levels of preformed mast cell-derived mediators (histamine and tryptase) and EOS-derived mediators (major basic protein and EOS-derived neurotoxin) in bronchoalveolar lavage fluid (BALF) obtained from patients with symptomatic (N = 14) and asymptomatic asthma (N = 9) and patients without asthma (N = 6). Both the FEV1 (1.52 +/- 0.33 L:55% +/- 15% of predicted FEV1) and the forced expiratory flow at 50% (FEF50) (1.11 +/- 0.62 L/sec:26% +/- 14% of predicted FEF50) in the patients with symptomatic asthma were significantly lower than the corresponding values for FEV1 (3.16 +/- 0.45 L:86% +/- 10% of predicted FEV1) and the FEF50 (4.04 +/- 1.54 L/sec:71% +/- 25% of predicted FEF50) in the patients with asymptomatic asthma. Levels of histamine (4.8 +/- 5.0 ng/ml versus 0.2 +/- 0.2 ng/ml) (p = 0.05), EOS-derived neurotoxin (420.6 +/- 959.4 ng/ml versus 12.6 +/- 7.7 ng/ml) (p = 0.05), major basic protein (31.4 +/- 46.6 ng/ml versus less than 9 ng/ml) (p = 0.05), and percent EOSs (10.6% +/- 7.0% versus 1.1% +/- 0.9% of BAL cells) (p = 0.0006) were all significantly elevated in BALF from symptomatic compared to asymptomatic patients with asthma. The elevated levels of tryptase (13.2 +/- 14.8 ng/ml versus 3.9 +/- 3.9 ng/ml) in BALF from symptomatic compared to asymptomatic patients with asthma approximated, but did not reach, statistical significance. Spontaneous histamine release from BAL mast cells of symptomatic patients with asthma was 46% +/- 5% compared to 5% +/- 2% in asymptomatic patients with asthma. In response to antihuman IgE, histamine release from BAL mast cells recovered from asymptomatic patients with asthma increased to 25% +/- 10%, whereas in BAL mast cells of symptomatic patients with asthma, no anti-IgE potentiation of histamine release occurred. This study suggests that mast cell and EOS degranulation is ongoing in the airway of patients with moderately symptomatic asthma.

Adolescent↗
PubMed1991

Effect of steroids on immunoglobulin-induced eosinophil degranulation.

Because glucocorticoids are a mainstay in the treatment of asthma and other allergic diseases, we tested the effect of various steroid hormones on secretory IgA- and IgG-induced eosinophil degranulation in vitro. Human normodense eosinophils were purified by discontinuous Percoll density gradient, and hypodense eosinophils were obtained by culture of normodense cells with recombinant human interleukin (rIL)-5. Eosinophils were incubated with various steroids, including dexamethasone, hydrocortisone, methylprednisolone, estradiol, or dihydrotestosterone at concentrations from 10(-9) to 10(-4) mol/L. Sepharose 4B beads coupled to ovalbumin, secretory IgA, or IgG were added as targets of degranulation and incubated at 37 degrees C for 4 hours. In some experiments, rIL-5 was added to eosinophils before addition of beads to activate the cells. The release of eosinophil-derived neurotoxin was measured by radioimmunoassay as an index of degranulation. Dexamethasone (10(-9) to 10(-4) mol/L), hydrocortisone (10(-9) to 10(-4) mol/L), estradiol (10(-9) to 10(-7) mol/L), and dihydrotestosterone (10(-9) to 10(-4) mol/L) had no effect on normodense eosinophil degranulation. Methylprednisolone, 10(-5) mol/L, inhibited degranulation of normodense eosinophils up to 20%, whereas 10(-4) mol/L inhibited degranulation of hypodense eosinophils, up to 30%. Overall, no difference in inhibition by steroids was observed between normodense and hypodense eosinophils. rIL-5 enhanced immunoglobulin-induced eosinophil degranulation, but this effect of rIL-5 was not blocked by any of the steroids tested. These results suggest that eosinophil degranulation and rIL-5-mediated eosinophil activation are not direct targets of glucocorticoids and that the beneficial effects of glucocorticoids on allergic inflammation in vivo are not likely due to direct effects on eosinophil degranulation.

Cell Degranulation↗
PubMed1991

Release of eosinophil granule proteins during IgE-mediated allergic skin reactions.

To determine whether the eosinophil (EOS), a prominent component of human allergic skin reactions, releases its potentially pathogenic components in vivo, we appended collection chambers to the bases of unroofed skin blisters and challenged the sites for varying time periods with either pollen antigen (Ag) or buffer (B)-control solutions. In seven sensitive subjects, continuous challenge with pollen Ag consistently induced release of more major basic protein (MBP) and eosinophil-derived neutrophil (EDN) than did B solution. Low levels of both MBP and EDN were observed during the first hour with increased accumulation during the second to fifth hour. Comparison of Ag- versus B-challenged site responses in individual subjects demonstrated significantly higher levels of both MBP and EDN at Ag than at B sites during the second to fifth hour. Levels of both MBP and EDN in the second to fifth hour correlated significantly with histamine release in the same sites in the first hour (r = 0.66 and 0.83, respectively). Imprints of the skin bases of the chambers after 5 hours demonstrated variable numbers of EOS at the Ag-challenged sites and only occasional EOS at the B-challenged sites; most cells on the skin bases were neutrophils. However, immunofluorescence localization of MBP in biopsy specimens of the blister bases revealed striking extra cellular MBP deposition. These findings indicate that EOS components accumulate in vivo in IgE-mediated human skin reactions, even when prominent EOS accumulation is not visualized, possibly because the EOS are degranulated in the allergic-reaction site. Release of EOS components in these reactions may be linked to earlier mast cell activation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Eosinophil differentiation of human umbilical cord mononuclear cells and prolonged survival of mature eosinophils by murine EL-4 thymoma cell conditioned medium.

Umbilical cord mononuclear cells, HL-60 cells, HL-60 clones selected for eosinophil differentiation, and the eosinophil leukemia cell line EoL were tested for their ability to produce eosinophil peroxidase. HL-60 clones selected for eosinophil differentiation produced eosinophil peroxidase, as judged by staining of cells for cyanide-resistant peroxidase activity; however, these cells lost their ability to produce eosinophil peroxidase in long-term culture. In contrast, eosinophil precursors from human umbilical cord blood mononuclear cells stimulated with murine EL-4 conditioned medium (EL-4 CM) were regularly induced to eosinophil protein synthesis, including eosinophil peroxidase, major basic protein, eosinophil cationic protein, and eosinophil-derived neurotoxin, as assessed by cyanide-resistant peroxidase and immunofluorescence staining. This induction by EL-4 CM is either at the level of gene transcription or mRNA stabilization, as shown by the increase of total mRNA for eosinophil peroxidase, major basic protein, and eosinophil-derived neurotoxin by Northern blot analyses. Purified peripheral blood eosinophils incubated for 4 days with EL-4 CM had increased survival over control eosinophils. Moreover, this enhanced survival was specifically blocked by antiserum to interleukin 5. Our results suggest that the effects of EL-4 CM on human umbilical cord mononuclear cells and mature eosinophils are due to the presence of interleukin 5.

Animals↗