The regulation of human eosinophil function by cytokines

The potential role of recombinant hematopoietic colony-stimulating factors in preventing infections in the immunocompromised host

Hematopoietic colony-stimulating factors coordinate the proliferation and maturation of bone marrow and peripheral blood cells during normal hematopoiesis. Most of these factors are now available as recombinant human colony-stimulating factors, and preclinical and clinical testing is proceeding rapidly. Granulocyte and granulocyte/macrophage colony-stimulating factors have been the most extensively studied to date. In human clinical trials, granulocyte colony-stimulating factor improves neutrophil counts and function, reduces episodes of febrile neutropenia, improves neutrophil recovery after disease- or treatment-induced myelosuppression, and reduces the number of serious infections in several neutropenic disease states. Granulocyte/macrophage colony-stimulating factor has similar biological properties but may also improve eosinophil proliferation and function, and platelet cell recovery after myelotoxic bone marrow injury, Interleukin-1 boosts the effects of granulocyte colony-stimulating factor and granulocyte/macrophage colony-stimulating factor, but also may promote the resolution of established infections in conjunction with antibiotics. The therapeutic realities and future therapeutic implications of these agents for the therapy of infections, cancer and hemopoietic disorders are discussed.

Electrocardiographic changes and myocarditis in trichinellosis: a retrospective study of 154 patients

The frequencies of electrocardiographic (ECG) abnormalities and myocarditis were determined, retrospectively, among 154 cases of trichinellosis [101 males and 53 females, with a mean (S.D.) age of 35.60 (14.64) years] who were hospitalized at the University Hospital for Infectious Diseases in Zagreb, Croatia, over a 5-year period. Eighty-seven (56%) of the patients, most of them in the invasive phase of infection with Trichinella spiralis, were found to have abnormalities when examined by 12-lead, resting electrocardiography. The ECG disorder most frequently observed was a non-specific ventricular repolarization disturbance (with ST-T wave changes), followed by bundle-branch conduction disturbances, and sinus tachycardia. The other ECG disorders recorded, during various phases of the infection, were sinus bradycardia, right bundle-branch block, supraventricular and ventricular extrasystoles, low-voltage QRS complexes in standard limb leads, first-degree atrio-ventricular block, and atrial fibrillation. Eighteen (12%) of the patients were identified as cases of myocarditis (13 in the invasive phase and five in the convalescent) and two (1.3%) as cases of myopericarditis. One patient developed acute myocardial infarction 28 days after the onset of disease and died soon thereafter; an autopsy revealed multiple necroses and fibroses of the myocardium and thrombus of a coronary artery. Although ECG abnormalities appear to be a common feature of trichinellosis, especially during the invasive phase of the disease, they are rarely associated with a poor prognosis. A transient, non-specific, ventricular-repolarization disturbance is the abnormality most commonly observed.

In allergic asthma experimental exposure to allergens is associated with depletion of blood eosinophils overexpressing LFA-1

BACKGROUND

In atopic individuals, exposure to allergens is followed by recruitment of blood eosinophils in the target tissue. We investigated whether allergen inhalation challenge could result in depletion of blood eosinophils overexpressing adhesion molecules involved in eosinophil migration.

METHODS

Blood eosinophils were isolated from seven atopic asthmatic patients and seven control subjects and the "at baseline" expression of lymphocyte function-associated antigen-1 (LFA-1), macrophage antigen-1 (Mac-1) and very late antigen-4 (VLA-4) was assessed by monoclonal antibody staining and flow cytometry analysis. Asthmatic patients underwent allergen challenge and the expression of LFA-1, Mac-1 and VLA-4 by blood eosinophils was again evaluated 3 h and 24 h after allergen challenge.

RESULTS

As compared to controls, eosinophils from atopics showed at baseline enhanced LFA-1 expression (P=0.0012), but similar Mac-1 or VLA-4 expression (P > 0.1, each comparison). In atopics, the percentage and absolute number of blood eosinophils were significantly decreased 3 h after allergen challenge (P=0.001 and P=0.022, respectively) but returned to similar values to prechallenge values after an additional 21 h (P > 0.1). Allergen challenge was also followed by a significant decrease in LFA-1 expression by eosinophils, at 3 h (P=0.002) and at 24 h (P=0.038), while no changes in Mac-1 and VLA-4 were observed. A significant correlation between postchallenge decrease in LFA-1 expression and in blood eosinophilia, both expressed as percentage (r=0.88; P < 0.01) or absolute number (r=0.87; P < 0.01) was demonstrated at 3 h (r=0.88; P < 0.01) but not at 24 h (r=0.64, P > 0.05 and r=0.11; P > 0.05, respectively).

CONCLUSION

In allergic asthma, an early recruitment of blood eosinophils overexpressing LFA-1 occurs in the first hours after allergen challenge.

Independent prognostic value of eosinophil and mast cell infiltration in colorectal cancer tissue

Overall peritumoural inflammatory cell infiltration is a prognostic variable in solid tumours, but the survival-related impact of the individual cell types within the infiltrate has still not been fully evaluated and compared with the conventional disease classification. In the present study, the prognostic value of individual white cell counts in the peritumoural inflammatory infiltrate in colorectal cancer was assessed. Intra-operative tumour tissue samples from 584 patients undergoing elective surgery for colorectal cancer were included. None of the patients received pre- or post-operative adjuvant chemotherapy. Tissue blocks were cut from the periphery of the tumours and embedded in paraffin. All blocks included both tumour tissue and normal bowel tissue. Serial sections of 4 microm were analysed for tumour tissue inflammatory cell infiltration using a computer- and video-assisted microscope, which allowed semi-automated quantification of cells within a fixed area. Total white cells and individual counts of eosinophils, neutrophils, mast cells, lymphocytes, and plasma cells were evaluated in every tumour specimen. Stratification into four groups with similar numbers of events was used to dichotomize the cell counts with respect to survival. The median observation period was 61 (49-75) months. In a multivariate analysis including Dukes' stage, gender, age, peri-operative blood transfusion, tumour location, and counts of specific inflammatory cells, only advanced Dukes' stage ( p< 0.0001), high age ( p=0.0003), and tumour location in the rectum predicted poor survival, while high counts of eosinophils ( p=0.006) and mast cells ( p=0.02) predicted good survival. Tumour-associated eosinophilia and mastocytosis appear to be independent prognostic variables in colorectal cancer. Future studies should investigate the potential biological role of tumour tissue eosinophils and mast cells in the modulation of tumour growth.

Functional expression of transmembrane 4 superfamily molecules on human eosinophils

BACKGROUND

Transmembrane 4 superfamily (TM4SF) molecules are exclusively found on hematopoietic cells. Several members of the TM4SF are reported to be associated with other cell surface molecules, including integrins, and might participate in signal transduction, but little is known about their role on eosinophils. In the present study, we determined the expression and function of TM4SF molecules on human eosinophils.

METHODS

Surface expression of TM4SF molecules on purified peripheral blood eosinophils was examined using indirect immunofluorescence and flow cytometry. Purified eosinophils were incubated with anti-TM4SF monoclonal antibodies (mAbs) for up to 24 h. Eosinophil activation was evaluated by measuring eosinophil homotypic aggregation as well as changes in surface expression of CD11b or CD62L by flow cytometry.

RESULTS

Freshly isolated eosinophils expressed CD9, CD37, CD53, CD63 and CD81. Incubation with anti-CD9 mAb but not with anti-CD37, CD53, CD63 or CD81 mAb induced significant eosinophil homotypic aggregation. Incubation with any of the anti-TM4SF mAb for 30 min failed to alter the expression of either CD11b or CD62L on eosinophils. In contrast, the expression of CD11b was significantly enhanced after 24 h of incubation with anti-CD53 mAb, while the expression of CD62L was significantly reduced with anti-CD81 mAb.

CONCLUSIONS

Cross-linking of some surface TM4SF molecules induced significant eosinophil homotypic aggregation, upregulation of CD11b expression, or CD62L shedding, consistent with activation of eosinophils. Our data suggest that several TM4SF molecules are functionally expressed on human eosinophils, and therefore might participate in allergic inflammation.

Effect of prednisolone on cytokine synthesis in nasal polyps

To investigate steroid effects on eosinophils and their associated cytokines in nasal polyps, we sampled nasal polyp tissue from 20 subjects during routine surgery. Freshley removed polyps were cut into small pieces and incubated in culture medium for 24 h in different concentrations of prednisolone (10(-2)-10(-6) mol/L). Cell viability was assessed by means of trypan dye exclusion of the supernatants. The number of eosinophils was quantified by means of cytocentrifuge smears stained by May-Giemsa-Grunwald stain. The cytokine protein content of interleukin-5 (IL-5), IL-3, and granulocyte-macrophage colony-stimulating factor (GM-CSF) was measured by ELISA technique in supernatants and in homogenates of nasal polyp tissue. Our results revealed a significant reduction in the number of eosinophils and total number of vital cells at concentrations of 10(-3) and 10(-2) mol/L. GM-CSF and IL-5 protein levels were significantly reduced in supernatants and in homogenates after treatment with prednisolone, whereas IL-3 synthesis was not diminished. Corticosteroid effects known to inhibit synthesis of eosinophil-associated cytokines could be measured in terms of a significant decrease in IL-5 and GM-CSF protein level as well as in a decrease in the number of vital cells.

C/EBPβ and GATA-1 Synergistically Regulate Activity of the Eosinophil Granule Major Basic Protein Promoter: Implication for C/EBPβ Activity in Eosinophil Gene Expression

Eosinophil granule major basic protein (MBP) is expressed exclusively in eosinophils and basophils in hematopoietic cells. In our previous study, we demonstrated a major positive regulatory role for GATA-1 and a negative regulatory role for GATA-2 in MBP gene transcription. Further analysis of the MBP promoter region identified a C/EBP (CCAAT/enhancer-binding protein) consensus binding site 6 bp upstream of the functional GATA-binding site in the MBP gene. In the cell line HT93A, which is capable of differentiating towards both the eosinophil and neutrophil lineages in response to retinoic acid (RA), C/EBP mRNA expression decreased significantly concomitant with eosinophilic and neutrophilic differentiation, whereas C/EBPβ expression was markedly increased. Electrophoretic mobility shift assays (EMSAs) showed that recombinant C/EBPβ protein could bind to the potential C/EBP-binding site (bp −90 to −82) in the MBP promoter. Furthermore, we have demonstrated that both C/EBPβ and GATA-1 can bind simultaneously to the C/EBP- and GATA-binding sites in the MBP promoter. To determine the functionality of both the C/EBP- and GATA-binding sites, we analyzed whether C/EBPβ and GATA-1 can stimulate the MBP promoter in the C/EBPβ and GATA-1 negative Jurkat T-cell line. Cotransfection with C/EBPβ and GATA-1 expression vectors produced a 5-fold increase compared with cotransfection with the C/EBPβ or GATA-1 expression vectors individually. In addition, GST pull-down experiments demonstrated a physical interaction between human GATA-1 and C/EBPβ. Expression of FOG (F̲riendo̲fG̲ATA), which binds to GATA-1 and acts as a cofactor for GATA-binding proteins, decreased transactivation activity of GATA-1 for the MBP promoter in a dose-dependent manner. Our results provide the first evidence that both GATA-1 and C/EBPβ synergistically transactivate the promoter of an eosinophil-specific granule protein gene and that FOG may act as a negative cofactor for the eosinophil lineage, unlike its positively regulatory function for the erythroid and megakaryocyte lineages.

C/EBPβ and GATA-1 Synergistically Regulate Activity of the Eosinophil Granule Major Basic Protein Promoter: Implication for C/EBPβ Activity in Eosinophil Gene Expression

Eosinophil granule major basic protein (MBP) is expressed exclusively in eosinophils and basophils in hematopoietic cells. In our previous study, we demonstrated a major positive regulatory role for GATA-1 and a negative regulatory role for GATA-2 in MBP gene transcription. Further analysis of the MBP promoter region identified a C/EBP (CCAAT/enhancer-binding protein) consensus binding site 6 bp upstream of the functional GATA-binding site in the MBP gene. In the cell line HT93A, which is capable of differentiating towards both the eosinophil and neutrophil lineages in response to retinoic acid (RA), C/EBP mRNA expression decreased significantly concomitant with eosinophilic and neutrophilic differentiation, whereas C/EBPβ expression was markedly increased. Electrophoretic mobility shift assays (EMSAs) showed that recombinant C/EBPβ protein could bind to the potential C/EBP-binding site (bp −90 to −82) in the MBP promoter. Furthermore, we have demonstrated that both C/EBPβ and GATA-1 can bind simultaneously to the C/EBP- and GATA-binding sites in the MBP promoter. To determine the functionality of both the C/EBP- and GATA-binding sites, we analyzed whether C/EBPβ and GATA-1 can stimulate the MBP promoter in the C/EBPβ and GATA-1 negative Jurkat T-cell line. Cotransfection with C/EBPβ and GATA-1 expression vectors produced a 5-fold increase compared with cotransfection with the C/EBPβ or GATA-1 expression vectors individually. In addition, GST pull-down experiments demonstrated a physical interaction between human GATA-1 and C/EBPβ. Expression of FOG (F̲riendo̲fG̲ATA), which binds to GATA-1 and acts as a cofactor for GATA-binding proteins, decreased transactivation activity of GATA-1 for the MBP promoter in a dose-dependent manner. Our results provide the first evidence that both GATA-1 and C/EBPβ synergistically transactivate the promoter of an eosinophil-specific granule protein gene and that FOG may act as a negative cofactor for the eosinophil lineage, unlike its positively regulatory function for the erythroid and megakaryocyte lineages.

Theophylline inhibits the production of nitric oxide by peripheral blood mononuclear cells from patients with asthma

BACKGROUND

Nitric oxide (NO), a reactive free radical synthesized from L-arginine by the enzyme NO synthase (NOS), may play a role in many pathophysiologic conditions, including asthma.

OBJECTIVE

The aim of this study was to investigate whether peripheral blood mononuclear cells (PBMCs) from asthmatics would spontaneously produce NO. A second objective was to ascertain whether commonly used asthma medications would modulate the production of NO.

METHODS

PBMCs were isolated from 24 subjects (10 with asthma, 4 with allergic rhinitis and 10 healthy controls) and were incubated either alone or in the presence of an RNA polymerase inhibitor (actinomycin D, 1 microg/mL), a NOS inhibitor (L-NG-nitroarginine methyl ester [L-NAME], 1 mM), and L-NAME plus L-arginine (5 mM). Furthermore, PBMCs were incubated with or without addition of therapeutic concentrations of hydrocortisone (15 microg/mL), theophylline (15 microg/mL), albuterol (15 microg/mL) and ipratropium bromide (12 microg/mL). Culture supernatants were collected and assayed for NO production.

RESULTS

NO production was significantly elevated in asthmatics compared with the control group (1.39+/-0.21 microM versus 0.46+/-0.01 microM; P < .05). L-NAME significantly reduced NO production in asthmatics (0.83+/-0.06 microM; P < .05), an effect completely reversed by L-arginine. Theophylline blocked NO production in asthmatics (1.39+/-0.21 microM to 0.92+/-0.11; P < .05). There was no significant effect with any of the other medications.

CONCLUSION

This study suggests that theophylline may be antiinflammatory by inhibiting the L-arginine-dependent production of NO in patients with asthma.

IL-4-Dependent Regulation of TGF-α and TGF-β1 Expression in Human Eosinophils

TGFs play important roles in wound healing and carcinogenesis. We have previously demonstrated that eosinophils infiltrating into different pathologic processes elaborate TGF-α and TGF-β1. Eosinophils infiltrating hamster cutaneous wounds were found to express TGFs sequentially. In this study, we examined the biologic mediators that may regulate the expression of TGF-α and -β1 by eosinophils. Eosinophils were isolated from the peripheral blood of healthy donors and cultured in the absence or presence of IL-3, IL-4, and IL-5. Cells were analyzed by in situ hybridization and immunohistochemistry. Supernatants from these cultures were assayed for secreted TGF-α and TGF-β1 using TGF-specific ELISAs. IL-3, IL-4, and IL-5 independently up-regulated TGF-β1 mRNA and product expression by eosinophils in all donors. Interestingly, TGF-α production by eosinophils was up-regulated by IL-3 and IL-5 but was down-regulated by IL-4. Consistent with the ability of IL-4 to regulate eosinophil responses, IL-4 signaling molecules are present in human eosinophils. The observation that IL-4 can differentially regulate the expression of TGF-α and TGF-β1 suggests that IL-4 may serve as a physiologic molecular switch of TGF expression by the infiltrating eosinophils in wound healing and carcinogenesis.

Mechanisms of Transcription in Eosinophils: GATA-1, but not GATA-2, Transactivates the Promoter of the Eosinophil Granule Major Basic Protein Gene

Granule major basic protein (MBP) is expressed exclusively in eosinophils, basophils, and placental trophoblasts. To identify thecis-elements and transcription factors involved in regulating MBP expression, we subcloned 3.2 kb of sequence upstream of the exon 9 transcriptional start site (P2 promoter) and serial 5′ deletions into the pXP2 luciferase reporter vector. An 80% decrement in promoter activity was obtained when MBP sequences between bp −117 to −67 were deleted. To identify transcription factors that bind to and transactivate through the bp −117 to −67 region, we first compared the upstream genomic sequences of human and murine MBP; a potential GATA binding consensus site was conserved in the 50-bp region between the two genes. To determine which GATA proteins bind this consensus site, we performed electrophoretic mobility shift assays (EMSAs), which showed that both GATA-1 and GATA-2 can bind to this consensus site. To determine the functionality of this site, we tested whether GATA-1 and GATA-2, either individually or in combination, can transactivate the MBP promoter in the Jurkat T cell line. Cotransfection with a GATA-1 expression vector produced 20-fold augmentation of MBP promoter activity, whereas GATA-2 had no activity. In contrast, combined cotransfection of GATA-1 and GATA-2 decreased the ability of GATA-1 to transactivate the MBP promoter by approximately 50%. Our results provide the first evidence for a GATA-1 target gene in eosinophils, a negative regulatory role for GATA-2 in MBP expression, and possibly eosinophil gene transcription in general during myelopoiesis.

Mechanisms of Transcription in Eosinophils: GATA-1, but not GATA-2, Transactivates the Promoter of the Eosinophil Granule Major Basic Protein Gene

Granule major basic protein (MBP) is expressed exclusively in eosinophils, basophils, and placental trophoblasts. To identify thecis-elements and transcription factors involved in regulating MBP expression, we subcloned 3.2 kb of sequence upstream of the exon 9 transcriptional start site (P2 promoter) and serial 5′ deletions into the pXP2 luciferase reporter vector. An 80% decrement in promoter activity was obtained when MBP sequences between bp −117 to −67 were deleted. To identify transcription factors that bind to and transactivate through the bp −117 to −67 region, we first compared the upstream genomic sequences of human and murine MBP; a potential GATA binding consensus site was conserved in the 50-bp region between the two genes. To determine which GATA proteins bind this consensus site, we performed electrophoretic mobility shift assays (EMSAs), which showed that both GATA-1 and GATA-2 can bind to this consensus site. To determine the functionality of this site, we tested whether GATA-1 and GATA-2, either individually or in combination, can transactivate the MBP promoter in the Jurkat T cell line. Cotransfection with a GATA-1 expression vector produced 20-fold augmentation of MBP promoter activity, whereas GATA-2 had no activity. In contrast, combined cotransfection of GATA-1 and GATA-2 decreased the ability of GATA-1 to transactivate the MBP promoter by approximately 50%. Our results provide the first evidence for a GATA-1 target gene in eosinophils, a negative regulatory role for GATA-2 in MBP expression, and possibly eosinophil gene transcription in general during myelopoiesis.

Inhibition of pulmonary eosinophilia does not necessarily prevent the airway hyperresponsiveness induced by Sephadex beads

BACKGROUND

The Lewis rat among highly inbred strains exhibits significant airway hyperresponsiveness (AHR) following intravenous administration of Sephadex G-200 (Sephadex). The aim of this study was to investigate the association of Sephadex-induced AHR with changes in airway inflammation in Lewis rats.

METHODS

A suspension (0.5 mg/ml/rat) of Sephadex was intravenously administered to male Lewis rats on days 0, 2 and 5. Measurement of airway responsiveness to serotonin, bronchoalveolar lavage (BAL) and histological study were performed on day 2-11.

RESULTS

Significant AHR induced by Sephadex was recognized on day2 (p < 0.05), and AHR reached a maximum on day 7 (p < 0.001). In the BAL study, eosinophils increased on day2 (p < 0.01) with a peak on day 5 (p < 0.05). In the histological study, we found Sephadex beads trapped in small arteries of the lung and granulomatous arteritis on day 2 or later. Pulmonary granulomas, horseshoe-shaped multinuclear giant cells, eosinophils and goblet cell hyperplasia were observed on day 2, and the degree became intense on day 5-7. GCC-AP0341 (10 mg/kg, i.p. x 3) inhibited the recruitment of eosinophils in BAL fluid and in lung tissue, but it did not inhibit AHR. The compound also inhibited pulmonary granulomas and goblet cell hyperplasia.

CONCLUSION

The mechanism of Sephadex-induced AHR may not be directly associated with inflammatory changes such as recruitment of eosinophils, pulmonary granulomas and hyperplasia of goblet cells in rats.

Curcumin inhibition of Dermatophagoides farinea-induced interleukin-5 (IL-5) and granulocyte macrophage-colony stimulating factor (GM-CSF) production by lymphocytes from bronchial asthmatics

Curcumin, a dietary pigment responsible for the yellow color of curry, has been used for the treatment of inflammatory diseases and exhibits a variety of pharmacological effects such as anti-inflammatory, anti-tumor, anti-oxidant, and anti-viral activity. However, it has not been determined whether the effect of curcumin on the production of cytokine affects eosinophil functions and IgE synthesis. In the present study, we examined the effect of curcumin on the production of interleukin (IL)-2, IL-5, granulocyte macrophage-colony stimulating factor (GM-CSF), and IL-4 by lymphocytes from atopic asthmatics in response to house dust mites (Dermatophagoides farinea: Df) in order to clarify a potential application for allergic diseases. Curcumin inhibited Df-induced lymphocyte proliferation and production of IL-2. Exogenous IL-2 reconstituted the proliferative responsiveness of lymphocytes to Df in the presence of curcumin. Furthermore, curcumin inhibited IL-5, GM-CSF, and IL-4 production in a concentration-dependent manner. These results indicate that curcumin may have a potential effect on controlling allergic diseases through inhibiting the production of cytokines affecting eosinophil function and IgE synthesis.

Eosinophilic myositis/perimyositis: frequency and spectrum of cutaneous manifestations

BACKGROUND

Eosinophilic myositis/perimyositis (EM/P) are a group of rare idiopathic muscle disorders associated with eosinophilia.

OBJECTIVE

We describe the frequency and spectrum of cutaneous manifestations in EM/P and compare them with the idiopathic hypereosinophilic syndrome (HES).

METHODS

We review the literature on EM/P and describe an additional case associated with angioedema.

RESULTS

Of a total of 26 reported patients with EM/P, cutaneous manifestations were observed in 10. These were, in order of frequency, deep subcutaneous induration, erythema, angioedema, urticaria, and papular lesions.

CONCLUSION

Skin lesions occur less frequently in EM/P than in HES. Although erythematous papulonodular lesions and urticaria/angioedema are most commonly observed in HES, the most frequent skin manifestations of EM/P are subcutaneous induration and erythema. In HES, angioedema has been correlated with a favorable prognosis. At least some of these patients apparently have an idiopathic eosinophilic disorder distinct from HES, including EM/P. In contrast to HES, the overall prognosis of EM/P is good, particularly when muscle lesions are focal, and the principal histopathologic finding is perimysial infiltrates.

Inhibition by the immunosuppressive agent FK-506 of antigen-induced airways eosinophilia and bronchial hyperreactivity in mice

1. The effect of the immunosuppressive agent, FK-506, an allergen-induced airways eosinophilia and bronchial hyperreactivity (BHR) in hyper IgE mice (BP2 selection) was investigated. 2. Administration of FK-506 at 2 mg kg-1 s.c., 1 h before and 5 h after the first four ovalbumin challenges, reduced the recruitment of eosinophils into the bronchoalveolar lavage fluid (BALF) from 1.36 +/- 0.22 x 10(5) to 0.53 +/- 0.24 x 10(5) cells ml-1 (n = 5-6, P < 0.05; 60% inhibition), inhibited by 80% BHR in response to i.v. 5-HT and practically suppressed BHR in response to inhaled methacholine. 3. The antigen-induced interleukin (IL)-5 formation in the BALF and serum was inhibited by FK-506 by 75% in both instances. 4. FK-506 failed to modify the bronchoconstriction in BP2 mice, suggesting that different mechanisms are involved in acute bronchoconstriction and BHR. 5. The increased number of CD4+, CD8+, CD3+ T lymphocytes in the BALF to antigen-challenged mice was unaffected by FK-506. 6. These findings indicate that antigen-induced in vivo IL-5 release and eosinophil, but not T-cell, infiltration into the bronchial lumen of sensitized BP2 mice are targets for the anti-allergic activities of FK-506.

Blood eosinophil counts and arterial oxygen tension in acute asthma

OBJECTIVE

To investigate whether during acute asthma episodes a decrease in blood eosinophil count could correlate with the severity of the disease.

DESIGN

Prospective study on paediatric asthmatic patients admitted for acute asthma exacerbation between January 1992 and August 1993. All patients were regularly followed up in an outpatient clinic and had had a complete clinical evaluation < 1 month before admission.

SETTING

Pulmonary division of the G Gaslini paediatric research institute, Genoa, Italy.

SUBJECTS

21 asthmatic patients, 59 (SEM 9) months of age, admitted for acute asthma exacerbation. On the basis of clinical evaluation and the results of blood and microbiological tests performed during acute asthma exacerbations, patients were divided into two subgroups: infected (n = 13) and non-infected (n = 8).

RESULTS

All but one of the patients showed a marked decrease in blood eosinophil count during the acute asthma episode, in comparison with recent count (< 1 month before admission) obtained in clinically stable conditions: 662 (116) v 210 (54) eosinophils/mm3, p < 0.0003. The decrease in the eosinophil count was more pronounced in the infected patients than in the non-infected patients, but the difference was not statistically significant (p > 0.05). Similarly, transcutaneous arterial oxygen pressure (PaO2) values measured during acute asthma exacerbations tended to be lower in infected patients, without, however, reaching statistical significance: 8.6 (0.7) v 10.1 (0.9) kPa, p > 0.05). The correlation between the decrease in blood eosinophil count and PaO2 during the acute asthma exacerbations was significant in all the patients (r2 = 0.235, p = 0.022) and in the non-infected patients (r2 = 0.653, p = 0.015), but not in infected patients. In this latter subgroup, a significant negative correlation was found between blood neutrophil counts during acute asthma exacerbations and PaO2 (r2 = 349, p = 0.026).

CONCLUSIONS

During acute asthma exacerbations in atopic patients without clinical evidence of infection, the decrease in blood eosinophil count correlates significantly with the decrease in PaO2, further supporting the role of eosinophils in allergic asthma.

Eosinophil and foam cell accumulation in lungs of Sprague-Dawley rats fed purified, biotin-deficient diets

One hundred twenty male Sprague-Dawley rats (3 weeks old) were given biotin-deficient diets containing ovalbumin as the protein source. Ten control rats of the same origin were fed a commercially available purified diet that used casein as a protein source. Eosinophils and histiocytes were observed at a higher frequency in lungs of rats fed the purified diets containing ovalbumin than in the controls. Foam cells were confined to subpleural and peribronchial regions, reacting positively to anti-lysozyme antibody. The incidence of pulmonary histiocytosis was 76/120 rats (63.3%) in the groups fed the ovalbumin-containing diets as compared with 1/10 (10.0%) in the controls. The accumulation of eosinophils in lung was highest (6/24 rats, 25%) at 3 months. This lesion was not seen in the controls. Eosinophils were first observed in the perivascular and peribronchiolar regions. In advanced lesions, macrophages and mast cells also appeared in the lesions, which at this stage resembled so-called idiopathic chronic eosinophilic pneumonia of human beings. Neither foam cells nor eosinophils were present in any of the other organs. Because there was no difference in the composition of the diets with the exception of the protein source, these lung lesions may be due to biotin deficiency resulting from the use of ovalbumin as the protein source.

Interleukin 5 expressing allergen-specific T-lymphocytes in patients with house dust mite sensitization: analysis at a clonal level

Interleukin 5 (IL-5) is a T-cell lymphokine known to stimulate development, functional activity, and in vitro survival of eosinophils. Tissue and blood eosinophilia occurring during allergic responses of the immune system are potentially mediated by IL-5 secreting T-cells. To test this hypothesis a series of allergen-specific T-cell clones were established from peripheral blood and skin lymphocytes of patients with atopic dermatitis and house dust mite sensitization. In addition, alloreactive T-cell clones were also prepared from peripheral blood lymphocytes of healthy donors. Cloned T-cells were analyzed for IL-5 mRNA expression and IL-5 secretion by means of in vitro gene amplification using the reverse transcriptase polymerase chain reaction and IL-5 specific oligonucleotide hybridization, as well as IL-5-specific ELISA. A majority of allergen-specific long-term cultured T-cell clones (84%) of different donors and of either phenotype (CD8+ or CD4+) disclosed IL-5 transcripts on stimulation with lectins. Almost all clones exhibiting IL-5 transcripts also released immunoreactive IL-5 protein into their culture supernatants. In contrast, only 2% of alloreactive T-cell clones obtained from healthy donors and none of alloreactive T-cell clones of one atopic patient investigated expressed detectable amounts of IL-5 mRNA in response to lectin stimulation, all of whom were CD4+. These results suggest that eosinophilia observed in allergic responses in the peripheral blood and in tissues at the site of induced late-phase cutaneous reaction may be associated with IL-5 release by allergen-specific T-cells.

Activation of the respiratory burst in eosinophil leucocytes--a transduction sequence decoupled from cytosolic Ca2+ rise

The activation of the respiratory burst by complement factor 5a (C5a), platelet-activating factor (PAF), formyl-Met-Leu-Phe (fMLP) and neutrophil-activating peptide IL-8 was explored in eosinophils from patients with the hypereosinophilic syndrome. The amplitude of the response increased with increasing concentrations of C5a and PAF, but the time for its induction was unaffected by the amount of stimulus applied. Respiratory burst activity resulting from phorbol 12-myristate, 13-acetate (PMA)-mediated activation of protein kinase C (PKC) produced longer onset times, which shortened with increasing PMA concentrations. Total inhibition of the C5a- and PMA-mediated burst could be achieved with the PKC inhibitor staurosporine at concentrations of 100 and 5nM, respectively. Calcium depletion abolished agonist-induced rises in cytosolic free calcium ([Ca2+]i) and respiratory burst activity, but not PMA-mediated NADPH-oxidase activation. While PMA reduced elevations in [Ca2+]i, it restored the burst response to agonists in Ca(2+)-depleted eosinophils. These results agree with the agonist-induced activation of the NADPH-oxidase via PKC, but suggest a parallel, Ca(2+)-, phospholipase C- and PKC-independent signal transduction pathway. Data obtained with B. pertussis toxin showed that the respiratory burst in eosinophils is blocked by ADP-ribosylation of G(i)-proteins, but that in the presence of PMA portions of the agonist response could be recovered.

Changes in the phenotypic characteristics of eosinophils from patients receiving recombinant human interleukin-2 (rhIL-2) therapy

We have studied the properties of eosinophils from 26 patients with malignant melanoma and 16 patients with renal cell carcinoma (RCC) who were entered into a phase II clinical trial using various schedules of low-dose rhIL-2 immunotherapy. Eosinophilia was observed in 65% of melanoma patients and 100% of renal patients when receiving rhIL-2 therapy. The eosinophil count increased up to 20-fold approximately 5 d after the appearance of lymphocyte activation markers. This would be consistent with eosinophil kinetics and the release of soluble mediators, for example IL-5, from lymphocytes. Eosinophils from eosinophilic patients became hypodense compared to their pre-treatment levels as demonstrated by sedimentation through a discontinuous metrizamide density gradient; they also showed an increased expression of CD4, CD25 and CD11b cell surface activation markers. Eosinophil count could not be correlated to either patient survival or response to therapy in melanoma patients; however, patients with renal cell carcinoma demonstrated a significant correlation (P < or = 0.05) between eosinophil count and survival but not with clinical response. Therefore the maximum eosinophil count achieved during rhIL-2 therapy is of prognostic significance in patients with renal cell carcinoma.

Biological response modifiers and infectious diseases: actual and potential therapeutic agents

Biological response modifiers (BRMs) are agents which can modify the immune response to cancer or invasion of the organism by infectious agents. An explosive appearance of new BRMs has resulted from the development of recombinant gene technology and the availability of monoclonal antibodies. Colony-stimulating factors first became available for the prevention of neutropenia but may also have a role in the treatment of infections. Interleukin-1 is being tested as a modular of hematopoiesis and may be useful as a helper factor for T- and B-cell function. Immunoglobulins are being used against viral and bacterial infections while interferons can prevent viral upper respiratory infections and suppress or irradicate some viral hepatitides. Other BRMs which show promise include chemical agents and traditional herbal medicines.

Eosinophil differentiation in response to Fasciola hepatica and its excretory/secretory antigens

Bone marrow cells from mice infected with Fasciola hepatica, from mice injected with F. hepatica excretory/secretory (ES) antigens, and from uninfected or uninjected control animals were cultured in the presence of F. hepatica ES antigens or the eosinophil differentiation cytokine IL-5. Eosinophil maturation in cultures was assessed quantitatively by measuring eosinophil peroxidase (EPO) activity and qualitatively by visual appraisal in stained preparations over a week. It was found that the presence in all cultures (including those from control animals) of either ES antigens at an optimal concentration of 100 micrograms ml-1 (established in preliminary trials) or IL-5 at 500 units ml-1 led to enhanced EPO activity. EPO activity in cultures without IL-5 or ES antigens remained static or fell over the culture period. At day 3 in all cultures containing IL-5 or ES antigens, there was maintenance of or only a slight decline in, the number of eosinophils that were present when cultures were initiated, and more of them were mature than at day 0 as evidenced by their EPO activity. However, there was a marked fall in eosinophil numbers in all cultures in the absence of IL-5 or ES antigens. The results indicate that F. hepatica ES antigens, like IL-5, stimulate eosinophil maturation in bone marrow with a consequent rise in EPO activity in the cells. Whether the antigen(s) acts directly or indirectly on the eosinophils or their precursors has yet to be established. Nevertheless, it seems clear that F. hepatica produces a molecule with a functionally similar effect to that of IL-5.

Comparison of two modified techniques for purifying blood eosinophils

As there is much heterogeneity in the morphology and function of blood eosinophils, comparison of their properties between groups of subjects requires recovering the majority of these cells. In two currently used techniques to isolate eosinophils, blood granulocytes are processed either on Percoll gradients after an incubation of granulocytes with 10(-8) M N-formyl-methionyl-leucyl-phenylalanine (fMLP) or on a magnetic cell sorter (MACS). In this study, these techniques were modified to increase the efficiency of eosinophil recovery. With the Percoll gradients, using 1.078 g/ml as the top gradient instead of 1.082 g/ml doubled the eosinophil recovery from 43 +/- 5.3% (mean +/- SEM) to 86.9 +/- 2.9%, without decreasing the purity (96.1 +/- 1.4% versus 96.2 +/- 0.9%). With a MACS, the neutrophils in granulocytes obtained on Ficoll-Paque (1.077 g/ml) instead of on Percoll gradient 1.082-1.094 g/ml, were tagged with anti-CD16 antibodies and eliminated by passing them through a magnetic field. When blood eosinophils of the same subjects were isolated using the two techniques, similar recovery and purity levels were obtained: Percoll gradients, 72.7 +/- 6.8% and 92.5 +/- 2.2%; MACS, 80.2 +/- 5.1% and 90.4 +/- 3.8%. Eosinophils isolated through the two techniques were also compared for their production of superoxide anion and leukotriene (LT) C4, with and without pre-incubation with cytokines interleukin-3, interleukin-5 and granulocyte-macrophage colony stimulating factor. The release of these products was similar between the two eosinophil preparations under all conditions tested except for interleukin-3 where eosinophils isolated with a MACS produced more LTC4. These results show that both techniques efficiently recover pure eosinophils. Furthermore, cell incubation with 10(-8) M fMLP did not enhance superoxide anion and LTC4 production nor modify the response to cytokines. The two modified techniques are therefore suitable for comparative studies of eosinophils from different groups of subjects.

Activated T cells in an animal model of allergic conjunctivitis

The aim of this study has been to determine whether the presence of lymphocytic infiltrates observed in the histology of ocular allergic conditions in humans or in the late phase of ocular anaphylactic reactions in experimental animals is a non-specific event dependent only on the degranulation of mast cells, or is conditioned by a specific response to antigen. With this in mind, responses to antigen and to a non-immunological mast cell degranulator (compound 48/80) were compared in an experimental model of allergic conjunctivitis. Rats were sensitised to ovalbumin and challenged topically in the left conjunctival sac either with ovalbumin or compound 48/80. The presence of T cells and activated T cells in the infiltrate was studied by immunohistochemical staining on conjunctival tissue obtained at 4, 24, and 48 hours after challenge. Ovalbumin sensitised and challenged rats showed increased numbers of T cells in the conjunctival infiltrate, statistically significant when compared with compound 48/80 challenged rats at 48 hours and with controls at 4, 24, and 48 hours. The number of T cells was significantly higher in compound 48/80 challenged rats only at 48 hours when compared with controls. As for the number of activated T cells, only ovalbumin sensitised and challenged rats showed significantly increased levels of these cells compared with both sensitised animals challenged with compound 48/80 and controls at 4 and 24 hours after challenge. These results suggest that the infiltration of the conjunctiva by activated T lymphocytes is, at least in part, dependent on a specific response to antigen.

Generation and partial characterization of an eosinophil chemotactic cytokine produced by sensitized equine mononuclear cells stimulated with Strongylus vulgaris antigen

Supernatants generated by stimulation of peripheral blood mononuclear cells (PBMC) from Strongylus vulgaris sensitized or immunized ponies were assayed in vitro for eosinophil chemotactic activity (ECA) using the filter system in blind well chambers. The supernatants from these cultures were chemotactic for eosinophils, but not for neutrophils. Supernates from cultures of unsensitized PBMC stimulated with S. vulgaris antigen were not chemotactic for eosinophils. ECA was first detected in culture supernatants after 1.5 h of incubation and was dependent on both antigen and PBMC concentrations, but independent of serum concentrations. Both female and male S. vulgaris worm antigens stimulated ECA production from sensitized PBMC. ECA was not induced by in vitro stimulation of sensitized S. vulgaris PBMC by female Strongylus edentatus worm antigen. Partial characterization of the eosinophil chemotactic cytokine showed it to be nondialyzable, greater than 8000 molecular weight (MW), and sensitive to heating (56 and 95 degrees C), trypsin, and sodium metaperiodate treatments, suggesting that the cytokine is a protein containing some essential carbohydrate moieties. The cytokine described in this paper could partially contribute to the in vivo blood and tissue eosinophilia in experimental S. vulgaris infection.

In vitro anti-tumor activity of eosinophils from cancer patients treated with subcutaneous administration of interleukin 2. Role of interleukin 5

Interleukin 2 (IL-2) administration is known to induce marked eosinophilia. To evaluate the potential role of eosinophils as anti-tumor effectors and to understand the direct or indirect effects of IL-2 on eosinophils, the physical and functional characteristics of eosinophils obtained during IL-2 therapy were compared with those of eosinophils obtained from the same patients before IL-2 administration, or from healthy donors. The treatment schedule consisted of subcutaneous (s.c.) injections of IL-2, and was performed in 7 patients with small-cell lung cancer (SCLC) in advanced stage. A marked increase of hypodense cells in peripheral blood was found to correlate with eosinophil activation in patients undergoing IL-2 therapy. Cytotoxic activity of eosinophils against allogeneic tumor cells (SCLC, K562 and melanoma lines), as assessed by direct and antibody (Ab)-dependent cellular cytotoxicity (ADCC), was markedly increased during IL-2 therapy. Conversely, eosinophils obtained before treatment, like those of healthy donors, lacked any activity against tumor cells. Sera from IL-2-treated, but not from untreated, patients, significantly improved the in vitro survival and anti-tumor cytotoxicity of eosinophils from healthy donors. Comparable effects were obtained with eosinophils cultured with interleukin 5 (IL-5), granulocyte-macrophage colony-stimulating factor (GM-CSF) and, to a lesser extent, by tumor necrosis factor-alpha (TNF alpha), while no direct activity was mediated by IL-2. A 91% inhibition of eosinophil ADCC was found after pre-incubation of the sera of IL-2-treated patients with anti-IL-5 but not with anti-GM-CSF or anti-TNF alpha Ab. IL-5 mRNA expression was detected in peripheral-blood lymphocytes (PBL) obtained 4 hr after IL-2 injection during the second and third week of IL-2 therapy. Phenotypic analysis of eosinophils from IL-2-treated patients showed enhanced expression of activation markers, including Fc gamma RII (CD32), HLA-DR, CR3 (CD11b) and CRI (CD35). These findings suggest that a significant cytotoxicity against tumor cells can be mediated by eosinophils after indirect, IL-5-mediated in vivo activation by IL-2, and that eosinophils may be involved in the anti-tumor response(s) induced in vivo by IL-2.

Relationship between eosinophilia and responsiveness to infection with Trichostrongylus colubriformis in sheep

Lambs with genetically determined increased immunological responsiveness to Trichostrongylus colubriformis (high responders) had more eosinophils in cutaneous reactions to the mitogen phytohaemagglutinin (PHA) both before and during infection compared with those bred for susceptibility (low responders). In contrast, eosinophil numbers in both blood and cutaneous reactions elicited by third-stage T. colubriformis larval antigen were similar in high and low responders before infection. Following vaccination and challenge, high responders had elevated eosinophil numbers in blood and antigen-stimulated skin. In unselected sheep, although eosinophil numbers in cutaneous reactions to PHA were related to responsiveness to a challenge infection with T. colubriformis, there was a closer relationship between blood eosinophil numbers and responsiveness. Infection with T. colubriformis increased eosinophil numbers in cutaneous reactions to PHA and appeared to augment the difference between eosinophil counts in high and low responder sheep. Measurement of the ability to produce eosinophil activating factors, or for eosinophils to respond to such factors might therefore be useful in identifying individual sheep with increased responsiveness to T. colubriformis infection.

Effect of anti-IL-5 and IL-5 on airway hyperreactivity and eosinophils in guinea pigs

Chronic ovalbumin challenge of sensitized guinea pigs induces bronchoalveolar lavage (BAL) eosinophilia, neutrophilia, and tracheal hyperreactivity. In the present study, the influence of monoclonal antibody to murine interleukin-5 (anti-IL-5) on these phenomena is examined. In ovalbumin-sensitized guinea pigs treated with isotype-matched control antibody and challenged daily with ovalbumin for 8 days, the number of BAL eosinophils and neutrophils is increased significantly six- and fivefold, respectively, compared with saline-challenged animals. The maximal contractions of tracheal rings to histamine and arecoline in ovalbumin-challenged animals are enhanced significantly to 155% compared with saline-challenged animals. In sensitized guinea pigs treated with anti-IL-5, the BAL eosinophil number is markedly inhibited compared with control antibody treatment in both saline- and ovalbumin-challenged animals. In contrast, the number of neutrophils is not affected by anti-IL-5 treatment. In guinea pigs treated with anti-IL-5, the development of hyperreactivity to histamine and arecoline after ovalbumin challenge is completely inhibited. The contractions to histamine and arecoline of tracheal rings isolated from guinea pigs treated with recombinant murine IL-5 for 3 or 7 days are enhanced significantly to approximately 140% compared with controls. Treatment with IL-5 for 7 days tends to increase the number of eosinophils in BAL fluid. It can be concluded that IL-5 is involved in airway eosinophilia and in the development of hyperreactivity in this animal model, but other cytokines may contribute. Development of IL-5 synthesis inhibitors and/or receptor antagonists could provide another therapeutic class of anti-asthma drugs.

Eosinophil migration in atopic dermatitis. I: Increased migratory responses to N-formyl-methionyl-leucyl-phenylalanine, neutrophil-activating factor, platelet-activating factor, and platelet factor 4

Eosinophil granular protein deposits have been demonstrated in lesional atopic dermatitis skin. This suggests active tissue infiltration of eosinophils. To find an explanation for the tissue influx of eosinophils, eosinophil migration was studied in vitro by means of a microchemotaxis assay. Eosinophils from the circulation of patients with atopic dermatitis showed an altered capacity to respond to chemotactic stimuli in vitro compared with eosinophils from healthy donors. Eosinophils from patients with atopic dermatitis had significantly increased migratory responses toward dose ranges of N-formyl-methionyl-leucyl-phenylalanine, neutrophil-activating factor, platelet-activating factor, and platelet factor 4. Eosinophils from normal individuals did not respond to N-formyl-methionyl-leucyl-phenylalanine and neutrophil-activating factor and responded only slightly to platelet factor 4. The migratory responses toward tumor necrosis factor-alpha and complement factor C5a were identical in both groups. Interleukin-5, an eosinophil-selective cytokine, is a strong modulator of the migratory responses to these chemotaxins in eosinophils from normal donors. A migratory response toward N-formyl-methionyl-leucyl-phenylalanine and neutrophil-activating factor was induced by interleukin-5, whereas the migratory response toward platelet-activating factor and platelet factor 4 was markedly potentiated. In contrast, the response to complement fragment C5a was only slightly influenced. Our findings indicate that the increased migratory responsiveness of eosinophils from patients with atopic dermatitis to various chemotaxins reflects in vivo "priming" of eosinophils, presumably by circulating cytokines such as interleukin-5. This in vivo "priming" is not optimal because it can be further potentiated by renewed contact with interleukin-5.

Modulation of eosinophil chemotaxis by interleukin-5

Eosinophilia and eosinophil function are regulated by cytokines such as granulocyte/macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), and interleukin-5 (IL-5). We have investigated the modulatory role of IL-5 on N-formyl-methionyl-leucyl-phenylalanine (FMLP), neutrophil-activating factor (NAF/IL-8), platelet factor 4 (PF4), and cytokine-induced chemotaxis of eosinophils from normal individuals. These eosinophils show a small chemotactic response toward PF4 but not to NAF/IL-8 and FMLP. Preincubation of eosinophils with low concentrations of IL-5 caused significantly increased responses toward PF4 and induced a significant chemotactic response toward FMLP and NAF/IL-8. In marked contrast, IL-5 (or IL-3) priming of eosinophils from normal donors resulted in a strong inhibition of GM-CSF-induced chemotaxis. A similar decrease in the chemotactic response toward GM-CSF was observed in eosinophils derived from allergic asthmatic individuals. This finding suggests that the latter eosinophils may have had a prior exposure to IL-5 (or IL-3). Washing of the cells after priming did not abrogate the inhibition of the GM-CSF response. Our data indicate that at low concentrations IL-5 is an important modulator of eosinophil chemotaxis, causing selective upregulation or downregulation of chemotactic responses toward different agents.