Lack of allergy to timothy grass pollen is not a passive phenomenon but associated with the allergen-specific modulation of immune reactivity.

BACKGROUND: Timothy grass (TG) pollen is a common seasonal airborne allergen associated with symptoms ranging from mild rhinitis to severe asthma. OBJECTIVE: The aim of this study was to characterize changes in TG-specific T cell responses as a function of seasonality. METHODS: Peripheral blood mononuclear cells (PBMCs) obtained from allergic individuals and non-allergic controls, either during the pollen season or out of season, were stimulated with either TG extract or a pool of previously identified immunodominant antigenic regions. RESULTS: PBMCs from allergic subjects exhibit higher IL-5 and IL-10 responses in season than when collected out of season. In the case of non-allergic subjects, as expected we observed lower IL-5 responses and robust production of IFN-γ compared to allergic individuals. Strikingly, non-allergic donors exhibited an opposing pattern, with decreased immune reactivity in season. The broad down-regulation in non-allergic donors indicates that healthy individuals are not oblivious to allergen exposure, but rather react with an active modulation of responses following the antigenic stimulus provided during the pollen season. Transcriptomic analysis of allergen-specific T cells defined genes modulated in concomitance with the allergen exposure and inhibition of responses in non-allergic donors. CONCLUSION AND CLINICAL RELEVANCE: Magnitude and functionality of T helper cell responses differ substantially in season vs. out of season in allergic and non-allergic subjects. The results indicate the specific and opposing modulation of immune responses following the antigenic stimulation during the pollen season. This seasonal modulation reflects the enactment of specific molecular programmes associated with health and allergic disease.

Group 2 innate lymphoid cells: new players in human allergic diseases.

Allergic diseases are characterized by tissue eosinophilia, mucus secretion, IgE production, and activation of mast cells and TH2 cells. Production of TH2 cytokines including IL-4, IL-5, IL-9, and IL-13 has mainly been attributed to CD4+T(H)2 cells. However, the recent discovery of group 2 innate lymphoid cells (ILC2s) in humans and findings from experimental disease models have challenged conventional concepts associated with the contribution of specific cells to type 2 inflammation in allergic diseases. ILC2s produce high levels of T(H)2 cytokines and have been detected in human lung tissue, peripheral blood, the gastrointestinal tract, skin, and sinonasal tissue, suggesting that ILC2s could contribute to chronic rhinosinusitis, asthma, atopic dermatitis, and gastrointestinal allergic disease. Moreover, depletion of ILC2s in animal models suggests a role for these cells in atopic dermatitis and asthma. This review will focus on the role of ILC2s in human allergy and asthma and provide a mechanistic insight from animal models.

Mutation of a new gene encoding a putative pyrin-like protein causes familial cold autoinflammatory syndrome and Muckle-Wells syndrome.

Familial cold autoinflammatory syndrome (FCAS, MIM 120100), commonly known as familial cold urticaria (FCU), is an autosomal-dominant systemic inflammatory disease characterized by intermittent episodes of rash, arthralgia, fever and conjunctivitis after generalized exposure to cold. FCAS was previously mapped to a 10-cM region on chromosome 1q44 (refs. 5,6). Muckle-Wells syndrome (MWS; MIM 191900), which also maps to chromosome 1q44, is an autosomal-dominant periodic fever syndrome with a similar phenotype except that symptoms are not precipitated by cold exposure and that sensorineural hearing loss is frequently also present. To identify the genes for FCAS and MWS, we screened exons in the 1q44 region for mutations by direct sequencing of genomic DNA from affected individuals and controls. This resulted in the identification of four distinct mutations in a gene that segregated with the disorder in three families with FCAS and one family with MWS. This gene, called CIAS1, is expressed in peripheral blood leukocytes and encodes a protein with a pyrin domain, a nucleotide-binding site (NBS, NACHT subfamily) domain and a leucine-rich repeat (LRR) motif region, suggesting a role in the regulation of inflammation and apoptosis.

Resolution of remodeling in eosinophilic esophagitis correlates with epithelial response to topical corticosteroids.

BACKGROUND: Esophageal remodeling occurs in eosinophilic esophagitis (EE) patients but whether the components of remodeling in the subepithelium are reversible by administration of topical oral corticosteroids is unknown. METHODS: We quantitated the degree of lamina propria remodeling in esophageal biopsies obtained before and after at least 3 months of therapy with budesonide in 16 pediatric EE subjects. In addition, we investigated whether corticosteroid therapy modulated vascular activation (expression of VCAM-1; level of interstitial edema), TGFbeta(1) activation (levels of TGFbeta(1), phosphorylated Smad2/3), and performed a pilot analysis of a polymorphism in the TGFbeta(1) promoter in relation to EE subjects who had reduced remodeling with budesonide therapy. RESULTS: EE subjects were stratified based on the presence (n = 9) or absence (n = 7) of decreased epithelial eosinophilia following budesonide. Patients with residual eosinophil counts of

Endobronchial allergen challenge in asthma. Demonstration of cellular source of granulocyte macrophage colony-stimulating factor by in situ hybridization.

Airway inflammation is thought to play an important role in the pathogenesis of asthma. We have used in situ hybridization and an immunoassay to determine whether granulocyte macrophage colony-stimulating factor (GM-CSF) (a cytokine capable of eosinophil activation) is present in the airway of asthmatics (n = 6) who have 37.0 +/- 15.1% airway eosinophilia after endobronchial allergen challenge. Levels of immunoreactive GM-CSF (less than 4 pg/ml pre-allergen versus 180.5 +/- 46.9 pg/ml post-allergen) increased significantly 24 h after endobronchial allergen stimulation. The cellular source of bronchoalveolar lavage (BAL) GM-CSF, as determined by in situ hybridization and immunoperoxidase staining, was derived predominantly from UCHL-1 positive BAL lymphocytes, as well as from a smaller population of alveolar macrophages. Before local endobronchial allergen challenge, less than 1% of lymphocytes and alveolar macrophages recovered by BAL expressed GM-CSF mRNA, whereas after allergen stimulation 92.6 +/- 3.4% of lymphocytes and 17.5 +/- 22.7% of alveolar macrophages expressed GM-CSF mRNA. This study provides evidence that in an experimental model of allergen-induced asthma, activation of the immune and inflammatory response (BAL lymphocyte and alveolar macrophage production of GM-CSF) is temporally associated with an inflammatory cell influx of eosinophils into the airway.

Eosinophils express interleukin 5 and granulocyte macrophage-colony-stimulating factor mRNA at sites of allergic inflammation in asthmatics.

IL-5 and granulocyte macrophage-colony-stimulating factor (GM-CSF) are important regulators of eosinophil survival, proliferation, and effector function. To determine whether IL-5 and/or GM-CSF are generated by eosinophils at sites of allergic inflammation, we have used in situ hybridization with 35S-labeled RNA probes to study the expression of IL-5 and GM-CSF mRNA in bronchoalveolar lavage (BAL) eosinophils derived from asthmatics (n = 5) before and after endobronchial allergen challenge. Endobronchial allergen challenge induced a significant airway eosinophilia (pre-allergen challenge 0.6 +/- 0.5% eosinophilia vs post-allergen challenge 48.2 +/- 25.6% eosinophilia). Post-allergen challenge eosinophils expressed IL-5 and GM-CSF mRNA, but did not express IL-1 beta or IL-2 mRNA. To determine whether the IL-5 mRNA-positive cells coexpressed GM-CSF mRNA, double mRNA labeling experiments with a digoxigenin-11-UTP nonradioactive labeled IL-5 RNA probe and a GM-CSF 35S-labeled RNA probe were performed. These studies demonstrated that individual eosinophils expressed one of four cytokine mRNA profiles (IL-5+, GM-CSF+, 34 +/- 13%; IL-5+, GM-CSF-, 34 +/- 5%; IL-5-, GM-CSF+, 11 +/- 9%; IL-5-, GM-CSF-, 21 +/- 25%). The expression of IL-5 and GM-CSF by eosinophils at sites of allergic inflammation in asthmatics may provide an important autocrine pathway, maintaining the viability and effector function of the recruited eosinophils.

Mast cell TNF mRNA expression in nasal mucosa demonstrated by in situ hybridization: a comparison of mast cell detection methods.

We have used 35S-labelled RNA probes to detect TNF cytokine gene expression in nasal mucosa derived from patients with perennial rhinitis. As mast cells comprise a minor component of the total cell population in nasal mucosa, additional methods are needed to determine whether mast cells contribute to the cytokine mRNA detected by in situ hybridization. We have combined in situ hybridization with alternate methods to detect mast cells (tryptase immunostaining or toluidine blue staining) and determined that in situ hybridization coupled with tryptase immunostaining provides optimal methods to detect mast cell cytokine gene expression in tissue sections. Using in situ hybridization and tryptase immunostaining, we demonstrate that mast cells in nasal mucosa can express TNF mRNA. However, the number of tryptase-, TNF+ cells (1.99 +/- 1.59 cells/mm2) exceeded the number of tryptase+, TNF+ mast cells (0.09 +/- cells/mm2). Mast cells thus comprised a subpopulation of the total number of TNF mRNA positive cells in nasal mucosa.

Differential regulation of eosinophil adhesion under conditions of flow in vivo.

The proinflammatory role of eosinophils in patients with allergic inflammation is now well recognized. However, the molecular mechanisms mediating the sequential events of eosinophil recruitment from the blood stream to sites of allergic inflammation under conditions of shear force have not been clearly established. Using the xenogeneic rabbit model system to study human eosinophil adhesion under conditions of flow in vivo, we have demonstrated that eosinophils like neutrophils roll, adhere, and extravasate across cytokine-stimulated endothelial cells at physiological shear rates in vivo. Eosinophils rolling on venular endothelial cells is mediated by L-selectin and VLA-4. Mediators of cellular activation such as GM-CSF, PAF, or PMA had a differential effect on neutrophil and eosinophil receptor expression and their rolling function. It would thus appear that acting sequentially or in concert a variety of cytokines, including GM-CSF, RANTES, IL-5, and specific cell adhesion molecules (VLA-4/VCAM-1) might play a critical role in the selective sequestration of eosinophils and other proinflammatory leukocytes into the inflamed tissues during episodes of allergic inflammation. Further understanding of the function of these mediators as well as other traffic signals that regulate eosinophil adhesion will help in developing better therapeutic strategies to block the emigration of eosinophils from the blood stream, and also to inhibit the activation of eosinophils once they have reached sites of tissue inflammation.

Cetirizine therapy for seasonal allergic rhinitis: alternative dosage schedules.

A double-blind, placebo-controlled clinical trial was undertaken for two weeks to evaluate three dosing schedules for administration of cetirizine in patients with seasonal allergic rhinitis. Average severity scores from the patients' ratings for sneezing and nasal itching were significantly reduced in all three cetirizine groups (10 mg QAM or QHS and 5 mg BID), compared with placebo. The effectiveness of cetirizine in once-daily dosing schedules indicates that significant antihistaminic activity is delivered over a full 24 hours. The possibility for flexibility in dosing combined with its relatively short half-life and low incidence of adverse effects make cetirizine an important second-generation H1-antihistamine for the management of seasonal allergic rhinitis.

Molecular and cellular mechanisms of allergic disease.

The molecular and cellular mechanisms mediating the allergic inflammatory cascade involve multiple mediators, cell types, and pathways. Of particular interest are the pathways regulated by the T(H)2 lymphocyte, which result in release of IL-4 (important to IgE synthesis) and IL-5 (important to eosinophil proliferation). IL-4 regulates differentiation of naïve T(H)0 cells to develop a T(H)2 phenotype and stimulates B cells to produce IgE. Cross-linking by allergen of IgE affixed to high-affinity receptors on mast cells and basophils triggers degranulation and the release of preformed inflammatory mediators (important to the early phase response), and subsequently initiates synthesis and the release of lipid mediators and cytokines (which may contribute to the late phase response). Eosinophils may also play a prominent role in the development of bronchial hyperreactivity. IL-5, which is a lineage-specific eosinophil growth factor, increases the formation of eosinophils from progenitor cells and, in concert with CCR3 active chemokines, increases their trafficking to sites of allergic inflammation. An improved understanding of the basic mechanisms of allergic inflammation has led to the discovery of molecular targets involved in the initial events of the inflammatory cascade. Potential targets for the development of novel therapies for allergic disease include IgE, the T(H)2 lymphocyte, and T(H)2-derived cytokines, IL-4 and IL-5.

Compartmentalization of eosinophil granulocyte-macrophage colony-stimulating factor expression in patients with asthma.

BACKGROUND: In patients with asthma the endobronchial instillation of an allergen induces recruitment of granulocyte-macrophage colony-stimulating factor (GM-CSF) messenger RNA-positive eosinophils into the airway. OBJECTIVE: The goal of the study was to determine whether peripheral blood (as opposed to bronchoalveolar lavage) eosinophils express GM-CSF mRNA and protein. METHODS: We performed in situ hybridization and immunocytochemistry on peripheral blood eosinophils, obtained at 0, 4, and 24 hours after either inhalation of diluent, inhalation of allergen, or endobronchial instillation of allergen. RESULTS: Each study subject (n = 6) had both an immediate and late-phase response to allergen inhalation but not to diluent inhalation. Allergen, but not diluent, challenge induced a significant increase in the number of peripheral blood eosinophils at 24 hours. In situ hybridization of peripheral blood eosinophils with a sulfur 35-labeled GM-CSF RNA riboprobe and immunostaining with a GM-CSF monoclonal antibody revealed that neither pre- nor postchallenge (allergen or diluent) peripheral blood eosinophils expressed GM-CSF mRNA or protein. In contrast, both bronchoalveolar lavage eosinophils and mononuclear cells expressed GM-CSF mRNA and protein. CONCLUSION: These studies suggest that the expression of GM-CSF by eosinophils after allergen inhalation is compartmentalized to the lungs.

Environmental and bronchoalveolar lavage Dermatophagoides pteronyssinus antigen levels in atopic asthmatics.

Overnight environmental home exposure to Dermatophagoides pteronyssinus in IgE-sensitized individuals is often clinically associated with increased morning symptoms of rhinitis and/or asthma. We have investigated whether household exposure to D. pteronyssinus is associated with the presence of immunoreactive D. pteronyssinus I antigen (Der p I) in bronchoalveolar lavage (BAL) fluid in nine atopic asthmatics sensitized to D. pteronyssinus. Significant environmental concentrations of D. pteronyssinus were noted by light microscopy and immunoassay in the subjects' bedroom carpets (13.4 +/- 3.8 micrograms immunoreactive Der p I/g dust), mattresses (27.3 +/- 7.2 micrograms immunoreactive Der p I/g dust), and living room carpets (5.9 +/- 1.5 micrograms immunoreactive Der p I/g dust). Immunoreactive Der p I was measurable in 20-fold concentrated BAL fluids (3.4 +/- 1.0 ng/ml concentrated BAL fluid) after overnight home exposure. A 24-h hospitalization in a D. pteronyssinus controlled environment (< 0.02 micrograms Der p I/g dust) resulted in a significant decrease in BAL Der p I concentrations (0.8 +/- 0.6 ng/ml). In vivo studies in nine asthmatics challenged endobronchially with D. pteronyssinus (5-60 ng Der p I) induced significant airway eosinophilia. These studies demonstrate that environmental exposure to microgram amounts of D. pteronyssinus is associated with airway recovery of small nanogram amounts of Der p I.

Functional and biochemical characterization of rat bone marrow derived mast cells.

The functional and biochemical characterization of rat bone marrow derived mast cells (RBMMC) confirms both species-related differences between rat and mouse bone marrow-derived mast cells (MBMMC) as well as mast cell heterogeneity in a single species. Such RBMMC have the staining characteristics of mucosal mast cells and contain the mucosal mast cell protease. The RBMMC release the preformed granule mediator beta-hexosaminidase both in response to immunologic stimulation with 200 ng Ag (net release 15.8 +/- 3.8%) and in response to 1 microM calcium ionophore A23187 (net release 21.8 +/- 6.8%). However, compound 48/80, substance P, and somatostatin did not induce mast cell degranulation. In experiments with optimal beta-hexosaminidase release, the RBMMC generated similar quantities of the newly formed arachidonic acid metabolites leukotriene C4 and PGD2 when stimulated with either Ag or calcium ionophore A23187. The RBMMC incorporate [35S]sulfate into proteoglycans consisting of 90% chondroitin sulfates and 10% heparin. The chondroitin sulfates were comprised of chondroitin 4 sulfate and chondroitin sulfate diB sulfated disaccharides in a ratio of 4/1. Although we show that RBMMC and MBMMC share a low histamine content, functional IgE receptors and unresponsiveness to cromolyn and selective secretagogues (compound 48/80, substance P, and somatostatin), we also provide evidence that RBMMC differ from MBMMC in their profile of newly generated mediators, preformed granule proteoglycan, and lack of proliferative response to mouse IL-3.

Mast cells and pulmonary fibrosis. Identification of a histamine releasing factor in bronchoalveolar lavage fluid.

As elevated bronchoalveolar lavage (BAL) fluid histamine levels are noted in patients with pulmonary fibrosis (PF), we assayed BAL fluid from 16 patients with PF for the presence of a histamine releasing factor (HRF). HRF activity was assayed by measuring release of the preformed mast cell-derived mediators, histamine, or beta-hexosaminidase (beta-hex) from a purified population of IL-3 dependent mouse bone marrow derived mast cells (MBMMC) or human blood basophils. Mean BAL cell free histamine levels in the patients with PF was 1226 +/- 1349 pg/ml, whereas BAL histamine levels in a comparison group of six non-PF patients was 118 +/- 60 pg/ml. HRF was significantly elevated in BAL fluid of patients with PF (mean beta-hex release 24.5 +/- 12.9%; range 6.8 to 52.4%) compared to the non-PF group of patients (mean beta-hex release 7.9 +/- 7.7%; range 1.8 to 20.7%). The PF HRF not only degranulated MBMMC, but also induced the generation of the arachidonic acid metabolite leukotriene C4 from MBMMC (24.6 +/- 4.2 ng leukotriene C4/10(6) MBMMC). The PF HRF did not appear to be a cytokine previously identified in BAL fluid of patients with PF (i.e., platelet derived growth factor or insulin growth factor-1) or a human cytokine able to degranulate human basophils (i.e., IL-1, or granulocyte-macrophage-CSF) as these recombinant human cytokines did not induce MBMMC beta-hex release. Physicochemical characterization of the HRF revealed that it was relatively heat stable, pronase sensitive and on Sephadex G-75 and G-200 column chromatography had an apparent molecular mass of 30 to 50 kDa. The ability of PF BAL to induce beta-hex release from MBMMC was not dependent on IgE as unsensitized or lactic acid treated MBMMC release similar amounts of beta-hex compared to MBMMC sensitized with IgE. Thus, BAL fluid of patients with PF contains an HRF that induces beta-hex release from MBMMC via an IgE-independent mechanism. The presence of the HRF could explain elevated BAL histamine levels in patients with PF.

Inhibition of eosinophil rolling and recruitment in P-selectin- and intracellular adhesion molecule-1-deficient mice.

To determine the relative in vivo importance of endothelial expressed adhesion molecules to eosinophil rolling, adhesion, and transmigration, we have induced eosinophilic peritonitis using ragweed allergen in P-selectin-deficient, intracellular adhesion molecule-1 (ICAM-1)-deficient and control wild-type mice. Circulating leukocytes visualized by intravital microscopy exhibited reduced rolling and firm adhesion in P-selectin-deficient mice and reduced firm adhesion in ICAM-1-deficient mice. Eosinophils exhibited reduced rolling and firm adhesion to endothelium in P-selectin-deficient mice. Eosinophil recruitment in P-selectin-deficient mice ( approximately 75% inhibition of eosinophil recruitment) and ICAM-1-deficient mice ( approximately 67% inhibition of eosinophil recruitment) was significantly reduced compared with wild-type mice. Eosinophil recruitment was not completely inhibited in P-selectin/ICAM-1 double-mutant mice (eosinophil recruitment inhibited approximately 62%). However, pretreatment of P-selectin/ICAM-1-deficient mice with an anti-vascular cell adhesion molecule (VCAM) antibody induced near complete inhibition of eosinophil recruitment. Overall, these studies show that eosinophil rolling and firm adhesion is significantly reduced in P-selectin-deficient mice and that P-selectin, ICAM-1, and VCAM are important to eosinophil peritoneal recruitment after ragweed challenge.

Familial cold autoinflammatory syndrome: phenotype and genotype of an autosomal dominant periodic fever.

BACKGROUND: Familial cold autoinflammatory syndrome (FCAS), commonly known as familial cold urticaria, is a rare autosomal dominant inflammatory disorder with episodic symptoms precipitated by exposure to cold. OBJECTIVE: The goal of this study was to formulate clinical diagnostic criteria for FCAS in a large cohort in whom the diagnosis of FCAS was supported by genetic linkage to chromosome 1q44. METHODS: We assessed 45 affected and 68 unaffected members from 6 American families. DNA analysis was performed to confirm linkage to chromosome 1q44. Clinical characteristics were determined by means of analysis of detailed questionnaires and medical histories. RESULTS: Pedigree and genetic analyses confirmed autosomal dominant transmission and linkage to chromosome 1q44 in all families. The most consistent symptoms during attacks were rash (100%), fever (93%), arthralgia (96%), and conjunctivitis (84%). Age of onset was within the first 6 months of life in 95% of affected subjects. The average delay between cold exposure and onset of symptoms was 2.5 hours, and the average duration of an episode was 12 hours. Renal disease with amyloidosis occurs infrequently in FCAS (2%). CONCLUSION: The most consistent clinical characteristics of FCAS that discriminate it from other periodic fevers are association with cold exposure, conjunctivitis, age of onset, duration of episodes, and an autosomal dominant inheritance pattern. On the basis of the analysis of genotype and phenotype of FCAS, we formulated clinical diagnostic criteria that can be used to distinguish FCAS from other hereditary periodic fever syndromes.

Inhibition of eosinophilic inflammation in allergen-challenged, IL-1 receptor type 1-deficient mice is associated with reduced eosinophil rolling and adhesion on vascular endothelium.

To determine the relative in vivo importance of IL-1 release after allergen challenge to the subsequent endothelial adhesion and recruitment of eosinophils, the authors used ovalbumin sensitization and inhalation challenge to induce airway eosinophilia in IL-1 receptor type 1-deficient and control wild-type mice. Bronchoalveolar lavage (BAL) eosinophil recruitment in IL-1 receptor type 1-deficient mice challenged with ovalbumin (24.3% +/- 6.3% BAL eosinophils) was significantly reduced compared with wild-type mice (63.7% +/- 2.5% BAL eosinophils). To determine whether the inhibition of eosinophil adhesion to vascular endothelium contributed to the inhibition of eosinophil recruitment in IL-1 receptor type 1-deficient mice, the authors used intravital microscopy to visualize the rolling and firm adhesion of fluorescence-labeled mouse eosinophils in the microvasculature of the allergen-challenged mouse mesentery. Eosinophil rolling, eosinophil firm adhesion to endothelium, and transmigration across endothelium (peritoneal eosinophils) were significantly inhibited in allergen-challenged IL-1 receptor type 1-deficient mice compared with wild-type mice. Overall, these studies demonstrate that cytokines such as IL-1, released after allergen challenge, are important in the induction of endothelial cell adhesiveness, a prerequisite for the recruitment of circulating eosinophils. (Blood. 2000;95:263-269)

Differential expression of vascular cell adhesion molecule mRNA and protein in nasal mucosa in response to IL-1 or tumor necrosis factor.

IL-1 and tumor necrosis factor (TNF) are cytokines that share many overlapping functions, including induction of expression of the vascular cell adhesion molecule (VCAM) by endothelial cells. However, because most studies of cytokine induction of adhesion molecules have used human umbilical vein endothelial cells (HUVECs) and not microvascular endothelial cells, the functional significance of such observations to sites of allergic inflammation, such as the nasal mucosa, are at present unknown. We have therefore used nasal mucosa to compare the functional response of these microvascular endothelial cells with HUVECs. HUVECs or nasal mucosal explants were stimulated in vitro with varying concentrations of IL-1 or TNF for 0 to 48 hours, and VCAM mRNA and protein expression were determined by means of immunostaining and in situ hybridization. TNF and IL-1 were equivalent in their ability to induce VCAM mRNA and protein expression by HUVECs. In contrast, TNF was significantly more potent than IL-1 in inducing VCAM mRNA and protein expression by nasal mucosal microvascular endothelial cells. The recovery of significant amounts of IL-1 after incubation of recombinant IL-1 with nasal mucosa, as well as the ability of IL-1 to induce intercellular adhesion molecular expression by nasal mucosa, suggests that neither degradation of IL-1 nor downregulation of IL-1 receptors in nasal mucosa is likely to explain the inability of IL-1 to induce VCAM expression by nasal mucosa. These studies suggest that microvascular endothelial cells in the nasal mucosa differ functionally from HUVECs and that TNF may be more important than IL-1 in induction of VCAM expression in the nasal mucosa.

Inhibition of pulmonary eosinophilia in P-selectin- and ICAM-1-deficient mice.

Adhesion molecule expression by pulmonary endothelial cells is considered to play an important role in the recruitment of circulating leukocytes to sites of inflammation in the lung. We have used P-selectin- and intercellular adhesion molecule type 1 (ICAM-1)-deficient mice to determine whether these adhesion molecules are important to pulmonary eosinophil recruitment after allergen challenge. There was a significant inhibition of lung tissue eosinophil recruitment in ICAM-1-deficient mice (approximately 84% inhibition compared to wild-type mice) and P-selectin-deficient mice (approximately 67% inhibition compared to wild-type mice) 3 h after allergen challenge. The number of bronchoalveolar lavage (BAL) eosinophils in P-selectin-deficient and ICAM-1-deficient mice was also significantly reduced compared with wild-type mice. Levels of BAL eosinophil peroxidase (EPO) were significantly lower in ICAM-1-deficient mice (0.21 +/- 0.03 EPO units) compared with wild-type mice (3.34 +/- 0.65 EPO units). There was no significant difference in the degree of inhibition of eosinophil recruitment in ICAM-1-deficient mice at the three time points (3, 12, and 24 h) of study after allergen challenge. However, in P-selectin-deficient mice there was a decline in the degree of inhibition of eosinophil recruitment from 3 h (67% inhibition) and 12 h (72% inhibition) postchallenge, to 24 h postchallenge (38% inhibition), suggesting that other adhesion molecules may be playing a more prominent role than P-selectin at later time points. These studies suggest an important role for ICAM-1 and P-selectin in eosinophil recruitment to the lung after allergen challenge.

Eosinophil peroxidase differs from neutrophil myeloperoxidase in its ability to bind antineutrophil cytoplasmic antibodies reactive with myeloperoxidase.

The majority of antineutrophil cytoplasmic antibodies (ANCA) in patients with systemic vasculitis (a subset of whom exhibit eosinophilia associated with systemic vasculitis) recognize two neutrophil primary cytoplasmic granule constituents, namely myeloperoxidase (MPO) and proteinase-3. As eosinophil peroxidase (EPO) shares 68% amino acid identity with neutrophil MPO, we have investigated whether serum ANCA reactive with MPO (P-ANCA) also reacts with EPO. In this study we demonstrate that P-ANCA-reactive serum binds to ethanol-fixed neutrophils but not to eosinophils in a perinuclear pattern as assessed by indirect immunofluorescence. In addition, P-ANCA reactive serum did not bind to purified EPO or alter purified EPO function as assessed in a guaiacol assay of EPO activity. These studies suggest that the antigenic epitope recognized by P-ANCA-reactive serum is not determined by the homologous 68% peroxidase sequence shared by neutrophil MPO and EPO.