Intraepithelial migration of mucosal mast cells in hay fever: ultrastructural observations

Nasal Administration of Lipopolysaccharide Exacerbates Allergic Rhinitis through Th2 Cytokine Production from Mast Cells

Background: Microbial infection or exposure to endotoxin later in life exacerbates established asthma. Mast cells are involved in the exacerbation of asthma. This exacerbation involves a toll-like receptor (TLR)–mediated response of mast cells. In the clinical practice of otolaryngology, otolaryngologists experience an exacerbation of nasal congestion when infectious rhinitis develops in patients with allergic rhinitis, but the mechanisms are unknown. Therefore, this study investigated the effect of lipopolysaccharide (LPS) on allergic rhinitis using a mouse allergic rhinitis model. Methods: Female BALB/c mice, TLR4 gene mutant C3H/HeJ mice or mast cell–deficient WBB6F1-W/Wv mice were sensitized intraperitoneally with ovalbumin (OVA)/alum, and were intranasal challenged with OVA and/or LPS. Nasal symptoms and histologic changes were examined. Cytokines in nasal tissue were examined by Western blot. The effects of LPS on degranulation and cytokine production of bone marrow–derived mast cells (BMMCs) were investigated. Results: Nasal administration of LPS together with the antigen exacerbated nasal symptoms, eosinophil infiltration of the nasal mucosa, and increased IL-5 production in the nasal mucosa. It was not observed in C3H/HeJ mice and WBB6F1-W/Wv mice. The addition of LPS increased the production of IL-5 from BMMCs in a dose-dependent manner, but no effect on degranulation was observed. Conclusions: Intranasal administration of LPS exacerbates allergic rhinitis through Th2 cytokine production from mast cells. This observation provides clues to the mechanism of exacerbation of allergic rhinitis caused by an infection in daily clinical practice.

Anti-allergic function of α-Tocopherol is mediated by suppression of PI3K-PKB activity in mast cells in mouse model of allergic rhinitis

BACKGROUND

Alpha-Tocopherol (α-TCP), one major form of vitamin E, has been known as a treatment for airway allergic inflammation. However, the role and mechanism of α-TCP in treating allergic rhinitis remains unclear.

OBJECTIVE

In this study we examined the inhibitory function of α-TCP in a mouse model of allergic rhinitis.

METHODS

Allergic phenotype was examined by hematoxylin and eosin staining. Total IgE, OVA-specific IgE, OVA-specific IgG1 and OVA-specific IgG2a levels were examined by ELISA. mRNA expression was measured by qPCR, protein levels were examined by Western Blot.

RESULTS

Histological analysis of the nasal membranes revealed that there was a significant reduction in inflammatory cells appearance in cross-sections in alpha-TCP treatment of Ovalbumin (OVA)-sensitized mice compared to OVA sensitized animals. In addition, eosinophils were significantly reduced in nasal mucosa of alpha-TCP treatment of OVA-sensitized mice compared to the OVA group. Lower total IgE, OVA-specific IgE, OVA-specific IgG1 and OVA-specific IgG2a levels were found in alpha-TCP treatment of OVA-sensitized mice compared to the OVA group. Furthermore, we found that the subepithelial distribution of tryptase positive mast cells was reduced in the alpha-TCP treatment of OVA-sensitized mice. More importantly, the PI3K-PKB pathway was suppressed by α-TCP in mast cells.

CONCLUSIONS

Our results demonstrated that α-TCP-mediated suppression of PI3K-PKB activity in mast cells is a potential mechanism of anti-allergic function of α-TCP.

Lipid droplets in activated mast cells - a significant source of triglyceride-derived arachidonic acid for eicosanoid production

Mast cells are potent effectors of immune reactions and key players in various inflammatory diseases such as atherosclerosis, asthma, and rheumatoid arthritis. The cellular defense response of mast cells represents a unique and powerful system, where external signals can trigger cell activation resulting in a stimulus-specific and highly coordinated release of a plethora of bioactive mediators. The arsenal of mediators encompasses preformed molecules stored in cytoplasmic secretory granules, as well as newly synthesized proteinaceous and lipid mediators. The release of mediators occurs in strict chronological order and requires proper coordination between the endomembrane system and various enzymatic machineries. For the generation of lipid mediators, cytoplasmic lipid droplets have been shown to function as a major intracellular pool of arachidonic acid, the precursor for eicosanoid biosynthesis. Recent studies have revealed that not only phospholipids in mast cell membranes, but also triglycerides in mast cell lipid droplets are a substrate source for eicosanoid formation. The present review summarizes current knowledge about mast cell lipid droplet biology, and discusses expansions and challenges of traditional mechanistic models for eicosanoid production.

Overview on the pathomechanisms of allergic rhinitis

Allergic rhinitis a chronic inflammatory disease of the upper airways that has a major impact on the quality of life of patients and is a socio-economic burden. Understanding the underlying immune mechanisms is central to developing better and more targeted therapies. The inflammatory response in the nasal mucosa includes an immediate IgE-mediated mast cell response as well as a latephase response characterized by recruitment of eosinophils, basophils, and T cells expressing Th2 cytokines including interleukin (IL)-4, a switch factor for IgE synthesis, and IL-5, an eosinophil growth factor and on-going allergic inflammation. Recent advances have suggested new pathways like local synthesis of IgE, the IgE-IgE receptor mast cell cascade in on-going allergic inflammation and the epithelial expression of cytokines that regulate Th2 cytokine responses (i.e., thymic stromal lymphopoietin, IL-25, and IL-33). In this review, we briefly review the conventional pathways in the pathophysiology of allergic rhinitis and then elaborate on the recent advances in the pathophysiology of allergic rhinitis. An improved understanding of the immune mechanisms of allergic rhinitis can provide a better insight on novel therapeutic targets.

Mast cells populations fluctuate along the spinal dura mater of the developing rat

The present study reveals developmental changes in the number, the phenotype and the distribution pattern of mast cells (MCs) along the cervical, the thoracic and the lumbar parts of the spinal dura mater. Postnatal infiltration of spinal dura by MCs does not appear to follow a sequential developmental pattern and meningeal MCs are unevenly distributed along the various parts of the examined dura. At each spinal level, areas most densely populated by MCs are the dorsal dura and the dural sleeves of the dorsal (sensory) spinal roots The developmental time course of the total MCs number is characterized by significant fluctuations in all three parts examined, with notable increases at P1, P4, P21 and P60 (peak value) for the cervical part, at P1 (peak value), P7 and P21 for the thoracic part and at P1, P7 (peak value) and P30 for the lumbar part. At P180, MCs number declines to 56%, 33% and 13% of the peak values for the cervical, the thoracic and the lumbar part, respectively. However, a different developmental pattern is followed by each subpopulation of MCs identified on the basis of their staining characteristics, namely connective tissue type mast cells (CTMCs), mucosal type or cells with characteristics of immature mast cells (MTMCs) and mixed type MCs, in each part examined. The findings may be of importance in elucidating physiological and pathological processes in the dura mater and the vertebral column.

Role of histamine and platelet-activating factor in allergic rhinitis

This review is focused on the effects of histamine and platelet-activating factor (PAF) in allergic rhinitis and the plausible implications for therapy. Rhinitis is defined as a heterogeneous disorder resulting from an IgE-mediated reaction associated with nasal inflammation of variable intensity. Two phases of response are triggered by an IgE/allergen cross-linking event: the first is the release of preformed mediators such as histamine or interleukins from mast cells and basophils; the second begins when cells start producing lipid-derived mediators. One of these mediators is PAF. Apart from leukotrienes, PAF is perhaps the most potent inflammatory mediator in allergic rhinitis for inducing vascular leakage, a response that may contribute to the appearance of rhinorrhea and nasal congestion.

Allergic rhinitis: past, present and the future

Allergic rhinitis represents a global health issue affecting between 10% to 25% of the world population, with increasing prevalence over the last decade. Although often trivialized by patients and doctors, allergic rhinitis is a significant cause of morbidity, in addition to its substantial economic impact. While allergic rhinitis is an inflammatory disorder of the upper airways, inflammation alone is insufficient to explain the chronic nature of the disease. An exciting concept which has recently emerged in asthma concerns the role of the bronchial epithelium as a key regulator of airway inflammatory and remodelling responses in asthma. It has been shown by our group that the disruption and alteration in the function of the lower airway epithelium in asthma leads to the generation of a variety of stimuli that lead to the restructuring of the airway wall. This raises interesting questions regarding a similar role for the upper airway epithelium in allergic rhinitis. This review aims to interpret past and current research into allergic rhinitis, and to address specific areas where future research is warranted, particularly in relation to the possibility of an altered upper airway epithelial phenotype in allergic rhinitis.

Mode of action of intranasal corticosteroids

The mode of action of intranasal corticosteroids (INCS) is complex. It is not known whether INCS penetrate the nasal mucosa or act on target cells; however, their low systemic activity supports the concept of local action on nasal mucosa. This local effect can nonetheless influence a variety of inflammatory cells and their mediators such as epithelial cells, lymphocytes, basophils, mast cells, and Langerhans cells. Corticosteroid-induced inhibition of immunoglobulin E-dependent release of histamine is a possible but unproven mode of action. Epithelial cells are an important target for corticosteroids, and INCS concentration is high at the epithelial surface. INCS may combine with the corticosteroid receptors in epithelial cells, which are then expelled into the airway lumen together with the dead epithelial cells or migrating inflammatory cells. A reduced influx of mediator cells may explain some of the effects of INCS on rhinitis symptoms, but it cannot explain all of the effects because INCS also reduce the early-phase sneezing and rhinorrhea after an allergen challenge outside the pollen season. In this situation, the number of surface mast cells/basophils is very low, as it is in the absence of allergic rhinitis. The mechanism by which INCS treatment of allergic rhinitis reduces itching, sneezing, and rhinorrhea, the characteristic symptoms of an early-phase response involving mast cell release of histamine, remains to be determined. Studies should be conducted to characterize the broad range of mechanisms by which INCS produce their therapeutic effects in allergic rhinitis.

Allergic rhinitis: not purely a histamine-related disease

Allergic rhinitis is an inflammatory disorder of the nasal mucosa typified by the symptoms of nasal itch, sneeze, anterior nasal secretions, and nasal blockage. These symptoms arise from the interaction between mediators and neural, vascular, and glandular structures within the nose. Nasal itch, sneezes, and rhinorrhoea are predominantly neural in origin, while nasal obstruction is predominantly vascular. Nasal biopsy studies show accumulation of eosinophils within the lamina propria and epithelium and an increase in tissue and cell surface basophils in both seasonal and perennial allergic rhinitis. These cells are in an activated state. Within the epithelium, increased numbers of mast cells, T cells and Langerhans' cells, which induce T-cell activation, are found. The accumulation of these cells can be linked to chemokine and cytokine generation by the epithelial cells themselves. Thus, the tissue cell recruitment is orchestrated by activated mast cells, T cells, and epithelial cells, with the recruited tissue eosinophils also contributing to their persistence at this site through autocrine mechanisms. Mast cells generate an array of mediators including histamine, tryptase, leukotrienes, and prostaglandins. Histamine is also generated by basophils. Eosinophils and basophils contribute to the leukotriene synthesis within the tissue. Histamine nasal insufflation induces nasal itch, sneeze, and rhinorrhoea as well as nasal blockage, thereby reproducing all the symptoms of allergic rhinitis. These effects are primarily mediated by H1-receptors, and H1-receptor antagonists are a prominent treatment. Antagonism of histamine at these receptors reduces symptoms by about 40-50%, with the greatest effect on the neurally mediated responses. Thus, histamine is a major mediator of allergic rhinitis, but not the sole contributor. Nasal insufflation with leukotrienes, prostaglandins, or kinins is associated with the development of nasal blockage. These mediators act primarily on the nasal vasculature and, in this respect, leukotrienes are potent mediators. Leukotrienes also induce plasma protein exudation, which contributes to the anterior nasal secretions. Studies with combination products have suggested that modifying the effects of both leukotrienes and histamine has complementary effects in relieving nasal symptoms, indicating that both these mediators are relevant to disease expression.

Pulmonary mononuclear cell responses to antigens of Mycobacterium tuberculosis in healthy household contacts of patients with active tuberculosis and healthy controls from the community

Protective immunity against Mycobacterium tuberculosis requires CD4+ lymphocyte-mediated immune responses and IFN-gamma activity. As the primary portal of entry of M. tuberculosis is the lung, pulmonary immune responses against multiple M. tuberculosis Ags were compared between both M. tuberculosis-exposed tuberculin skin test-positive healthy household contacts (HHC) of patients with active sputum smear and culture-positive tuberculosis and tuberculin skin test-positive healthy control individuals from the community (CC). Frequencies of M. tuberculosis Ag-specific IFN-gamma-producing cells, IFN-gamma concentrations in culture supernatants, and DNA synthesis in bronchoalveolar cells (BAC) and PBMC were studied in HHC (n = 10) and CC (n = 15). Using enzyme-linked immunospot assay we found higher frequencies of IFN-gamma-producing cells with specificity to M. tuberculosis-secreted Ag 85 (Ag 85) in BAC from HHC than in BAC from CC (p < 0.022) and relative to autologous PBMC, indicating compartmentalization of Ag 85-specific cells to the lungs. Further, IFN-gamma-producing cells with specificity to components A and B of Ag 85 were specifically compartmentalized to the lungs in HHC (p < 0. 05). IFN-gamma concentrations in culture supernatants of BAC and Ag-specific DNA synthesis were low and comparable in the two subject groups. Increased immune responses to Ag 85 at the site of repeated exposure to M. tuberculosis (the lung) may represent an important component of protective immunity against M. tuberculosis. Correlates of protective immunity against M. tuberculosis are required for assessment of the efficiency of anti-tuberculous vaccines.

Lung epithelial H292 cells induce differentiation of immature human HMC-1 mast cells by interleukin-6 and stem cell factor

BACKGROUND

Immature mast cells migrate into tissues where they differentiate into mature mast cells under the influence of local factors. In the airways of asthmatics increased numbers of chronically activated mast cells are located nearby the airway epithelium.

OBJECTIVE

The aim of this study was to evaluate whether and, if so, which products released by epithelial cells may affect mast cell proliferation and differentiation.

METHODS

We performed in vitro studies using the human lung mucoepidermoid carcinoma-derived H292 cell line and the immature human mast cell line, HMC-1. Proliferation was assessed by 3H-thymidine incorporation. Differentiation of HMC-1 cells was inferred from tryptase production.

RESULTS

Exposure of HMC-1 cells to medium conditioned for 48 h by H292 cells resulted in a reduction of proliferation with 65 +/- 4.9% (mean +/- SEM, n = 9) at day 5. Culturing HMC-1 cells for 8 days in the presence of H292-conditioned medium resulted in morphological changes indicative of differentiation, and in a 3.0 +/- 0.4-fold increase of tryptase production (P = 0.0039, n = 9). Conditioned medium from H292 cells that were stimulated by LPS also inhibited HMC-1 proliferation. Inhibitory antibodies against two mediators from H292 cells, interleukin-6 (IL-6) and stem cell factor (SCF), abolished the increase in HMC-1 tryptase production induced by H292-conditioned medium. Recombinant human (rh) IL-6, but not rhSCF, reduced HMC-1 proliferation with 44% and 13% at day 3 and 5, respectively. Surprisingly, rhIL-6 did not increase HMC-1 tryptase production significantly whereas incubation with rhSCF did (1.5 +/- 0.1-fold, P = 0.002, n = 10) although the increase was less than observed for conditioned medium.

CONCLUSION

Epithelial-derived IL-6 and SCF are implicated in differentiation of HMC-1 cells but additional factors are not excluded. As activated primary bronchial epithelial cells also express IL-6 and SCF, it should be considered that these cells are involved in mast cell differentiation within the airways, particularly in diseases where epithelial cells are activated, such as asthma.

Effect of topical corticosteroids on seasonal increases in epithelial eosinophils and mast cells in allergic rhinitis: a comparison of nasal brush and biopsy methods

BACKGROUND

Nasal brushing and nasal biopsy are well-tolerated sampling techniques. Seasonal grass pollen-induced rhinitis is characterized by epithelial mast cell infiltration and seasonal increases in both epithelial and sub-mucosal eosinophils.

OBJECTIVE

To compare the ability of the nasal brush and nasal biopsy techniques to detect natural seasonal increases in eosinophils and mast cells, and to assess the influence of topical corticosteroid.

METHODS

Nasal brush samples and nasal biopsies were collected from 46 grass pollen-sensitive seasonal rhinitis patients before the grass pollen season and at the peak of the pollen season following 6 weeks' treatment with either fluticasone propionate aqueous nasal spray (200 microg, twice daily) or placebo nasal spray.

RESULTS

Placebo patients showed seasonal increases in epithelial eosinophils both with nasal brushing (P < 0.0001) and biopsy (P < 0.001). Epithelial mast cell numbers also increased during the pollen season as detectable by brushing (P < 0.0001) and biopsy (P < 0.03). Changes in cell numbers measured by nasal brushing correlated with those observed with nasal biopsy, both for eosinophils and mast cells (P < 0.05). Sub-mucosal eosinophils but not mast cells also increased during the pollen season (P < 0.002). Nasal brushing and biopsy revealed that fluticasone treatment inhibited seasonal increases in epithelial eosinophils (P < 0.00001) and epithelial infiltration by mast cells (nasal brushing P < 0.00001 and nasal biopsy P < 0.01). Fluticasone also inhibited seasonal increases in sub-mucosal eosinophils (P < 0.001) and significantly reduced nasal symptoms (P < 0.001).

CONCLUSION

Nasal brushing harvests sufficient inflammatory cells from the surface of the nasal mucosa to be used in lieu of nasal biopsies in observation of the effect of drugs on the nasal epithelium.

Inflammatory mediators in naturally occurring rhinitis

BACKGROUND

The mediators released during the allergic inflammatory reaction induce the clinical symptoms of the allergic disease and although there have been numerous studies investigating mediator release in allergen challenge models of allergic rhinitis very few have extended this approach to the study of natural disease.

OBJECTIVE

The aim of this investigation was therefore to measure mast cell and eosinophil mediator levels and indices of vascular permeability in naturally occurring rhinitis.

METHODS

Three groups of subjects were studied, normal non-rhinitics, seasonal allergic rhinitics in and out of the grass pollen season and perennial allergic rhinitics. Mediators were recovered using the technique of nasal lavage and the levels of tryptase, histamine, eosinophil cationic protein and albumin were determined. In addition, eosinophils were enumerated in nasal smears as an indices of underlying inflammation.

RESULTS

The levels of tryptase, eosinophil cationic protein and albumin were significantly higher in the lavage recovered from the symptomatic seasonal allergic rhinitics than when asymptomatic (P = 0.05, P = 0.003, P = 0.009, respectively). These levels of eosinophil cationic protein and albumin were also significantly higher than those of the normal non-rhinitics (P = 0.0008, P = 0.0.003, respectively). In the perennial allergic rhinitics the levels of tryptase, eosinophil cationic protein and albumin were higher than the normal non-rhinitics (P < 0.0001, P = 0.0003, P = 0.0001, respectively). The levels of tryptase and histamine were higher in the perennial allergic rhinitics than the seasonal allergic rhinitics (P = 0.0003, P = 0.006, respectively). These changes in mediator levels were accompanied by a significant influx of eosinophils into the nasal mucosa of both the symptomatic seasonal rhinitics, compared with asymptomatic (P = 0.04) and normal controls (P = 0.0006) and the perennial rhinitics compared to normal controls (P = 0.03).

CONCLUSION

These results indicate that in both naturally occurring seasonal allergic rhinitis and perennial allergic rhinitis mast cell and eosinophil activation occurs and this is accompanied by an increase in vascular permeability. These measurements in lavage fluid provide a method of monitoring the mucosal cellular events in response to therapy.

Mast cell interaction with tumor cells in small early gastric cancer: ultrastructural observations

The authors studied the mast cells by light and electron microscopy in four small intramucosal early gastric cancers (EGC). Mast cells were found in the tumor stroma and among neoplastic cells of adenocarcinoma glands. Stromal and adenocarcinoma-infiltrating mast cells were ultrastructurally identified as T mast cells, and exhibited anaphylactic or piecemeal degranulation. Tumor cells in intimate contact with mast cells showed no cytopathic changes. These data do not support a mast cell-mediated cancer lysis, such as that reported in some systems in vitro. The interepithelial localization of T mast cell in adenocarcinoma glands is similar to that observed in some disease states, including interstitial cystitis, fibrotic lung disorders, and mucosal allergic reaction. The findings suggest that T mast cells may be involved in the pathophysiology of the host reaction to small intramucosal EGC.

Effect of natural allergen exposure during the grass pollen season on airways inflammatory cells and asthma symptoms

BACKGROUND

Bronchial challenge with allergen causes a specific form of airways inflammation consisting of an influx of neutrophils, eosinophils, and T cells. Because the relevance of the challenge model to clinical asthma is uncertain, the cellular changes that occur in the lungs of asthmatic subjects during natural seasonal allergen exposure were investigated.

METHODS

Seventeen grass pollen sensitive asthmatic subjects with previously reported seasonal exacerbations of asthma kept records of symptoms and underwent fibreoptic bronchoscopy with bronchoalveolar lavage (BAL) and endobronchial biopsy before and during the peak of the grass pollen season. The BAL cells were analysed for differential cell counts and by flow cytometry for T cell subsets and surface activation markers. The biopsy samples were processed into glycol methacrylate resin and immunohistochemical analysis was performed for mast cells, activated eosinophils, T cells and interleukin 4 (IL-4), a cytokine with a pivotal role in allergen-induced inflammation.

RESULTS

In the pollen season there was an increase in T lymphocyte activation in the BAL fluid as identified by increased expression of interleukin 2 receptor (IL-2R). In the submucosa these changes were paralleled by an increase in CD4+ T cells. By contrast, the numbers of metachromatic cells in BAL fluid staining with toluidine blue were reduced, possibly because of degranulation following allergen stimulation. In keeping with mast cell activation, the number of mucosal mast cells staining for secreted IL-4 increased during the season. In comparison with the period shortly before the onset of the season, all but two subjects experienced an asthma exacerbation which followed the rise in pollen counts but, compared with the period preceding the first bronchoscopic examination, asthma symptoms were not increased during the pollen season.

CONCLUSIONS

The data suggest that natural allergen exposure, leading to a clinical exacerbation of asthma, may induce an inflammatory response involving T cells, mast cells and eosinophils. The relationship between allergen exposure, cellular infiltration and activation, and clinical symptoms appears to be complex, with factors other than allergen also contributing to asthmatic activity.

Pathology of rhinitis and bronchial asthma

Studies of the pathology of rhinitis and asthma have identified similarities and differences between these two clinical conditions. With regard to symptoms, both the nose and the lower airways respond to neural stimulation by irritant substances, but a major difference is that engorgement of the capacitance vessels is the main cause of nasal obstruction in rhinitis, while muscle constriction is the major determinant of lower airway narrowing. There are also similarities and differences with respect to the role of inflammatory cells. In both conditions there is evidence of allergen-induced mast cell activation, with production of an array of mediators (some mast cell-derived and others originating from a variety of other cell types). Eosinophilia is also characteristic of both diseases--it is prominent even in mild forms of asthma, but is low in pollen-sensitive rhinitics outside of the season. T-cell activation and production of cytokines plays an important role in the development and maintenance of allergic disease, but the level of T-cell activation may differ between asthma and rhinitis. Further research into differences in cellular activity and response to treatment between these two diseases may help define factors which will determine whether atopic disease is expressed in the upper, lower, or both parts of the respiratory tract.

Inflammatory markers in nasal lavage fluid from Industrial Arts teachers

Exposure to wood dust can cause allergic and nonallergic rhinitis. Inflammatory markers [cells, albumin, tryptase, and eosinophil cationic protein (ECP)] were examined in nasal lavage fluid (NAL) sampled from 24 Industrial Arts (IA) teachers exposed to wood dust and other irritants and from 24 control subjects. The IA teachers had more nasal complaints but they did not differ significantly from the controls regarding ECP concentration (median 4.1 and 4.7 micrograms/L, respectively), albumin concentration (median 30.7 and 20.7 g/L), and percentage of neutrophils (median 56 and 34) in NAL. Tryptase was not detected. No marked inflammation was thus found, but the albumin concentration was higher in subjects reporting nasal stuffiness. In the IA teachers, a relationship between the percentage of neutrophils and the number of classes during the working week was found (Spearman's rank correlation coefficient 0.53, p < 0.01) indicating a possibility of wood-dust-related inflammatory effects on the nasal mucosa.

Proteinase content of mast cells of nasal mucosa; effects of natural allergen exposure and of local corticosteroid treatment

The distribution and density of metachromatic cells (MCC) and mast cells containing chymase plus tryptase (MCTC) or tryptase alone (MCT) were studied in the nasal mucosa by dye-binding methods and immunohistochemical analysis. Biopsies were obtained from 17 subjects with birch pollen allergy before and during the peak season and from nine healthy controls. Six patients were treated with an intranasal glucocorticosteroid before and during the season in an open study. Hay fever patients, even when asymptomatic, showed signs of mast cell system activation, exhibiting an increased number of mast cells in the nasal epithelium. Basophils, lacking immunohistochemically detectable tryptase, were not a major component of the mast cell response. MCT, most conspicuous in the epithelium, were found to be the most frequent mast-cell type in the nasal mucosa of allergic, but not of normal, subjects. Only 33% of the epithelial, but 90% of the stromal, immunopositive cells in the atopic mucosa before as well as during the season were MCC. Intraepithelial MCT thus displayed a low capacity to stain metachromatically, indicating a relative deficiency of the glycosaminoglycan (heparin) component of the granules. Intraepithelial mast cells also appeared to be markedly sensitive to steroid treatment and aldehyde fixation. The findings suggest that the lack of chymase, the characteristic feature of MCT, may reflect a functional activation of the mast cells, rather than a stable phenotypic differentiation related to anatomic site.

The cellular basis for allergic rhinitis

In both seasonal and perennial rhinitis there is epithelial mast cell accumulation and tissue infiltration by eosinophils. Activation of these cells can be observed by electron microscopy and by elevated levels of tryptase and eosinophil cationic protein in nasal lavage fluid. Furthermore, seasonal increases in the antigen presenting cell (Langerhans' cell) are also evident. Investigations into the mechanisms involved in cell accumulation and activation reveals upregulation of leucocyte endothelial adhesion molecules and an increase in interleukin-4 (IL-4) in naturally occurring rhinitis, while mRNA for IL-4, IL-5 and granulocyte macrophage colony stimulating factor activity and lavage tumour necrosis factor-alpha (TNF alpha) levels are increased following local allergen challenge. These cytokines may be derived from a variety of sources, including mast cells, eosinophils and T-lymphocytes, and contribute to the underlying inflammatory process in rhinitis.

Nasal mast cells in experimentally induced allergic rhinitis in guinea-pigs

The kinetics of mast cell accumulation in the nasal mucosa during allergen exposure were investigated in the animal model of experimentally induced allergic rhinitis. Guinea-pigs were divided into an unsensitized control group and five sensitized groups each containing five animals. Five sensitized groups were immunized intraperitoneally with ovalbumin, followed by intranasal administration of ovalbumin in each of four groups for 1, 2, 3 and 4 weeks, respectively. There were significant increases in the number of mast cells in the epithelium after 2 and 3 weeks in the groups receiving intranasal ovalbumin. No significant changes were detected in the lamina propria and the total number of mast cells. In the lamina propria, the distance between a mast cell and the basement membrane was significantly decreased in the groups after 2, 3 and 4 weeks of intranasal administration. These findings suggest that an infiltration of mast cells from the lamina propria to the epithelium occurred after 2 weeks of intranasal administration of allergen. An electron microscopic study showed no mast cells at the luminal surface of the epithelium and the majority of mast cells lying around the basal cells. This finding suggests that the allergen must penetrate into the epithelium in order to interact with mast cells in guinea-pig nose.

Metachromatic, IgE-bearing and tryptase-containing cells on the nasal mucosal surface in provoked allergic rhinitis

We studied the relationship between mast cells or basophils and symptoms in provoked allergic rhinitis. Nasal brush and lavage samples were obtained before nasal allergen challenge and every 2 h for 12 h after the challenge in 10 allergics and 3 controls. The cells were identified by their metachromatic staining properties (brush and lavage samples) or with immunohistochemical methods using specific antibodies to IgE and tryptase, a selective mast-cell marker (brush samples). Histamine was determined in the brush samples using liquid chromatography. After an initial decrease, the numbers of metachromatic, IgE-bearing and tryptase-containing cells, as well as the histamine content of the cells in the brush samples, increased during the subsequent observation hours. The prechallenge cell and histamine values correlated with the symptom score 15 min after the challenge. The prechallenge lavage samples lacked metachromatic cells, but these cells were found in increasing numbers after the provocation. Three of the patients differed from the remaining seven in that their prechallenge brush samples contained many positively stained cells. All patients showed a positive cellular response to the allergen challenge, but these three individuals showed the most vivid response. The morphology of the metachromatic cells in the prechallenge brush samples agreed with that of mast cells, but the morphology of metachromatic cells which outnumbered tryptase-containing cells in samples at 8 to 12 h rather agreed with their being basophils.

Mast cells and mediators in the nasal mucosa after allergen challenge. Effects of four weeks' treatment with topical glucocorticoid

The study focuses on the relationship between the tissue density of mast cells, the tissue histamine levels and the levels of markers of mast cell activation after an allergen challenge of the nasal mucosa of allergic patients. The effect of 4 weeks' treatment with a topical glucocorticoid, fluticasone propionate, was studied in a double-blind, placebo-controlled study of 25 hay fever patients. Nasal biopsies were obtained before and after the treatment period for the evaluation of mast cell density and tissue histamine levels. Nasal challenges were performed at 2-week intervals for 8 weeks using a standardized nasal lavage model. TAME-esterase was analysed in the returned lavage fluid from all the challenges (weeks 0-8), while the levels of histamine and tryptase were analysed in lavage fluids from challenges performed before and after the treatment period (weeks 0 and 4). The symptoms of nasal allergy were assessed after each challenge. Treatment with fluticasone propionate did not influence mast cell density, the tissue histamine concentration, the lavage histamine levels or the TAME-esterase activity, while a reduction in nasal symptoms and tryptase in nasal lavage fluid was revealed. Our present study again emphasizes the fact that the mast cell is an important trigger cell in the immediate nasal allergic response. The study also demonstrates the usefulness of the measurements of tryptase as an indicator of both mast cell activation and the efficacy of topical steroid treatment.

The effect of BAY u 3405, a thromboxane receptor antagonist, on prostaglandin D2-induced nasal blockage

BACKGROUND

Nasal lavage and challenge studies in allergic rhinitis implicate prostaglandin (PG) D2 in the genesis of nasal blockage. PG D2 is known to act via at least two receptors, the thromboxane prostanoid receptor and the PG D2 prostanoid (DP) receptor; the lower airway effects are mediated chiefly by the TP receptor. The receptor involved in the genesis of PG D2-induced nasal blockage is unknown. BAY u 3405 is a potent selective competitive TP receptor antagonist, which inhibits the lower airway response to PG D2, and shifts the dose-response curve to the right by up to 16-fold.

METHODS

The efficacy of a single oral dose of 20 mg of BAY u 3405 was examined in comparison with PG D2 nasal insufflation in a randomized, double-blind, placebo-controlled crossover study, with objective measurement of nasal resistance by active posterior rhinomanometry.

RESULTS

BAY u 3405 afforded no protection against PG D2-induced nasal blockage.

CONCLUSIONS

This suggests that PG D2-induced nasal blockage may be mediated by the DP receptor rather than the TP receptor and that TP receptor antagonists are unlikely to be of benefit in the treatment of allergic rhinitis. In vivo investigation with specific potent DP receptor antagonists is awaited.

Mast cells and eosinophils in the allergic mucosal response to allergen challenge: changes in distribution and signs of activation in relation to symptoms

An allergen challenge was performed in 10 asymptomatic patients with strictly seasonal allergic rhinitis. For comparison; seven nonallergic subjects were challenged with allergen, and seven allergic patients were challenged with diluent. Cell samples, obtained with use of a brush technique to recover cells from within the epithelium and nasal lavage to collect cells from the epithelial surface, and symptom scores were taken before challenge and at 2-hour intervals during 12 hours. The cell suspensions were cytocentrifuged onto object slides for light microscopy. Histamine was determined in the cell pellets. In brush samples from the allergic patients challenged with allergen, eosinophils, expressed as a percentage of the total granulocytes, increased from 4.3% +/- 2.7% (mean +/- SEM) to 10.3% +/- 3.8% (p < 0.05) 4 hours after challenge. This level was maintained for up to 12 hours. A similar increase was noted in the lavage specimens 2, 6, and 8 hours after the challenge. In the brush samples the proportion of eosinophils containing two or more cytoplasmic vacuoles, taken as a sign of activation, increased from 20% to 72% (p < 0.05) 8 hours after provocation. In brush samples from the allergic patients challenged with allergen, the numbers of metachromatic cells increased to a maximum of eightfold at 10 hours. In the lavage specimens, no metachromatic cells were observed before provocation, but they progressively increased in number 2 to 12 hours after provocation. Cell pellet histamine content decreased temporarily 2 to 4 hours after challenge (p < 0.05) in brush samples from allergen-challenged allergic patients. The local metachromatic cell density before challenge, as reflected in the brush specimens, correlated with nasal congestion, sneezing, and the degree of eosinophilia.

A family of cross-reacting proteins secreted by Mycobacterium tuberculosis

Cross-reactions between five proteins actively secreted by Mycobacterium tuberculosis were studied by crossed immunoelectrophoresis, SDS-PAGE with immunoblotting, and ELISA using polyclonal rabbit antisera and mouse monoclonal antibodies to the purified proteins. The monoclonal antibody HBT4 was demonstrated to react with the MPT51 protein. The 85A, 85B and 85C constituents of the M. tuberculosis and Mycobacterium bovis BCG antigen 85 complex cross-react extensively, each of the components containing component-specific as well as cross-reacting epitopes. These components also cross-reacted with MPT51 and MPT64. N-terminal sequence studies revealed striking homology at the amino acid level between 85A, 85B, 85C and MPT51. MPT64 showed less homology. In addition, striking homology was demonstrated between two different stretches within the 85B sequence and indicated between three stretches within the MPT64 molecule. Thus, a family of at least four secreted proteins with common structural features has been demonstrated in mycobacteria. MPT64 may also belong to this family.

Molecular and immunological analysis of a fibronectin-binding protein antigen secreted by Mycobacterium leprae

By screening a Mycobacterium leprae lambda gt11 genomic DNA library with leprosy-patient sera we have previously identified 50 recombinant clones that expressed novel M. leprae antigens (Sathish et al., 1990). In this study, we show by DNA sequencing and immunoblot analysis that three of these clones express a M. leprae homologue of the fibronectin-binding antigen 85 complex of mycobacteria. The complete gene was characterized and it encodes a 327-amino-acid polypeptide, consisting of a consensus signal sequence of 38 amino acids followed by a mature protein of 289 amino acids. This is the first sequence of a member of the M. leprae antigen 85 complex, and Southern blotting analysis indicated the presence of multiple genes of the 85 complex in the genome of M. leprae. The amino acid sequence displays 75-85% sequence identity with components of the antigen 85 complex from M. tuberculosis, M. bovis BCG and M. kansasii. Furthermore, antibodies to the antigen 85 complex of M. tuberculosis and M. bovis BCG reacted with two fusion proteins containing the amino acid regions 55-266 and 266-327 of the M. leprae protein. The M. leprae 30/31 kDa protein induces strong humoral and cellular responses, as judged by Western blot analysis with patient sera and proliferation of T cells derived from healthy individuals and leprosy patients. Amino acid regions 55-266 and 265-327 both were shown to bind to fibronectin, indicating the presence of at least two fibronectin-binding sites on the M. leprae protein. These data indicate that this 30/31 kDa protein is not only important in the immune response against M. leprae, but may also have a biological role in the interaction of this bacillus with the human host.

Tryptase in nasal lavage fluid after local allergen challenge. Relationship to histamine levels and TAME-esterase activity

The activation of mast cells is generally considered to be an important trigger mechanism in the immediate allergic response. This study focused on the determination of three markers of mast cell activation after an allergen challenge. Nasal allergen challenges were performed in 25 subjects with seasonal allergic rhinitis using three allergen doses increasing in 10-fold steps in a standardised nasal lavage model for the subsequent recovery of the markers of mast cell activation. The levels of histamine and tryptase in the nasal lavage fluid were determined using radioimmunoassays, while the TAME-esterase activity was determined using a radiochemical technique. The nasal symptoms obtained on challenge were assessed using a scoring technique. The allergen challenge resulted in significant increases in the levels of all three markers, tryptase, histamine and TAME-esterase. In the individual measurements after the challenges there was a highly significant correlation between the TAME-esterase levels and the tryptase levels (r = 0.71; P less than 0.001), while the generation of histamine and tryptase was not significantly correlated. When comparing the cumulative generation of the three markers, significant correlations were found between all three. Allergen challenges in six non-allergic controls using the same technique did not result in any increase in tryptase levels. The findings suggest that the determination of tryptase in nasal lavage fluid may be a valuable indicator of mast cell activation in the upper airways.

Bronchial epithelial inflammation in children with chronic cough after early lower respiratory tract illness

We studied the ultrastructural findings in biopsies from the main carina of seven school-aged children who had had chronic cough for at least 3 months and who all had a history of early lower respiratory illness (LRI). They had their first LRI between birth and 7 yr of age (range, 5 to 11 yr). The cross-sectional area of the epithelium was quantified by point counting for the percentage area of intercellular spaces (ICS) denoting edema, and the numbers of both inflammatory cells (leukocytes, including eosinophils, and mast cells) and ciliated cells. The children (excluding the one using inhaled steroids) demonstrated nearly 17- and more than sevenfold increases in the mean area of ICS and number of inflammatory cells per epithelial area, respectively, and a nearly three-fold decrease in the mean number of ciliated cells per epithelial area compared with the biopsy specimens from the orifice of the right upper lobe bronchus of two healthy adults. In the children, the increase in inflammatory cells (greater than 91% were lymphocytes) was more prominent in the children with two LRI before the age of 1 yr. Our findings imply a close association of early LRI and later epithelial inflammation during chronic cough. Allergic mechanisms in the epithelial inflammation cannot be ruled out as six of the patients had, either alone or in combination, signs of atopia, positive family history of allergic rhinitis or asthma, and eosinophils or mast cells in the epithelium.(ABSTRACT TRUNCATED AT 250 WORDS)

Nasal mucosal response to repeated challenges with pollen allergen

In order to explore the dynamics of the cellular response of the airway mucosa to allergen exposure, controlled daily allergen challenges were performed for 7 days during the pollen-free winter months in nine patients with strictly seasonal allergic rhinitis caused by birch pollen allergen. Symptoms obtained after the challenge were related to morphologic changes within and on the surface of the nasal mucosa. Cell samples were obtained daily prior to challenge from the nasal mucosa using mucosal imprints on plastic strips, brush samplings from the nasal mucosa, and nasal lavage. For light microscopy, the cellular material obtained by brushing and nasal lavage were cytocentrifuged onto object slides. Histamine was measured in the cell pellets that were obtained using the lavage and brush procedures as well as in the lavage supernatant fluid. Four symptoms (sneezes, itching, secretion, and blockage) were recorded and expressed individually as well as in the form of a composite symptom score. Nasal blockage was measured using a nasal peak flow meter. The patients displayed an increase in nasal symptoms after the allergen challenge, which was further increased between Days 2 to 7 (p less than 0.05). The light microscopic evaluation of the lavage revealed an immediate increase in eosinophils from 2.3 to 13.1% and was maintained on the same level throughout the period of challenges. A similar increase was noted in the brush specimens, and a strong correlation was obtained between these two methods of sampling.(ABSTRACT TRUNCATED AT 250 WORDS)

The cellular response of the human allergic mucosa to natural allergen exposure

It has been suggested that the IgE-dependent late-phase reaction to allergen exposure, with the features of an inflammatory cellular infiltration and airway hyperreactivity, is a link between anaphylaxis and continuous allergic airway disease. Our main knowledge of the cellular response to allergen in sensitized individuals has been derived from allergen-challenge models. To explore the dynamics of the cellular response during the actual disease, patients with a strictly seasonal allergic rhinitis were studied during natural allergen exposure. Ten patients suffering from an isolated birch-pollen allergy were followed from a symptom-free state before, during, and to the height of the birch-pollen season. Repeated parallel cell samplings from the nasal mucosa were performed with cytologic imprints on plastic strips, nasal lavages with the recovery of the cells in the lavage fluid with cytocentrifugation on object slides for cytologic study, and scrapings from the nasal surface with a curette for histologic and ultrastructural evaluation. The histamine content was determined in lavage fluid and cell pellets. The tosyl-alpha-tosyl-L-arginine methyl esterase activity of the nasal lavage fluid was also determined as a biochemical marker of the allergic inflammatory reaction. The birch-pollen season was moderate in terms of pollen counts, and this resulted in mild to moderate nasal symptoms that ran parallel to the birch-pollen counts. The total number of cells recovered in the lavage fluid was 1.2 +/- 0.4 (SEM) x 10(6) before and 3.2 +/- 2.0 per 10(6) cells (not significant) during pollen exposure. Most cells were neutrophils and mononuclear cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Phenotypic expression of proteoglycan in mast cells of the human nasal mucosa

The phenotypic expression of the proteoglycan of human mast cells in the nasal mucosa and normal skin was analysed using histochemical techniques. Nasal mucosa was obtained from normal subjects, from patients with seasonal allergic rhinitis before and during the pollen season and from patients with nasal polyps. In the latter groups, specimens were taken from both polyp tissue and adjacent nasal mucosa. Formaldehyde treatment blocked the cationic dye binding in 75-84% of the mast cells located in the nasal mucosa, as compared to the optimum fixation with IFAA (iso-osmotic formaldehyde-acetic acid). A significantly lower degree of blocking of dye binding was obtained in the human skin where 45% of the mast cells were susceptible to formaldehyde treatment (P less than 0.01). The mast cells of the polyp tissue also showed a relatively low degree of blocking (54%), which was significantly lower than the blocking of mast cells of the nasal mucosa taken from the same individuals (P less than 0.05). Staining of serial tissue sections in Alcian Blue containing graded concentrations of MgCl2 was used to determine the critical electrolyte concentration (CEC) of the dye binding, defined as the salt concentration at which the staining of 50% of the mast cells is extinguished. The CEC of the skin mast cells was 0.64M MgCl2 which is significantly higher than that of the mast cells of the nasal mucosa of normal subjects [0.49M (P less than 0.05)], allergic subjects [0.52M (P less than 0.01)], patients with polyp disease [0.52M (P less than 0.01)] and the polyp tissue proper [0.57M (P less than 0.05)].(ABSTRACT TRUNCATED AT 250 WORDS)

A brush method to harvest cells from the nasal mucosa for microscopic and biochemical analysis

A method is described for the sampling of epithelial cells and other effector cells from the human airway mucosa for structural and biochemical analysis. The cell samples are obtained from the nasal mucosa using a small nylon brush which is rotated over the epithelium and soaked and shaken in a small volume of a balanced salt solution. Morphological evaluation using light microscopy and transmission electron microscopy revealed excellently preserved cytological detail. In asymptomatic individuals the cells harvested were as follows: 45 +/- 5.9% (mean +/- SEM) epithelial cells, 38 +/- 7.1% granulocytes, 16 +/- 2.3% large mononuclear cells (monocytes), and 1.3 +/- 2.3% eosinophils. Repeated measurements in the same individual revealed a coefficient of variation of the order of 40% for the proportions of cells harvested. In comparison with nasal airway lavage, a higher proportion of epithelial cells and monocytes were obtained with the brush method. The cells harvested could also be used for biochemical analysis. The histamine content of the cell pellets was found to be strongly correlated with the mast cell count (r = 0.93) and was estimated to about 10 pg/cell, which is higher than previously reported for mast cells obtained from human lung tissue dispersed by an enzymatic method. The present method appears to be appropriate for the study of cellular events in the nasal mucosal epithelium.

Allergen-induced nasal hyperreactivity appears unrelated to the size of the nasal and dermal immediate allergic reaction

It has been previously demonstrated in nasal challenge studies that there is an increased sensitivity to allergen following an initial allergen challenge. A similar feature has been demonstrated following natural allergen exposure in patients with seasonal allergic rhinitis. To further explore the characteristics of this "priming" phenomenon and its relationship to other expressions of their allergic airway disease, 28 hay fever patients with strictly seasonal disease were studied. Skin tests with the relevant pollen allergen and histamine were performed and the size of the immediate and late phase allergic reaction was determined. An initial nasal allergen challenge was followed by a rechallenge of the nose with allergen 24 h later using a lavage technique. Determinations of TAME-esterase activity, as a biochemical marker of the allergic reaction, were made in the returned lavage fluid. The number of sneezes was counted and nasal symptoms were also assessed using a scoring technique. 19 of 28 patients (67%), displayed an increased responsiveness at rechallenge with similar findings in terms of symptom scores and TAME-esterase measurements. The increase was statistically significant for the symptoms of nasal blockage, which increased from 0.7 +/- 0.1 (mean +/- SEM) to 1.1 +/- 0.2 (P less than 0.05), and nasal secretion which rose from 1.1 +/- 0.2 to 1.7 +/- 0.2 (P less than 0.01). A composite nasal symptom score which also took account of the number of sneezes, increased from 2.9 +/- 0.4 to 4.0 +/- 0.3 (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)