Allergen-induced accumulation of eosinophils and lymphocytes in skin chambers is associated with increased levels of interleukin-4 and sVCAM-1.

BACKGROUND: The aim of the study was to characterize the kinetic accumulation of various inflammatory mediators in allergen-challenged skin chambers applied on patients with pollen-related allergic rhinitis/mild asthma. METHODS: Skin blisters were induced on the forearms and challenged with allergen or phosphate-buffered saline (PBS). Peripheral blood was drawn before and 8 h after challenge for analysis of differential cell counts, sVCAM-1, and alpha2-macroglobulin. Chamber fluids, collected at 1, 4, and 8 h after allergen application, were analyzed for differential cell counts, histamine, interleukin (IL)-4, sVCAM-1, and alpha2-macroglobulin. RESULTS: The number of recruited leukocytes was equal in allergen and PBS chambers; however, the numbers of eosinophils and lymphocytes were significantly (P< or =0.05) elevated in allergen-challenged chambers at 8 h. Compared to PBS chambers, allergen chambers contained significantly (P<0.01-0.05) higher levels of histamine (at 1 and 4 h), IL-4 (at 4 and 8 h), alpha2-macroglobulin (at 1 and 8 h), and sVCAM-1 (at 1 and 8 h). In contrast to alpha2-macroglobulin, levels of sVCAM-1 in peripheral blood were significantly (P<0.05) increased at 8 h. CONCLUSIONS: Increased levels of sVCAM-1 and IL-4 in allergen-challenged chambers, in parallel with increased recruitment of eosinophils and lymphocytes, points to the participation of IL-4 and VCAM-1 in the development of the late-phase reaction. Increased levels of sVCAM-1 in allergen-challenged chambers probably reflects a combination of leakage and local production.

Conformational isomerism of IgG antibodies.

The purpose of this study was to determine why apparently homogeneous IgG antibodies were, in some cases, fractionated into at least two components by liquid-liquid partition chromatography (LLPC) in an aqueous two-phase system. Four mouse monoclonal IgG antibodies, two against albumin, one against IgG and one against thyroxine, were shown to adopt different conformational isomeric forms. The four antibodies existed in an equilibrium between two or three conformational forms, the proportion of which could also be estimated by LLPC. Since LLPC detects mainly conformational differences within the antigen-binding sites of IgG antibodies, it could be concluded that the conformational forms differed with respect to their combining sites. Moreover, the isomeric forms of an antibody directed against a protein antigen, formed antigen-antibody complexes with almost identical surface properties. In contrast, complexes with different surface properties were formed when the hapten or hapten conjugated to BSA was bound. Thus, both the conformational isomers could bind antigen, at least when the antigen was a small hapten or a hapten conjugated to a carrier protein. Our results suggest that six out of 57 monoclonal IgG antibodies exist in equilibrium between at least two conformational forms and the biological significance of this isomerism is discussed.

Effects of two weeks of topical budesonide treatment on microvascular exudative responsiveness in healthy human nasal airways.

Extravasation and luminal entry of plasma (mucosal exudation) is not only a key feature of airway inflammation in rhinitis and asthma but also a major first-line respiratory defence mechanism. Topical steroids are effective antiexudative agents in disease but, so far, little is known about the direct effects of these drugs on the responsiveness of the microcirculation in human airways. In this study, the effects of prolonged budesonide treatment on histamine-induced mucosal exudation of plasma was examined in 42 healthy subjects. Placebo and budesonide (100 microg per nasal cavity b.i.d.) were given for 2 weeks in a double-blind and placebo-controlled parallel-group protocol. Using a nasal pool technique, nasal challenges with isotonic saline and histamine (40 and 400 microg x mL(-1)) were carried out before and late in the treatment periods. The lavage fluid levels of alpha2-macroglobulin were measured as an index of mucosal exudation of bulk plasma. Histamine produced concentration-dependent mucosal exudation of plasma before as well as after treatment with either placebo or budesonide. The topical steroid treatment only marginally (1.8 fold) decreased the response to the low concentration histamine (40 microg x mL(-1)) and, although it was significantly (2.8 fold) reduced, histamine 400 microg x mL(-1) still produced significant mucosal exudation of plasma in the budesonide group. If the present observations are extrapolated to inflammatory conditions, the antiexudative effects of topical steroids in rhinitis (and asthma) may reflect only a small degree of microvascular antipermeability effects. We suggest that topical steroid treatment may not impede mucosal exudation responses when called for in acute human airway defence reactions.

Effects of inhaled histamine, methacholine and capsaicin on sputum levels of alpha 2-macroglobulin.

BACKGROUND: Plasma exudation-derived proteins and peptides contribute significantly to inflammation in the airway mucosa in vivo. In the guinea pig trachea both histamine and the neurogenic stimulant capsaicin produce acute mucosal tissue distribution and luminal entry of bulk plasma, whereas cholinergic agonists fail to produce this effect. Of these agents, only histamine induces mucosal exudation of plasma in human nasal airways. The exudative effect of the above agents on human bronchi remains unknown. METHODS: The bronchial exudative responses to inhalation of histamine, methacholine, and capsaicin were examined in two groups of healthy volunteers. Sputum was induced on three occasions in each study group by inhalation of hypertonic saline (4.5%) given as an aerosol for 40 minutes using an ultrasonic nebuliser. The second and third occasions were preceded by histamine and capsaicin challenges in the first study group, and by histamine and methacholine challenges in the second study group. Histamine and methacholine were given in cumulative doses (total doses 3160 micrograms, respectively) or until a 20% reduction in forced expiratory volume in one second (FEV1) was achieved. Cumulative doses of capsaicin were inhaled until coughing prevented the subjects from drawing a full breath. Sputum levels of alpha 2-macroglobulin (729 kDa) were measured as an index of mucosal exudation of bulk plasma. RESULTS: Histamine increased mean (SE) sputum levels of alpha 2-macroglobulin from 2.72 (1.01) micrograms/ml (95% confidence interval (CI) 0.49 to 4.94) to 18.38 (8.03) micrograms/ml (95% CI 0.49 to 36.27) in the first group, and from 1.66 (0.84) micrograms/ml (95% CI -0.18 to 3.49) to 9.43 (3.63) micrograms/ml (95% CI 1.59 to 17.27) in the second group. In contrast, capsaicin evoked no exudation (sputum levels of alpha 2-macroglobulin 1.21 (0.28) micrograms/ml (95% CI 0.59 to 1.83)) and methacholine produced a minor increase in sputum levels of alpha 2-macroglobulin (2.90 (0.92) micrograms/ml (95% CI 0.90 to 4.89)). CONCLUSIONS: These results indicate that histamine is a useful agent for studying bronchial exudative responsiveness in man and that exudative effects are only of marginal importance in the cough and bronchoconstriction produced by capsaicin and methacholine.

Anti-IgE-induced accumulation of leukocytes, mediators, and albumin in skin chamber fluid from healthy and atopic subjects.

The aim of this study was to examine potential differences between healthy and atopic subjects with regard to IgE-mediated cutaneous inflammation. For this purpose, we analyzed histamine, tryptase, leukotriene B4, albumin, eosinophils, and total leukocytes in skin chamber fluid after challenge with anti-human IgE. We also measured gross skin reactivity (wheal, flare, and late-phase reactions), circulating IgE, and eosinophils, as well as the state of eosinophil activation. It was found that despite having more circulating IgE, the skin responsiveness of the atopic subjects did not differ significantly from that of the nonatopic subjects with respect to mediator release, albumin extravasation, or total recruitment of leukocytes. Moreover, the sizes of anti-IgE-induced wheal, flare, and late-phase reactions were very similar in the two groups. On the other hand, significant recruitment of eosinophils during the IgE-mediated reaction was more or less restricted to the atopic group. Yet the recruited eosinophils, of which the majority was in an early state of activation before degranulation, did not seem to contribute significantly to the IgE-mediated delayed skin edema. Furthermore, the eosinophil count in anti-IgE chambers of the atopic subjects did not correlate with any of the other parameters monitored. Thus because the anti-IgE-induced recruitment of eosinophils appeared to be unrelated to factors such as the number of peripheral blood eosinophils, the degree of mast cell activation, the intensity of inflammatory skin changes, and the level of circulating IgE, it is apparent that the mechanisms for and pathophysiologic role of IgE-mediated dermal eosinophil accumulation in atopic subjects require further investigation.

Day-night differences in mucosal plasma proteins in common cold.

Aggravation of symptoms in inflammatory airway diseases is common in the early morning hours, but little is known about day-night differences in the occurrence of plasma exudate on the airway surface. We have therefore examined the plasma macromolecules on the nasal mucosa at different time points. The study comprised 20 subjects who had been inoculated (day 0) with coronavirus intranasally. Ten subjects remained healthy and 10 developed common cold with significant symptoms from day 2 to day 6. Starting on day 3 at 8.00 h and repeated at 4 h intervals until 4.00 h on day 4, nasal lavages were carried out by employment of a nasal pool-device which fills the entire unilateral nasal cavity and gently but effectively irrigates its surface. Lavage fluid levels of albumin (Mw 69,000 D) and fibrinogen (Mw 340,000 D) were determined. In the healthy subjects the levels of albumin and fibrinogen remained low throughout the experiment, however, with mean peak values of the two proteins occurring at 4.00 h (p < 0.05 compared to daytime nadir at 16.00 h). In subjects with common cold both albumin (p < 0.05) and fibrinogen (p < 0.01) exhibited marked variation with individual and mean peak levels recorded at 8.00 h day 3, and 4.00 h day 4. These mean peak values were 5-20 times higher (p < 0.01 - p < 0.05) than the mean levels recorded in these subjects at the other time periods. The present data indicate a marked day-night difference in the occurrence of plasma proteins on the airway surface in common cold, whereas in health the difference is much less. We conclude that different-sized plasma proteins may accumulate on the mucosa in healthy airways during late night hours and that in common cold this nocturnal accumulation may be considerably increased.

Antiallergic actions of high topical doses of terbutaline in human nasal airways.

It is debatable whether beta 2-receptor agonists produce antiallergic effects in human airways. This question has been addressed in the present study by examination of both mast-cell indices and the physiologic response to allergen challenge in human nasal airways. Twelve asymptomatic patients with seasonal allergic rhinitis were investigated outside the pollen season. Intranasal allergen provocation was carried out with diluent and three increasing doses of allergen. Topical terbutaline sulfate (1.0 mg) was given 5 min prior to each allergen challenge and nasal lavage was carried out 10 min after each challenge. The study design was double-blind, placebo-controlled, crossover, and randomized. The allergen challenge-induced mast-cell activation and the ensuing physiologic response of the airway tissue were investigated by measuring a mast-cell-derived mediator (tryptase) and plasma proteins (albumin and alpha 2-macroglobulin), respectively, in the lavage fluids. Allergen provocation produced dose-dependent increments of nasal symptoms and lavage fluid levels of tryptase, albumin and alpha 2-macroglobulin. Both nasal symptoms (P < 0.05) and lavage fluid levels of tryptase (P < 0.05), albumin (P < 0.05), and alpha 2-macroglobulin (P < 0.01) were reduced by pretreatment with topical terbutaline sulfate. We conclude that high doses of topical terbutaline may produce significant antiallergic effects in human airways by equally reducing both tryptase release and plasma exudation in the acute allergic reaction in human airways. Further studies are now warranted to determine whether microvascular antipermeability effects of beta 2-receptor stimulation contribute to the present observations.

Modulation of antigen-antibody complexations by immunoglobulins.

In this investigation, the modulating effects of non-immune human IgG and rheumatoid factors (RFs) on antigen-antibody complexations were studied. Non-immune human IgG, as well as RF, were found to inhibit the binding of antigen to specific antibodies of both human and rabbit origin. In addition, human immunoglobulins were also able to modify the composition of preformed antigen-antibody complexes. The effects were detected by immunological methods in two different antigen-antibody systems (human serum albumin-rabbit anti-HSA and tetanus toxoid-human anti-TT). Changes in biological activities could be followed by employing enzymes (glucose-6-phosphate dehydrogenase and human placental alkaline phosphatase) as antigens. The outcome of the effects was found to be dependent on the ratio of antigen to antibody, the antigen-binding properties of the antibody and its origin, and on the properties of the immunoglobulins added. The observed changes could not be explained only by the presence of specific antibodies in the immunoglobulin preparations. The ability of immunoglobulins to modulate antigen-antibody complexations may provide a rationale for the large amounts of non-specific immunoglobulins in the circulation by preventing premature precipitation and promoting the elimination of antigenic molecules.

Exudative hyperresponsiveness of the airway microcirculation in seasonal allergic rhinitis.

BACKGROUND: Mucosal exudation of plasma is a non-injurious, physiological response of the airway microcirculation to different inflammatory processes. The exudative response is similar in the nose and bronchi and exudation occurs in both allergic asthma and rhinitis. The exudative response is a specific end-organ function of the mucosal microcirculation that may be altered in airway diseases. OBJECTIVE: This study examines the hypothesis of altered responsiveness of the superficial airway microcirculation to vascular permeability-increasing challenges in sustained allergic inflammation. METHODS: Fourteen patients with birch-pollen induced allergic rhinitis were studied for 7 weeks during a Swedish birch-pollen season. Nasal symptoms (itching, sneezing, blockage, and discharge) were recorded and the occurrence of pollen was determined. The plasma exudation response was examined by topical histamine challenges at the end (May) and well out of (December) the season. Challenge and lavage were carried out concomitantly using a 'nasal pool'-device. The unilateral nasal cavity was filled for consecutive 10 minute periods with saline and two concentrations of histamine (80 micrograms/mL and 400 micrograms/mL). The lavage fluid levels of different-sized plasma proteins (albumin-66,000 D, fibrinogen-340,000 D, and alpha 2-macroglobulin-725,000 D) were determined. RESULTS: The pollen season was mild resulting in only minor nasal symptoms. Histamine produced exudation of all plasma proteins across the microvascular epithelial barriers with particularly strong correlation between the levels of albumin and alpha 2-macroglobulin (r = 0.98; P < 0.001). The exudative response to histamine was concentration-dependent (P < 0.05) and, furthermore, it was significantly greater late into the season compared with outside the pollen season (albumin: P < 0.05, fibrinogen; P < 0.05, alpha 2-macroglobulin: P < 0.01). CONCLUSION: We conclude that histamine produced concentration-dependent nasal airway exudation of bulk plasma in subjects with seasonal rhinitis and that this response is abnormally great during the pollen season. Whether angiogenesis or increased responsiveness of the microvascular endothelium may explain this phenomenon now remains unknown. We suggest that a microvascular exudative hyperresponsiveness may characterize allergic airway disease.

Allergen challenge-induced entry of alpha 2-macroglobulin and tryptase into human nasal and bronchial airways.

BACKGROUND: Microvascular-epithelial exudation of bulk plasma may characterize inflammatory airway diseases. This study compares the acute allergen challenge-induced mast cell and exudative responses in nasal and bronchial airways. The focus is on alpha 2-macroglobulin as an index of luminal entry of plasma exudates. METHODS: Separate nasal and bronchial allergen challenges were carried out outside the pollen season in eight patients with pollen-induced seasonal allergic rhinitis. The levels of different-sized plasma proteins (albumin molecular weight, 66,000 d and alpha 2-macroglobulin molecular weight, 725,000 d) and tryptase were determined in pre- and postchallenge nasal lavage and bronchoalveolar lavage (BAL) fluids. Diluent and increasing doses of allergen were sprayed into the right nasal cavity, and each challenge was followed by a nasal lavage (volume, 15 ml) with a "nasal pool" device (recovery, > 80%). Endobronchial allergen challenge (individual doses) and BAL (volume, 2 x 25 ml) were performed in a lobe bronchus through a fiberoptic bronchoscope (recovery, 30%). Saline challenge and BAL were carried out in the contralateral lung as control. RESULTS: The levels of albumin, alpha 2-macroglobulin, and tryptase increased dose-dependently in postchallenge nasal lavage fluids (p < 0.05) and correlated to nasal symptoms. In particular, albumin and alpha 2-macroglobulin correlated (r = 0.98, p < 0.001). Both alpha 2-macroglobulin and tryptase, but not albumin, were increased in BAL fluids from the allergen-challenged side (p < 0.05). CONCLUSION: Local allergen challenge causes luminal entry of tryptase and alpha 2-macroglobulin in the nose and bronchi of patients with allergy. We suggest that mast cell and plasma exudation responses may be similar in human nasal and bronchial airways and that albumin levels (in BAL fluids) may not well reflect the exudation process in bronchial airways.

Glucocorticoids may not inhibit plasma exudation by direct vascular antipermeability effects in human airways.

In animal airways, single topical treatment with glucocorticoids produces a prompt vascular anti-permeability effect that may last for several hours. This has been considered a potentially important anti-inflammatory action in human airways. The present study, involving nine healthy subjects, examines whether nasal budesonide application affects histamine-induced mucosal exudation of plasma and plasma-derived mediators in human airways. A selected low concentration (40 micrograms.ml-1) of the vascular permeability-inducing agent histamine was kept in one of the nasal cavities for 10 min, and this challenge was repeated at 50 min intervals over 4 h. Ten minutes after the first histamine-challenge, a clinical dose of budesonide (100 micrograms) was sprayed into the same nasal cavity. Nasal lavage fluid levels of albumin and fibrinogen were measured as indices of mucosal exudation of bulk plasma, and bradykinins were analysed to indicate generation of plasma-derived mediators. The baseline levels of albumin and fibrinogen were evaluated in 24 healthy control subjects by means of a 10 min saline lavage. Histamine produced significant mucosal exudation of albumin and fibrinogen, compared to control subjects. Topical budesonide treatment did not affect the histamine-induced mucosal exudation of albumin or fibrinogen, nor did budesonide affect the mucosal output of bradykinins. The present human airway data do not support the view, based on animal findings, that airway glucocorticoids reduce mucosal exudation of plasma by direct vascular effects. We suggest that anti-exudative effects of topical glucocorticoids in airway diseases indirectly reflect the inhibition of cellular inflammatory processes by these drugs, rather than any direct effects on the airway microcirculation.

Glucocorticoid-induced attenuation of mucosal exudation of fibrinogen and bradykinins in seasonal allergic rhinitis.

The mucosal plasma exudate with its proteins, enzymes, derived peptides, and matrix molecules is an important factor in inflammatory airway diseases. This study investigated whether topical glucocorticosteroid treatment influences mucosal exudation of bulk plasma (fibrinogen) and the generation of plasma-derived mediators (bradykinins) in seasonal allergic rhinitis. Twenty-two patients with birch-pollen-induced allergic rhinitis participated in a double-blind, randomized, placebo-controlled study during the birch pollen season in 1989. After a 2-week run-in period, the participants received treatment with budesonide (200 micrograms per nasal cavity and day) or placebo. The patients kept a diary to record their daily nasal symptoms (itching, sneezing, nasal blockage, and secretion). The amount of birch pollen in the air was determined with the aid of a Burkhard pollen trap. A nasal lavage was performed once a week, and the levels of bradykinins and fibrinogen were determined in the lavage fluid samples. The birch pollen season was very mild, resulting in only minor nasal symptoms. In spite of the low pollen exposure, treatment with budesonide reduced the lavage fluid levels of both bradykinins and fibrinogen. The present results show that topical glucocorticosteroid treatment attenuates plasma exudation and the generation of plasma-derived mediators in seasonal allergic rhinitis. This action may not result from simple vascular antipermeability effects of the drug but may rather reflect the anti-inflammatory efficacy of topical glucocorticoids in the airway mucosa.

Microvascular exudative hyperresponsiveness in human coronavirus-induced common cold.

BACKGROUND: The inflammatory response of the airway microcirculation in rhinitis and asthma may be recorded as luminal entry of plasma macromolecules (mucosal exudation). This study examines the exudative responsiveness of the subepithelial microvessels in subjects with and without common cold after inoculation with coronavirus. METHODS: The airway mucosa was exposed to exudative concentrations of histamine (40 and 400 micrograms/ml) before and six days after inoculation. To assess whether mucosal penetration of a topically applied agent was altered, nasal absorption of chromium-51 labelled ethylene diamine tetraacetic acid (51Cr-EDTA, MW 372) was also examined. A nasal pool technique kept the challenge and tracer solutes in contact with the same ipsilateral mucosal surface. Concentrations of albumin in lavage fluids were measured as an index of mucosal exudation of plasma. Nasal absorption of 51Cr-EDTA was determined by the cumulated 24 hour urinary excretion of radioactivity. RESULTS: Nine subjects developed common cold after coronavirus inoculation and 10 remained healthy. Histamine produced concentration dependent mucosal exudation of plasma in all subjects before and after coronavirus inoculation. In subjects with common cold, however, the histamine-induced mucosal exudation was significantly augmented compared with the group without common cold. This exudative hyperresponsiveness is not explained by an increased baseline exudation because the lavage regimen used produced comparably low baseline exudation in both groups of subjects, nor is it explained by an increased penetration of topical histamine because the ability of the nasal mucosa to absorb 51Cr-EDTA was not significantly increased in the subjects with common cold. CONCLUSIONS: An increased proclivity of the airway subepithelial microcirculation to respond with plasma exudation develops during coronavirus-induced common cold. This specific exudative hyperresponsiveness may be a feature of inflammatory airway diseases.

Histamine-induced airway mucosal exudation of bulk plasma and plasma-derived mediators is not inhibited by intravenous bronchodilators.

Experimental data suggest the possibility that common bronchodilators, such as the xanthines and beta 2-adrenoceptor agonists, may produce microvascular anti-permeability effects in the subepithelial microcirculation of the airways. In this study, we have examined the effect of bronchodilators given intravenously on exudation of different-sized plasma proteins (albumin and fibrinogen) and the generation of plasma-derived peptides (bradykinins) in human nasal airways challenged with histamine. In a double-blind, crossover, placebo-controlled and randomised trial, 12 normal volunteers were given i.v.infusions of terbutaline sulphate, theophylline and enprofylline to produce therapeutic drug levels. The effect of topical nasal provocation with histamine was closely followed by frequently nasal lavage with saline. The lavage fluid levels of albumin, fibrinogen and bradykinins increased significantly after each histamine provocation. The ratio of albumin-to-fibrinogen in plasma and the lavage fluid was 24 and 56, respectively, indicating that topical histamine provocation induced a largely non-sieved flux of macromolecules across the endothelial-epithelial barriers. The systemically administered drugs did not affect the nasal symptoms (sneezing, secretion and blockage), nor did they significantly reduce the levels of plasma proteins and plasma-derived mediators in the nasal lavage fluids. The present data suggest that systemic xanthines and beta 2-adrenoceptor agonists, at clinically employed plasma levels, may not affect the microvascular (and epithelial) exudative permeability and the bradykinin forming capacity of human airways.

Mucosal exudation of fibrinogen in coronavirus-induced common colds.

We studied the mucosal exudation of plasma in relation to pathophysiological events during an induced common cold. Coronavirus 229E was inoculated nasally in 20 healthy volunteers under controlled conditions. Ten volunteers developed the common cold, determined by symptom scores and serology. The bulk plasma exudate was monitored, using fibrinogen (MW 340 kD) in nasal lavage fluids as an endogenous marker. Following inoculation, anterior rhinoscopy and objective registrations of nasal mucosal temperature, nasal discharge weight, and nasal blockage index by peak expiratory air flow, were followed twice daily for 6 days. Mucosal plasma exudation, as assessed by fibrinogen in lavage fluids, increased hundredfold after virus inoculation, concomitantly with the subjective symptoms and objective physiological changes. We propose that this exudation reflects the degree of subepithelial inflammation, and suggests that plasma bulk exudate, including all potent plasma protein systems may be involved in the resolution of acute viral rhinitis--common cold.

Allergen-induced biphasic plasma exudation responses in guinea pig large airways.

In this study involving sensitized guinea pigs (anesthetized intramuscularly with a 3:2 mixture of ketamine+xylazine, 1 ml/kg), we applied allergen (ovalbumin) selectively to the tracheobronchial mucosa (sparing the nasal passages and the terminal airways) and examined the occurrence of immediate and late-phase inflammatory exudation of plasma and plasma-derived mediators (bradykinins) into the airway lumen. The experiments were terminated 10 to 480 min after challenge. A selective lavage that sampled the surface liquids of the extrapulmonary bronchi and the lower trachea was performed. The amount of plasma (microliter) was determined by analysis of a plasma tracer, [125I]albumin, in lavage fluid and blood (plasma) samples. Ovalbumin, 3 to 12 pmol, and histamine, 5 and 10 nmol, produced a dose-dependent immediate exudation response (p < 0.001). The effects were nonneurogenic because they were not affected by topical lidocaine given in a dose (3 nmol) that prevented the exudative effect of capsaicin. The 6- and 12-pmol doses of ovalbumin (but not 3 pmol) produced a significant late-phase exudative response at 5 h (p < 0.001), and both the immediate and late phases were associated with increased (p < 0.01 to p < 0.001) levels of bradykinin in the lavage fluids. Histamine, even in doses that produced a greater early response than the allergen, did not produce a late-phase response. A single topical dose of an antiasthma steroid (budesonide, 12 mumol/kg) administered just before ovalbumin (6 pmol) had little effect on the immediate response but inhibited the late-phase response (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma exudation and solute absorption across the airway mucosa.

The airway mucosa responds to inflammatory provocations with bulk exudation of plasma into the airway tissue (vascular exudation) and lumen (mucosal exudation). The intensity and time course of the exudative response can be relevantly examined by sampling and analysing airway surface liquids, because the luminal entry of plasma proteins/tracers promptly and quantitatively reflects the exudative response of the airways. The process of mucosal exudation of plasma is a prominent feature of airway inflammation and has been demonstrated in rhinitis, asthma, and bronchitis. Inflammatory mediators and allergen produce mucosal exudation of plasma into the airway lumen (outward permeability) whereas the solute absorption across the mucosa (inward permeability) is unaffected. Hence, in contrast to current views, we have demonstrated that in airway inflammation the solute absorption across the airway mucosa is not increased. The findings suggest the plasma exudation response also as a first line respiratory mucosal defence, allowing potent plasma protein systems to appear on an airway mucosa functionally intact as a barrier toward undue luminal material. Our data on plasma exudation and solute absorption across the mucosa of upper and lower airways further suggest the human nasal airways as a model relevant also for the tracheobronchial airways.

Bronchial exudation of bulk plasma at allergen challenge in allergic asthma.

This study examined plasma exudation into the bronchial lumen after allergen challenge. A novel low-trauma technique was developed to challenge and lavage a medium-sized lingular or middle lobe bronchus. Eleven subjects with challenge-assessed pollen-sensitive asthma were allocated to fiberbronchoscopy in the supine position. In the control bronchus 0.5 ml diluent was instilled. The bronchus was occluded proximally 3 min later by inflation of a balloon, and lavage was carried out twice with 25 ml saline. Incremental doses of allergen solution (0.5 ml) were then instilled in the contralateral lung. The challenge continued until a clearly visible bronchial reaction occurred and was immediately followed by the same lavage as on the control side. The lavage liquids were analyzed for the presence of plasma exudation and mast cell activation indices. On the allergen-challenged side, tryptase, reflecting mast cell activation, was increased by 150% (p < 0.01) compared with the control side. Fibrinogen (mol wt 340,000), reflecting large protein exudation, was increased by 840% (p < 0.05), and N-alpha-tosyl-L-arginine-methyl esterase activity, reflecting both large protein exudation and mast cell activation, increased by 480% (p < 0.01). The level of albumin (mol wt 69,000), the major luminal protein under baseline conditions, increased but not significantly. We conclude that activation of mast cells and luminal entry of little sieved plasma exudates occur early after endobronchial allergen provocation in human subjects with allergic asthma.