Early Asthmatic Reaction Research Articles

Relationship between serum heat-stable neutrophil chemotactic activity during early airway reaction to allergen and the pattern of airway response (early versus late reactions) in asthmatic subjects.

In order to evaluate the relationship between allergen-induced heat-stable neutrophil chemotactic activity (HS-NCA) release during early asthmatic reaction (EAR) and the presence of a late asthmatic reaction (LAR), serum HS-NCA was measured at three serum dilutions (1:5, 1:40, 1:200) during EAR induced by allergen in 26 atopic asthmatics, 13 with isolated EAR and 13 with EAR followed by LAR. HS-NCA was measured using a 48-well microchamber with 5-micron-pore-size nitrocellulose filters, using isolated neutrophils from healthy donors and the leading front technique. Subjects with LAR developed EAR after inhalation of a lower dose of allergen than subjects with isolated EAR. Increase in serum HS-NCA during EAR was significantly higher in subjects with isolated EAR than in subjects with EAR plus LAR at the 1:5 dilution, while it was significantly higher in subjects with EAR plus LAR than in the subjects with isolated EAR at the 1:200 dilution; the 1:40 dilution gave similar results in both groups. Changes in serum HS-NCA during EAR significantly correlated with the maximum decrease in forced expiratory volume in 1 s (FEV1) during LAR: a higher decrease in FEV1 during LAR was associated with a lower increase in HS-NCA at the 1:5 dilution (Spearman's rho = 0.43, rho = 0.03), and with a higher increase in NCA at the 1:200 dilution (Spearman's p = -0.46, p = 0.02). These results can be explained by the 'high-dose-inhibition' phenomenon. Assuming that HS-NCA is associated with mast cell degranulation in the airways after allergen challenge, these findings demonstrate that higher mast cell activation during EAR is present in subjects with a subsequent LAR than in subjects with isolated EAR.

Tolerance to the Protective Effect of Salmeterol on Allergen Challenge

Long-term treatment with inhaled beta 2-agonists may be associated with a deterioration in asthma control, potentially due to tolerance. Regular use of short-acting beta 2-agonists has been shown to induce tolerance to allergen or adenosine 5'-monophosphate challenge. The aim of the study was to detect the efficacy of a single dose and a short-term treatment with salmeterol, a long-acting beta 2-agonist, to protect against early asthmatic reaction (EAR) to allergen. Eight subjects with mild allergic asthma underwent two treatment periods in which subjects performed an allergen challenge (specific bronchial provocation test) protected by a single dose (50 micrograms) of salmeterol (Salm-1) followed by a second specific bronchial provocation test after regular treatment with salmeterol for 1 week (Salm-2), or a single dose of placebo (Plac-1) and regular treatment (1 week) with placebo (Plac-2). Each subject performed both treatments in a randomized order. Each time allergen challenge was performed 1 h after last drug inhalation and it was stopped when the same provocative dose of allergen of a previous screening allergen challenge was achieved. The maximum decrease in FEV1 and area under curve in the first hour after allergen inhalation were significantly lower in Salm-1 (max delta FEV1 %, median [range]: 4%[0 to 9]) with respect to Salm-2, Plac-1, Plac-2 (24%[13 to 38], 31%[19 to 50], 30%[6 to 44], respectively, p < 0.001); there was no difference among Salm-2, Plac-1 and Plac-2. In Salm-1, all subjects were protected against EAR, whereas in Salm-2 only 2 subjects showed a partial protection. In conclusion the protective effect of a single dose of salmeterol against allergen-induced EAR was lost after regular treatment with salmeterol for 1 week. The clinical relevance of this mechanism remains to be elucidated.

Deficiency of nitric oxide in allergen-induced airway hyperreactivity to contractile agonists after the early asthmatic reaction: an ex vivo study.

1. Using a guinea-pig model of allergic asthma, we investigated the role of nitric oxide (NO) in allergen-induced airway hyperreactivity after the early asthmatic reaction, by examining the effects of the NO-synthase inhibitor N omega-nitro-L-arginine methyl ester (L-NAME) on the responsiveness to methacholine and histamine of isolated perfused tracheae from unchallenged (control) animals and from animals 6 h after ovalbumin challenge. 2. All animals developed airway hyperreactivity to inhaled histamine at 6 h after ovalbumin challenge, with a mean 3.11 +/- 0.45 fold increase in sensitivity to the agonist (P < 0.001). 3. In perfused tracheal preparations from the ovalbumin-challenged guinea-pigs, the maximal responses (Emax) to methacholine and histamine were significantly enhanced compared to controls, both after intraluminal (IL) and extraluminal (EL) administration of the contractile agonists. In addition, a small but significant increase in the pD2 (-log10 EC50) for IL and EL methacholine and for IL histamine was observed. As a consequence, the delta pD2 (EL-IL) for histamine was slightly decreased from 1.67 +/- 0.13 to 1.23 +/- 0.14 (P < 0.05). However, the delta pD2 for methacholine was unchanged (1.85 +/- 0.11 and 1.77 +/- 0.12, respectively; NS). 4. Incubation of control tracheae with 100 microM L-NAME (IL) significantly enhanced the Emax for both IL and EL methacholine and histamine to approximately the same degree as observed after ovalbumin challenge, with no effect on the pD2 and delta pD2 for both agonists. On the contrary, L-NAME had no effect on Emax and pD2 values of tracheal preparations from ovalbumin-challenged guinea-pigs. 5. L-NAME (10 microM-1 mM) had no effect on methacholine-induced contraction of isolated tracheal strip preparations obtained from control animals, indicating that L-NAME has no antimuscarinic effect on tracheal smooth muscle. 6. Histological examination of the intact tracheal preparations indicated epithelial and subepithelial infiltration of eosinophils after ovalbumin challenge. However, no apparent damage of the airway epithelium was observed in these preparations. 7. The results indicate that a deficiency of NO contributes to allergen-induced airway hyperreactivity after the early asthmatic reaction and that this deficiency appears not to be due to epithelial shedding.

A comparison of the effects of oral cetirizine and inhaled beclomethasone on early and late asthmatic responses to allergen and the associated increase in airways hyperresponsiveness

Cetirizine is a non-sedating H1 antihistamine which is effective in the treatment of allergic rhinitis and urticaria. It inhibits eosinophil and basophil chemotaxis in late cutaneous allergic reactions in skin windows. Its effect on early (EAR) and late asthmatic reactions (LAR) is less certain. We examined the effect on EAR and LAR of 3 days treatment with oral cetirizine (15 mg twice daily) compared with a single dose of inhaled beclomethasone 10 min prior to allergen challenge in a placebo-controlled (oral and inhaled) double-blind cross-over design with three treatment arms separated by 14 days. Cetirizine did not significantly inhibit either the EAR or LAR documented by maximum percentage fall in FEV1 (0-3 and 6-9 h) or as area under the curve (AUC between 0 and 3 and 6-9 h). Beclomethasone inhibited the LAR compared with placebo (P = 0.02) when expressed as AUC (6-9 h). This did not quite reach statistical significance (P = 0.06) when expressed as maximal percentage late fall in FEV1 between 6 and 9 h. A greater than twofold increase in airways responsiveness to methacholine was observed 3 h after challenge which was significantly reduced by beclomethasone compared with placebo (P < 0.02) and cetirizine (P < 0.05). The data suggest that oral cetirizine does not significantly inhibit either the EAR or LAR. Beclomethasone inhibited both the early increase in airways responsiveness and the subsequent LAR. Our study also confirms the view that early increases in airway responsiveness precede the late response and suggests that these associated events are not dissociable by the pharmacological treatments employed in this study.

Enhanced production and gene expression of IL-5 in bronchial asthma. Possible management of atopic diseases with IL-5 specific gene transcription inhibitor.

Infiltration of various inflammatory cells into the bronchial mucosa and submucosa is a prominent pathological feature of bronchial asthma.1–3 Persistent mucosal inflammation, particularly epithelial damage caused by eosinophil-derived products, is believed to contribute to the pathogenesis of bronchial hypersensitivity.4–7 Inhalation of a relevant allergen results in an early asthmatic reaction (EAR) that subsides within 1 to 2 hours. In 40–60% of patients, this early reaction is followed after 6 to 10 hours by a late asthmatic reaction (LAR), which usually subsides during the next 1 to 2 days.8 Accumulating evidence suggests that LAR is a consequence of eosinophilic inflammation in the lung induced by a T cell cytokine, interleukin 5 (IL-5).9–15

681 The influence of loratadine (LO) on bronchial histamine challenge, early (EAR) and late (LAR) asthmatic reactions and the development of bronchial reactivity after single allergen challenge

681 The influence of loratadine (LO) on bronchial histamine challenge, early (EAR) and late (LAR) asthmatic reactions and the development of bronchial reactivity after single allergen challenge

Oligoclonality of lung T lymphocytes following exposure to allergen in asthma.

We were interested in studying the lung allergen-specific T cell repertoire in different conditions of allergen exposure in subjects with atopic asthma. Twenty-one allergic individuals were studied: 17 subjects suffering mainly from asthma and 4 from rhinitis. They all performed spirometry and methacholine challenge. All patients were subjected to bronchoalveolar lavage (BAL), either at base line (no challenge) or after allergen or histamine challenge, and the TCR repertoire of their lung T cells was studied with heteroduplex analysis. Expansion of single T cell clones was observed in one (of seven) asthmatic subject that reported a recent exposure to allergen and had high bronchial hypersensitivity to methacholine, and in seven/seven asthmatic subjects who underwent BAL after they suffered an early asthmatic reaction to experimental allergen inhalation. Remarkably, ex vivo expanded clones included allergen-specific T cells. In two of the seven subjects who underwent BAL after allergen challenge, two different lung segments were lavaged. A strikingly symmetrical distribution of the expanded clones was found in these samples. Control subjects and six of seven asthmatic patients studied at base line showed polyclonality of lung T cells. In conclusion, T lymphocytes are clonally expanded in the lower respiratory tract only in asthmatic subjects exposed to allergen. These results suggest that in allergic asthma, the inhalation of sensitizing allergens can recruit to the lung T lymphocytes that include allergen-specific T cell clones.

Individual time-courses of ECP and EPX during allergen provocation tests in asthmatic children.

To study the time-course of eosinophil cationic protein (ECP) and eosinophil protein X (EPX) during bronchial allergen provocation, we investigated 32 asthmatic children sensitive to house-dust mites as well as 6 non-atopic young adult controls. In all subjects, allergen challenges were performed with house dust mite extracts of Dermatophagoides pteronys-sinus or Dermatophagoides farinae. Blood samples were taken at regular intervals during the 24-h observation period. The individual time-courses of ECP and EPX revealed different characteristic groups of patterns: (1) an isolated early serum peak of both mediators during or within the first 60 min after provocation (2) an early plus a late peak (3) an isolated late peak 12 h after provocation (4) an isolated late peak 24 h after provocation, and (5) no significant variation during the 24-h observation period. The early peak could be due to short-term changes in eosinophil activation, while late peaks may reflect eosinophil proliferation, recruitment, subsequent priming and enhancing of the propensity to release their proteins. ECP and EPX showed a corresponding parallel time-course in nearly all challenges, with EPX-concentration exceeding that of ECP. There was no correlation between ECP/EPX serum concentrations and clinical parameters such as lung function data. From our results we conclude that the striking groups of time-courses of ECP/EPX serum concentration indicate different uniform patterns of eosinophil activation during allergen challenge-but do not predict clinical outcome of provocation. The role of the eosinophil in early asthmatic reactions remains to be established in further studies.

Phosphodiesterase inhibitors reduce bronchial hyperreactivity and airway inflammation in unrestrained guinea pigs

A new guinea pig model of allergic asthma was used to investigate the effects of low doses of the phosphodiesterase inhibitors, rolipram (phosphodiesterase IV selective), ORG 20241 ( N-hydroxy-4-(3,4-dimethoxyphenyl)-thiazole-2-carboximidamide; dual phosphodiesterase III/IV inhibitor with some selectivity for the phosphodiesterase IV isoenzyme), and of theophylline (non-selective) on allergen-induced early and late phase asthmatic reactions, bronchial hyperreactivity to histamine inhalation, and airway inflammation. Theophylline (25 mg/kg i.p.) and ORG 20241 (5 mg/kg i.p.) did not affect histamine-induced bronchoconstriction, whereas rolipram (75 μg/kg i.p.) only slightly reduced the response to histamine at 7 h after administration. However, bronchial hyperreactivity after the early and after the late reaction was significantly reduced by theophylline, rolipram and ORG 20241, while bronchoalveolar lavage studies revealed a selective inhibition of airway inflammation by the phosphodiesterase inhibitors. Theophylline significantly reduced the number of eosinophils, neutrophils and macrophages; rolipram reduced the number of neutrophils and lymphocytes, and ORG 20241, the number of eosinophils and macrophages. None of the compounds at the dosage indicated reduced the early and late reaction when administered i.p. 1 h before allergen exposure to defined dual responding animals. These results indicate that non-bronchodilator doses of these phosphodiesterase inhibitors markedly reduce the allergen-induced development of bronchial hyperreactivity as well as airway inflammation, presumably by selectively inhibiting cellular migration. The results suggest that an orchestrated series of cellular interactions is involved in the development of bronchial hyperreactivity. It is concluded that phosphodiesterase inhibitors may be very useful in the treatment of bronchial asthma.

The effect of MK-0591, a novel 5-lipoxygenase activating protein inhibitor, on leukotriene biosynthesis and allergen-induced airway responses in asthmatic subjects in vivo

Background: The 5-lipoxygenase metabolites of arachidonic acid are likely to be involved in the pathophysiology of atopic asthma. We investigated the effect of pretreatment with MK-0591, a novel 5-lipoxygenase activating protein inhibitor, on allergen-induced early asthmatic reactions (EARs) and late asthmatic reactions (LARs), and subsequent airway hyperresponsiveness to histamine. Methods: Eight atopic men with mild to moderate asthma aged 19 to 31 years, (forced expiratory volume in 1 second [FEV 1] ≥67% of predicted value, histamine provocative concentration causing a 20% fall in FEV 1 [PC 20] <4 mg/ml) and documented EAR and LAR to house dust mite extract participated in a two-period, double-blind, placebo-controlled, crossover study. During each study period histamine PC 20 was measured 2 days before and 1 day after a standardized allergen inhalation challenge test. MK-0591 was administered in 3 oral doses of 250 mg each at 24, 12, and 1.5 hours before inhalation of allergen. Biochemical activity of MK-0591 was determined by calcium ionophore A-23187–stimulated leukotriene (LT)B 4 biosynthesis in whole blood ex vivo and by urinary LTE 4 excretion. Airway response to allergen was measured by FEV 1 (percent fall from baseline). The EAR (0 to 3 hours) and the LAR (3 to 8 hours) were expressed as corresponding areas under the time-response curves. Results: MK-0591 and placebo did not differ in their effects on prechallenge FEV 1 ( p = 0.10). As compared with the value before pretreatment, MK-0591 blocked LTB 4 biosynthesis and LTE 4 excretion by a mean of 98% (range, 96% to 99%; p < 0.002) and 87% (range, 84% to 96%; p < 0.046), respectively, from 0 to 24 hours after allergen challenge. Both the EAR and the LAR were significantly reduced after administration of MK-0591 as compared with placebo, with a mean inhibition of 79% ( p = 0.011) and 39% ( p = 0.040), respectively. Allergen-induced airway hyperresponsiveness was not significantly different between the two pretreatment periods ( p = 0.37). Conclusions: In this study oral MK-0591 prevented leukotriene biosynthesis after allergen challenge in patients with mild to moderate asthma. The results of our study indicate that 5-lipoxygenase products play an important role during the EAR, whereas their contribution to the pathophysiology of the LAR seems to be of less importance. (J A LLERGY C LIN I MMUNOL 1995;95:42-51.)

Influence of sensitization and allergen provocation procedures on the development of allergen-induced bronchial hyperreactivity in conscious, unrestrained guinea-pigs

The effects of different sensitization and allergen provocation regimens on the development of allergen-induced bronchial hyperreactivity (BHR) to histamine were investigated in conscious, unrestrained guinea-pigs. Similar early and late phase asthmatic reactions, BHR for inhaled histamine after the early (6 h) as well as after the late reaction (24 h), and airway inflammation were observed after a single allergen provocation in animals sensitized to produce mainly IgG or IgE antibodies, respectively. Repeating the allergen provocation in the IgE-sensitized animals after 7 days, using identical provocation conditions, resulted in a similar development of BHR to histamine inhalation. Repetition of the allergen provocation during 4 subsequent days resulted in a decreased development of BHR after each provocation, despite a significant increase in the allergen provocation dose necessary to obtain similar airway obstruction. The number of inflammatory cells in the bronchoalveolar lavage was not significantly changed after repeated provocation, when compared with a single allergen provocation. Finally, we investigated allergen-induced bronchial hyperreactivity by repetition of the sensitization procedure at day 7 and 14 (booster), followed by repeated allergen provocation twice a week for 5 weeks. Surprisingly, no BHR to histamine could be observed after either provocation, while the number of inflammatory cells in the bronchoalveolar lavage fluid after 5 weeks was enhanced compared with controls. These data indicate that both IgE and IgG sensitized guinea-pigs may develop bronchial hyperreactivity after a single allergen provocation. Repeated allergen exposure of IgE sensitized animals causes a gradual fading of the induced hyperreactivity despite the on-going presence of inflammatory cells in the airways, indicating a mechanism of reduced cellular activation.

The importance of eosinophil activation for the development of allergen-induced bronchial hyperreactivity in conscious, unrestrained guinea-pigs.

Using a newly developed guinea-pig model of asthma, characterized by allergen-induced early and late phase asthmatic reactions, bronchial hyperreactivity (BHR) and airway inflammation, the importance of eosinophil activation for the development of BHR to inhaled histamine was investigated at 6 h (after the early reaction) and 24 h (after the late reaction) after allergen provocation. Eosinophil activation was assessed by a sensitive kinetic assay for eosinophil peroxidase (EPO) activity, suitable for bronchoalveolar lavage (BAL) analysis. A significant 2.9-fold (P < 0.01) increase in bronchial reactivity to histamine was observed at 6 h after allergen exposure, which was associated with a 2.9-fold increase in the number of eosinophils (P < 0.05) and a 6.7-fold increase in EPO activity (P < 0.01) in the BAL fluid. At 24 h after allergen exposure the bronchial reactivity to histamine was lower (1.7-fold), but still significantly enhanced (P < 0.01). By contrast, the number of eosinophils was further increased compared with 6 h after provocation (3.8-fold, P < 0.05), while the EPO activity remained stable at 6 h levels. The number of eosinophils was significantly correlated with EPO activity at 6 h (r = 0.62; P < 0.05), but not at 24 h after provocation. No significant correlation was observed between the number of eosinophils in the BAL fluid and BHR to histamine at either time point.(ABSTRACT TRUNCATED AT 250 WORDS)

Lack of effect of cetirizine on early and late asthmatic response after allergen challenge

Background: Cetirizine hydrochloride has proved effective in reducing allergic symptoms and can inhibit the infiltration of eosinophils in allergic late-phase responses in the skin. Because eosinophils are likely to play an important role in allergic late-phase reactions, we studied the effect of cetirizine on early and late asthmatic reactions and on levels of eosinophil cationic protein (ECP) in the blood after allergen challenge. Methods: The effect of 15 mg cetirizine given twice daily was studied in 16 patients allergic to house dust mites in a double-blind, placebo-controlled study. Patients were treated for 3 weeks. Before and after treatment, bronchial challenges with house-dust mites were performed. Blood ECP levels were measured 6 hours after challenge. Methacholine provocation was performed 72 hours before and 24 hours after each challenge. Results: Early and late asthmatic response-measured as mean maximal fall in forced expiratory volume in 1 second (FEV1) and the provocative dose of allergen that causes a 15% fall in FEV1 (PD15 allergen)-were not significantly reduced after treatment with cetirizine, compared with placebo. There was also no significant effect on the concentration of methacholine, which causes a 20% fall in FEV1 (PC20 methacholine). The increase in the level of ECP in the blood after allergen challenge was reduced after cetirizine treatment, compared with placebo, but this difference was not statistically significant. Conclusion: Eighteen days of treatment with cetirizine did not significantly reduce the intensity of the early and late asthmatic responses. (J ALLERGYCLINIMMUNOL1994;94:231-9.)

273 EFFECT OF LORATADIN AND CETIRICIN ON EARLY AND LATE PHASE ASTHMATIC REACTION IN THE SENSITIZED GUINEA PIG

The new generation of antihistaminic drugs has been considered for prophylactic use in asthma. We investigated the effect of Loratadin and Cetiricin on early and late phase asthmatic reaction in the sensitized guinea pig. Sensitization was performed by inhalation of 1% ovalbumin aerosol for 3 min. twice in two weeks. 7 days after the last inhalation Loratadin or Cetiricin were given by pharyngeal tube (1 mg/kg) and followed by specific bronchial provocation with ovalbumin using a two chamber bodyplethysmograph with measurement of compressed air (CA) as sensitive parameter of airway obstruction in the guinea pig. Late phase allergic reaction was investigated by eosinophilic count in the bronchoalveolar fluid 24 hours after provocation. In the guinea pigs treated with either drug (n=6 for each) the incidence (p<0.04) and severity (CA, p<0.01) of bronchial reaction on specific provocation differed significantly from the non-treated control group (n=18). The best protection of early phase reaction was achieved by Cetiricin, late phase reaction was not inhibited by either drug. However, in a parallel experiment (n=6) late phase reaction was completely inhibited by inhalation of 1% Nedocromil-Sodium in the same model. The effect of both antihistamins in this experiment underlines the importance of histamin in the early phase allergic reaction in the guinea pig. However, there was no effect on for chronic asthma important late phase reaction in this model, in contrary to the effect of pretreatment with inhaled Nedocromil-Sodium.

Relationships among allergen-induced early and late phase airway obstructions, bronchial hyperreactivity, and inflammation in conscious, unrestrained guinea pigs

The relationships among allergen-induced early asthmatic reactions (EARs) and late asthmatic reactions (LARs), early (between EAR and LAR) and late (after LAR) changes in bronchial reactivity to histamine and infiltration of inflammatory cells into the airways were investigated with a new model of chronically instrumented, unrestrained, and ovalbumin-sensitized guinea pigs. Two different provocation strategies were examined. With the use of stepwise increasing allergen concentrations, all 21 animals responded with an EAR, which in 15 animals (71%) was followed by an LAR. By inhalation of a single allergen concentration for up to 15 minutes, 11 of 14 animals showed an EAR, which in 10 animals (71%) was followed by an LAR. One animal did not respond, whereas the remaining two showed only an LAR. At 6 hours (after the EAR) and 24 hours (after the LAR) after allergen provocation, a significant bronchial hyperreactivity (BHR) toward histamine aerosol was observed in the dual responding animals (both protocols), but no significant changes were observed in animals with a single EAR or a single LAR. Significant correlations were found between the initial increase in airway obstruction after allergen provocation and the severity of the EAR and LAR, as well as the early and late BHR; in addition, a significant correlation was found between the early and late BHR. In contrast, the severity of the LAR did not correlate with the BHR at 6 hours and 24 hours. At 6 hours, there was a marked tendency to an increase in the number of eosinophils and a significant increase in the number of neutrophils in the bronchoalveolar lavage. At 24 hours after provocation, the number of eosinophils and neutrophils was significantly enhanced. These data suggest that early activation of mast cells and/or inflammatory leukocytes may determine the development of the LAR, as well as the early and late BHR, although there appears to be no causal relationship between the BHR at both time points and the severity of the LAR. The relationships among allergen-induced EAR and LAR, early and late BHR, and airway inflammation observed in this new guinea pig model are strikingly similar to those observed in patients with asthma. (J A LLERGY C LIN I MMUNOL 1994;93:1021-30.)

Dissociation between bronchial hyperreactivity in vivo and reduced beta-adrenoceptor sensitivity in vitro in allergen-challenged guinea pigs.

In a recently developed guinea pig model of allergic asthma, we investigated the relationships between allergen-induced bronchial hyperreactivity in vivo, tracheal smooth muscle function in vitro, and the number of inflammatory cells in the bronchoalveolar lavage. At 6 h after allergen provocation (after the early asthmatic reaction) bronchial hyperreactivity to histamine aerosol was observed, which was still present, but reduced, at 24 h after the challenge (after the late asthmatic reaction). The severity of bronchial hyperreactivity at 6 h and at 24 h after each of four daily allergen provocations was progressively reduced. The contractile properties of tracheal smooth muscle preparations in response to methacholine or histamine were not changed at 6 h and 24 h after a single allergen provocation, as well as at 24 h after the fourth of the repeated provocations. However, the sensitivity to isoprenaline-induced relaxation of a half-maximal contraction obtained with methacholine or histamine was significantly reduced at 24 h after either a single or the fourth of the repeated provocations. The time course of the reduced beta-adrenoceptor sensitivity in vitro did not correlate with that of bronchial hyperreactivity in vivo. However, it was parallelled by a progressive infiltration of inflammatory cells in the airways, suggesting that mediators from these cells may decrease airway smooth muscle beta-adrenoceptor sensitivity.

Role of histamine in allergen-induced asthmatic reactions, bronchial hyperreactivity and inflammation in unrestrained guinea pigs

In a new model using conscious, unrestrained and ovalbumin-sensitized guinea pigs, we investigated the effects of the selective histamine H 1 receptor antagonist, mepyramine, on the development of allergen-induced early and late asthmatic reactions, bronchial hyperreactivity and airway inflammation, having each animal as its own control. In guinea pigs responding to a first allergen exposure with an early as well as a late asthmatic reaction (82% of the animals) a second, identical, allergen provocation was performed, in the absence (control) or presence of 1 mg/ml mepyramine aerosol, inhaled for 10 min, 1 h before provocation. The mepyramine treatment significantly reduced both early and late asthamatic reactions and prevented the development of bronchial hyperreactivity to histamine and methacholine after both reactions. Examination of the bronchoalveolar lavage fluid 24 h after the second allergen provocation revealed a general reduction of inflammatory cells after mepyramine treatment. The results indicate that histamine, released during the early asthmatic reaction, contributes to the development of the late asthmatic reaction as well as of early and late bronchial hyperreactivity, possibly via an effect on airway inflammation.

Immunophenotyping of eosinophils recovered from blood and BAL of allergic asthmatics.

Studies of bronchoalveolar lavage (BAL) fluid from patients with allergic asthma have demonstrated active migration of eosinophils into the bronchial lumen after allergen challenge. The mechanisms mediating this eosinophil infiltration and cell activation are largely unexplained. The expression of several cell-surface molecules was measured on eosinophils derived from blood and BAL fluid 4 h after an allergen-induced early asthmatic reaction in order to find indications for a role of these molecules during extravasation to and activation in the bronchial compartment. Nine patients with allergic asthma participated in the study. An eosinophil-specific, high-depolarization signal enabled us to measure expression on eosinophils in a fluorescence activated cell sorter (FACS) analysis without isolation of these cells. Eosinophils recovered from BAL showed a different phenotype than blood eosinophils; upregulation of CR-3, p150/95, CD67, and CD63, and downregulation of L-selectin indicate that the cells are activated in terms of degranulation. Up-regulation of intercellular adhesion molecule-1 (ICAM-1), LFA-3, and human leukocyte antigen II (HLA-II) might enable cell-cell contact between T-lymphocytes and eosinophils, probably leading to immunomodulation and cell activation. The finding that eosinophils in BAL are activated and can interact with T cells is further evidence for the proinflammatory role of these cells in allergic asthma.

Sputum eosinophilia after asthmatic responses induced by isocyanates in sensitized subjects.

To assess the nature and the time-course of the cellular component of airway inflammation induced by isocyanates, we examined nine subjects with occupational asthma induced by toluene- or methylene diphenyl-diisocyanate (TDI, MDI) and four control subjects never exposed to isocyanates. Sputum was induced by inhalation of ultrasonically nebulized hypertonic saline (3-4% NaCl) before and 8, 24, 48 h after inhalation challenge with TDI or MDI. Expectorated samples were incubated with dithiothreitol, washed and cytocentrifuged. Differential cell counts were obtained on slides stained with May-Grünwald-Giemsa. Metachromatic cells (mast cells and basophils) were counted on slides stained with toluidine blue at pH 0.1. One occupational asthmatic exhibited a dual reaction to TDI, two exhibited a single early asthmatic reaction to MDI, six exhibited a late asthmatic reaction to TDI (n = 5) or MDI (n = 1), whereas no reactions were observed in control subjects after TDI challenge. In sensitized subjects eosinophils increased from a median value (interquartile range) of 5 (15)% before challenge to 29 (29)% (P = 0.014) and to 30 (31)% (P = 0.031) 8 and 24 h after TDI/MDI challenges, respectively. Sputum eosinophilia was observed both in early and late reactors and declined to near to baseline values 48 hr after challenge. Percentages of eosinophils in control subjects did not exceed 7% during the study.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of multiple doses of nedocromil sodium given after allergen inhalation in asthma

Aim: Twelve subjects with asthma took part in a placebo-controlled crossover study designed to investigate whether nedocromil sodium given after the occurrence of the early phase asthmatic reaction to allergen has an effect on the late-phase response and the associated increase in airway responsiveness. Methods : The treatments were administered four times at 4-hour intervals at a dose of 4 mg, with the first dose given 1 hour after the last allergen challenge. Changes in airway caliber were monitored for 15 hours after allergen exposure by measuring forced expiratory volume in 1 second hourly. Airway responsiveness to methacholine was determined 24 hours before and 24 hours after allergen challenge. Results : Nedocromil sodium failed to reduce significantly the maximum late fall in forced expiratory volume in 1 second as compared with placebo but delayed its occurrence by 1.5 hours ( p = 0.05). Nonspecific airway responsiveness to methacholine was similarly increased after allergen challenge when patients received nedocromil sodium and placebo. No unusual events were reported during the study period by any patient. These results indicate that nedocromil sodium is not able to interrupt the ongoing cascade of inflammatory events leading to the late-phase reaction and the associated increase in airway responsiveness. Conclusion : In allergic asthma, nedocromil can be used only as a preventive treatment.