Cysteinyl-leukotrienes contribute to sputum eosinophil chemotactic activity in asthmatics

BACKGROUND: Cysteinyl-leukotrienes are lipid derived mediators involved in asthma. They are able to stimulate eosinophil chemotaxis in vitro. Induced sputum from asthmatics has been shown to contain eosinophil chemotactic activity. The purpose of our study was to evaluate the contribution of cysteinyl-leukotrienes to sputum eosinophil chemotactic activity in asthmatics and to seek whether there might be differences between asthmatics free of inhaled corticosteroids vs those regularly receiving this treatment. METHODS: Twenty-two patients (11 corticosteroid free, mean FEV1 99% predicted, 11 corticosteroid-treated, mean FEV1 77% predicted) recruited from our asthma clinic underwent a sputum induction. Sputum was processed according to standard procedure. Eosinophil chemotactic activity contained in the fluid phase was assessed using Boyden microchamber model and expressed as chemotaxis index (CI). Cysteinyl-leukotrienes were measured in sputum supernatant by ELISA and their role in sputum eosionophil chemotactic activity was evaluated by using montelukast, a selective antagonist of a cys-LT1 receptor. RESULTS: Cysteinyl-leukotrienes were well detectable in sputum supernatants from both steroid-naive (247 +/- 42 pg/ml) and steroid-treated (228 +/- 26 pg/ml) asthmatics. Sputum eosinophil chemotactic activity was indiscriminately present in both corticosteroid-naive (CI: 2.61 +/- 0.22) and corticosteroid-treated (2.98 +/- 0.35) asthmatics. Montelukast (100 microM) significantly inhibited the eosinophil chemotactic activity in both groups achieving a mean inhibition of 54.2 +/- 9.2% (P < 0.001) and 64.7 +/- 7.8% (P < 0.001) in steroid-naive and steroid-treated asthmatics respectively. CONCLUSION: Cysteinyl-leukotrienes actively participate in sputum eosinophil chemotactic activity found in asthmatics irrespective of whether they are or not under treatment with inhaled corticoids.     

Airway mast-cell activation in asthmatics is associated with selective sputum eosinophilia

BACKGROUND: Tryptase is a serine endoprotease selectively released from mast cells. Although mast cells are known to be activated after experimental allergic provocation, their role in naturally occurring asthma is still debated. METHODS: We have investigated the levels of tryptase in the whole induced sputum collected from 51 asthmatics (31 atopic and 20 intrinsic) seen in our outpatient clinic and 22 normal nonatopic healthy volunteers. Tryptase was measured by a new immunoassay based on B12 monoclonal antibody recognition of total tryptase (UniCAP System, Pharmacia) with a sensitivity of 1 ng/ml. RESULTS: While being below the threshold of detection in all normal volunteers, tryptase was detectable in the sputum from 9/51 asthmatics (18%) including five atopic and four intrinsic asthma cases. In these patients, among whom three were asymptomatic asthmatics, the values ranged between 1 and 6.1 ng/ml. The asthmatics with detectable sputum tryptase had greater sputum eosinophil counts (P<0.05) but lower neutrophil counts (P<0.05) than those in whom tryptase was undetectable. When compared to control subjects, asthmatics without tryptase had still greater eosinophil counts (P<0.0001) but also raised neutrophil counts (P<0.05). No significant difference could be found between asthmatics with tryptase and those without tryptase with respect to the age, the baseline lung function, the methacholine bronchial responsiveness, and the frequency of treatment with inhaled steroids. CONCLUSIONS: With the UniCAP System, tryptase was detectable in the sputum from 18% of asthmatics irrespective of atopy and current symptoms. Asthmatics with tryptase appeared to have a selective increase in sputum eosinophil counts while those without tryptase displayed a mixed sputum granulocyte infiltration with raised eosinophil and neutrophil counts.     

Eotaxin in induced sputum of asthmatics: relationship with eosinophils and eosinophil cationic protein in sputum

BACKGROUND: Eosinophilic inflammation is a crucial aspect of allergic diseases such as bronchial asthma. An eosinophil-active chemokine, eotaxin, may play a role in the pathogenesis of the tissue eosinophilia accompanying asthma. METHODS: Induced sputa were obtained from 53 patients with atopic asthma and six healthy subjects, and the concentration of eotaxin in the sputum was measured by ELISA. We investigated whether the sputum content of eotaxin is related to 1) asthma status or corticosteroid therapy, and 2) other sputum indices, including percentage of eosinophils and concentration of eosinophil cationic protein (ECP). RESULTS: The patients with stable or unstable asthma showed significantly higher concentrations of sputum eotaxin than the normal controls. The level of sputum eotaxin demonstrated a positive correlation with the percentage of eosinophils in stable asthmatics not receiving corticosteroid therapy, but not in stable patients treated with corticosteroids, or in unstable patients. Sputum eotaxin demonstrated a positive correlation with ECP in asthmatic patients who were either in a stable state or not receiving steroid therapy. CONCLUSIONS: The elevated level of eotaxin detected in association with increased eosinophils and ECP in the sputum of asthmatics suggests that eotaxin is involved in the pathogenesis of eosinophilic airway inflammation. The relationship of eotaxin to airway eosinophilia may be modified by the stability status of asthma and corticosteroid therapy.     

Nasal and pharyngeal eosinophil peroxidase levels in adults with poorly controlled asthma correlate with sputum eosinophilia

The objective of the study was to compare nasal, pharyngeal, and sputum eosinophil peroxidase (EPX) levels with induced sputum eosinophil percentage in 10 adults with poorly controlled asthma and 10 normal controls. EPX was measured using an ELISA and normalized for grams of protein for nasal and pharynx specimens and for mL‐gram of protein for sputum. Sputum EPX levels were statistically different between asthma and control subjects (P = 0.024). EPX levels measured in the nasal and pharyngeal swab samples derived from the same patients were also different between asthma and control subjects, each displaying a high degree of significance (P = 0.002). Spearman's correlation coefficients for nasal EPX and pharyngeal EPX levels compared to induced sputum eosinophil percentage were 0.81 (P = 0.0007) and 0.78 (P = 0.0017), respectively. Thus, there is a strong association in a given patient between both nasal and pharyngeal EPX levels and the eosinophil percentage of induced sputum.     

Sputum eosinophil count in a large population of patients with mild to moderate steroid-naive asthma: distribution and relationship with methacholine bronchial hyperresponsiveness

BACKGROUND: Although airway eosinophilia is seen as a cardinal feature of asthma, data eosinophilia are still lacking on the proportion of the asthma group exhibiting raised airway eosinophilia. This study aimed to assess the distribution of sputum eosinophil count and its relationship with methacholine bronchial hyperresponsiveness in mild to moderate steroid-naive asthmatic people. METHODS: Sputum was induced by inhalation of hypertonic saline (NaCl 4.5%) in 118 mild to moderate steroid-naive asthmatic people consecutively recruited from our outpatient clinic, and in 44 healthy people. The asthma group was selected on the basis of an forced expiratory volume in 1 s (FEV(1)) of > or = 70% predicted, and a provocative methacholine concentration causing a fall of 20% in FEV(1) (PC20 methacholine; PC(20)M) < or = 16 mg/ml. RESULTS: In the asthma group, the median (range) of the percentage and the absolute values of sputum eosinophils were 4.8% (0-75) and 38 10(3)/g (0-14,191), respectively, vs 0% (0-2.3) (P < 0.001) and 0 10(3)/g (0-53) (P < 0.001) in healthy participants. Based on the 95% percentile for normal values calculated from our healthy group, 69% of the asthma group had significantly raised sputum eosinophil count (that is > 2%). In the asthma group, multiple regression analysis followed by a stepwise procedure revealed that sputum eosinophil count was significantly and inversely associated with PC(20)M accounting for 16% of its total variance (P < 0.001) while neutrophil counts positively related to PC(20)M accounting for 4% of total variance (P < 0.05). By contrast, no significant relationship was found between either eosinophil or neutrophil counts and the slope of forced vital capacity (FVC) vs FEV(1) from the methacholine challenge. CONCLUSIONS: We conclude that two-thirds of people in the mild to moderate asthma group had increased sputum eosinophilia, which plays a limited role in determining the degree of methacholine airway hyperresponsiveness.     

Once-daily theophylline reduces serum eosinophil cationic protein and eosinophil levels in induced sputum of asthmatics

BACKGROUND: Because eosinophilic airway inflammation is a characteristic feature of bronchial asthma, the treatment of airway inflammation is important in the management of asthma. Theophylline has been reported to reduce airway inflammation, in addition to its well-known bronchodilating effect. OBJECTIVE: In order to evaluate the effects of theophylline on airway inflammation, we investigated 48 subjects with mild and moderate asthma. METHODS: The patients were randomly divided into two groups, with or without theophylline treatment (control n = 24; theophylline, n = 24). We examined the level of serum eosinophil cationic protein (ECP), induced sputum samples, and peak expiratory flow (PEF) and obtained spirograms before and after 4 weeks of treatment with once-daily theophylline (200-600 mg/day) of subjects with mild or moderate asthma. RESULTS: Theophylline significantly increased morning and evening PEF and significantly decreased the diurnal variation of PEF. After treatment with theophylline, both serum ECP and the percentage of eosinophils in induced sputum were significantly decreased. In contrast, peripheral blood eosinophil count was unchanged after treatment with theophylline. Conclusions: These findings suggest that theophylline reduces airway inflammation and the severity of asthma, presumably via suppression of both eosinophil activity and subsequent eosinophil infiltration of the airways.     

Analysis of induced sputum before and after withdrawal of treatment with inhaled corticosteroids in asthmatic patients

To assess whether sputum eosinophilia predicts the recurrence of asthma symptoms after withdrawal of therapy in moderate stable asthmatics on low-dose inhaled corticosteroids. Randomized, double-blind, placebo-controlled study involving 30 subjects with stable asthma, asymptomatic, with low PEF variability measured over two run-in weeks, on treatment with low-dose inhaled beclomethasone dipropionate (BDP, 250 microgram b.i.d. in the last 3 months). At the end of the run-in, all patients underwent a methacholine challenge test and sputum induction (T1). They then stopped therapy and received either placebo (20 subjects, study group) or BDP at the same dose as in the previous 3 months (10 subjects, control group). They continued to monitor PEF and symptom score for 3 months, or until asthma symptoms recurred (diurnal and nocturnal symptom score >/=2 on two consecutive days). At the end of the study (T2), i.e., either within 5 days from the beginning of asthma symptoms or after 3 months in subjects without recurrence of asthma symptoms, all subjects repeated the methacholine challenge test and sputum induction. In the placebo-treated group, sputum eosinophils at T1 were significantly higher in subjects who subsequently developed recurrence of asthma symptoms (n = 7) after cessation of treatment than in subjects who remained asymptomatic for 3 months (8.2% [0-56.6] vs 0.9% [0-11], P < 0.05). At the time of recurrence of asthma symptoms, sputum eosinophil percentages significantly increased (from 8.2% [0-56.6] to 16.6% [5.8-73.6], P < 0.05). The positive predictive value of sputum eosinophils for the recurrence of asthma symptoms was 71%, while the negative predicting value was 84%. In the BDP-treated control group, none of the subjects experienced recurrence of asthma symptoms, and sputum eosinophil percentages measured at the beginning (T1) and at the end (T2) of the study were similar. Sputum eosinophil percentages may vary over a wide range in asthmatic subjects, although regularly treated and apparently well controlled. However, high sputum eosinophil percentages are related to early recurrence of asthma symptoms after cessation of inhaled corticosteroids.     

Differential dependence of eosinophil chemotactic responses on phosphoinositide 3-kinase (PI3K)

BACKGROUND: Control of eosinophil migration to sites of inflammatory responses is a potentially therapeutic intervention in diseases such as bronchial asthma. Chemoattractants, their receptors and the associated signalling pathways may, therefore, be important targets for novel therapeutics. While several potentially important chemoattractants have been identified, the signalling pathways mediating their actions are incompletely understood. AIMS OF THE STUDY: The role of phosphoinositide 3-kinase (PI3K) in responses of human eosinophils to two important eosinophil chemoattractants -- platelet-activating factor (PAF) and eotaxin (CCL11) -- was studied to determine whether this enzyme activity might be crucial for eosinophil migration. METHODS: Eosinophils were isolated from atopic donor blood by immunomagnetic selection. Chemotaxis was assayed in a 96-well blind-chamber cell fluorescence assay. Respiratory burst and leukotriene C(4) secretion were also assayed. RESULTS: Two PI3K inhibitors, wortmannin and LY294002, caused concentration-dependent inhibition of PAF-induced eosinophil chemotaxis (IC(50) = 0.54 nM and 0.15 microM, respectively) but exhibited at least 100-fold lower potency against eotaxin-induced responses (IC(50) = 48 nM and >100 microM, respectively), indicating that these responses were not dependent upon PI3K. Wortmannin and LY294002 also inhibited PAF induced respiratory burst but not PAF-induced LTC(4) secretion. CONCLUSIONS: We conclude that PI3K-dependence varies with stimulus and response, and that eotaxin-induced eosinophil migration is not controlled by PI3K. This may indicate a limit to the potential of PI3K inhibitors to suppress tissue eosinophilia in diseases such as asthma.     

Salbutamol pretreatment does not change eosinophil percentage and eosinophilic cationic protein concentration in hypertonic saline-induced sputum in asthmatic subjects

BACKGROUND: Sputum induction by inhalation of hypertonic saline (HS) is usually preceded by beta2-agonist pretreatment, to prevent severe bronchoconstriction. OBJECTIVE: To evaluate whether salbutamol pretreatment may influence cell counts and concentrations of soluble mediators in induced sputum. METHODS: We studied 22 patients who randomly underwent HS sputum induction after pretreatment with either 200 microg salbutamol or placebo. Sputum was induced by means of HS inhalation (3, 4, 5% NaCl, 10 min each), measuring FEV1 every 5 min until it fell >/= 20% from baseline. Collected sputum was diluted 1 : 1 with 0.1% DTT, incubated at 37 degrees C for 20 min, and total and differential cell counts were measured. ECP and histamine levels were measured in the supernatant. RESULTS: Sputum volume, percentages of inflammatory cells, squamous cell counts and quality of the slides were not different after the two pretreatments, while sputum total inflammatory cells after salbutamol tended to be higher than after placebo (8.3 [1-41] 10(6) vs 6.3[0.2-40] x10(6); P = 0.09). Eosinophilic cationic protein (ECP) did not significantly change (260 [8-900] microg/L after salbutamol vs 200 [8-800] microg/L, n = 19), while histamine levels tended to be lower after salbutamol (140.9 [39.9-236.5] nm) than after placebo (190.4 [72. 2-322.6] nm, P = 0.09, n = 17). The airway response to HS inhalation was significantly greater after placebo and the duration of the test was significantly different (median: 15 min after placebo and 30 min after salbutamol). Similar results were obtained when patients who differed for more than 15 min in the duration of HS-inhalation in the two tests were selected (n = 11). CONCLUSION: Salbutamol pretreatment reduces the severity of bronchoconstriction induced by HS inhalation without significantly affecting the percentages of inflammatory cells and the levels of soluble mediators in induced sputum.     

Tissue eosinophilia in pemphigoid gestationis: association with eotaxin and upregulated activation markers on transmigrated eosinophils

PROBLEM: We studied chemotactic cytokines and activation of skin-homed eosinophils in pemphigoid gestationis, a rare autoimmune bullous disease of late pregnancy. METHOD OF STUDY: Eotaxin and interleukin (IL)-5 were analysed in patients' blister fluid and serum by enzyme-linked immunosorbent assay. Lesional tissue was investigated for eotaxin deposition by immunohistochemistry. Adhesion molecules and activation markers on tissue eosinophils were analysed by immunofluorescence staining. RESULTS: Eotaxin was elevated in serum of two pemphigoid gestationis patients compared with nine healthy pregnant women. Blister fluid contained even higher amounts of eotaxin and in addition IL-5. Eotaxin was mainly expressed in subepidermal tissue in close proximity to eosinophils that expressed high levels of adhesion molecules (CD11b, CD11c, CD18 and CD49d) and the activation marker HLA-DR. CONCLUSIONS: High local levels of eotaxin and IL-5 as present in the blister fluid correspond to the high state of activation of the infiltrated eosinophils.     

Cytokine production from peripheral whole blood in atopic and nonatopic asthmatics: relationship with blood and sputum eosinophilia and serum IgE levels

BACKGROUND: The cytokine network is thought to be essential in orchestrating airway inflammation in asthma. Although evidence has accumulated to suggest that atopic asthma is a Th2 disease, much less is known about nonatopic asthma. METHODS: We have compared the production of IL-4, IL-6, IFN-gamma, and TNF-alpha from peripheral blood leukocytes between atopic (n=21) and nonatopic (n=22) asthmatics and healthy nonatopic subjects (n=20). Peripheral blood was incubated for 24 h either without stimulus or with LPS or PHA. Cytokines were measured by the immunotrapping technique (Dynamic Immunoassay). RESULTS: When compared to healthy nonatopic subjects, both atopic and nonatopic asthmatics showed increased blood and sputum eosinophilia associated with raised total serum IgE levels. Similarly, both asthma groups displayed spontaneous, endotoxin-induced overproduction of IL-6. Enhanced spontaneous, endotoxin-induced release of IL-4 combined with reduced spontaneous IFN-gamma production was seen only in atopic asthma. In this group of patients, the production of IL-4 was related to the extent of blood and sputum eosinophilia. In nonatopic asthmatics, serum levels of IgE were inversely related to the production of IFN-gamma. CONCLUSIONS: Both atopic and intrinsic asthma display raised blood and airway eosinophilia, raised total serum IgE, and overproduction of IL-6 from peripheral blood. Atopic asthma is also characterized by impaired spontaneous release of IFN-gamma and increased production of IL-4 that correlates with the magnitude of eosinophilic inflammation.     

激素治疗对运动诱发性哮喘患者痰嗜酸性粒细胞计数的影响

目的探讨气道嗜酸性粒细胞性炎症和运动诱发的支气管痉挛（EIB）之间的关系,及其对吸入糖皮质激素（ICS）治疗的反应。方法本研究为随机、双盲、二阶段交叉试验,将26例有运动诱发性支气管痉挛发作史且从未接受过激素治疗的哮喘患者随机分为两组,每组分别给予两个剂量水平的布地奈德吸入：①100μg/d与400μg/d对比;②200μg/d与800μg/d对比。每一阶段为3周,洗脱期3～8周。治疗前及开始治疗后每隔1周进行1次运动激发试验并留取痰液标本行嗜酸性粒细胞计数。结果高剂量ICS治疗（400μg/d和800μg/d）可显著减少痰嗜酸性粒细胞比例。痰嗜酸性粒细胞百分比与运动诱发性支气管痉挛严重程度相关,且对EIB的严重程度有预测作用;高剂量ICS治疗时,尚可预测EIB对激素治疗有效,而对低剂量ICS组（100μg/d和200μg/d）则无预测作用。低剂量ICS治疗,不管基线痰嗜酸性粒细胞计数是否增多,EIB在第1周末发作显著减轻,尔后几无改善。而高剂量ICS治疗对EIB的改善作用在痰嗜酸性粒细胞增多的患者中显著优于嗜酸性粒细胞计数小于5%者,这种明显的差异在开始治疗1周后即显现,且随时间的推移而继续加大。结论气道嗜酸性粒细胞性炎症可能在EIB的发生及其对ICS治疗有效的调节机制中起重要的作用。测定痰嗜酸性粒细胞计数在预测EIB的严重程度及其对不同剂量ICS治疗的反应具有一定的临床应用价值。     

Expression of eotaxin in induced sputum of atopic and nonatopic asthmatics

BACKGROUND: The chemokine eotaxin has been implicated in airway eosinophilia in atopic asthma. We have compared airway eosinophils and eotaxin expression in induced sputum from well-matched atopic and nonatopic asthmatics. METHODS: Eosinophil numbers, eosinophil cationic protein (ECP), and the expression of eotaxin were examined in induced sputum from atopic asthmatics (AA = 11), nonatopic asthmatics (NAA = 11), and atopic (AC = 12) and normal (NC = 10) controls. Slides were prepared for differential cell counts by Romanowsky stain, and ECP levels were measured by RIA. Eotaxin expression was detected by in situ hybridization, with 35S-labelled riboprobes and immunocytochemistry. RESULTS: The numbers of eosinophils and ECP concentration were increased in the sputum of AA and NAA compared with AC and NC (P < 0.05). The numbers of eotaxin mRNA+ and immunoreactive cells were increased in NAA, but not AA, when compared with controls (P < 0.05). Eotaxin immunoreactive cells in NAA were significantly higher than in AA (P < 0.05). Eotaxin was expressed predominantly by macrophages, eosinophils, and epithelial cells. In NAA, but not AA, the numbers of eotaxin mRNA+ cells were correlated with histamine PC20 (r = -0.81, P < 0.01) and eosinophil numbers in sputum (r = 0.7, P < 0.05). CONCLUSIONS: Eotaxin production by macrophages, eosinophils, and epithelial cells may play a more pronounced role in airway eosinophilia in nonatopic than in atopic asthma.     

The effect of immunotherapy on eosinophil accumulation and production of eosinophil chemotactic activity in the lung of subjects with asthma during natural pollen exposure

Two groups of birch pollen--allergic patients with seasonal rhinoconjunctivitis and asthma were followed during two consecutive birch-pollen seasons, one group, N = 10, during a season with high pollen load, and one group, N = 15, during a season of low pollen load. Half the patients were treated with immunotherapy (IT) for 3 and 4 years, respectively. The other half of the patients served as control group (non-IT). Bronchoalveolar lavage (BAL) was performed once before each season and once during the pollen season. Eosinophil (EOS) numbers in BAL were increased (p less than 0.01) during the season with high pollen load but not in the season with a low pollen load, and this increment was absent in the IT-treated group. Also, the EOS cationic protein levels were raised in the non-IT-treated group during the season with a high pollen load. The levels of EOS and neutrophil chemotactic activity were raised in BAL in both seasons in the non-IT-treated group compared with the IT-treated group (p less than 0.02, p less than 0.003, p less than 0.04, and p less than 0.005 in high- and low-load pollen season, respectively). Serum and BAL eosinophil chemotactic activity (ECA) were positively correlated (p less than 0.001). We conclude that there is an influx of active EOSs into the lung of pollen-allergic patients with asthma during a pollen season, which may be abrogated by IT. Furthermore, the generation of ECA appears to be an extremely sensitive marker of antigenic exposure, and the potent inhibition of the generation of ECA by IT may provide a clue as to the mechanism of this treatment.     

Expression of the apoptosis inhibitor Bcl-2 in sputum eosinophils from children with acute asthma

BACKGROUND: Apoptosis of eosinophils is of increasingly important value in modulating allergic airway inflammation in asthma. Our purpose was to investigate the degree of expression of the antiapoptotic B-cell lymphoma/leukaemia-2 (Bcl-2) protein in sputum eosinophils during acute asthma exacerbation and its relationship with exacerbation severity. METHODS: Sputum was obtained from 33 asthmatic children and 15 healthy children as a control group. Patients were studied during an acute asthma exacerbation. They were classified according to the severity of exacerbation into mild, moderate and severe (n=11 for each). Patients with severe exacerbation were followed up until remission and another sputum sample was obtained. Number of sputum eosinophils was expressed as percentage of leucocytes. Bcl-2 expression in sputum eosinophils was assessed by immunohistochemical staining techniques; the results were expressed as percentage of positively stained cells over total eosinophils. RESULTS: Sputum eosinophils and Bcl-2(+) eosinophils' percentages were significantly higher in patients with acute exacerbation than controls (P<0.01). Patients with severe exacerbation had significantly higher sputum Bcl-2(+) eosinophils' percentage than those with mild-to-moderate exacerbation (mean+/-SD=42.4+/-31.96% vs. 5.7+/-14.5%, P<0.01). A significant negative correlation was found between Bcl-2(+) eosinophils' percentage and peak expiratory flow rate % predicted (P<0.05). After remission, patients with severe exacerbation showed a significant decrease of Bcl-2(+) eosinophils' percentage (P<0.05). CONCLUSION: Our findings suggest that Bcl-2 prolongs survival and decreases apoptosis of airway eosinophils in asthma especially during exacerbation. Eosinophil apoptosis and Bcl-2 represent a target for new and effective therapeutic strategies of asthma.     

Comparison of the effects of salmeterol and salbutamol on clinical activity and eosinophil cationic protein serum levels during the pollen season in atopic asthmatics

Background In atopic asthma there is strong evidence of eosinophils playing an active role in pathogencsis. Some investigations demonstrated that eosinophil cationic protein (ECP) serum levels increased in atopic patients with asthma during pollen season. Objective The aim of the study was to evaluate the effects of short-term (1 week) β2-agonist treatment on lung function and eosinophil activity in asthmatic patients. Methods We used an open, randomized, cross-over design to compare the effects of salbutamol (200μg q.i.d.) and salmeterol (50μg b.i.d.) on peak expiratory flow rate (PEFR), blood eosinophil count and serum levels of ECP as a measure of eosinophil activity in 20 mild atopic asthmatics. Results Morning and evening PEFR values were both significantly higher during salmeterol treatment than during the salbutamol period. Conversely, both morning and evening daily asthma symptom scores were significantly lower during salmeterol treatment compared with those recorded during the salbutamol period. The mean basal eosinophil blood count on salmeterol treatment (601 ± 189mm³) was not higher than the mean count on salbutamol treatment (612 ± 204 mm³). After both treatments the mean eosinophil blood counts were unchanged (619 ± 189mm³ and 576 ±212 mm³, respectively). No significant differences in blood eosinophil counts were observed between or within treatments at any time. No significant difference was observed in baseline mean ECP serum concentration (43.8 ± 263 μg L on salmeterol treatment and 41.7 ± 29.8 μg L on salbutamol treatment, respectively). After salmeterol treatment the mean ECP serum concentration had fallen significantly to 20.9± 18.6μg/L (P < 0.01), whereas after salbutamol treatment it was unchanged (42.0 ± 25.1 μg /L). Salmeterol treatment produced a decrease in ECP serum levels without any changes in blood eosinophil count. Conclusion This study demonstrates that salmeterol affords a significant improvement in asthma control during the pollen season, measured by both subjective and objective parameters, compared with salbutamol. This greater efficacy may be related to inhibition of eosinophil degranulation during the pollen season.