Effect of anti-ICAM-1 on bronchial response: bronchoalveolar lavage fluid (BALF) and ultrastructural changes of bronchial epithelium in guinea pigs with dual phase bronchial response

Eosinophils play an important role in the development of bronchial asthma, and the association between ICAM-1 and activation and migration of local eosinophils is attracting attention. Using an asthmatic model of dual phase bronchial response, the effects of anti-ICAM-1 antibody on the airway resistance, cell composition in the bronchoalveolar lavage fluid (BALF) and ultrastructure of bronchial ciliated epithelium were examined under the provoked response by inhalation of the antigen. By administration of anti-ICAM-1 antibody, the late asthmatic response (LAR) was suppressed. In the examination of bronchoalveolar lavage fluid, a significant decrease in eosinophils was found in LAR. In examining transmission and scanning electron microscopies, no difference was found in the immediate asthmatic response, but marked suppression of deciduation of bronchial ciliated epithelium was observed in LAR. These results indicated that anti-ICAM-1 antibody suppressed bronchial asthmatic attack, mainly in LAR, by controlling differentiation and migration of eosinophils.

Discordant and anomalous results among cytotoxicity assays: the confounding properties of eosinophil granule major basic protein on cell viability assays

When five cytotoxicity methods compared the toxicity of eosinophil granule major basic protein (MBP) and melittin to K562 and HL-60 cells, strikingly discrepant results were noted. Trypan blue staining, propidium iodide/CellTrackerGreen staining and incorporation of 14C-leucine assays indicated MBP damages > 75% of cells by 1 h. In contrast, 51Cr and lactic dehydrogenase (LDH) release assays indicated MBP damages most cells only at 20 h. All methods indicated melittin damages nearly all cells by 1 h. Further studies showed that without cell transfer, dye staining methods indicated MBP produces < 10% cytotoxicity after 4 h. A modified 14C-leucine assay, employing sodium dodecyl sulfate solubilization and trichloroacetic acid precipitation, showed lower cytotoxicity, 48%, at 4 h. Modified 51Cr and LDH assays showed increased cytotoxicities at 4 h, 34% and 58%, respectively. Overall, MBP's ability to cause molecular and cellular adhesion systematically confounds standard cytotoxicity measurements. However, the modified 14C-leucine assay provides a valid measure of MBP's cytotoxicity and may be useful for analyses of 'sticky' cytotoxins.

Effects of saiboku-to on dual-phase bronchoconstriction in asthmatic guinea pigs

In recent years, bronchial asthma has come to be regarded pathologically as a chronic inflammatory disease of the respiratory tract. Inhalational steroids and antiinflammatory drugs are recognized as being effective against bronchial asthma. In this study, the effects of Saiboku-to, a Chinese herbal (Kampo) formulation, were investigated on asthmatic guinea pigs sensitized to ovalbumin (OA). Following 7-day administration of Saiboku-to (500 micrograms/kg), the late asthmatic response (LAR) to an antigen challenge was found to be inhibited. The number of eosinophils in fluid obtained by bronchoalveolar lavage (BAL) 4 h after antigen challenge was decreased while the infiltration of eosinophils and T-lymphocytes into the lung parenchyma was inhibited. These findings suggest that Saiboku-to has the potential to become a useful drug in the treatment of bronchial asthma.

Effects of saiboku-to on the survival of human eosinophils

In recent years, bronchial asthma has come to be regarded as a chronic inflammatory disease of the respiratory tract, with mast cells, lymphocytes and eosinophils playing important roles in its pathogenesis. Proteins contained in eosinophil granules, especially major basic protein (MBP), eosinophil cationic protein (ECP), eosinophil-derived neurotoxin (EDN) and eosinophil peroxidase (EPO), can cause tissue injury. When stimulated, eosinophils release mediators such as leukotriene C4 (LTC4) and platelet activating factors (PAF). Thus, they are recognized as effector cells that are actively involved in the development of allergic inflammation. In this study, eosinophils from healthy volunteers were used to investigate the effects of Saiboku-to on eosinophils whose survival had been prolonged through stimulation with eosinophil-activating cytokines such as interleukin (IL)-3, IL-5 and granulocyte macrophage colony stimulating factors (GM-CSF). As a result, the cytokine-enhanced survival of eosinophils was significantly shortened by the addition of Saiboku-to. These findings suggest that Saiboku-to has the potential to inhibit allergic responses by directly affecting eosinophils which are related to allergic inflammation.

Intrapleural administration of cisplatin and etoposide to treat malignant pleural effusions in patients with non-small cell lung cancer

BACKGROUND

To determine the efficacy, toxicity and pharmacokinetics of intrapleural cisplatin (CDDP) and etoposide as a treatment for malignant pleural effusions (MPE) in patients with non-small cell lung cancer (NSCLC).

METHODS

Seventy patients with MPE associated with NSCLC were enrolled in this study. In 68 patients, a catheter was inserted into the pleural cavity, within 24 h after complete drainage of the pleural effusion, CDDP (80 mg/m2) and etoposide (80 mg/m2) were simultaneously administered successfully via the catheter and the catheter was clamped. Seventy-two hours later, the catheter was unclamped to allow drainage. The catheter was removed when the accumulated intrapleural fluid decreased to 20 ml or less per day.

RESULTS

The pharmacokinetic profiles showed high maximum concentrations of CDDP (free form, 88 microg/ml) and etoposide (182. 4 microg/ml) in intrapleural fluids. CDDP did not remain for a long period (free form, beta-phase half-life = 10.51 h) in the fluids, while etoposide persisted for a long period (beta-phase half-life = 62.53 h). The overall response rate was 46.2%, the median survival time 32.3 weeks, the 1-year survival rate 28.7% and the 2-year survival rate 12.8%. The most serious adverse reactions were WHO grade 3 anemia (3 patients), grade 3 nausea and vomiting (17 patients), grade 3 constipation (1 patient), grade 3 pulmonary toxicity (1 patient), grade 4 fever (1 patient), grade 3 infection (1 patient) and grade 3 mental disorder (1 patient).

CONCLUSION

Intrapleural administration of CDDP and etoposide was an effective and acceptable regimen for patients with MPE due to NSCLC.

Role of substance P in increased airway hypersensitivity following induced stress in a guinea pig asthma model

Stress is one of the important factors influencing bronchial asthma, but many questions still remain unanswered. To clarify this point we examined airway hypersensitivity before and after electric shock stress and the role of substance P in an animal model of asthma. We determined airway hypersensitivity to histamine and the substance P levels in serum, bronchoalveolar lavage fluid, and bronchial tissue before and after electric shock stress in biphasic asthma-responsive guinea pigs which had been sensitized using ovalbumin. The cell components in bronchoalveolar lavage fluid were also examined. Airway hypersensitivity to histamine (4.9-156 micrograms/ml) was significantly increased (p < 0.01) by electric shock stress. The substance P level was also significantly increased in plasma and bronchoalveolar lavage fluid, but it was significantly decreased in bronchial tissue. The number of eosinophils in bronchoalveolar lavage fluid increased significantly after electric shock stress. These findings demonstrated that airway hypersensitivity to histamine was increased by stress and suggested that substance P, as well as eosinophils, contribute to the pathogenesis of hypersensitivity.

Roles of histamine receptor in a guinea pig asthma model

Histamine plays an important role in bronchoconstriction mediated by histamine receptors which provoke bronchial asthma attack. In this study, we measured H1 and H2 receptors in the guinea pig lung membrane fraction and obtained the following results. The maximum binding (Bmax) of H1 receptors in the guinea pig lung membrane fraction was significantly higher in the OA-sensitized group than that in the non-sensitized group, but affinity (Kd) did not differ between the groups. Otherwise, the maximum binding (Bmax) of H2 receptors in the guinea pig lung membrane fraction was significantly lower in the OA-sensitized group than that in the non-sensitized group. But affinity (Kd) did not differ between the groups. These findings suggest a close association of Histamine receptors both H1 and H2 in the pathology of asthma.

Effects of theophylline on lymphocyte phosphodiesterase activity

1. To clarify part of the bronchodilating effects of theophylline, lymphocyte cyclic AMP (cAMP) and phosphodiesterase (PDE) activity in asthmatic patients and healthy adults were measured. 2. No clear differences in lymphocyte PDE activity were found regarding sexes, ages or the types of asthma. 3. Lymphocyte PDE activity in the asthma group was significantly higher than that in the control group. 4. Lymphocyte cAMP significantly increased at 30 and 60 min after intravenous injection of aminophylline in the asthma group. 5. Lymphocyte PDE activity significantly decreased 60 min after intravenous injection of aminophylline in the asthma group.

Effect of TYB-2285 on early and late bronchial responses and airway hyperreactivity in actively sensitized guinea pigs

1. The effect of a new antiasthmatic drug, TYB-2285 [3,5-bis (acetoxyacetylamino)-4-chlorobenzonitrile], on dual bronchoconstriction and airway hyperreactivity in actively sensitized guinea pigs was investigated. 2. Immediate and late bronchial responses were induced at 1-10 min and 4-7 hr after antigen inhalation, respectively. Guinea pigs were pretreated with TYB-2285 (300 mg kg(-1) PO, as a single dose or consecutively for 7 days). 3. The immediate bronchial response was inhibited only by a multiple administration of TYB-2285. Late bronchial response was inhibited by both administration methods. 4. The numbers of eosinophils, neutrophils and macrophages, but not lymphocytes, in the bronchoalveolar lavage fluid were increased at 4 hr after antigen inhalation. TYB-2285, given singly and consecutively, decreased the numbers of total cells, eosinophils, neutrophils and macrophages. 5. Sensitized guinea pigs showed significant airway hyperreactivity to inhaled histamine. This airway hyperresponsiveness was reversed by a single administration of TYB-2285. 6. Luminol-dependent chemiluminescence of airway-infiltrated cells was slightly inhibited by TYB-2285 (20 microg ml(-1)). 7. The present study shows that TYB-2285 inhibits late asthmatic response and airway hyperresponsiveness, presumably by inhibiting the accumulation and activation of eosinophils and other inflammatory cells.

Role of GABA receptors in the bronchial response: studies in sensitized guinea-pigs

BACKGROUND

Gamma-aminobutyric acid (GABA), an important inhibitory neurotransmitter in the mammalian central nervous system, is also found in peripheral tissues, including the lung. GABA has recently been shown to modulate the contraction of airway smooth muscle.

OBJECTIVE

We studied the effect of GABA on the contractile properties of tracheal smooth muscle by measuring the tension of the trachea isolated from non-sensitized and ovalbumin (OA)-sensitized guinea-pigs under isometric conditions.

METHODS

Guinea-pigs were sensitized by intraperitoneal doses of OA to prepare a bronchial asthma model. Tracheal spiral rings were prepared from the OA-sensitized as well as normal, non-sensitized guinea-pigs. Using the tracheal preparations, the effects of GABA and GABAa and GABAb receptor agonists (muscimol and baclofen) and antagonists (bicuculline and saclofen) on the basal tone of the trachea and on tracheal contraction induced by electrical field stimulation (EFS) were determined. The effect of GABA on tracheal contraction induced by exogenous acetylcholine was also studied.

RESULTS

GABA and GABA agonists and antagonists had no effect on the basal tone of normal guinea-pig tracheae. Both GABAa and GABAb receptor agonists, as well as GABA, suppressed EFS-induced contraction of normal guinea-pig tracheae in a reversible, dose-dependent manner. Moreover, this suppression was reserved to the control level by either GABAa and GABAb receptor antagonists. In tracheal spiral ring prepared from OA-sensitized guinea-pigs, GABA and baclofen caused a smaller reversible inhibition of EFS-induced contraction than in normal tracheal spiral ring, while muscimol inhibited EFS-induced tracheal contraction to a similar extent to that observed in normal tracheae. GABA had no effect on the tracheal contractile response to acetylcholine.

CONCLUSION

The results suggest that there may be a biological mechanism mediated by prejunctional GABAb receptors which attenuates cholinergic contraction of airway smooth muscle and that dysfunction of the receptors may underlie the airway obstruction in asthmatics.

The effect of theophylline on blood and sputum eosinophils and ECP in patients with bronchial asthma

It was recently reported that theophylline has an anti-inflammatory and bronchodilating effect on bronchial asthma. Accordingly, to examine the anti-inflammatory effect of theophylline on asthma, especially its effect on eosinophil activation, a sustained-release theophylline preparation (Theolong) was administered (daily dose: 400 mg) to 18 patients with mild to moderate bronchial asthma. This was done in order to study the preparation's effects on lung function, blood and sputum eosinophils and ECP four weeks pre- and post-administration. Lung function was determined by spirometry and sputum by induced sputum. Blood and sputum ECP levels were determined using an ECP RIA kit. In lung function, there were no differences in vital capacity (VC) or in forced expiratory volume 1 s (FEV 1.0) pre- and post-administration. There were also no differences in the number of blood and sputum eosinophils, but serum and sputum ECP levels decreased. Theophylline is thus expected to exert an inhibitory effect on eosinophil activation and it is suggested as an effective therapeutic drug for bronchial asthma.

Theophylline suppresses the release of interleukin-4 by peripheral blood mononuclear cells

To elucidate the mechanism of the anti-inflammatory effect of theophylline, peripheral blood mononuclear cells (PBMCs) collected from patients with bronchial asthma who had a RAST score for Dermatophagoides farinae (Df) > = 3 were stimulated with Df antigen, and the interleukin-4 (IL-4) production by the stimulated PBMCs was determined in the presence and absence of theophylline. The stimulated IL-4 production in the PBMCs was significantly suppressed by simultaneous treatment with theophylline (8 microg/ml). Furthermore, the intracellular 3',5'-adenosine monophosphate (cAMP) level following stimulation with Df was significantly higher in PBMCs simultaneously treated with theophylline (8 microg/ml) than in nontreated controls. These results suggest that theophylline suppresses the IL-4 production in inflammatory cells by increasing the intracellular cAMP level; this effect may thus provide an additional basis for the benefit of theophylline in antiasthmatic therapy.

Evaluation of a cytokine combination including thrombopoietin for improved transduction of a retroviral gene into G-CSF-mobilized CD34+ human blood cells

We examined cell culture conditions with various combinations of cytokines including thrombopoietin (TPO) to obtain the most efficient transduction of recombinant retrovirus vectors into G-CSF-mobilized blood CD34+ cells which were obtained from children and purified with an Isolex 50 system (Baxter; Deerfield, IL). Three different 4-day culture conditions for the stimulation of CD34+ cells were compared in terms of a cell-cycle analysis by fluorometry and gene transduction efficiency as determined by resistance to G418 and NeoR polymerase chain reaction (PCR) for individual colony-forming unit-granulocyte/macrophage (CFU-GM) grown in a methylcellulose culture system. The cytokines tested were: A) interleukin (IL)-6 + stem cell factor (SCF); B) IL-3 + IL-6 + SCF, and C) IL-3 + IL-6 + SCF + TPO. Without a cell culture, the percentage of CD34+ cells in the cell cycle (the percentage of cells in phases S and G2/M) was 4.6%. After a four-day culture (n = 5), this value increased with the addition of IL-3 (22%) or IL-3 + TPO (27%, p < 0.05) as compared to that with the baseline cocktail of IL-6 + SCF (15%). The cell number uniformly increased approximately 10-fold in each culture condition. The average efficiency of gene transfer into incubated CD34+ cells with the corresponding combinations of cytokines was, respectively, 57%, 47%, and 30% for G418-screened CFU-GM and 72%, 68%, and 51% for polymerase chain reaction-positive CFU-GM. A statistically significant difference (p < 0.01) was found for G418/CFU-GM with IL-3 + IL-6 + SCF (57%) versus IL-3 + IL-6 + SCF + TPO (30%). Hence, it is likely that the increased cell proliferation produced by the addition of TPO was not necessarily translated into an increased rate of retroviral-mediated gene transduction, possibly because TPO preferentially induced the differentiation of stem cells into mature progenitors in these culture systems.

[Clinical features of eight cases of opportunistic fungal pneumonias]

We evaluated eight cases of pulmonary mycosis in immuno compromised hosts. The underlying diseases were lung cancer with chemotherapy in one case, post bone marrow transplantation (post BMT) in two cases, acquired immunodeficiency syndrome (AIDS) in one case and bronchial asthma with massive steroid therapy in four cases. The causative fungi were Candida sp. in three cases, Aspergillus sp. in four cases, Tricosporon sp. in one case. Prognosis was guarded despite antifungal treatment. Five cases deteriorated and died of fungal infection. In five cases, who died of deterioration, 31.6 days was required from appearance of abnormal infiltration in the chest X-ray to determination of the causative fungi (including two cases who were diagnosed by autopsy) on the average. In three successfully treated cases, the average duration from the appearance of abnormal infiltration in the chest X-ray for the determination of the causative fungi was 8.3 days. On the contrary, the average duration between the appearance of abnormal infiltration in the chest X-ray and the initiation of antifungal treatment was 2.6 days who died of deterioration and 8.3 days who survived. We conclude that early identification of causative fungi and not quick institution of antifungal treatment was mandatory in the treatment of opportunistic fungal pneumonia.

The inhibitory effect of TMK688, a novel anti-allergic drug having both 5-lipoxygenase inhibitory activity and anti-histamine activity, against bronchoconstriction, leukotriene production and inflammatory cell infiltration in sensitized guinea pigs

BACKGROUND

TMK688 is being developed as an anti-allergic drug having both 5-lipoxygenase inhibitory activity and anti-histamine activity.

METHOD

We compared the inhibition of the late asthmatic responses by TMK688 with that by other anti-allergic agents in actively sensitized guinea pigs, and examined the relationship between 5-lipoxygenase inhibition and the late asthmatic responses.

RESULTS

At 1-3.2 mg/kg, TMK688 inhibited the increases in respiratory resistance, leukotriene (LT) B4 and C4 production in the lungs and eosinophil infiltration into the alveoli during the late asthmatic response, whereas the effects tended to lessen at the dose of 10 mg/kg. These effects are thought to be caused by the 5-lipoxygenase inhibitory activity of TMK688 because Azelastine, an anti-allergic drug having potent antihistamine activity, exhibited no effect. ONO-1078, a peptide LT antagonist, inhibited the late-phase bronchoconstriction at a dose of 100 mg/kg p.o., but not the increase in the infiltration of inflammatory cells into the alveoli, suggesting that the late-phase bronchoconstriction is induced, in part, by peptide LTs, i.e. LT C4, D4 and E4 and that the inflammatory cell infiltration may be caused by LTB4. TMK688 inhibited the immediate bronchoconstriction dose-dependently, and the effect was significant at a dose of 10 mg/kg orally. Since Azelastine, Ketotifen and Oxatomide suppressed the bronchoconstriction at far lower doses than did TMK688, the inhibitory effect was mainly caused by its antihistamine activity.

CONCLUSIONS

TMK688 appears to be a novel anti-allergic drug having inhibitory effects on both the bronchoconstriction and the infiltration of inflammatory cells during late asthmatic responses.

[Function testing of bronchial responsiveness]

Asthma patients have bronchial hyperreactivity compared with normal subjects. The pathophysiological characteristics of bronchial asthma show the reversible bronchial obstruction (air-flow limitation) caused by several physical and chemical stimuli. Thus, it is important to verify the bronchial responsiveness for diagnosis of bronchial asthma. Function testing of bronchial responsiveness is one of the bronchial reactivity tests which is important for the diagnosis of bronchial asthma as well as the judgment of severity, therapeutic effect and the differential diagnosis. Function testing of bronchial responsiveness consists of 2 major parts : 1) standard method of acetylcholine or histamine inhalation test 2) direct-writing recorder of the dose-response curves of the airway to methacholine test (Astograph).

Bronchoalveolar lavage with trypsin in pulmonary alveolar proteinosis

Two cases of pulmonary alveolar proteinosis were treated with bronchoalveolar lavage (BAL) via a fibreoptic bronchoscope. Additional clinical improvement was seen when trypsin was added to the lavage fluid. Analysis of effluents in the BAL fluid showed marked reduction of protein constituents with clinical improvement after treatment with trypsin in the lavage. BAL with trypsin was well tolerated.

Assessment of serum CYFRA 21-1 in lung cancer

BACKGROUND

Cytokeratins are the intermediate filaments of the cytoskeletal protein located in normal epithelia, tumor, and cultured cells. Recently, a fragment of cytokeratin subunit 19, referred to as CYFRA 21-1, detected in the serum of patients with nonsmall cell lung cancer, has been reported as a new tumor marker. This article reports the results of a study of serum fragment CYFRA 21-1, measured by immunoradiometric assay, as a marker of lung cancer.

METHODS

One hundred fourteen patients with primary lung cancer, 6 patients with malignant solid tumor, 116 patients with a variety of benign diseases, and 29 normal individuals were entered into the study. Serum CYFRA 21-1 levels were obtained by means of immunoradiometric assay using the CYFRA 21-1 EIA (enzyme immunoassay) kit. In addition, we studied other tumor markers, including carcinoembryonic antigen (CEA), squamous cell carcinoma antigen (SCC), and neuron specific enolase (NSE), as a means of lung cancer diagnosis.

RESULTS

The diagnostic accuracy and sensitivity of serum CYFRA 21-1 for the detection of lung cancer were highest among the four markers. The serum CYFRA 21-1 levels were most highly elevated in lung carcinoma patients (in particular UICC Stage IV patients) across different histologic types and attained 85.1% sensitivity when using a threshold of 3.5 ng/mL. The diagnostic sensitivity for detecting lung carcinoma was substantially enhanced by means of combined assays of CYFRA 21-1 with CEA overall for lung cancer, with SCC for squamous cell carcinoma, and with CEA for adenocarcinoma.

CONCLUSIONS

These findings suggest that serum assays of CYFRA 21-1 are clinically useful for the diagnosis of lung carcinoma.

[Persistent reactive airway dysfunction syndrome after exposure to chromate]

A 42-year-old man was admitted to the hospital because of wheezing and dyspnea that began 20 minutes after accidental exposure to irritant gas containing chromate at a chrome pellet manufacturing plant. The patient had a positive skin reaction to chromite (Cr2O3). Reduction of FEV1.0 was observed 120 minutes after Cr2O3 inhalation challenge. By 150 minutes after Cr2O3 inhalation, FEV1.0 had decreased by 32%. Chest X-ray film revealed no abnormalities. Histological findings of the lung tissue obtained by open lung biopsy revealed bronchospasm and peri-bronchial inflammatory cell infiltration without bronchiolar obstruction, and thus bronchiolitis obliterans was ruled out. This patient fulfilled the criteria of reactive airway dysfunction syndrome (RADS) proposed by Brooks; onset of symptoms very soon after a single exposure to an irritant, persistence of asthmatic symptoms, obstructive pulmonary dysfunction, and the presence of airway hyperreactivity to methacholine. During the initial hospital stay, asthmatic symptoms were relieved by intensive anti-asthmatic treatment including oral and parenteral corticosteroids. However, the patient's asthmatic symptoms have lasted for eight years and necessitate the use of systemic steroids, and regular use of inhaled steroids and bronchodilators. We know of no previous reported case of RADS after chromate exposure.

[Scimitar syndrome with diagnostic MRI findings]

A fifty-year-old woman was admitted to our hospital because of an abnormal shadow on a chest X-ray film. She was asymptomatic. Chest X-ray film showed a scimitar-like vessel in the right lung, dextroposition of the heart, and hypoplasia of the right pulmonary artery. MRI revealed that the scimitar vein was anomalous pulmonary venous return from the right lung. Normal venous return from the right lower lobe to the left atrium was confirmed by pulmonary artery angiography. MRI findings have been useful in the diagnosis of scimitar syndrome.

[Effect of inhaled steroid on bone metabolism in the treatment of bronchial asthma]

In order to clarify the effects of longterm inhaled steroid therapy on bone metabolism, we examined 72 patients with bronchial asthma treated mainly with BDP (beclomethasone dipropionate). Multiple scanning X-ray photodensitometry was used to evaluate the degree of bone mineral loss. Osteocalcin, alkaline phosphatase (total and type III) was measured as a marker of bone synthesis and urinary pyridinoline, and deoxy-pyridinoline was measured as a marker of bone resorption. There was age related bone mineral loss. Urinary pyridinoline increased with aging. Treatment related bone mineral loss was not observed either in cases treated with BDP or in cases treated with continual oral steroids. Urinary pyridinoline and deoxy-pyridinoline decreased in patients treated with larger doses of for longer periods with BDP. Serum osteocalcin levels were lower in patients on continual oral corticosteroids. We conclude that inhaled steroid do not deteriorate bone metabolism in patients with bronchial asthma, when used appropriately.

The effect of TYB-2285 on dual phase bronchoconstriction and airway hypersensitivity in guinea-pigs actively sensitized with ovalbumin

The effect of a new anti-asthmatic drug, TYB-2285 (3,5-bis(acetoxyacetylamino)-4-chlorobenzonitrile), was investigated in ovalbumin-sensitized guinea-pigs. When guinea-pigs were pretreated with TYB-2285 (300 mg kg-1, p.o., single dose or consecutively for 7 days), the immediate asthmatic response was inhibited as demonstrated by diminished cyanosis, but not the bronchoconstriction. TYB-2285, given singly or consecutively, inhibited the appearance of late asthmatic response and the infiltration of inflammatory cells, such as eosinophils, into the airway. Additionally, airway hyper-responsiveness was also reversed by the single administration of TYB-2285. Luminol-dependent chemiluminescence of airway-infiltrated cells stimulated with A23187 was inhibited by TYB-2285 in a dose-dependent manner. The present study suggests that TYB-2285 inhibits late asthmatic response and airway hyperresponsiveness by inhibiting the accumulation of eosinophils and other inflammatory cells into the airway, and also by inhibiting the production of oxygen radicals from airway-infiltrated cells.