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To investigate the role of interleukin-5 (IL-5) on airway hyperreactivity and pulmonary inflammation in nonhuman primate airways, the effect of a neutralizing monoclonal antibody to murine IL-5 (TRFK-5) was investigated in a cynomolgus monkey model of allergic asthma. Anesthetized Ascaris-sensitive monkeys underwent bronchoalveolar lavage (BAL) to assess the granulocyte content of this fluid before and 24 h after aerosolized Ascaris suum extract inhalation. Airway reactivity was assessed by the concentration of inhaled histamine required to produce a 40% reduction in dynamic lung compliance (Cdyn40). Exposure to A. suum extract produced an increase in airway reactivity (Cdyn40 = 0.065 +/- 0.024% before Ascaris; Cdyn40 = 0.014 +/- 0.004% after Ascaris) and an inflammatory reaction in the airways characterized by an increase in BAL eosinophils (0.05 +/- 0.03 x 10(3) cells/ml before Ascaris; 176 +/- 76 x 10(3) cells/ml after Ascaris) and neutrophils (3 +/- 1 x 10(3) cells/ml before Ascaris; 406 +/- 211 x 10(3) cells/ml after Ascaris). In contrast, only small nonsignificant changes in airway reactivity and granulocyte influx into the BAL occurred after aerosolized saline as a sham challenge. When the monkeys were treated 1 h before Ascaris challenge with the TRFK-5 antibody (0.3 mg/kg, intravenously), there was no increase in airway reactivity after Ascaris challenge (Cdyn40 = 0.032 +/- 0.016% before Ascaris; Cdyn40 = 0.217 +/- 0.196% after Ascaris) and there were only small increases in the number of eosinophils and neutrophils in the BAL after Ascaris challenge. The inhibition of this pulmonary eosinophilia and bronchial hyperresponsiveness by TRFK-5 was seen for up to 3 mo after treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulmonary inflammation with eosinophil (EOs) infiltration is a prominent feature of allergic respiratory diseases such as asthma. In order to study the cellular response during the disease development, an animal model of IgE-mediated pulmonary inflammation with characteristic eosinophilia is needed. We developed a method for inducing severe pulmonary eosinophilia in the mouse and also studied the numbers of EOs in blood and bone marrow and the response to corticosteroid treatment. Animals were sensitized with alum-precipitated ovalbumin (OVA) and challenged with aerosolized OVA 12 days later when serum IgE levels were significantly elevated. Four to eight hours after challenge there were moderate increases in the number of EOs in the bone marrow and peripheral blood, but only a few EOs were observed in the lung tissue and in bronchoalveolar lavage (BAL) fluid. Twenty-four hours after challenge, there was a marked reduction of EOs in bone marrow, while the number of EOs peaked in the perivascular and peribronchial regions of the lung. Forty-eight hours after challenge, the highest number of EOs was found in the BAL fluid, making up80% of all cells in that compartment. The high levels of EOs in the lung tissue and BAL fluid lasted for 2-3 days and was followed by a more moderate but persistent eosinophilia for another 10 days. Nonsensitized animals showed no significant changes in the number of EOs in BAL fluid, lungs, blood or bone marrow. Histopathological evaluation also revealed epithelial damage, excessive mucus in the lumen and edema in the submucosa of the airways.(ABSTRACT TRUNCATED AT 250 WORDS)

Interleukin-5 (IL-5) is important in the control of differentiation, migration, and activation of eosinophils. In order to study the role of IL-5 in the development of eosinophilic inflammation of the airways, we have used a monoclonal antibody to murine IL-5 (TRFK-5) in a murine model of allergic pulmonary inflammation. B6D2F1 mice were sensitized with alum-precipitated ovalbumin and were challenged with aerosolized ovalbumin on day 12 after sensitization. Samples of bronchoalveolar lavage (BAL) fluid, lung tissue, blood, and bone marrow aspirate were collected at different times after ovalbumin challenge. Twenty-four hours after challenge there were significant increases in the number of eosinophils in the BAL fluid, lung tissue, and blood while bone marrow eosinophils were decreased. Treatment of sensitized mice with TRFK-5 (0.01-1 mg/kg, i.p.) 2 h before ovalbumin challenge reduced the numbers of eosinophils in the BAL fluid and lung tissue and prevented the decrease in bone marrow eosinophils in a dose-dependent fashion. The number of eosinophils in the BAL fluid, peribronchial and alveolar regions of the lung was also reduced when TRFK-5 (2 mg/kg, i.p.) was given up to 5 d after ovalbumin challenge. Furthermore, there was no evidence of increased epithelial damage, edema, or the presence of mucus that could have resulted from eosinophil apoptosis and release of toxic proteins after neutralization of IL-5. These results demonstrate an important role for IL-5 in the development of eosinophilic inflammation of the airways and for the migration of eosinophils from the bone marrow into blood in response to antigen challenge.(ABSTRACT TRUNCATED AT 250 WORDS)

We examined the role of endothelium-derived nitric oxide during antigen-induced contraction in pulmonary arteries isolated from actively sensitized guinea pigs. Ovalbumin (10(-2) mg/ml)-induced contraction was not sustained, and tension returned to baseline within 15 min. Pretreatment with methylene blue (10(-5) M) increased both the amplitude and the duration of the contractile response in these tissues. At 15 min, tension remained elevated and was > 70% of the peak amplitude. Removal of the endothelium with saponin (200 micrograms/ml) increased the magnitude of the contraction by > 125%; however, the duration of the response was unaffected. After pretreatment with saponin, methylene blue no longer increased the amplitude of antigen-induced contraction but its effect on the duration was unchanged. Pretreatment with nitro-L-arginine methyl ester significantly increased the magnitude of the contraction in each of the tissues. These results suggest that the response of guinea pig pulmonary arteries to antigen is modulated by two types of endogenous vasodilators, endothelium-derived nitric oxide that inhibits the initial phase of the response and an endothelium-independent relaxing factor that is guanosine 3′,5′-cyclic monophosphate dependent and attenuates the duration of anaphylactic contraction.

To maximize deposition of an aerosolized dose of insulin (mean +/- SD = 0.99 +/- 0.06 U/kg of body weight) in the lungs of subjects with non-insulin-dependent diabetes mellitus (NIDDM), and investigate its efficacy in normalizing plasma glucose levels during the fasting state.Nonrandomized, placebo-controlled trial.A primary care facility.Six nonobese, nonsmoking volunteers with NIDDM. No subjects withdrew from the study.Aerosolized insulin was administered by oral inhalation after a 12-hour period of fasting. Aerosol was generated by a raindrop nebulizer from regular 500 U/mL pork insulin. During inhalation, inspiratory flow was regulated at 17 L/min. Plasma samples were collected after inhalation and analyzed for insulin and glucose levels.Plasma insulin and glucose levels.Deposition of the aerosol was maximized within the lungs, with 79% +/- 17% of the inhaled dose depositing below the larynx. Geometric mean fasting plasma insulin level was 71 pmol/L (11.8 microU/mL), rising to 269 pmol/L (44.8 microU/mL) after insulin inhalation. Average time to peak insulin level was 40 +/- 34 minutes. The mean fasting plasma glucose level (12.63 +/- 2.59 mmol/L [225.5 +/- 46.3 mg/dL]) was reduced to within the normal range in five subjects and was almost normal in the sixth subject (5.52 +/- 0.89 mmol/L [98.6 +/- 15.9 mg/dL]). Average maximum decrease in plasma glucose from baseline was 55% +/- 10% (n = 6) vs 13% +/- 9% after placebo aerosol inhalation (n = 3). No side effects were reported following insulin or placebo aerosol inhalation.These preliminary results indicate that a dose of approximately 1.0 U of aerosolized insulin per kilogram of body weight, delivered by oral inhalation and deposited predominantly within the lungs, is well tolerated and can effectively normalize plasma glucose levels in patients with NIDDM.

We characterized the kinetics of and determined the mediators involved in antigen-induced contraction of pulmonary arteries (PA) and lung parenchyma isolated from actively sensitized guinea pigs. Ovalbumin (10(-2) mg/ml) induced contractions of PA rings, which reached maximum amplitude by 2 min and decayed to 50% of maximum by 4–6 min. Pyrilamine (10(-6) M) delayed the onset of contraction and decreased the peak of the response by > 50%. Metiamide (10(-4) M) partially reversed this effect. The addition of indomethacin (10(-6) M) to the combination of pyrilamine and metiamide had no significant effect. The further addition of the leukotriene (LT) D4/LTE4 receptor antagonist SKF 104353 (10(-5) M) reduced the contraction by > 80%. The maximum amplitude of antigen-induced contraction of parenchymal strips was reached by 15 min and was sustained for > 60 min. In these tissues, SKF 104353 inhibited the contraction by approximately 35%, but the histamine receptor antagonists and indomethacin had no significant effect. These results suggest that both histamine and sulfidopeptide LTs mediate antigen-induced contraction of PA, whereas sulfidopeptide LTs, but not histamine, are involved in the parenchymal response.

While pharmacotherapy is often necessary to effectively treat depression, many depressed patients do not fully respond to, or will not cooperate with, medication trials. Nonpharmacologic interventions such as patient and family education, self-help efforts, cognitive therapy, family involvement and behavioral scheduling may, in various combinations, provide either primary or adjunctive treatment for mild to moderate depression. Family physicians can adapt these techniques to the primary care setting. Recent changes in the economic climate as it affects the availability of psychiatric care have magnified the role of primary care physicians in the treatment of depression.

To determine whether hypoxic pulmonary vasoconstriction was associated with release of sulfidopeptide leukotrienes (SPLTs) from the lung, we measured SPLT activity by bioassay (guinea pig ileum) and radioimmunoassay in lymph, perfusate, and bronchoalveolar lavage (BAL) fluid from sheep lungs (n = 20) isolated and perfused in situ with a constant flow of autologous blood (100 ml.kg-1.min-1) containing indomethacin (60 micrograms/ml). The protocol consisted of three periods, each at least 1 h in duration. In experimental lungs, inspired O2 concentration (FIO2) was 28.2% in periods 1 and 3 and 4.2% in period 2. In control lungs, FIO2 was 28.2% throughout. Hypoxia increased pulmonary arterial pressure but did not alter peak tracheal pressure, lung lymph flow, or weight gain measured during the last 30 min of each period. SPLT activity was greatest in lung lymph and least in BAL fluid. Hypoxia did not alter SPLT activity in any fluid. Similar results were obtained in lungs not treated with indomethacin (n = 15). These data do not support the hypothesis that hypoxic pulmonary vasoconstriction is mediated by SPLTs.

We studied the effect of indomethacin on immunologic mediator release from human bronchial tissue (n = 6) and lung parenchyma (n = 7). Tissues were obtained from surgical specimens, minced, passively sensitized, and challenged with antigen E or anti-IgE in the presence or absence of indomethacin. At maximal levels of immunologic stimulation with either antigen or anti-IgE, the bronchial and parenchymal tissues released approximately 5 and 20% of total histamine (net), respectively, and approximately 3.5 and 45 ng/g of immunoreactive sulfidopeptide leukotriene, respectively. Analysis by high performance liquid chromatography followed by radioimmunoassay revealed that the airway supernatants contained LTD4 and LTE4, whereas the lung parenchymal samples contained predominantly LTE4. Little or no LTC4 was detected in either airway or parenchymal samples. Incubation with indomethacin (5 x 10(-6) M) resulted in approximately a 3-fold increase in antigen or anti-IgE-induced release of leukotrienes from the bronchial tissue. Indomethacin also enhanced antigen-induced histamine release approximately 2-fold but had no effect on anti-IgE-induced histamine release from this tissue. In contrast, indomethacin had no effect on antigen or anti-IgE-induced histamine or leukotriene release from the lung parenchymal tissue at any level of immunologic stimulation. These results support the hypothesis that indomethacin enhances human anaphylactic bronchospasm in vitro through an increase in mediator release from bronchial mast cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Purified human lung mast cells released histamine, leukotrienes, prostaglandin (PG) D2, thromboxane B2 (TxB2), and PGF2 alpha in response to anti-IgE stimulation. Incubation of the cells for 24 h with 10(-6) M dexamethasone, a treatment that inhibits mediator release from human basophils, had no effect on the release of these mediators from mast cells. Dexamethasone treatment of human lung fragments led to little or no inhibition of anti-IgE-induced release of the mast cell-derived mediator, histamine, but produced a significant inhibition of the release of PGE2, PGF2 alpha, and 6-keto-PGF1 alpha. As was the case with purified mast cells, the steroid did not inhibit the release of PGD2 or TxB2 from human lung fragments. Comparison of the quantities of PGD2 and TxB2 produced by purified cells and human lung fragments reveals that the mast cells produce quantities of these metabolites sufficient to account for the entire amount produced by challenged lung fragments. Dexamethasone inhibited spontaneous release from lung fragments of all cyclooxygenase products measured. These results suggest that the human lung parenchymal mast cell phospholipase is not inhibited by dexamethasone, whereas other phospholipase(s) in the lung are inhibited by the steroid. These results may be useful in explaining the resistance of acute allergic reactions, including anaphylaxis, to steroids, despite the potent antiinflammatory activity of steroids on subacute and chronic inflammation, such as in bronchial asthma, which may be initiated by IgE-dependent mechanisms.

Inhaling cold, dry air nasally induces in some persons symptoms of rhinitis that are associated with an increase in the level of mast-cell-associated mediators in nasal lavages. The present study, directed at understanding the mechanism of this reaction, showed that 9 subjects who displayed symptoms and inflammatory mediator release had significant (p less than 0.01) increments in nasal fluid osmolality, whereas the osmolality of the fluids of 6 subjects unaffected by cold, dry air challenge did not differ from baseline. Significant correlations were found between the mediator concentration and the osmolality of recovered nasal lavages (rs = 0.617, p less than 0.02; rs = 0.679, p less than 0.01 for histamine and TAME-esterase(s), respectively). No changes in the osmolality of nasal secretions were found in atopic subjects undergoing nasal challenge with antigen, despite the generation of symptoms and significant elevations in the levels of inflammatory mediators in their nasal lavages. Because increasing the osmolality of the medium surrounding isolated mast cells in vitro triggers mediator secretion, these observations support the concept that the response to cold, dry air nasal inhalation is caused by the release of mediators secondary to an increase in the osmolality of the mucosal secretions.

We studied the effects of repeated exposures of antigen on airway reactivity to mediators of anaphylaxis and immediate response to the antigen. Seven antigen-sensitive sheep were exposed to aerosols of Ascaris suum antigen 5 times biweekly; a control group of seven sheep underwent the same exposure regimen with saline vehicle. Sheep were assigned to experimental (Ascaris) or control groups so the distribution of animals with regard to bronchial reactivity to mediators was about the same. Airway reactivity was assessed by determining the effects of aerosolized histamine (10–1,000 micrograms), prostaglandin F2 alpha (PGF2 alpha, 10–300 micrograms), and a stable analogue of thromboxane A2 (U-46619, 1–100 micrograms) on lung resistance (RL) and dynamic lung compliance (Cdyn). Before treatment, experimental and control groups showed similar changes in RL and Cdyn, with analogue greater than histamine greater than PGF2 alpha. At the highest dose of each agonist, mean increases in RL were 50, 123, and 29%, respectively, and mean decreases in Cdyn were 21, 45, and 12%. During the first 15-min exposures to antigen aerosol, mean RL had increased by 125% and Cdyn decreased by 38% of base-line values; hyperinflation following the exposures reduced the changes to 56 and 31%, respectively. Changes in RL and Cdyn during the final antigen exposures and following postexposure hyperinflation were reduced significantly (P less than 0.05) compared with the initial exposures. Baseline RL and Cdyn before and after the exposures to antigen or saline were not significantly different. Airway reactivity to histamine, PGF2 alpha, or analogue was not significantly altered in these atropinized animals over the range of doses studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Tracheobronchial secretions (TBS) were collected in situ from intact, anesthetized dogs, and the protein composition and distribution were studied. TBS were separated into supernatant and pellet phases by centrifugation. The supernatant phase comprised 85%, by weight, of the secretory mixture; yet it contained only 58% of the total protein. Peptides of apparent molecular weights ranging from 16,000 to 154,000 daltons were present in the supernatant phase. Electrophoretic and immunochemical comparisons with canine serum suggested that certain of the peptides were of plasma origin including albumin, IgG, IgA, and IgM. Albumin and IgG comprised approximately 70% of the supernatant phase protein. Three percent of the total TBS protein was contributed by the peptide portion of mucous glycoproteins (mucins), and 97% of the mucin protein separated into the pellet phase. When compared to mucus collected from a canine tracheal pouch, TBS was less concentrated in mucins, and differences were observed in electrophoretic profiles between the two samples.

We have studied the effect of repeated in vivo antigen exposure on in vitro airway responsiveness in sensitized sheep. Fourteen sheep underwent five biweekly exposures to aerosolized Ascaris suum antigen or saline. Following this exposure regimen, the animals were killed and tracheal smooth muscle and lung parenchymal strips were prepared for in vitro studies of isometric contraction in response to histamine, methacholine, prostaglandin F2 alpha, and a thromboxane A2 analogue. No alteration in tracheal smooth muscle responsiveness was observed between saline- and antigen-exposed tissue. In contrast, by use of lung parenchymal strips as an index of peripheral airway responsiveness, significant increases in responsiveness to histamine and a thromboxane A2 analogue (10(-6) and 10(-5) M) were observed in antigen-exposed tissue compared with saline controls. These results demonstrate that repeated antigen exposure in vivo selectively increase the responsiveness of peripheral lung smooth muscle to certain chemical mediators of anaphylaxis.

It has long been known that explosives can be ignited by electric sparks. Compounds such as lead styphnate are particularly sensitive, and electric discharges, arely visible to the naked eye, are capable of igniting them. This is a source of azard in the manufacture and handling of those primary explosives used as itiatory materials, and there is an extensive literature on methods of measurement and on experimental values of the minimum ignition energy of these materials Langevin & Bicquard 1934; Brown, Kusler & Gibson 1946; Morris 1947, 1953; Lathsburg & Schmitz 1949). A review of the literature followed by some experimental determinations, showed that widely varying values of ignition energy ould be obtained for the same substance by using different experimental test methods and conditions. A systematic investigation of this problem by Wyatt, Moore and Sumner at the Explosive Research and Development Establishment, Waltham Abbey, has revealed a number of factors which influence the ignition energy and this paper presents a brief summary of some aspects of their work. There are two types of test apparatus commonly used to measure the ease of ignition of initiator materials by electric sparks; first, a fixed-gap method in which e voltage is applied across two electrodes, one of which is covered by the material sted, the voltage being sufficient to break down the gap and cause a spark to ass; second, an approaching-electrode method in which the gap is initially too ide for a discharge to take place with the voltage applied, but a spark is produced moving one electrode towards the other. The energy dissipated in the discharge varied by changing the applied voltage or the capacity of the condenser used to ore the electrical energy.

Two methods of producing sparks of high brightness and short duration at high repetition frequencies are described. The circuits used are simplified versions of standard radar techniques and moderate voltages (5-10 kV), and standard components are used. The first method gives a limited number of discharges (four to eight) at individually determined time intervals of ten microsecond or greater with an error of less than one microsecond, and is intended for the production of superimposed photographs on a stationary film. The second method, used with a rotating drum or mirror camera, gives a greater number of light pulses at preset repetition frequencies up to 10 000 per sec. The energy of each spark is of the order of 1 joule, and the effective photographic duration less than 1 μsec. Adequate negative densities are obtained on process type emulsions at distances not greater than 1 metre. The elementary principles underlying the methods are briefly discussed and suggestions are made for increasing the flash energy and repetition frequency.

Airway secretions were collected from the upper trachea of eight healthy nosebreathing mongrel dogs under general anesthesia, and the electrolytes and osmolality of these secretions were determined. Compared to plasma, secretions contained 15% higher Na+ and 33% higher Cl-, were 18% higher in osmolality, but had a lower Na+/Cl- throughout the 6-h experiments. When six nose-breathing dogs were exposed to air at 28.5 degrees C and 95% relative humidity, secretion osmolality became lower, but Na+/Cl- remained unchanged. In four other dogs, secretions approached the osmolality of plasma when inspired air was at 36.4 degrees C and 100% relative humidity. These secretions contained 22% higher Cl- and a lower Na+/Cl- than plasma. The differences between airway secretions and interstitial fluid suggest that secretions are formed by active Cl- transport. In another four dogs, secretion osmolality was higher with mouth breathing than breathing through the nose. Inasmuch as humidified and warmed air lowered and mouth breathing raised the osmolality of airway secretions, we postulate that the hyperosmolality of secretions results from water loss from the airway surface during conditioning of inspired air.

Atopic disease in humans results primarily from the activity of tissue mast cells and circulating basophils. These two very similar cell types have recently been purified to near homogeneity and studies have begun to identify the biochemical mechanisms of mediator release, to explore the effects of pharmacologic manipulation of the response, and to determine unambiguously which mediators are derived from mast cells and basophils. This report will review studies examining various parameters of histamine release, the role of cyclic AMP in histamine release, and the production of arachidonic acid metabolites and their pharmacologic modulation.

A technique is described for the collection of tracheobronchial secretions from the upper trachea of anesthetized dogs. The method is simple, relatively quantitative, and provides secretory material in quantity suitable for biochemical or rheological studies. In 42 experiments comprising 184 individual samples we have found the collection rate of tracheobronchial secretions to be 1.0 ± 0.1 mg/min per kg (mean ± SEM). airway mucus; trachea; anesthetized dogs Submitted on June 11, 1975

These studies examined the ability of electrical field stimulation (EFS) to influence antigen-induced responses in the guinea pig isolated trachea and main-stem bronchi. Airways isolated from guinea pigs actively sensitized to ovalbumin were superfused and stimulated transmurally with square pulses of 1 msec duration at a frequency of 16 pulses per sec. In the trachea, EFS caused an atropine-sensitive contraction followed by a maintained relaxation. The relaxation consisted of adrenergic and nonadrenergic components. In the bronchus, EFS caused a maintained contraction. This contraction was due to a combination of cholinergic (atropine-sensitive) and noncholinergic (capsaicin-sensitive) mechanisms. Histamine could not be detected in superfusate samples during electrical stimulation alone of either the trachea or bronchus. EFS significantly inhibited ovalbumin-induced tracheal contractions by about 30% without altering ovalbumin-induced histamine or immunoreactive peptido-leukotriene release from the tissues. EFS had a similar inhibitory effect on the contraction induced by application of exogenous histamine (10(-5) M). The electrical stimulus-induced inhibition of the antigen-induced contraction was abolished by tetrodotoxin and propranolol and reduced by a combination of atropine, propranolol and phentolamine. Norepinephrine (5 x 10(-6) M) inhibited ovalbumin-induced histamine release by about 30% without altering the contraction. Carbamylcholine had no effect on ovalbumin-induced histamine release. In the guinea pig bronchus, EFS stimulation had no effect on either histamine release or contraction induced by ovalbumin. These results demonstrate that in the guinea pig trachea nerve stimulation can significantly antagonize antigen-induced contractions and suggest that this is due to a functional antagonism by adrenergic and nonadrenergic relaxant neurotransmitters at the level of the airway smooth muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

We characterized homogeneity of bronchopulmonary distribution of a 0.9% saline aerosol with a mass median aerodynamic diameter (MMAD) of 1.12 micron (sigma g = 2.04) labeled with [99mTc]sulfur colloid in nine normal subjects and nine patients with asthma. Aerosol distribution was quantified from frequency distribution histograms generated from Anger camera scans. Skew (a measure of histogram asymmetry) and kurtosis (a measure of histogram range) were significantly elevated (p less than 0.05) in the asthma patients with 0.68 +/- 0.30 and 2.62 +/- 0.81, respectively, compared with 0.39 +/- 0.12 and 1.89 +/- 0.18, respectively, in the normal subjects. Skew and kurtosis were significantly correlated with baseline forced expiratory volume in 1 sec (FEV1, an index of airway obstruction) with rs = -0.4799 (p less than 0.05) and -0.5929 (p less than 0.01), respectively. Skew and kurtosis were also significantly correlated with mucociliary clearance after approximately 90 min (an index of large, central airway deposition) with rs = 0.6801 and 0.6373, respectively (p less than 0.01). This simplified method of analysis does not require additional study days or procedures and facilitates the detection of airflow obstruction in asthma.

Although mediator release from mast cells and basophils plays a central role in the pathogenesis of human allergic disease, biochemical studies have been restricted to rat peritoneal mast cells and basophilic leukemia cells because they could be easily purified. We have used two new techniques of cell separation to purify human lung mast cells to 98% homogeneity. Lung cell suspensions were obtained by dispersion of chopped lung tissue with proteolytic enzymes. Mast cells were then purified from the suspensions by countercurrent centrifugal elutriation and affinity chromatography. The purified mast cells released both histamine and slow-reacting substance of anaphylaxis (SRS-A) (leukotriene C and D) during stimulation with goat anti-human IgE antibody. Moreover, these preparations were able to generate significant quantities of SRS-A (32 +/- 7 x 10(-17) LTD mole-equivalents/mast cell) at all stages of purification, indicating that a secondary cell is not necessary for the antigen-induced release of SRS.

The crosslinking of cell surface IgE molecules on basophils and mast cells by a specific antigen to which an individual has been sensitized leads to cell activation, eventually culminating in the release of potent inflammatory mediators. Included among these mediators are products of arachidonic acid derived by lipoxygenation. This report describes the production of lipoxygenase products by purified preparations of human basophils and pulmonary mast cells and the possible role of lipoxygenase products in the mechanism of release and in the modulation of the release process in these cells.

We studied the effect of bronchial obstruction on central airway deposition of a 0.9% saline aerosol (MMAD = 1.12 micron; sigma g = 2.04) labeled with 99mTc sulfur colloid. Radioaerosol was inhaled on 2 occasions by 8 patients with asthma. The degree of bronchial obstruction at the time of radioaerosol inhalation was measured by the FEV1. Mucociliary clearance of the radioaerosol was used as an index of regional aerosol distribution, because clearance from the densely ciliated central airways occurs more rapidly than from the peripheral, nonciliated regions of the lung. Using the Weibel lung model and an average mucociliary clearance rate of 1 mm/min, we determined that clearance of the radioaerosol from lung generations 1 to 5 (central airways) would be complete within approximately 90 min. Central airway deposition was therefore quantified as radioaerosol clearance in 97 min using a gamma camera. On Days 1 and 2, clearance ranged from 0 to 45% and from 0 to 17%, respectively; FEV1 as a percent of predicted FEV1 ranged from 36 to 88 on Day 1, and on Day 2 from 54 to 92. Radioaerosol clearance was inversely correlated with the baseline FEV1, with r = -0.7673 (linear regression analysis; p less than 0.05). These data suggest that the magnitude of bronchial obstruction is a determinant of aerosol distribution within the lung of patients with asthma and that increased bronchial obstruction enhances central airway deposition of inhaled particles.

Exposure of sensitized guinea pig tracheal rings or human bronchial strips to specific antigen in vitro resulted in a rapidly developing, prolonged contraction that was resistant to washing. Treatment of the tissue with diphenhydramine, a histamine H1 antagonist, before antigen delayed the onset and decreased the amplitude of the initial phase of the contraction but did not reduce the duration. Diphenhydramine treatment after development of the contraction did not relax the airway tissue. Antigen-induced histamine release from guinea pig trachea and from human bronchus was complete within the initial 15% of the duration of the contraction. Treatment of sensitized airway tissue with FPL 55712, a SRS-A antagonist, before antigen selectively inhibited the prolonged phase of the response. FPL 55712 administration after the development of antigen-induced contraction resulted in relaxation. These data suggest that both histamine and SRS-A are involved in the response of sensitized guinea pig and human airway tissue to antigen, with histamine mediating the early phase of the contraction and SRS-A primarily mediating the protracted phase.

We studied the effect of indomethacin, an inhibitor of the cyclooxygenase pathway of arachidonic acid metabolism, on antigen-induced contraction of passively sensitized human bronchus in vitro. Incubation with indomethacin (3 microM) prior to antigen challenge produced significant enhancement of both the early (histamine-dependent) and late (SRS-A-dependent) phases of the contraction. Indomethacin potentiated anaphylactic histamine release from the bronchial tissue by approximately twofold but had no significant effect on basal tone or responsiveness to exogenous histamine. These data suggest that inhibition of the cyclooxygenase pathway results in potentiation of antigen-induced constriction of human bronchus principally through enhanced release of anaphylactic mediators from airway mast cells.

We examined the effect of removal of the epithelium on antigen-induced smooth muscle contraction and the release of mediators of inflammation from superfused, sensitized guinea-pig tracheal spirals in vitro. The epithelium was stripped from one-half of each trachea by mechanical means, and immunologic responses were evaluated by paired analysis. Removing the epithelium potentiated antigen-induced contraction, as reflected by a 5-fold leftward shift in the antigen dose-response curve, but the maximum response to antigen was not altered. This potentiation was not inhibited by pretreating the tissues with indomethacin (5 X 10(-6) M). At maximum concentrations of antigen removing the epithelium had no effect on the magnitude or kinetics of release of immunoreactive sulfidopeptide leukotrienes, prostaglandin (PG) D2, PGF2 alpha or thromboxane B2. Removing the epithelium did, however, significantly decrease the release of PGE and 6-keto-PGF1 alpha, a prostacyclin metabolite. Antigen-induced histamine release was enhanced by removing the epithelium; this effect varied inversely with antigen concentration. Selectively exposing either the luminal or serosal surface of an intact, superfused trachea to antigen resulted in the release of less than 5% of the total tissue histamine. Removing the epithelium from the intact trachea increased histamine release to approximately 25% following luminal but not serosal exposure to antigen. These studies demonstrate that the tracheal epithelium can act to inhibit antigen-induced airway contraction in vitro. This may in part reflect the role of the intact epithelium as a diffusion barrier which can limit the rate of influx of antigen molecules and thereby influence tissue mast cell activation.

A forced oscillations technique for measuring total respiratory system resistance was used to quantitate the bronchomotor activity of Sch 15280: (5[4-(N-methyl)-piperidylidine]5H-[1]-benzopyrano[2,3,b]-pyridine maleate) and to compare its potency to that of standard bronchodilator agents. By the intravenous route, Sch 15280 was 48 times more potent than aminophylline and 1/78 as potent as atropine in inhibiting methacholine-induced bronchoconstriction in rabbits. In cats Sch 15280 was 1/12 as potent as ephedrine in inhibiting histamine-induced bronchoconstriction and had a greater protective activity against histamine-induced bronchoconstriction and had a longer duration of action than 0.5% solution of isoproterenol. Statistical tests of parallelism revealed a significant difference between the log dose-response curves of Sch 15280 and ephedrine but not between those of Sch 15280, atropine and aminophylline. The results suggest that Sch 15280 can act via, a nonadrenergic mechanism to block both histaminergically and cholinergically mediated responses in the tracheobronchial tree. This pharmacologie profile may have important therapeutic application in the type I immediate hypersensitivity reactions of man.

A study was undertaken of the acute effect of the inhalation of ozone (1.0-1.5 ppm) on the concentration of proteins in the airway secretions harvested from the trachea of intact anesthetized dogs. Secretions were first collected during a control day during which room air was breathed. The dogs breathed ozone (1.0-1.5 ppm) on a second day. This protocol permitted each dog to serve as its own control. During the inhalation of ozone the concentration of total aqueous-soluble proteins, as well as of albumin and IgG were not significantly effected. However, when expressed as a percentage of total protein, both albumin and IgG were significantly enriched in the secretions. The quantitative changes of certain proteins in airway secretions may be an important reflection of the pulmonary response to ozone.

Functional interactions between several contractile agonists were examined in the guinea pig isolated trachea. Cumulative concentration-response effects of agonist A were obtained in the absence and presence of steady-state contractions induced by agonist B. The agonists examined included histamine, prostaglandin D2, platelet activating factor, leukotrienes E4 and D4 and carbamylcholine. We found that none of the agonists studied caused a leftward shift in the concentration-response curve of a second agonist, nor did any agonist decrease the concentration of a second agonist required to evoke a maximum response. In general the functional interactions fit the predictions based on the early models of functional additivity. However, the interactions deviated categorically from this model in that there was less than predicted additivity at concentrations of the interactants that alone induced greater than a 50% response. The degree to which this deviation occurred was agonist dependent. The results suggest that in the guinea pig trachea a contractile agonist does not uncover or increase a reserve in the receptor-subeffect-response chain of a second contractile agonist. The findings that the quantitative nature of the interactions were somewhat agonist dependent supports the hypothesis that more than one biochemical mechanism is involved in the receptor-mediated contraction of airway smooth muscle.

Treatment for 24 h in vitro with dexamethasone inhibited the antigen-induced contractile response in guinea pig tracheal rings and parenchymal strips without inhibiting the contractile response of the tissues to either methacholine or histamine, respectively. Antigen-induced histamine release was inhibited by approximately 50% in both tissues by prior treatment with dexamethasone. Dexamethasone treatment also inhibited the release of immunoreactive sulfidopeptide leukotriene from parenchymal strips. In tracheal rings, dexamethasone treatment reduced spontaneous release of all cyclooxygenase metabolites (PGE2, PGF2 alpha, TXB2, PGD2, and 6-k-PGF1 alpha were tested), with the exception of PGD2, and also inhibited the antigen-induced release of all cyclooxygenase metabolites studied. Dexamethasone-treatment did not inhibit the spontaneous release of cyclooxygenase metabolites in the guinea pig lung strips, and only modestly inhibited the antigen-induced release of PGE2, PGF2 alpha, and PGD2. The results suggest that the inhibition of contractile response of guinea pig lung strips and airway tissue to antigen by dexamethasone is the result of a reduced release of inflammatory mediators. The inhibition by dexamethasone of antigen-induced release of mast cell mediators from guinea pig lung parenchyma contrasts with results previously obtained with human parenchymal lung tissue.