Local generation of sulfidopeptide leukotrienes upon nasal provocation with cold, dry air

In order to assess whether sulfidopeptide leukotrienes are generated following nonimmunologic stimulation of inflammatory cells in vivo, 11 subjects complaining of symptoms of rhinitis when exposed to cold and dry environments were challenged by nasal breathing, first with warm, moist air and then with cold, dry air. Nasal lavages with normal saline were performed before and after each exposure. Immunoreactive leukotriene in the lavage fluids was significantly increased following cold, dry air exposure (2.6 ng/ml) compared with that after warm, moist air exposure (0.7 ng/ml) or at baseline (0.4 ng/ml) (p less than 0.01 in both instances). Six more subjects, denying cold-air sensitivity, were subjected to the same protocol and had no mediator and symptom score changes after cold, dry air challenge. Leukotriene changes after cold, dry air were highly concordant with increments in histamine, prostaglandin D2,N-alpha-tosyl-L-arginine methyl ester (TAME) esterase(s) activity and symptom scores (p less than 0.001). Separation of leukotrienes by high performance liquid chromatography in the nasal washes of 3 subjects showed variable amounts of LTC4, D4, and E4, suggesting metabolism of the former to the latter 2. To our knowledge, this is the first in vivo demonstration of leukotriene production in response to a physical stimulus, and it suggests a possible role of these and other inflammatory mediators in pathologic conditions, such as exercise-induced asthma, that involve physical causative factors.

Effects of the calcium channel blocker, verapamil, on asthmatic airway responses to muscarinic, histaminergic, and allergenic stimuli

The effect of calcium channel blocking agents on bronchomotor tone and airway responsiveness to inhaled provocative stimuli remains controversial. In this study we examined the effects of verapamil (a papaverine derivative) on baseline airway function as well as the response to methacholine, histamine, and ragweed allergen. Verapamil was chosen because of its aqueous solubility and hence suitability for aerosol administration in higher doses than previously given. The effects of 5 mg and 12.5 mg aerosolized verapamil doses were compared with placebo as separate parts of the same study in subjects with ragweed-allergic asthma. Neither dose of verapamil was found to produce bronchodilatation within 30 min after aerosol administration. At the 12.5 mg dose, however, we observed mild to moderate bronchospasm occurring within 5 min of administration, with a return toward baseline within 30 to 40 min. This bronchoconstrictor effect was unrelated to the low osmolarity of the drug solution (33 mosmol/L). Responses to methacholine, histamine, and ragweed allergen were unaltered by drug pretreatment at the 5-mg dose. At the 12.5-mg dose, however, we found significant inhibition of methacholine responsiveness but no effect on histamine or allergen responses. From these studies we conclude that verapamil can influence airway function by modulating agonist-induced bronchoconstriction. The selectivity of this inhibitory effect on muscarinic responses alone, however, leaves questionable the importance of this activity with regard to its clinical implications.

The effect of bronchial obstruction on central airway deposition of a saline aerosol in patients with asthma

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.

Identification of histamine releasing factor(s) in the late phase of cutaneous IgE-mediated reactions

We have shown that fluids collected from antigen-challenged skin blisters during the late phase reaction cause the release of substantial amounts of histamine (means = 42%, n = 14) from human basophils in vitro. Control fluids collected either during the immediate phase or from an unchallenged blister released less than or equal to 10% histamine from both basophils and lung mast cells. Late phase blister fluids induced low levels of histamine release from human lung cells (means = 11%, n = 4) that were slightly but not significantly greater than levels induced by control blister fluids. The characteristics of basophil release were similar to IgE-mediated stimuli in dose dependence, calcium and temperature requirements, and kinetics. The IgE dependence of the late phase blister fluid was demonstrated by desensitization of the basophils to anti-IgE, which obviated the response to anti-IgE and blister fluid but did not affect a non-IgE-mediated stimulus. Removal of the cell surface IgE with lactic acid also abolished the response to both anti-IgE and late phase blister fluid. Incubation of the "stripped" cells with serum containing IgE myeloma restored the response to anti-IgE but failed to affect response to late phase blister fluid. The characteristics of release obtained with this factor closely resemble those of an IgE-dependent histamine releasing factor from cultured macrophages previously described by our group.

Identification of histamine releasing factor(s) in the late phase of cutaneous IgE-mediated reactions

We have shown that fluids collected from antigen-challenged skin blisters during the late phase reaction cause the release of substantial amounts of histamine (means = 42%, n = 14) from human basophils in vitro. Control fluids collected either during the immediate phase or from an unchallenged blister released less than or equal to 10% histamine from both basophils and lung mast cells. Late phase blister fluids induced low levels of histamine release from human lung cells (means = 11%, n = 4) that were slightly but not significantly greater than levels induced by control blister fluids. The characteristics of basophil release were similar to IgE-mediated stimuli in dose dependence, calcium and temperature requirements, and kinetics. The IgE dependence of the late phase blister fluid was demonstrated by desensitization of the basophils to anti-IgE, which obviated the response to anti-IgE and blister fluid but did not affect a non-IgE-mediated stimulus. Removal of the cell surface IgE with lactic acid also abolished the response to both anti-IgE and late phase blister fluid. Incubation of the "stripped" cells with serum containing IgE myeloma restored the response to anti-IgE but failed to affect response to late phase blister fluid. The characteristics of release obtained with this factor closely resemble those of an IgE-dependent histamine releasing factor from cultured macrophages previously described by our group.

Demonstration of inhibition of mediator release from human mast cells by azatadine base. In vivo and in vitro evaluation

In vitro experimentation using dispersed human lung mast cells demonstrated that azatadine base, a compound with known H1-antihistamine properties, inhibited anti-IgE-induced release of histamine and leukotriene C4 by 45% and 85%, respectively. To assess the clinical relevance of these findings and to compare in vitro mast cell data with results obtained in vivo, nasally instilled azatadine was tested in a double-blind, placebo-controlled clinical trial in which nasal challenges with antigen were performed on eight allergic individuals. Pretreatment with azatadine significantly suppressed the number of sneezes following antigen challenge and inhibited the associated elevations in histamine, kinins, and enzyme(s) hydrolyzing the artificial substrate N-alpha-tosyl-L-arginine-methyl-ester in nasal secretions, whereas placebo was inactive. Hence, we showed agreement between our in vitro and in vivo experimental models of the allergic reaction. Topical application of azatadine base has the potential to become an effective antiallergic treatment.

Kininogens in nasal secretions after allergen challenge

Allergic individuals and nonallergic controls were subjected to nasal challenge with allergen; and nasal washes, obtained before and after challenge, were assayed for high molecular weight kininogen (HMWK), total kininogen (TK), albumin and kinins. Following challenge of allergic individuals, HMWK, TK, kinin and albumin all increased dramatically, correlating (p less than 0.001) with the onset of clinical symptoms and with increases in histamine and TAME-esterase activity. No such increases were seen upon challenge of nonallergics. The time course of appearance and disappearance of the kininogens, kinins and albumin were all highly correlated (p less than 0.001 in each case) by linear regression analysis, as were the increases in kinin and each of the proteins during antigen titrations. For each individual, the plasma ratio of HMWK/TK was similar to the ratio of these two proteins in post-challenge nasal washes from the same individual. These findings are consistent with the hypothesis that, during the allergic reaction, vascular permeability increases, allowing a transudation of kininogens from plasma into nasal secretions, where they can provide substrate for kinin-forming enzymes.

Mediator release during nasal provocation. A model to investigate the pathophysiology of rhinitis

The pathogenesis of rhinitis was investigated using a model of nasal provocation with different types of stimuli. Allergic subjects had an immediate response to antigenic challenge with symptoms of rhinitis highly correlated with increments in the concentrations of histamine, prostaglandin D2, kinins and kininogens, leukotrienes, and toluene sulfonyl arginine methyl ester esterase activity in their nasal secretions. This reaction was abated by a tricyclic antihistamine also capable of inhibiting mediator release from human mast cells in vitro and, in some subjects, by disodium cromoglycate. In a number of patients, symptoms reappeared three to 12 hours after nasal provocation. This late reaction also involves release of all of the aforementioned mediators except for prostaglandin D2, and preliminary data suggest that it can be inhibited by oral or topical steroids. Cold, dry air can induce rhinitis with mast cell mediator release from selected subjects. The pathogenesis of this reaction is unclear, but there are indications that osmolarity changes are responsible for mast cell activation. Thus, mast cells can be induced to release mediators and cause nasal symptoms by both immunologic and physical mechanisms, which may account for the pathophysiology of several types of rhinitis.

Nasal challenge with ragweed pollen in hay fever patients. Effect of immunotherapy

Challenge of the nasal mucosa of allergic subjects with specific allergen induces not only the expected sneezing and rhinorrhea, but also the appearance in nasal secretions of mediators commonly associated with activation of mast cells or basophils: histamine, leukotrienes, prostaglandin D2 (PGD2), kinins, and TAME ([3H]-N-alpha-tosyl-L-arginine methyl ester)-esterase. To determine whether specific immunotherapy alters mediator release in vivo, nasal pollen challenge was used to compare 27 untreated highly sensitive ragweed (RW)-allergic subjects with 12 similarly sensitive patients receiving long-term immunotherapy (3-5 yr) with RW extract (median dose, 6 micrograms RW antigen E). The two groups were equally sensitive based on skin tests and basophil histamine release. The immunized group had a diminished response as demonstrated by (a) the treated group required higher pollen doses to excite sneezing or mediator release; (b) significantly fewer subjects in the treated group released mediators at any dose (TAME-esterase [P = 0.005], PGD2 [P = 0.04]), and (c) the treated group released 3-5-fold less mediator (TAME-esterase [P = 0.01], and histamine [P = 0.02]).

Suppression of late-phase skin reactions by immunotherapy with ragweed extract

The cutaneous late-phase reaction (LPR) to ragweed was studied in untreated ragweed-allergic individuals and patients receiving 3 to 5 years of immunotherapy demonstrating clinical improvement. The magnitude of immediate skin reactions and the initial levels of the specific IgE and IgG antiragweed antibodies were similar in both groups. The LPR was elicited by administering a skin test with ragweed extract at 10 times the concentration required to elicit a 4 + immediate reaction and appeared as an erythematous-edematous lesion associated with pruritus. In the untreated group 94% developed an LPR (59 +/- 32 mm at 4 hours and 67 +/- 30 mm at 8 hours) at this dose. In the treated group only one third developed an LPR, one third had partial response measurable at one of these two times, and one third failed to develop any LPR (21 +/- 20 mm at 4 hours, p less than 0.002, and 20 +/- 22 mm at 8 hours, p less than 0.001). Therapy resulted in a twentyfold increase of IgG antiragweed level and in a decline of IgE antiragweed. The size of the LPR correlated inversely with the level of IgG antiragweed (p less than 0.01; r = -0.52) but not with IgE antibody. Thus, in a retrospective analysis immunotherapy was associated with the suppression of the skin LPR, and the magnitude of the LPR was correlated with the level of IgG antiragweed. We suggest that the clinical efficacy of immunotherapy is related in part to effects on the LPR.

The effect of inspiratory flow rate regulation on nebulizer output and on human airway response to methacholine aerosol

Increased inspiratory flow rate has been demonstrated to decrease pulmonary deposition of inhaled aerosols. To study the effect of inspiratory flow rate regulation on the physiologic response to an active substance administered by aerosol, we compared the effect of high unregulated flow rate (66 to 212 L/min) with regulated low flow rate (20 to 35 L/min) on nebulizer output and on the pulmonary response to methacholine in patients with asthma. Four No. 646 DeVilbiss nebulizers were used in sequence with a nebulization dosimeter to deliver tenfold incremental concentrations of methacholine aerosol (mass median aerodynamic diameter = 1.52 micron; geometric standard deviation = 1.96) ranging from 0.025 to 25 mg/ml. When flow was unregulated, nebulizer output was not greater than when flow was regulated, but coefficients of variation of output were significantly greater (p less than 0.01). The PD20 on the two unregulated days was significantly different (p = 0.01), whereas the PD20 on the two flow regulated days was not significantly different (p greater than 0.05). We conclude that regulation of inspiratory flow rate at rates within the range of tidal breathing significantly decreases variability in nebulizer output and variation of pulmonary responses to methacholine challenge.

Nasal challenge with cold, dry air results in release of inflammatory mediators. Possible mast cell involvement

The purpose of our study was to assess the effect of cold, dry air (CDA) on the nasal mucosa of selected individuals in relation to the release of inflammatory mediators associated with mast cells. 12 subjects with a history of nasal symptoms of rhinorrhea and congestion upon cold or dry environmental exposure were challenged by nasal breathing of CDA and warm, moist air (WMA). Each subject was tested on two occasions with the order of the challenges reversed. Symptom scores were recorded, and the levels of histamine, prostaglandin (PG) D2, kinins, and [3H]-N-alpha-tosyl-L-arginine methyl ester (TAME)-esterase activity in nasal lavage fluids were measured. CDA caused a significant increase in mediator levels and in symptom scores as compared to baseline or to WMA. No significant increase in symptom scores or mediators was noted after WMA challenge, with the exception of a marginal increase in kinins. The response to CDA was similar, regardless of challenge order. Changes in mediators correlated with one another, and symptom scores correlated significantly with the levels of histamine, kinins, and PGD2. Five subjects without a history of nasal symptoms on cold air exposure had no change in mediators or symptom scores after CDA or WMA challenge. We conclude that CDA causes the release of inflammatory mediators possibly associated with mast cells and speculate that such a mechanism may be involved in the bronchospasm induced by CDA in asthmatics.

Newer antihistaminic agents

Two new antihistamines with properties different from those of currently available drugs are nearing licensure. Named terfenidine and astemizole, they are almost exclusively H1-antagonists, lacking anticholinergic and sympathetic activity. They fail to penetrate the central nervous system and lack sedative effects. They are long-acting and require less frequent doses. Thus they allow sustained antihistaminic action without the usual side effects.

Inflammatory mediators in late antigen-induced rhinitis

To investigate the mechanisms responsible for the late-phase response in patients with allergies, we measured four biochemical mediators (histamine, tosyl-L-arginine methyl ester [TAME]-esterase, kinin, and prostaglandin D2) in nasal secretions after nasal challenge with pollen antigen in 12 patients with allergy. Nine patients had an immediate response and a recurrence of symptoms 3 to 11 hours after challenge. The clinical symptoms during recurrence were accompanied by a second increase in levels of histamine, TAME--esterase, and kinin over base-line values, although kinin levels were lower than during the immediate response. In contrast, although the levels of prostaglandin D2 were significantly increased during the immediate response, they did not increase above base line during the late response. Rechallenge with allergen 11 hours after the initial provocation, however, was associated with reappearance of all four biochemical mediators, including prostaglandin D2. We conclude that the late response to nasal challenge with allergen is accompanied by a second increase in the concentrations of histamine and TAME--esterase but differs from the immediate response in the lack of prostaglandin D2 production and in the amount of kinin generated. Since histamine is released only by mast cells and basophils and prostaglandin D2 is not produced by basophils, we suggest that these cells are partly responsible for the late-phase response.

Influx of kininogens into nasal secretions after antigen challenge of allergic individuals

We have recently demonstrated that kinins are generated in vivo after nasal challenge with antigen of allergic, but not nonallergic, individuals. The present study was undertaken as a first step in determining the mechanism(s) of kinin formation during the allergic reaction and was directed towards establishing the availability and origin of kininogens in nasal secretions. Allergic individuals (n = 6) and nonallergic controls (n = 5) were challenged with antigen; and by using specific radioimmunoassays, nasal washes, obtained before and after challenge, were assayed for high molecular weight kininogen (HMWK), total kininogen (TK), albumin, and kinins. Dramatic increases in HMWK (1,730 +/- 510 ng/ml), TK (3,810 +/- 1035 ng/ml), kinin (9.46 +/- 1.75 ng/ml), and albumin (0.85 +/- 0.2 mg/ml) were observed after challenge of allergic individuals which correlated (P less than 0.001) with increases in histamine and N-alpha-tosyl-L-arginine methyl esterase activity and with the onset of clinical symptoms. For nonallergic individuals, levels of kininogens, albumin, and all mediators after antigen challenge were not different from base line. Linear regression analysis revealed excellent correlations (P less than 0.001 in each case) between increases in HMWK, TK, kinin, and albumin during antigen titration experiments and between the time courses of appearance and disappearance of HMWK, TK, kinin, and albumin after antigen challenge. Gel filtration revealed no evidence of degradation products of kininogens in nasal washes. For each allergic individual the ratio of HMWK/TK in postchallenge nasal washes was similar to the ratio of these two proteins in the same individual's plasma. These data suggest that, during the allergic reaction, there is an increase in vascular permeability and a transudation of kininogens from plasma into nasal secretions, where they can provide substrate for kinin-forming enzymes.

Immunotherapy--state of the art

Immunotherapy for hay fever due to ragweed, grass, birch, and mountain cedar pollens and for asthma due to ragweed, grass, house dust mite, and cat dander allergens relieves symptoms in controlled studies. Clinical improvement is specific for the allergen employed, depends on the dose administered, and may relapse six months to a year after injections are stopped. Immunological changes include a rise in IgG antibodies, an early rise and later decline in IgE antibodies, sometimes a rise in secretional antibodies, reduced basophil reactivity and sensitivity, and reduced lymphocyte responsiveness to allergens.

Effect of seasonal ragweed exposure on immunoglobulin E antiragweed antibodies in cultures of peripheral mononuclear cells, plasma and nasal secretions

To determine the effects of seasonal ragweed exposure on in vitro IgE antibody production, the antiragweed IgE antibody content of 7-day cultures of peripheral blood mononuclear cells was assessed in samples obtained before, during and after the ragweed season, in 4 ragweed-allergic and 11 nonallergic individuals. The levels of ragweed-specific IgE and total IgE in unstimulated culture supernatants were measured by solid phase radioimmunoassays. Antiragweed IgE antibody was apparently detectable in the 7-day culture supernatants of both allergic and nonallergic individuals, and the antibody concentrations increased after natural ragweed exposure. However, the bindable counts of IgE antibody in supernatants from allergic patients were inhibited by soluble ragweed antigen, while those from nonallergics were not inhibitable, suggesting that supernatants from nonallergics did not contain true ragweed-specific IgE antibody. Because, for most subjects, the quantity of IgE in culture supernatants from 7-day cultures of living cells was the same as that derived from cells which were either frozen and thawed prior to culture, or briefly exposed to pH 3.7 buffer, the majority of IgE antibody in supernatants from allergic subjects, and of total IgE in supernatants from all subjects, was apparently not newly synthesized, but was preformed, and appeared to be largely derived from the cell surface. IgE antiragweed antibody was detected in the nasal secretions and plasma of allergic, but not nonallergic individuals, and the levels of antibody in allergic subjects increased after seasonal exposure. The fraction of total IgE protein accounted for by IgE antiragweed antibody in nasal secretions collected postseasonally was higher than that in both culture supernatants and plasma, suggesting that ragweed-specific IgE antibody is synthesized locally in the nose.

Mediator release after allergic and physical nasal challenges

Intranasal challenge of allergic subjects with the allergen to which they are sensitive rapidly produces sneezing, rhinorrhea, and airway obstruction. Nasal washings during the response reveal increased amounts of histamine, leukotrienes, prostaglandin D2 (PgD2), kinins and TAME-esterase in secretions. Although appearance of these mediators ceases shortly after challenge, many patients have a recrudescence of symptoms 3-11 h later, with a reappearance of the same mediators with the notable exception of PgD2. Subjects who respond to exposure to cold with rhinorrhea and nasal stuffiness were subjected to a 15-min nasal challenge with cold (-3-10 degrees C) dry (10% relative humidity) air and also responded with typical symptoms and the appearance of histamine, PgD2, TAME-esterase and leukotrienes. Nasal challenge with ragweed pollen by patients on immunotherapy showed that the threshold for response was greater and the amount of mediator found was less after treatment.

Regulatory effects of insulin and experimental diabetes on neutral amino acid transport in the perfused rat exocrine pancreas. Kinetics of unidirectional L-serine influx and efflux at the basolateral plasma membrane

Relatively little is known about the hormonal regulation of amino acid transport in the normal and diabetic exocrine pancreas. In this study unidirectional influx and tracer efflux of L-serine at the basolateral interface of the rat pancreatic epithelium was investigated in the perfused exocrine pancreas using a rapid (less than 30 s) paired-tracer dilution technique. In the non-diabetic pancreas L-serine influx was saturable and stimulated by perfusion with exogenous bovine insulin (100 microU/ml). Transport of L-serine and methylaminoisobutyric acid was markedly elevated in pancreata isolated from streptozotocin diabetic rats and insulin partially reversed the stimulation of L-serine transport induced by experimental diabetes. These results suggest that insulin and diabetes modulate the epithelial transport activity for small neutral amino acids in the intact exocrine pancreas.

Modulation of the bronchomotor effects of chemical mediators by prostaglandin F2 alpha in asthmatic subjects

Prostaglandin F2 alpha (PGF2 alpha) is generated by human lung tissue in response to a number of stimuli and is widely viewed as a bronchoconstrictor mediator. We have shown that aerosolized PGF2 alpha in concentrations between 1 and 100 micrograms/ml caused dose-related bronchoconstriction, but that continued stimulation at higher concentrations resulted in a partial return of pulmonary function toward control, suggesting that airways were refractory to further stimulation. To explore the mechanism and specificity of airway refractoriness induced by PGF2 alpha, we examined bronchomotor responses evoked by repeated PGF2 alpha stimulation, repeated histamine stimulation, and PGF2 alpha stimulation followed by histamine. Studies were carried out on 3 separate days in 7 subjects with allergic asthma. For each subject the aerosol concentration of each agonist remained constant throughout the study. Responses were measured as the percent change in FEV1 versus time, and comparisons were made between the first and second agonist challenge of each study day. We found that prior stimulation with PGF2 alpha resulted in diminished airway responsiveness, not only to PGF2 alpha but to histamine as well. In contrast, similar refractoriness could not be induced by repeated histamine stimulation, indicating that the PGF2 alpha-induced decrease in responsiveness was not a nonspecific effect of bronchoconstriction per se. Further, the finding that PGF2 alpha caused a decrease in the response to histamine suggests that diminished airway responsiveness was not due to down-regulation of specific PGF2 alpha receptors. Our findings suggest that in addition to its bronchoconstrictor properties, PGF2 alpha may play a role in the modulation of acute airway responses.

Peptide leukotriene release after antigen challenge in patients sensitive to ragweed

Slow-reacting substance of anaphylaxis (composed of leukotrienes C, D, and E) is released in vitro by the interaction of antigen and IgE antibody on human mast cells and basophils. When we challenged ragweed-sensitive patients intranasally with pollen grains, their clinical response was significantly correlated with the release of the peptide leukotrienes (P less than 0.001). Nonallergic subjects had neither symptoms nor leukotriene release. The leukotrienes were released in a dose-dependent fashion, with a peak mean level of 827 +/- 234 pg per 0.1 ml of a 10-ml nasal wash. High-performance liquid chromatography revealed the presence of leukotrienes C, D, and E, suggesting that nasal cells or fluids had the ability to degrade leukotriene C enzymatically. The in vivo release of these potent inflammatory mediators after exposure to pollen suggests that leukotrienes may have an important role in human allergic reactions.