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Biomedical subjects

D Proud

Publications and source records attributed to D Proud.

At least 163 records · Page 9Linked to original sources
PubMed1986

Basophil histamine release induced by a substance from stimulated human platelets.

Platelet activation may occur during immunoglobulin E antibody (IgE)-mediated reactions. In these studies, we confirm that platelet-derived supernatants (PDS) induce histamine release from human mixed leukocytes containing basophils, one of the initial target cells in IgE-mediated reactions. In extending this observation, we have shown that this PDS-induced histamine release is both temperature- and calcium-dependent. Kinetic studies of release induced by PDS indicate that release is more rapid than that associated with IgE-dependent mechanisms. This platelet-derived, histamine-releasing activity is produced by platelet stimulation with collagen (5 micrograms/ml) and acetylglyceryl ether phosphorylcholine (10(-7)), as well as thrombin (1 U/ml). Initial characterization has shown that it is stable to acid and to freeze-thawing but not to boiling for 10 min. In addition, although this histamine-releasing activity is nondialyzable (i.e., greater than 3500 m.w.), it cannot be attributed to platelet factor 4. Thus, platelets, once activated, can produce a soluble substance or substances which can initiate basophil-mediated reactions, further suggesting that platelet activation can enhance allergic and inflammatory reactions.

Antigens↗
PubMed1986

Differences between basophils and mast cells: failure to detect Charcot-Leyden crystal protein (lysophospholipase) and eosinophil granule major basic protein in human mast cells.

Human eosinophils contain several distinctive proteins including eosinophil granule MBP and the membrane-associated CLC protein (lysophospholipase). Human basophils also contain these proteins, indicating biochemical similarities between eosinophils and basophils. To determine whether MBP or CLC protein is present in connective tissue mast cells, we studied human lung and cutaneous mast cells by immunofluorescence by utilizing specific antibodies to CLC and MBP. Cytocentrifuge slides of enriched lung mast cells and mast cells in sections of formalin-fixed, paraffin-embedded cutaneous tissue from urticaria pigmentosa lesions were stained for CLC and MBP. Neither pulmonary nor cutaneous mast cells stained for CLC protein or MBP. In contrast, lung and cutaneous eosinophils in the same preparations showed bright staining for both proteins. The failure to find CLC protein and MBP in mast cells provides additional evidence of dissimilarity between mast cells and basophils, and an immunochemical means to distinguish between them.

Basophils↗
PubMed1986

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.

Adolescent↗
PubMed1986

Kinins as mediators of human allergic reactions.

We have demonstrated that kinins are generated following nasal challenge with allergen of allergic (5.6 +/- 0.17 ng/m-), but not nonallergic (0.04 +/- .02 ng/ml), individuals (n = 8 in each case). The presence of kinin was highly correlated with that of histamine and TAME-esterase activity and with clinical symptoms (p less than 0.001). In a double blind, placebo-controlled study, topical administration of the drug Azatadine, which inhibits mast cell mediator release in vitro, reduced the clinical response to allergen challenge and reduced the concentrations of kinins, histamine, and TAME-esterase activity observed following allergen challenge. In addition to the immediate response to allergen, some individuals experience a recurrence of symptoms some 3-12 hours after challenge; in seven such individuals (13.5 +/- 3.2 ng kinin/ml in the immediate reaction), there was a second increase in nasal kinins (2.95 +/- 1.4 ng/ml) during this late reaction, again correlating with increases in histamine and TAME-esterase activity. HPLC analysis revealed that a mixture of bradykinin and lysylbradykinin is produced during both responses. Finally, 12 subjects with a history of nasal symptoms upon exposure to cold, dry air (CDA) were compared to five asymptomatic individuals in a nasal challenge system involving nasal breathing of CDA and warm, moist air (WMA). For the symptomatic group the levels of kinin in nasal lavages were significantly increased after CDA (2.9 +/- 0.8 ng/ml) compared to baseline (0.06 +/- 0.01 ng/ml) or WMA (0.3 +/- 0.07 ng/ml). Kinin generation again correlated with increases in histamine, PGD2 and TAME-esterase activity and with onset of symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Antigens↗
PubMed1986

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.

Antigens↗
PubMed1986

Theophylline reduces histamine release during pollen-induced rhinitis.

In an attempt to understand how theophylline achieves its in vivo therapeutic effect, a double-blind crossover study of the effect of theophylline on the immediate response of the upper airways to challenge with antigen was performed. Ten subjects with allergic rhinitis were challenged with increasing doses of antigen extract, and their responses were assessed by counting the number of sneezes and measuring the level of histamine, N-alpha-p-tosyl-L-arginine-methyl ester-esterase activity, and kinin in nasal secretions. One-week premedication with theophylline led to serum levels in the therapeutic range (8 to 21 micrograms/ml). There were significant reductions in both the physiologic response to antigen challenge and the appearance of mediators in secretions after drug administration as compared to placebo. These data suggest that theophylline, at therapeutic blood levels, achieves at least part of its in vivo efficacy by reducing the release of histamine and other mediators from mast cells/basophils.

Histamine Release↗
PubMed1986

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.

Air↗
PubMed1986

A human lung mast cell chymotrypsin-like enzyme. Identification and partial characterization.

We have used a high performance liquid chromatography assay, which detects chymotryptic cleavage of the phe8-his9 bond of angiotensin I to yield angiotensin II, in order to examine human lung mast cells for the presence of chymotryptic activity. Mast cells, purified from human lung by enzymatic dispersion, countercurrent elutriation, and Percoll gradient centrifugation, were lysed or challenged with goat anti-human IgE. In multiple experiments angiotensin II-converting activity was detected in lysates of 10-99% pure mast cell preparations. Regression analysis of net percent release values of histamine and the angiotensin I-converting activity from dose-response experiments demonstrated a correlation between the two parameters, indicating that the chymotrypsin-like enzyme is a constituent of the mast cell secretory granule. The chymotryptic activity was completely inhibited by 10(-3) M phenylmethylsulfonylfluoride but not by 10(-3) M Captopril, and the pH optimum of activity was 7.5-9.5. Gel filtration of released material separated the activity from tryptase and demonstrated an approximate molecular weight of 30-35,000. The mast cell enzyme, like a human skin chymotrypsin-like proteinase, can be distinguished from leukocyte cathepsin G by lack of susceptibility to inhibition by bovine pancreatic trypsin inhibitor. Thus, an enzyme with limited chymotryptic specificity is present in human lung mast cells. The Michaelis constant of the enzyme for angiotensin I of 6.0 X 10(-5) M is similar to that of endothelial cell angiotensin-converting enzyme and is consistent with a reaction of physiologic importance.

Angiotensin I↗
PubMed1986

Dexamethasone inhibits plasminogen activator activity in experimental pemphigus in vivo but does not block acantholysis.

In vitro studies have suggested that autoantibody-stimulated increases in epidermal plasminogen activator (PA) may be an important pathogenetic mechanism in pemphigus vulgaris (PV). We measured PA in murine epidermis after i.p. injection of normal human IgG (NH IgG) and PV IgG, with and without exposure to dexamethasone (DEX). BALB/c neonates received i.p. injections of saline control or DEX (20 mg/kg). Twenty-four hours later, they received a second injection of saline or DEX and a single dose of NH or PV IgG (20 mg/gm body weight). After 24 hr, epidermis was obtained and was sequentially extracted in 0.14 M NaCl, pH 6.8, and 0.5% Triton X-100 in 0.1 M Tris, pH 8.1. Epidermal PA was assayed in the Triton-Tris supernatant by a two-stage colorimetric reaction and was expressed as milliPloug units per milligram of protein (mPu/A280). PA in animals injected with NH IgG was 0.21 +/- 0.11 mPu/A280 (n = 8). Epidermal PA was increased in animals with cutaneous lesions of pemphigus to 0.42 +/- 0.29 (n = 15). Treatment with DEX decreased PA levels in both animals receiving NH IgG and PV IgG by 80%, to 0.04 +/- 0.05 (n = 15) and 0.09 +/- 0.07 (n = 7), respectively. Despite the decreased PA activity, all animals in the PV IgG and the PV IgG-plus-DEX group had identical and extensive cutaneous disease, and lesions developed at the same time points. This finding shows that PV autoantibodies can stimulate increases in epidermal PA, but reduction of PA by corticosteroids does not inhibit acantholysis in vivo. There is no clear correlation between PA and disease activity in the murine model of pemphigus.

Acantholysis↗
PubMed1985

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.

Air↗
PubMed1985

Theophylline reduces the response to nasal challenge with antigen.

A nasal challenge model of allergic rhinitis was used to determine if pretreatment with oral theophylline reduces histamine release in vivo. Ten subjects were entered into a double-blind, cross-over trial. The results showed that both the physiologic response (sneezing) (p = 0.02) and the amount of mediators (histamine, kinins, toluene sulfonyl arginine methyl ester esterase activity) (p less than 0.01 for all) released into nasal secretions were significantly reduced after one week of pretreatment with theophylline. At the time of challenge, the serum concentrations of theophylline were between 8 and 22 micrograms/ml. It is speculated that the ability of theophylline to block the clinical response to antigen challenge and to decrease the release of mast cell mediators contributes to its clinical efficacy in the treatment of asthma.

Adolescent↗
PubMed1985

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.

Adult↗
PubMed1985

Human lung macrophages induce histamine release from basophils and mast cells.

Human lung macrophages isolated from surgical specimens, when cultured for 24 h, acquired the capacity to induce histamine release from human basophils. This releasing activity was entirely accounted for by soluble, nondialyzable factor(s) (molecular weight, more than 2,000 daltons) released from cultured macrophages. The basophil release reaction was dose-dependent, and also Ca++ (optimal concentration = 5 mM) and temperature (optimal = 37 degrees C) dependent. Supernatants derived from the equivalent of 3 X 10(6) macrophages/ml released 50% histamine from basophils of sensitive donors. The supernatants also induced histamine release from lung mast cells. These results are the first report of a human macrophage-derived product that activates basophils and mast cells to release histamine.

Basophils↗
PubMed1985

Immunoglobulin E-mediated release of a kininogenase from purified human lung mast cells.

Certain manifestations of the allergic response, such as vasodilation and edema, may be attributed to the involvement of kinins, but, as yet, little data exist to show how these peptides could be produced during IgE-mediated events. We now report that purified human lung mast cells contain a kininogenase that is released in a dose-dependent fashion by anti-IgE. Release of kinin-generating activity parallels that of histamine and, like histamine release, kininogenase release is temperature-dependent. Kininogenase release also parallels increasing histamine release when mast cells of increasing size are stimulated with an optimal level of anti-IgE. Finally, when mast cells of greater than 99% purity were optimally challenged, kininogenase activity again paralleled histamine levels in the release supernatant and residual cell pellet. The mast cell kininogenase appears to be a preformed mediator in that it occurs in lysates of unstimulated mast cells of greater than 99% purity. Optimal generation of kinin from highly purified human low molecular weight kininogen occurred at pH 5.5 and in 8 preparations was 380 +/- 237 ng kinin/h/10(6) mast cells (means +/- SD). Thus, human lung mast cells contain a kininogenase that is released during, and may participate in, IgE-mediated inflammatory disorders in humans.

Antibodies, Anti-Idiotypic↗
PubMed1985

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.

Adult↗
PubMed1985

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.

Adolescent↗