An in vitro model of canine immediate-type hypersensitivity reactions.

Fragmented lung prepared from dogs cutaneously sensitive to ascaris antigen released histamine and a slow-reacting substance of anaphylaxis-like (SRS-A) material upon antigen challenge. Passive sensitization of fragments with serum obtained from ascaris-sensitive donor dogs enhanced the release of both substances; heating (56 degrees C for 4 h) destroyed the ability of the serum to enhance release. In passively sensitized tissues isoproterenol and papaverine inhibited the release of histamine and SRS-A; propranolol antagonized the effect of isoproterenol. Carbachol enhanced the release of both substances from passively sensitized lung wheras disodium cromoglycate and aminoguanidine were without effect. It is concluded that fragmented canine lung is a useful model for study of immediate-type hypersensitivity reactions.     

Passive sensitization of guinea-pig skin in vitro for the antigen-induced release of anaphylactic mediators

Guinea-pig skin fragments were passively sensitized for the antigen-induced release of histamine, SRS-A and ECF-A. Skin histamine was chemically identified by fluorimetry; SRS-A gave a characteristic dose-dependent contraction of the guinea-pig ileum; and ECF-A selectively attracted eosinophils. The antibody mediating the release of these agents was shown to be IgG₁. Following antigen challenge different time courses of release were demonstrable for histamine, SRS-A and ECF-A. Skin SRS-A was resistant to treatment with the enzyme pronase and skin ECF-A had an estimated molecular size of between 500 and 1000. They were therefore comparable to similar agents released from the lung. Thus SRS-A and ECF-A join histamine as chemical mediators in cutaneous anaphylaxis.     

Inactivation by alveolar macrophages of slow-reacting substance of anaphylexis released from pig lung cells

The influence of alveolar macrophages on the release of slow-reacting substance of anaphylaxis (SRS-A) and histamine from dispersed pig lung cells was studied. The addition of alveolar macrophages to lung cells (1:3) decreased SRS-A release by 62% ± 7% without a significant decrease in histamine release. Increased numbers of alveolar macrophages (1:1) decreased both SRS-A release (by 90% ± 5%) and to a lesser extent histamine release (by 59% ± 18%). The decrease in released SRS-A was not caused by prostaglandin release from macrophages, and kinetic data indicated that in contrast to histamine the decrease was predominantly the result of SRS-A inactivation rather than inhibition of its release. When alveolar macrophages were incubated with SRS-A, inactivation (191 units /10⁷ cells/30 min) was confirmed. SRS inactivation was not reproduced by glutaraldehyde-treated macrophages or by granulocyte and mononuclear populations obtained from peripheral blood. Alveolar macrophages may limit the consequences of SRS-A release in the peripheral air spaces.     

The influence of a new corticosteroid,budesonide, on anaphylactic bronchoconstriction and SRS-A release in the guinea pig

Groups of guinea pigs sensitized with ovaibumin were treated with budesonide and beclomethasone dipropionate, respectively, in an intraperitoneal dose of 50 mg/kg. 20 h later, the anaphylactic release of histamine and slow reacting substance of anaphylaxis (SRS-A) from chopped lung tissue was studied. Whereas the corticosteroids studied had no effect on the tissue content of histamine or on the amount of antigen-induced release of this autacoid, budesonide and beclomethasone dipropionate to a great extent inhibited the release of SRS-A. The anti-anaphylactic effect of budesonide and beclomethasone was also shown in sensitized guinea pigs pretreated with mepyramine, 2.5 mg/kg intraperitoneally, and challenged with nebulized ovalbumin. We suggest that the partial protection given by the corticosteroids budesonide and beclomethasone dipropionate is due to the inhibition of SRS-A release.Subsidiary of AB Astra, Sweden.     

Anti-allergic effects of milrinone and sulmazole in isolated rat lungs in comparison with theophylline

Milrinone and sulmazole, two recently developed drugs, inhibit specific fractions of the phosphodiesterase (PDE) isozyme system. Since theophylline aspecifically inhibits the PDE complex, we compared the effects of milrinone and sulmazole with those of theophylline on antigen-induced bronchoconstriction, vasoconstriction, mediator release and leukotriene production. In the isolated perfused and ventilated lung of actively sensitized rats, we elicited antigen-induced bronchoconstriction, vasoconstriction and release of mediators like histamine, 5-hydroxytryptamine (5-HT) and slow-reacting substance of anaphylaxis (SRS-A). Milrinone, sulmazole and theophylline inhibited antigen-induced bronchoconstriction and vasoconstriction in a dose-dependent manner with minor differences in potency. Antigen-induced release of preformed mediators like histamine and 5-HT was inhibited only at high concentrations of milrinone, whereas sulmazole failed to inhibit mediator release. Theophylline also failed to inhibit 5-HT release. However, SRS-A synthesis was markedly reduced by these drugs in relatively low concentrations. It is concluded that milrinone and sulmazole have anti-allergic effects similar to those of theophylline and that all three PDE inhibitors reduce SRS-A synthesis.     

The effect of Ro 21-7634 on the antigen-induced production of bronchoconstrictive arachidonic acid metabolites in the guinea pig lung

Ro 21-7634 has previously been shown to inhibit histamine and SRS-A release from actively-sensitized guinea pig lung fragments upon antigen challenge. In the studies described herein, it was observed that Ro 21-7634 does not decrease SRS-A release but instead acts to inhibit the synthesis of this mediator. This was confirmed by studying SRS-A synthesisin vitro in rat peritoneal cells after challenge with ionophore A23187. In the peritoneal cell system, Ro 21-7634 exhibited an IC₅₀ of 500 M, in comparison with 5,8,11,14-eicosatetraynoic acid, phenidone and BW755C (IC₅₀'s of 2, 100, and 100 M, respectively). When studied at 10^–4 and 10^–3 M in perfused guinea pig lung, Ro 21-7634 inhibited antigen-induced thromboxane A₂ production by 68 and 96%, respectively. In this system, antigen is believed to induce thromboxane A₂ production through the release of histamine and SRS-A from lung tissue. These mediators then interact at receptor sites in the lung parenchyma to induce thromboxane A₂ synthesis. Ro 21-7634 could thus be inhibiting thromboxane A₂ production by preventing the release of histamine and synthesis of SRS-A in the perfused lung system. Such a mechanism is suggested by the fact that although Ro 21-7634 was effective in inhibiting antigen-induced thromboxane production, it was ineffective in inhibiting thromboxane A₂ production induced in the guinea pig lung system by the direct perfusion of histamine or SRS-A through the lung.     

Release of slow-reacting substance of anaphylaxis from dispersed pig lung cells: effect of cyclo-oxygenase and lipoxygenase inhibitors

Study of the release of slow-reacting substance of anaphylaxis (SRS-A).from lung cells has been hampered by the lack of a suitable animal model. Using both immunologic and pharmacologic stimuli, we have obtained histamine and SRS-A release from dispersed pig lung cells containing 6% mast cells (with a histamine content of 1.9 pglcell). Lung cells dispersed from actively sensitized (with intratracheal Ascaris antigen) but not unsensitized pigs released both histamine (mean net release 33%) and SRS-A (mean release, 47 units/10⁷ cells) when challenged with Ascaris antigen. Greater release of histamine (mean net release 52%) and of slow-reacting substance (SRS) (mean release 701 units/10⁷ cells) was induced by challenge with the calcium ionophore A23187. The pharmacologic and physicochemical characteristics of the SRS together with its profile of enzymatic inactivation resembled those described for SRS-A released from human lung. Both antigen-induced and A23187-induced SRS(-A) release were enhanced by indomethacin, a cyclo-oxygenase inhibitor, but inhibited by both phenidone (IC₅₀ 35 μM) and eicosatetraenoic acid (IC₅₀ 15 μM), inhibitors of both cyclo-oxygenase and lipoxygenase, confirming that generation of SRS(-A) by either stimulus required an intact lipoxygenase pathway of arachidonic acid metabolism.     

Rat alpha 2 macroglobulin is a selective inhibitor of antigen-induced leucotrienes in rat isolated lungs.

Exogenously administered, purified rat alpha 2 macroglobulin (alpha 2M, recognized as an acute phase reactant with anti-inflammatory properties) greatly inhibits the increase of the pulmonary resistance during the antigen-induced bronchoconstriction in rats in vivo, whereas a BaSO4 pretreatment (a method to induce a broad spectrum of serum acute phase reactants, including alpha 2M) covers a broader bronchoprotection: suppression of the decrease of the dynamic lung compliance as well. To explain these differences we studied the influence of both alpha 2M and BaSO4 on the antigen-induced bronchoconstriction in rat isolated lungs in relation to the mediator release in lung-effluents. We report here that in this model alpha 2M only inhibits the antigen-induced SRS-A release, whereas the concomitant release of histamine and 5-HT was unaffected. As distinct from alpha 2M the BaSO4 pretreatment suppressed both the antigen-induced bronchoconstriction and the histamine, 5-HT and SRS-A release to a high extent. These data suggest that alpha 2M can be considered as a selective inhibitor of leucotrienes, which offers an explanation for several anti-inflammatory properties of alpha 2M, including protection against the antigen-induced increase of the pulmonary resistance in vivo.     

Rat alpha 2 macroglobulin is a selective inhibitor of antigen-induced leucotrienes in rat isolated lungs

Exogenously administered, purified rat alpha 2 macroglobulin (alpha 2M, recognized as an acute phase reactant with anti-inflammatory properties) greatly inhibits the increase of the pulmonary resistance during the antigen-induced bronchoconstriction in rats in vivo, whereas a BaSO4 pretreatment (a method to induce a broad spectrum of serum acute phase reactants, including alpha 2M) covers a broader bronchoprotection: suppression of the decrease of the dynamic lung compliance as well. To explain these differences we studied the influence of both alpha 2M and BaSO4 on the antigen-induced bronchoconstriction in rat isolated lungs in relation to the mediator release in lung-effluents. We report here that in this model alpha 2M only inhibits the antigen-induced SRS-A release, whereas the concomitant release of histamine and 5-HT was unaffected. As distinct from alpha 2M the BaSO4 pretreatment suppressed both the antigen-induced bronchoconstriction and the histamine, 5-HT and SRS-A release to a high extent. These data suggest that alpha 2M can be considered as a selective inhibitor of leucotrienes, which offers an explanation for several anti-inflammatory properties of alpha 2M, including protection against the antigen-induced increase of the pulmonary resistance in vivo.     

In vitro studies on the mechanism of action of a new antiallergic,Ro 21-7634

The effects of Ro 21-7634 and disodium cromoglycate (cromoglycate) on the in vitro release of mediators of anaphylaxis from rat peritoneal cells and guinea pig lung tissue were compared. Ro 21-7634 was 25 fold more potent than cromoglycate as an inhibitor of antigen-induced histamine release from passively sensitized (IgE) rat peritoneal cells. Ro 21-7634 was also the more potent inhibitor of both compound 48/80- and concanavalin A-induced histamine release from rat peritoneal cells. The two drugs shared the common properties of producing the same maximal level of inhibition in each of the above releasing systems and exhibiting a time and concentration dependent loss of inhibitory activity when added to the cells prior to the releasing agent. Neither drug inhibited ionophore A23187- or ionophore X537A-induced histamine release from these cells. Ro 21-7634 inhibited antigen-induced (IgG₁) histamine and SRS-A release from actively sensitized guinea pig lung fragments, whereas cromoglycate did not. The results indicate that Ro 21-7634 and cromoglycate act through a common mechanism to inhibit allergic mediator release and that Ro 21-7634 is the more potent inhibitor.     

Effect of a histamine H2-receptor antagonist on immunologically induced mediator release in vitro

The histamine H₂-receptor has been implicated in the autoregulation of endogenous histamine release from actively sensitized human basophils. Consequently, the activity of metiamide (SK & F 92058), a specific histamine H₂-receptor antagonist, was investigated for its effect on immunologically-induced histamine release in several in vitro models of immediate hypersensitivity. Metiamide enhanced the release of histamine from passively sensitized fragmented Rhesus monkey lung and skin when these tissues were challenged in a reversed type anaphylactic reaction with antihuman IgE. The enhancing effect of metiamide on the release of ‘slow reacting substance of anaphylaxis, from monkey lung was considerably less pronounced. In contrast, metiamide failed to significantly enhance the antigen-induced release of histamine from fragmented rat lung which had been passively sensitized with rat anti-ovalbumin serum. The data supports a species-specific enhancement of immunologic histamine release in vitro, perhaps by H₂-receptor blockade on cells responsible for such release.     

Reduction of antigen-induced contraction of sensitized guinea-pig tracheal smooth muscle in vitro by calmodulin inhibitors

The effect of two calmodulin inhibitors, 1-[bis(p-chlorophenyl)methyl]-3-[2,4-dichloro-beta-(2,4-dichlorobenzylox y) phenethyl]imidazolinium chloride (R 24571) and chlorpromazine (CPZ) on antigen-induced contraction of guinea-pig tracheal smooth muscle was studied. Ketotifen, an anti-allergic compound, was used as a comparative drug. Contraction of sensitized guinea-pig trachea induced by antigen challenge was reduced by all three agents. The two calmodulin inhibitors effected relaxation of contraction of guinea-pig trachea induced by histamine and leukotriene D4 (LTD4). Ketotifen relaxed histamine-induced contraction, but hardly affected LTD4-induced tone. Contrary to chemical mediator induced tone, all examined agents had no effect on resting tone. These three agents shifted histamine- and LTD4-induced concentration-contraction curves to the right. They produced a downward displacement of the maximum, without a parallel shift in histamine- and LTD4-induced concentration-contraction curves. The two calmodulin inhibitors did not affect the antigen-induced release of histamine and SRS-A from sensitized guinea-pig lung tissue. Ketotifen slightly inhibited the release of histamine. These results suggest that R 24571 and CPZ, calmodulin inhibitors, reduced an antigen-induced contraction of sensitized guinea-pig trachea in vitro mainly by affecting the contractility of tracheal smooth muscle by chemical mediators but not by interfering with the release of mediators.     

Effect of cinnarizine on IgE antibody-mediated experimental allergic reactions in guinea pigs

The anti-allergic activity and mechanism of cinnarizine was investigated in guinea pigs. Nifedipine, a calcium antagonist, and tranilast, a potent, orally active anti-allergic agent, were used as comparative drugs. Cinnarizine protected against fatal systemic anaphylactic shock in guinea pigs passively sensitized with IgE antibody. Cinnarizine reduced many of the features of severe respiratory disorders. Nifedipine and tranilast showed similar effects. Cinnarizine and nifedipine inhibited the contractile response to antigen of sensitized tracheal smooth muscle when the challenge was carried out at low antigen concentrations. Tranilast showed a tendency to inhibit the antigen-induced contraction of tracheal smooth muscle. Cinnarizine and nifedipine inhibited Ca-induced contraction in potassium-depolarized tracheal smooth muscle, tranilast had no effect. Cinnarizine showed antagonistic action to the contraction by histamine or leukotriene D4 (LTD4) of tracheal muscle. Nifedipine showed similar antagonistic action, although its potency is lower than cinnarizine. Tranilast showed slight antagonistic action to LTD4. Antigen-induced release of histamine and slow reacting substance of anaphylaxis (SRS-A) from sensitized lung tissues was inhibited by nifedipine and tranilast but not by cinnarizine. The release of histamine and SRS-A from lung tissues by calcium ionophore A23187 was inhibited by nifedipine and tranilast but not by cinnarizine. These results suggest that the anti-allergic action of cinnarizine is mainly due to the antagonistic action to allergic mediators and not by interfering with the release of mediators. Cinnarizine's mechanism seems to be related to its antagonistic action to Ca in smooth muscle, but not to the transport of Ca in releasing the anaphylactic chemical mediators in mast cells and other target cells.     

Peritoneal anaphylaxis in the rat after sensitization with mouse antiserum.

Passive peritoneal anaphylaxis in rats, sensitized with mouse antiserum, had characteristics of an IgE-mediated reaction, in that the serum was heat-labile and pretreatment of the rats with disodium cromoglycate (DSCG), or sodium nivimedone, inhibited the release of both histamine and slow-reacting substance of anaphylaxis (SRS-A). Sodium nivimedone was more potent than DSCG as an inhibitor of histamine release. Peak concentrations of histamine and SRS-A in the peritoneal fluids of the rats, were reached within 2 min of antigen challenge and fell to control levels after 20-30 min.     

The role of calcium in the generation of intracellular SRS-A in passively sensitized human lung challenged with antigen

Calcium deprivation inhibits the formation and subsequent release of SRS-A as well as histamine from passively sensitized human lung fragments challenged with antigen. Antimycin A inhibits the release of histamine and SRS-A in a dose dependant fashion, while causing a mild inhibition of SRS-A formation throughout the dose range studied. These data suggest that the influx of calcium is the critical event for the generation of SRS-A within the cell.     

Effect of NZ-107, a newly synthesized pyridazinone derivative, on antigen-induced contraction of human bronchial strips and histamine release from human lung fragments or leukocytes.

The effects of a newly synthesized pyridazinone derivative, NZ-107, 4-bromo-5-(3-ethoxy-4-methoxybenzylamino)-3(2H)-pyridazinone, and two well-known antiasthmatic drugs, amlexanox (orally active disodium cromoglycate-like drug) and disodium cromoglycate (DSCG) on antigen-, histamine- and leukotriene C4 (LTC4)-induced constriction of isolated human tracheal muscle, and histamine release from human lung tissues and leukocytes were investigated in vitro. In some experiments, salbutamol was used as a reference drug. NZ-107 inhibited antigen-, histamine- and LTC4-induced contraction of tracheal muscle. Amlexanox and DSCG did not affect the contractile response of tracheal muscle caused by each stimulant. Salbutamol inhibited antigen-induced contraction of tracheal muscle. NZ-107, amlexanox, DSCG and salbutamol clearly inhibited the antigen-induced release of histamine and LTC4 from human lung tissue. The antigen-induced histamine release from atopic human leukocytes was inhibited by NZ-107 and amlexanox, but not by DSCG. Pretreatment with IL-3 did not alter antigen-induced contraction of tracheal muscle and histamine release from lung tissue, but antigen- or calcium ionophore A 23187-induced histamine release from leukocytes was clearly enhanced. Amlexanox inhibited the IL-3-induced enhancement of histamine release from leukocytes in the case of both stimuli, but NZ-107 and DSCG had no effect. These data suggest that NZ-107 has potent anti-allergic actions based on the inhibition of antigen-induced contraction of human tracheal muscle and mediator release from human lung tissue and leukocytes.     

CI-922--a novel, potent antiallergic compound--I. Inhibition of mediator release in vitro

CI-922 (3,7-dimethoxy-4-phenyl-N-1H-tetrazol-5-yl-4H-furo[3,2-b]-indole- 2-carboxamide, L-arginine salt) is a novel antiallergy compound which inhibits the release of the inflammatory mediators histamine and leukotriene (LT) from stimulated cells. CI-922 showed potent, effective inhibition of antigen-induced mediator release from human basophils and isolated guinea pig lung. The drug inhibited ragweed or housedust-induced histamine release from basophils of allergic human donors (IC50 = 8.6 microM). The antiallergy agents proxicromil (IC50 = 80 microM) and cromolyn (100 microM) were less potent than CI-922 or inactive, respectively. In fragmented lung from actively sensitized guinea pigs, CI-922 (IC50 = 1.5 microM), blocked the antigen-induced production of LT and was a more potent inhibitor of histamine release (IC50 = 13.4 microM) than proxicromil (IC50 = 72.9 microM), or cromolyn (inactive at 1 mM). CI-922 (IC50 = 0.9 microM) completely inhibited repeated contractions of guinea pig lung strips that were induced by low antigen concentration in the presence of antihistamine (H1). Nordihydroguaiaretic acid (NDGA) (IC50 = 2.8 microM), proxicromil (IC50 = 6.2 microM) and the LT antagonist FPL-55712 (IC50 = 3.3 microM) also were fully effective, but cromolyn (300 microM) was inactive. In other experiments, CI-922 (IC50 = 7.0 microM) inhibited a strong, nonrepeatable lung contraction induced with high antigen concentration (histamine responses blocked), and was six times more potent than FPL-55712. Other investigations in isolated tissue preparations showed CI-922 to be a weak inhibitor of LT or histamine-induced effects with no anticholinergic activity.(ABSTRACT TRUNCATED AT 250 WORDS)     

Release of slow-reacting substance from anaphylactic lung tissue and its modification by beta-sympathomimetics.

Anaphylactic release of slow-reacting substance of anaphylaxis (SRS-A) from chopped guinea pig lung was studied. The antibodies mediating the anaphylactic reaction were classified as IgG antibodies by PCA technique. Isoprenaline was found to inhibit the release of SRS-A in the concentration range 10-8-10-6M, while the beta2-selective agonist terbutaline showed inhibition in the concentration range 10-6-10-5M. The beta1-selective beta-agonist tazolol was ineffective when tested in the concentration range 10-7-10-5M. The rank order of inhibitory potency of the compounds on SRS-A release agree with that for histamine release.     

Antigen-induced release of histamine from passively sensitized guinea pig lung slices. I. Optimum conditions for in vitro passive sensitization and challenge with antigen.

The effect of several parameters (pH, Ca++ concentration, time, temperature, lung slice size) on in vitro antigen-induced histamine release from passively sensitized guinea pig lung slices was investigated. With respect to pH, Ca++ concentration and time, the optimal conditions for the passive sensitization step (pH 7.8, Ca++ 1.5 mM, 2 h) were distinctly different from those for the antigen challenge step (pH 8.2, Ca++ 10mM, 15 min). Maximum antigen-induced release was obtained with 3 X 0.25 X 0.25 mm lung slices at 37 degrees C using air as gas phase.     

Increased vascular permeability during passive peritoneal anaphylaxis in the rat. The effects of disodium cromoglycate and a nitroindanedione.

Following intraperitoneal sensitisation of rats with rat serum containing reaginic antibody, intravenous injection of blue dye and intraperitoneal challenge with antigen caused a release of histamine, slow-reacting substance of anaphylaxis (SRS-A) and dye into their peritoneal fluids. The times taken to reach peak concentrations after challenge were less than 2 min for histamine and between 5 and 10 min for SRS-A, whilst concentrations of dye were still increasing after 2 1/2 h. The amounts of histamine released by antigen were sufficient to account for about 60% of this extravasation of dye. Disodium cromoglycate (DSCG) and a nitroindanedione (BRL 10833) inhibited extravasation by inhibition of mediator release. BRL 10833, unlike DSCG, was active after oral administration, and for a given inhibition of histamine release it produced a greater effect on extravasation when given orally than when injected intraperitoneally.