Inhibition of IgE-mediated histamine release from human basophils and mast cells by fenoterol

Fenoterol, a beta 2-adrenergic agonist recently introduced to treat asthmatic disorders, inhibits antigen-induced histamine release from human basophil leukocytes and lung mast cells in a dose-dependent fashion. The dose-response inhibition curve is paralleled by a fenoterol-induced increase in the cAMP levels of human leukocyte preparations. The relationship between the effect of fenoterol and cAMP level is supported by the finding that the beta 2-adrenergic agonist only inhibits the first stage of antigen-induced histamine release and not the release caused by the Ca2+ ionophore, A23187. Propranolol, a competitive antagonist of beta 2-adrenergic receptor, blocks the inhibition of release and the cAMP accumulation caused by fenoterol. Finally, theophylline, a cAMP phosphodiesterase inhibitor, synergistically potentiates the inhibitory effect of fenoterol on histamine release and the accumulation of cAMP. These data suggest that fenoterol may modulate the in vivo release of the mediators of immediate hypersensitivity reactions via the activation of beta 2-adrenergic receptor linked to adenylate cyclase on human basophils and mast cells.     

The role of 5-lipoxygenase pathway activation in basophil histamine release

This study was performed to evaluate the role of products of the 5-lipoxygenase pathway in histamine release from human basophils. AA-861, a specific inhibitor of 5-lipoxygenase, did not inhibit anti-IgE-induced histamine release from human basophils with 6 +/- 11% inhibition at 10(-6)M. Neither was there a marked inhibition of histamine release induced by ionophore A23187 and formyl-L-methionyl-L-leucyl-L-phenylalanine with 16 +/- 10 and 11 +/- 6% inhibition respectively at 10(-6)M of AA-861. In contrast, AA-861 enhanced 12-0-tetradecanoyl-phorbol-13-acetate-induced histamine release with 20 +/- 3% at 10(-6)M. These results suggest that 5-lipoxygenase activation may not play a role in basophil histamine release.     

Interleukin-8 and RANTES inhibit basophil histamine release induced with monocyte chemotactic and activating factor/monocyte chemoattractant peptide-1 and histamine releasing factor.

The objective of this study was to investigate the effect of interleukin-8 (IL-8) and RANTES on basophil histamine release induced with monocyte chemoattractant peptide-1 (MCP-1) and crude histamine releasing factor (HRF). IL-8 induced low levels of histamine release (8.5 +/- 0.5%) from basophils obtained from only six of 20 donors at high concentrations (10(-6) M). RANTES induced histamine release (16 +/- 2%) from basophils of four of 15 donors at 10(-7) M concentration. However, both IL-8 and RANTES inhibited MCP-1 and HRF-induced histamine release from basophils dose-dependently at concentrations of 10(-9) to 10(-7) M. Basophils from all donors showed a significant inhibitory response (greater than 15%). The maximal inhibition of MCP-1 and HRF by IL-8 was 28 +/- 4% and 48 +/- 8%, respectively. The maximal inhibition of MCP-1 and HRF by RANTES was 26 +/- 4% and 43 +/- 6%, respectively. Peripheral blood mononuclear cell-derived HRF was purified into three distinct peaks by reverse-phase high performance liquid chromatography. Peak I contained MCP-1 as judged by binding to an immunoaffinity column that was prepared with anti-MCP-1 antibody. IL-8 inhibited histamine release induced with all three peaks of HRF. The inhibition of histamine release by IL-8 was significantly higher in normal subjects than in allergic patients (59 +/- 9% versus 31 +/- 7%, P less than 0.05). Both IL-8 and RANTES inhibited cytokine-induced histamine release only and did not affect histamine release by anti-IgE, FMLP, and C5a.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of a selective beta 2 adrenergic agonist and theophylline on skin test reactivity and cardiovascular parameters.

Fenoterol, a selective beta 2-adrenergic agent, and aminophylline in the "therapeutic range" were compared with placebo for their inhibitory effect on skin test reactivity to allergens and histamine. Cardiovascular parameters were also assessed. A new, inexpensive micrometer adaptor to a tuberculin syringe was used to deliver allergens and histamine more accurately. No inhibition of skin test reactivity to antigens or histamine was found after a loading dose or after 1 wk of round-the-clock therapy with these bronchodilators. Although there was increased heart rate after 1 and 2 hr with fenoterol, there was no patient preference for one bronchodilator over the other. The results of this study point out some of the difficulties in trying to extrapolate in vitro findings to in vivo correlates since neither fenoterol nor therapeutic doses of theophylline interfere with immediate skin test reactivity.     

Neutrophil attractant/activation protein-1 (NAP-1) causes human basophil histamine release

Basophils from five of six human donors released histamine in response to neutrophil attractant/activation protein-1 (NAP-1). Histamine release by this protein was concentration-dependent over the range of 3 x 10(-7) M to 4 x 10(-6) M. At 4 x 10(-6) M, the mean agonist-induced release was 16 +/- 3% (SEM) of total basophil histamine. For the same basophil preparations, release by anti-IgE was 35 +/- 6%. The chemotactic protein did not cause release of histamine from basophils at 0 degrees C or in the presence of 10 mM EDTA. The time-course of histamine release was rapid; release was 43% of maximal after 30 s and maximal after 1 min of incubation. Thus, in addition to its previously characterized neutrophil chemotactic and activating properties, this protein activates human basophils.     

Desensitization of beta2-adrenoceptor and hypersensitization to phosphodiesterase inhibitors elicited by beta2-agonists in guinea pig eosinophils

BACKGROUND: Although the existence of functional beta(2)-adrenoceptor on eosinophils has been reported, the effects of desensitization of beta(2)-adrenoceptors on eosinophils have not been well documented. OBJECTIVE: The effects of desensitization of beta(2)-adrenoceptors on the degranulation of guinea pig eosinophils were investigated. METHODS: Guinea pig eosinophils were stimulated with the calcium ionophore A23187, and eosinophil peroxidase (EPO) release was determined. Changes in intracellular cyclic adenosine monophosphate (cAMP) levels were also measured. RESULTS: A23187-induced EPO release from guinea pig eosinophils was inhibited in a concentration-dependent manner by pretreatment for 5 minutes with fenoterol, clenbuterol, and salbutamol. Such effects of beta(2)-agonists were abolished by pretreatment with KT5720, an inhibitor of protein kinase A. Desensitization of the inhibitory effects of beta(2)-agonists was observed when the incubation time was prolonged. Fenoterol (10(-6) mol/L) induced almost complete desensitization after 120 minutes of incubation, whereas clenbuterol did not bring about significant desensitization. The inhibitory effects of fenoterol and clenbuterol on A23187-induced EPO release were correlated with increases in the intracellular cAMP levels evoked by either compound. After incubation of eosinophils with 10(-6) mol/L fenoterol for 120 minutes to induce complete desensitization of beta(2)-adrenoceptors, the inhibitory effects of theophylline and rolipram were increased by about 100-fold in the desensitized cells, although the effects of forskolin and dibutyryl cAMP were not affected by beta(2)-adrenoceptor desensitization. CONCLUSIONS: Prolonged incubation with beta(2)-agonists induced desensitization of beta(2)-adrenoceptors. Also, we postulated that hypersensitization of phosphodiesterase to its inhibitors occurs in beta(2)-adrenoceptor-desensitized guinea pig eosinophils.     

The beta2- and beta3-adrenoceptor-mediated relaxation induced by fenoterol in guinea pig taenia caecum.

Fenoterol, a beta2-adrenoceptor selective agonist, belongs to the arylethanolamine class. To understand the receptor subtypes responsible for beta-adrenoceptor-mediated relaxation of guinea pig taenia caecum, we investigated the effect of fenoterol. Fenoterol caused concentration-dependent relaxation of the guinea pig taenia caecum. Propranolol, bupranolol and butoxamine produced shifts of the concentration-response curve for fenoterol. Schild regression analyses carried out for propranolol, butoxamine and bupranolol against fenoterol gave pA2 values of 8.41, 6.33 and 8.44, respectively. However, in the presence of 3 x 10(-4) M atenolol, 10(-4) M butoxamine and 10(-6) M phentolamine to block the beta1-, beta2- and a-adrenoceptor effects, respectively, Schild regression analysis carried out for bupranolol against fenoterol gave pA2 values of 5.80. These results suggest that the relaxant response to fenoterol in the guinea pig taenia caecum is mediated by both the beta2- and the beta3-adrenoceptors.     

Role of protein kinase C in histamine release from human basophils

In this study, we investigated the role of calcium and phospholipid-dependent protein kinase (protein kinase C, PKC) in the modulation of histamine release from human basophils. A novel and potent inhibitor of PKC, K-252a, inhibited the release of histamine induced by anti-IgE in a dose-dependent manner with ID50 (the dose required for 50% inhibition of histamine release) of 2.2 x 10(-8) M. Histamine release stimulated with 12-0-tetradecanoyl-phorbol-13-acetate(TPA) was also suppressed by K-252a with maximal inhibition of 48.0 +/- 9.3% at 10(-7) M. In contrast, K-252a did not inhibit the release of histamine in response to FMLP and ionophore A23187. Another inhibitor of PKC, H-7, exhibited a dose-dependent inhibition of anti-IgE-induced histamine release with ID50 of 8.6 x 10(-4) M. H-8 and HA1004, which closely resemble H-7 in chemical structure but are less potent in inhibiting PKC, did not inhibit histamine release stimulated with anti-IgE, but rather enhanced the release at higher concentrations. These results strongly suggest that PKC activation plays a crucial role in the mediation of IgE-mediated histamine release from human basophils.     

Attenuation of antigen-induced bronchospasm by fenoterol in the guinea-pig

When guinea-pigs sensitized to ovalbumin were challenged with ovalbumin, the histamine concentrations in lung tissue decreased, whereas those in tracheal and heart tissues increased during the 15 min following challenge. Fenoterol (2.5 mg/kg, i.p.), administered 30 min prior to challenge, attenuated both the decrease and the increase in lung and tracheal histamine concentrations, respectively. The challenge-induced increase in heart histamine was also prevented. In the anaesthetized guinea-pig, a marked increase in intratracheal pressure (ITP) occurred on challenge. This was of longer latency than the increase in ITP induced by histamine and was consistent with a release process. Treatment of challenged guinea-pigs with fenoterol (2.5 mg/kg, i.v.) markedly reduced the increased ITP. However, when fenoterol was administered prior to challenge, the increase in ITP was abolished. These results indicate that there is an apparent relationship between the inhibition of histamine releasein vivo by fenoterol pretreatment and the greater inhibitory effect of fenoterol on antigen-induced increases in ITP when administered prophylactically.     

LY 186655, a phosphodiesterase inhibitor, inhibits histamine release from human basophils, lung and skin fragments.

LY 186655 (Tibenelast, Lilly) is a new phosphodiesterase inhibitor, not derived from the xanthine, possessing bronchodilating activity in animals. The aim of this work was to study the effect of LY 186655 and theophylline on histamine release from human leukocytes, skin and lung fragments. Histamine was measured using a spectrofluorometric method. Both drugs (3 x 10(-5)-3 x 10(-3) M) exhibited a dose-dependent inhibition on anti-IgE (1/2000)-induced histamine release from human leukocytes. At 3 x 10(-3) M, theophylline was significantly more effective than LY 186655 (mean inhibition 94 and 42%, respectively). On lung fragments, theophylline and LY 186655 (3 x 10(-5)-3 x 10(-3) M) caused strong and comparable inhibitory effects on anti-IgE (1/500)-induced histamine release with a mean inhibition reaching maximally 65%. Histamine release induced by compound 48/80 (1 mg/ml) on sliced human foreskin was reduced with both drugs (3 x 10(-3) M) by about 37%. We conclude that LY 186655 inhibits in vitro immunological histamine release from human lung and cutaneous mast cells as well as basophils with a similar pattern of activity to theophylline.     

Inhibition of human basophil leukotriene release by antiinflammatory steroids

We have previously shown that 24-hour culture of human basophils with the antiinflammatory steroid dexamethasone produces an inhibition of the IgE-dependent release of histamine. In contrast, similar treatment of purified human lung mast cells does not inhibit the subsequent release of either histamine, prostaglandin D2, or leukotriene (LT) C4. We now show that incubation of mixed leukocytes for 24 h with 10(-7) M dexamethasone produces an inhibition of anti-IgE-induced basophil LTC4 release as detected by radioimmunoassay. In three experiments, control (CON) and dexamethasone (10(-7) M; DEX)-treated cells were challenged with 0.01, 0.03 and 0.1 micrograms/ml of anti-IgE, and histamine and LTC4 were monitored. LTC4 release (ng LTC4/micrograms total cell histamine) from cells stimulated with anti-IgE was: 0.01 micrograms/ml anti-IgE, 6.9 +/- 4, 0.3 +/- 0.1 (CON, DEX); 0.03 micrograms/ml anti-IgE, 13.8 +/- 4.7, 0.9 +/- 0.5; 0.1 micrograms/ml anti-IgE, 19.5 +/- 2.3, 4.9 +/- 1.2. Histamine release was inhibited by 50-75% by treatment with DEX in these experiments. Dose-response studies (n = 4) indicate that the inhibitory actions of DEX on LTC4 release occur in the range of 10(-10) to 10(-7) M. The concentration of DEX at which LTC4 release was inhibited by 50% (IC50) was approximately 2 X 10(-9) M. Another glucocorticoid (betamethasone) inhibited LTC4 release, while the nonglucocorticoids tetrahydrocortisone and beta-estradiol were inactive. High performance liquid chromatography (HPLC) analysis (coupled with RIA) indicated that the relative proportions of LTC4, LTD4, and LTE4 did not differ in supernatants from CON- and DEX-treated, anti-IgE-challenged cells.(ABSTRACT TRUNCATED AT 250 WORDS)     

Regulation of human basophil activation; the role of Na+ and Ca2+ in IL-3-induced potentiation of IgE-mediated histamine release from human basophils.

The release of mediators from human basophils is strongly enhanced by IL-3. However, the signalling pathways of IL-3 are poorly defined in these cells. Since external Ca2+ and Na+ play important regulating roles in histamine release, the possibility that these cations could be involved in the potentiation by IL-3 of the anti-IgE-induced histamine release from human basophils was considered, and it was observed that: (i) IL-3 dramatically decreased the external Ca2+ requirement for IgE-mediated histamine release. However, histamine release from IL-3-treated basophils became only partially independent of external Ca2+, since addition of EGTA in the external medium abolished the effect of IL-3; (ii) decreasing Na+ influx by lowering external Na+ concentration in isosmotic medium inhibited the potentiating effect of IL-3 on IgE-mediated release; (iii) amiloride, an inhibitor of Na+/Ca2+ and Na+/H+ exchanges, and its derivative, benzamil, more specific for Na+/Ca2+ exchanges, inhibited the release potentiated by IL-3. In contrast, the amiloride derivative 5-(N,N-dimethyl)-amiloride, more specific for Na+/H+ exchanges, slightly increased the IL-3-enhanced release. Thus, the decreased requirement for external Ca2+ and the dependence on external Na+, taken with the effect of the Na+/Ca2+ exchange inhibitors, suggest that Na+/Ca2+ exchanges are involved in the IL-3-induced enhancement of IgE-mediated human basophil histamine release.     

Activation of human basophils by staphylococcal protein A. I. The role of cyclic AMP, arachidonic acid metabolites, microtubules and microfilaments

Protein A from Staphylococcus aureus (Staph A) induces histamine secretion from human basophil leucocytes in the concentration range 10(-4) - 10 micrograms/ml. This reaction has great similarities to that of antigen or anti-IgE-induced release. It is characterized by a two stage reaction, requires extracellular calcium and is optimal at 37 degrees C. The rate of release is similar to that of IgE-mediated reactions. Histamine release induced by Staph A is inhibited by metabolic inhibitors, drugs which increase intracellular cyclic AMP levels, inhibitors of lipoxygenase pathways and a phospholipase A2 inhibitor. D2O and cytochalasin B which affect microtubules and microfilaments respectively, enhance histamine release induced by Staph A. These results suggest that Staph A-induced release is modulated by intracellular cyclic AMP, arachidonic acid metabolites, requires energy and is enhanced by the disruption of microfilaments and stabilization of microtubules.     

Effect of interleukin 2 on basophil histamine release

Accumulating evidence suggests a link between immediate hypersensitivity and cellular immunity. In this study, we examined the effect of interleukin 2 (IL-2) on basophil histamine release. Histamine-releasing activity of IL-2 was very weak with % histamine release of 2.9 +/- 1.3 (mean +/- SEM, n = 9) at 1:12 dilution. IL-2 at 1:1200 dilution slightly inhibited anti-IgE-induced histamine release by 22.4 +/- 18.6% (P greater than 0.05). There was a significant potentiation of release at 1:12 dilution of IL-2 with % enhancement of 78.7 +/- 42.2 (P less than 0.05). IL-2 enhanced the calcium ionophore A23187-induced histamine release in a dose-dependent fashion. IL-2 at 1:12 dilution significantly potentiated release by 28.8 +/- 6.3% (P less than 0.05). There was a slight suppression of formyl-methionyl-leucyl-phenylalanine (FMLP)-induced histamine release at 1:1200 dilution with % inhibition of 23.4 +/- 7.4 (P greater than 0.05). At 1:12 dilution, IL-2 significantly potentiated FMLP-induced release by 73.7 +/- 41.6% (P less than 0.05). Recombinant IL-2 (RIL-2) augmented anti-IgE-induced histamine release with a significant enhancement at 200 units/ml. Conventional IL-2 was more potent than RIL-2 in enhancing release. These results indicate that IL-2 enhances basophil histamine release and some part of the effect of IL-2 on basophils is derived from other factors contained in conventional IL-2.     

Fenoterol inhibits superoxide anion generation by human polymorphonuclear leukocytes via beta-adrenoceptor-dependent and -independent mechanisms.

BACKGROUND: Beta2-adrenoceptor agonists, used widely as bronchodilator in treating bronchial asthma, may have anti-inflammatory activity. OBJECTIVE: We examined whether various widely prescribed beta2-adrenoceptor agonists differ in anti-inflammatory mechanisms. METHODS: We investigated effects of these drugs on superoxide anion generation by stimulated human polymorphonuclear leukocytes in vitro using chemiluminescence. RESULTS: At high concentrations, fenoterol significantly inhibited both N-formylmethionyl-leucyl-phenylalanine- and phorbol myristate acetate-induced superoxide generation by neutrophils. In contrast, salbutamol or procaterol partially inhibited generation with the former stimulus but not the latter. Inhibition by salbutamol or procaterol was completely reversed by either propranolol, a nonselective beta-adrenoceptor antagonist, or ICI-118551, a beta2-adrenoceptor-selective antagonist. In contrast, the effect of fenoterol at concentrations exceeding 10(-6) M against superoxide generation with the former stimulus was only partially reversed by antagonists, and the effect of high concentrations of fenoterol against generation with the latter stimulus was not reversed. No drugs scavenged superoxide at the highest concentration used (10(-5) M). CONCLUSIONS: Fenoterol at high concentrations has an inhibitory effect on superoxide generation that includes a component not mediated via beta2-adrenoceptors. Direct inhibition at or downstream from protein kinase C may be involved.     

Influenza A virus enhances basophil histamine release and the enhancement is abolished by carbohydrates

Basophil histamine release was studied in leukocyte suspensions from normal individuals and from patients allergic to house dust mite or birch pollen. Mediator release caused by IgE-mediated reactions was examined by stimulating the cells with anti-IgE or specific antigens, and the calcium ionophore A23187 was used for a non-immunological histamine release. In all experiments influenza A virus caused a synergic enhancement of the mediator release and the potentiation was abolished by galactose (10(-7) to 10(-6) M) and by 10(-6) to 10(-5) M of N-acetylglucosamine, alpha-methyl-D-glucoside, alpha-methyl-D-mannoside, N-acetylneuraminic acid and lactose, but not by glucose. Wash-out experiments show that the sugars prevent the aggravation of mediator release by a binding of sugar to the basophil cell membrane, thereby causing a blockade of binding sites responsible for the potentiating effect of virus.     

Effect of misoprostol on the secretion of histamine from basophils of whole blood.

BACKGROUND: Misoprostol (MSP), the synthetic prostaglandin E1 (PGE1) analog, possesses multifunctional features, including modulating some inflammatory aspects of immune and allergic disorders. OBJECTIVES: To investigate the effect of MSP on histamine release (HR) from basophils of whole blood using anti-IgE, specific allergens, and calcium ionophore. METHODS: The study was performed using the automated glass fiber-based whole blood leukocyte histamine release test (LHRT). RESULTS: Very low concentrations of MSP produced a marked inhibition of HR induced with anti-IgE. Maximum inhibition was observed at 10-9 M. It was also shown that the levels of HR inhibition with MSP varied at different incubation times. The greatest inhibition of HR was noted at 1 to 2 hours of incubation at MSP concentrations of 10-8 and 10-9 M, respectively. Incubation of blood from allergic patients at the optimal MSP concentration and optimal elapsed time (2 hours) resulted in significant reductions of allergen-specific HR induced by both Timothy pollen grass allergen and D.pteronissinus. Incubation of blood with varying concentrations of MSP and subsequent stimulation with calcium ionophore A23187 also inhibited HR from basophils. In the latter case, the most effective concentrations of MSP ranged from 10-8 to 10-6 M. CONCLUSIONS: This study demonstrated that MSP can inhibit basophil HR indicating a potentially beneficial role of PGE1 analogs as pharmacotherapy for allergic diseases.     

Inhibition of IgE and compound 48/80-induced histamine release by lectins.

Lectins from Ricinus communis and Glycine max, as well as wheat germ agglutinin and concanavalin A, caused a dose-dependent release of histamine from mast cells present in the mixed peritoneal cells from the rat. In addition, histamine release in an IgE-mediated and a compound 48/80-mediated reaction was inhibited in cells which had been pretreated with these lectins. With concanavalin A and the R. communis lectin both effect were prevented by the addition of the appropriate monosaccharides to the incubations. However, the lectin-induced histamine release and the lectin-induced inhibition of subsequent IgE-mediated histamine release could be dissociated: thus L-rhamnose, a hexose not ordinarily found on mammalian cell membranes, a specifically inhibited histamine release which was caused by the lectin from R. communis without affecting the inhibition of IgE-mediated histamine release. Conversely, D-fucose, which also is not a constituent of cell membrane glycolipids or glycoproteins prevented the inhibition of IgE-mediated histamine release by this lectin without affecting the lectin-induced histamine release. Furthermore, the nominally galactose-specific lectins from Sophora japonica and Ulex europeus inhibited IgE-mediated histamine release while causing little if any histamine release themselves. High concentrations of the lectin from Lotus tetragonolobus failed to cause histamine release or to affect the IgE-mediated histamine release reaction. Based on the known structural specificity of these lectins and the amounts of the lectins which were required to demonstrate an effect, it was concluded that D-galactose, alpha-linked, intrachain D-glucose (or mannose), and N-acetylglucosamine residues but probably not N-acetyl-galactosamine or L-fucose residues in the glycolipids or glycoproteins of the mast cell membrane can play a role in the initiation of histamine release and in the desensitization of the cells to subsequent histamine release-inducing stimuli.     

Mouse IL-3 induces histamine release from mouse peritoneal mast cells.

In this study, we have attempted to determine whether mouse peritoneal mast cells released histamine in response to IL-3. Recombinant mouse (m)IL-3 induced histamine release from mouse peritoneal mast cells in a dose-dependent fashion. Histamine release did not occur in the absence of phosphatidyl serine (PS), and was dependent on PS concentrations. The release was 14.3 +/- 3.8 and 43.5 +/- 11.5% (mean +/- SEM, n = 5) at 1 nM IL-3 in the presence of 10 and 20 micrograms/ml of PS. Calcium was required for the response, and in the absence of calcium, significant histamine release was not observed. The kinetics were slower than those of anti-IgE-induced response. IL-3-induced histamine release reached a peak within 15 min, while that by anti-IgE reached 80% of the maximum in 3 min. Lower concentrations of IL-3, which failed to directly induce histamine release, did not enhance anti-IgE-induced histamine release. Other cytokines, including mIL-4, mIL-5, m-granulocyte-macrophage colony-stimulating factor, human (h)IL-1 alpha, hIL-1 beta and hIL-8, neither induced histamine release nor enhanced anti-IgE induced histamine release. IL-4 had no capacity to enhance IL-3-induced histamine release. These results suggest that locally produced IL-3 might modulate mast cell-related inflammation through histamine release from mast cells.