Dose-dependent Histamine Release Research Articles

Cisatracurium induces mast cell activation and pseudo-allergic reactions via MRGPRX2

BackgroundPseudo-allergic reactions occur when patients receive muscle relaxants during perioperative anesthesia. These reactions may result in a serious threat to the patient's life, particularly to a child's life. Cisatracurium, a relatively new NMBA, has resulted in bronchospasms and cardiovascular collapse. However, the mechanisms underlying the anaphylactoid reactions caused by cisatracurium have not been fully elucidated. MethodsIn the present study, the MRGPRX2-related pseudo-allergic reactions induced by cisatracurium were investigated using hindpaw swelling and extravasation assays in vivo and mast cell degranulation assays. ResultsCisatracurium caused anaphylactoid reactions in wild-type mice. However, cisatracurium did not induce a similar phenomenon in KitW-sh/W-sh mice. Furthermore, mast cell-related G protein-coupled receptor B2-knockout mice did not display an inflammatory response upon treatment with cisatracurium. Cisatracurium induced LAD2 cell degranulation, leading to the dose-dependent release of β-hexosaminidase, histamine and TNF-α. However, cisatracurium only induced the release of low levels of these mediator LAD2 cells transfected with MRGPRX2 siRNA. Cisatracurium also stimulated intracellular Ca2+ influx in MRGPRX2-HEK293 cells compared with that in NC-HKE293 cells. Interestingly, cytokine release was not observed in LAD2 cells even with high dose of cisatracurium. ConclusionsCisatracurium activated MRGPRX2 and triggered mast cell degranulation, leading to anaphylactoid reactions. Therefore, strategies targeting MRGPRX2 might potentially block cisatracurium-induced pseudo-allergic reactions.

Histamine metabolism and transport are deranged in human keratinocytes in oral lichen planus.

Recent reports have indicated that nonimmune cells can produce low concentrations of histamine. This observation, together with the discovery of the high-affinity histamine H4 receptor (H4 R), has added additional layers of complexity to our understanding of histamine signalling. Human oral keratinocytes (HOKs) possess a uniform H4 R pattern, which is deranged in oral lichen planus (OLP). To investigate histamine metabolism and transport in HOKs of healthy controls and patients with OLP. Tissue sections and cultured primary HOKs were studied using immunostaining, quantitative real-time polymerase chain reaction and confocal microscopy. Histamine levels were analysed using high-performance liquid chromatography. l-histidine decarboxylase (HDC) and organic cation transporter (OCT)3 were increased in mRNA and protein levels in patients with OLP compared with controls. In contrast, histamine N-methyltransferase (HNMT) immunoreactivity was decreased in OLP. OCT1/OCT2 and diamine oxidase were not detectable in either tissue sections or in HOKs. Immunolocalization of HDC and OCT3 in HOKs revealed moderate-to-high expression within cytoplasm and cell boundaries. Stimulation with lipopolysaccharide (LPS) or interferon-γ upregulated HDC-gene transcript in HOKs, whereas this was downregulated with high histamine concentration and tumour necrosis factor-α. LPS induced a dose-dependent release of low histamine in HOKs, while high histamine concentration downregulated epithelial adhesion proteins. HOKs are histamine-producing cells. They release histamine via OCT3 channels in concentrations too low to activate the classical low-affinity H1 R and H2 R, but high enough to stimulate the high-affinity H4 R in autocrine and paracrine modes. The substantially deranged histamine metabolism and transport in OLP could, in part, contribute to the disease pathogenesis.

Identification of a Neuronal Receptor Controlling Anaphylaxis.

Allergic reactions can in severe cases induce a state of circulatory shock referred to as anaphylaxis. Histamine, the primary mediator of this condition, is released from immune cells, and, therefore, anaphylaxis has so far been considered an immune system disorder. However, we here show that the glutamatergic receptor mGluR7, expressed on a subpopulation of both peripheral and spinal cord neurons, controls histamine-induced communication through calcium-dependent autoinhibition with implications for anaphylaxis. Genetic ablation of mGluR7, and thus altered regulation of histamine-sensing neurons, caused an anaphylaxis-like state in mGluR7(-/-) mice, which could be reversed by antagonizing signaling between neurons and mast cells but not by antagonizing a central itch pathway. Our findings demonstrate the vital role of nervous system control by mGluR7 in anaphylaxis and open up possibilities for preventive strategies for this life-threatening condition.

Purification and IgE-binding properties of soybean β-conglycinin subunits

The purpose of this study was to purify soybean β-conglycinin subunits and analyze their IgE-binding properties with IgE immunoblotting and their response in a basophil histamine release test. The method presented in this paper offers an effective procedure to purify β-conglycinin subunits with higher yield and purity compared with previous methods by using a combination of ion exchange and metal chelate affinity chromatography. Beginning with a column load of 600mg β-conglycinin, the new method yielded 100.4mg of protein containing 96.7% α subunit, 97.0mg of protein containing 91.6% α′ subunit and 89.4mg of protein containing 96.1% β subunit. All of the purified subunits of β-conglycinin reacted with IgE from sera of soybean-allergic patients and induced dose-dependent histamine release from basophils from these patients, suggesting that purified α, α′, and β subunits of β-conglycinin retained allergenic activity and could be used for in vitro and in vivo diagnosis of soybean-induced food allergy.

TRPM8 mediates cold and menthol allergies associated with mast cell activation

Exposure to low temperatures often causes allergic responses or urticaria. Similarly, menthol, a common food additive is also known to cause urticaria, asthma, and rhinitis. However, despite the obvious clinical implications, the molecular mechanisms responsible for inducing allergic responses to low temperatures and menthol have not been determined. Because a non-selective cation channel, transient receptor potential subtype M8 (TRPM8) is activated by cold and menthol, we hypothesized that this channel mediates cold- and menthol-induced histamine release in mast cells. Here, we report that TRPM8 is expressed in the basophilic leukemia mast cell line, RBL-2H3, and that exposure to menthol or low temperatures induced Ca 2+ influx in RBL-2H3 cells, which was reversed by a TRPM8 blocker. Furthermore, menthol, a TRPM8 agonist, induced the dose-dependent release of histamine from RBL-2H3 cells. When TRPM8 transcripts were reduced by siRNA (small interfering RNA), menthol- and cold-induced Ca 2+ influx and histamine release were significantly reduced. In addition, subcutaneous injection of menthol evoked scratching, a typical histamine-induced response which was reversed by a TRPM8 blocker. Thus, our findings indicate that TRPM8 mediates the menthol- and cold-induced allergic responses of mast cells, and suggest that TRPM8 antagonists be viewed as potential treatments for cold- and menthol-induced allergies.

Activation of human tonsil and skin mast cells by agonists of proteinase activated receptor-2

Aim: To investigate the effects of the agonists of proteinase activated receptor (PAR)‐2, and histamine on degranulation of human mast cells. Methods: Human mast cells were enzymatically dispersed from tonsil and skin tissues. The dispersed cells were then cultured with various stimuli, and tryptase and histamine levels in cell supernatants collected from challenge tubes were measured. Results: PAR‐2 agonist peptide SLIGKV provoked a dose‐dependent release of histamine from skin mast cells. It also induced tryptase release from tonsil mast cells. tc‐LIGRLO appeared less potent than SLIGKV in induction of release of histamine and tryptase. Trypsin was able to induce a “bell” shape increase in tryptase release from tonsil mast cells. It was also able to induce a dose‐dependent release of histamine from both tonsil and skin mast cells. The actions of trypsin on mast cells were inhibited by soy bean trypsin inhibitor (SBTI) or α1‐antitrypsin (α1‐AT). Time course study revealed that both stimulated tryptase or histamine release initiated within 10 s and reached their peak release between 4 and 6 min. Pretreatment of cells with metabolic inhibitors or pertussis toxin reduced the ability of mast cells to release tryptase or histamine. Conclusion: It was demonstrated that the in vitro tryptase release properties of human tonsil and skin mast cells suggested a novel type of mast cell heterogeneity. The activation of mast cells by PAR‐2 agonists indicated a self‐amplification mechanism of mast cell degranulation.

Activation of human lung mast cells by monomeric immunoglobulin E

The mechanism of chronic mast cell activation in asthma is unclear. Monomeric immunoglobulin (Ig)E in the absence of allergen induces mediator release from rodent mast cells, indicating a possible role for IgE in the continued activation of mast cells within the asthmatic bronchial mucosa. In this study it was investigated whether monomeric IgE induces Ca2+ influx and mediator release from human lung mast cells (HLMC). Purified HLMC were cultured for 4 weeks and then exposed to monomeric human myeloma IgE. Ratiometric Ca2+ imaging was performed on single fura-2-loaded cells. Histamine release was measured by radioenzymatic assay; leukotriene C4 (LTC4) and interleukin (IL)-8 were measured by ELISA. At concentrations experienced in vivo, monomeric IgE induced dose-dependent histamine release, LTC4 production and IL-8 synthesis. This was associated with a rise in cytosolic free Ca2+. Enhanced histamine release was still evident 1 week after initial exposure to IgE suggesting that continued exposure maintains enhanced secretion. Monomeric immunoglobulin E alone activates cultured human lung mast cells initiating Ca2+ influx, degranulation, arachidonic acid metabolism and cytokine synthesis. These findings support the hypothesis that immunoglobulin E loading of mast cells within the asthmatic airway contributes to the disordered airway physiology of this disease.

Induction of tryptase and histamine release from human colon mast cells by IgE dependent or independent mechanisms.

To investigate the tryptase and histamine release ability of human colon mast cells upon IgE dependent or independent activation and the potential mechanisms. Enzymatically dispersed cells from human colons were challenged with anti-IgE or calcium ionophore A23187, and the cell supernatants after challenge were collected. Both concentration dependent and time course studies with anti-IgE or calcium ionophore A23187 were performed. Tryptase release was determined with a sandwich ELISA procedure and histamine release was measured using a glass fibre-based fluorometric assay. Both anti-IgE and calcium ionophore were able to induce dose dependent release of histamine from colon mast cells with up to approximately 60% and 25% net histamine release being achieved with 1 microg/mL calcium ionophore and 10 microg/mL anti-IgE, respectively. Dose dependent release of tryptase was also observed with up to approximately 19 ng/mL and 21 ng/mL release of tryptase being achieved with 10 microg/mL anti-IgE and 1 microg/mL calcium ionophore, respectively. Time course study revealed that both tryptase and histamine release from colon mast cells stimulated by anti-IgE initiated within 10 sec and reached their maximum release at 6 min following challenge. Pretreatment of cells with metabolic inhibitors abolished the actions of anti-IgE as well as calcium ionophore. Tryptase and histamine release, particularly that induced by calcium ionophore was inhibited by pretreatment of cells with pertussis toxin. Both anti-IgE and calcium ionophore are able to induce significant release of tryptase and histamine from colon mast cells, indicating that this cell type is likely to contribute to the pathogenesis of colitis and other mast cell associated intestinal diseases.

Severe oral allergy syndrome and anaphylactic reactions caused by a Bet v 1– related PR-10 protein in soybean, SAM22

Background: Anaphylactic reactions to soy products have been attributed to stable class 1 food allergens. Objective: IgE- mediated reactions to a soy- containing dietary food product in patients allergic to birch pollen were investigated. Methods: Detailed case histories were taken from 20 patients. Their sera were analyzed for IgE (UniCAP) specific for birch, grass, mugwort, the recombinant birch allergens rBet v 1 and rBet v2, and soy protein. Extracts from birch pollen, soy isolate, rBet v 1, and the recombinant PR-10 soy protein rSAM22 were coupled to paper disks or nitrocellulose for IgE measurements (enzyme allergosorbent test) or Western blot analysis. Enzyme allergosorbent testing, Western blot inhibition, and histamine release studies were performed with the same allergens. Results: Most patients (17/20) experienced facial, oropharyngeal, and/or systemic allergic symptoms within 20 minutes after ingesting the soy product for the first time. Birch pollen allergy (16/20) was common, along with oral allergy syndrome to apple (12/20) or hazelnut (11/20). IgE levels to birch and Bet v 1 but not to other inhalants were high in 18 of 20 patients. Significant IgE binding to rSAM22 occurred in 17 of 20 patients. Blot experiments with the soy isolate revealed IgE- binding bands at 17 kd (15/20), 22 kd (1/20), and 35 to 38 kd (2/20); the former was inhibited by preincubation of the sera with rBet v 1 or rSAM22. Birch extract and soy isolate, rBet v 1, and rSAM22 induced dose-dependent histamine release in the nanomolar range. Conclusion: Immediate-type allergic symptoms in patients with birch pollen allergy after ingestion of soy protein–containing food items can result from cross- reactivity of Bet v 1 – specific IgE to homologous pathogenesis-related proteins, particularly the PR-10 protein SAM22. (J Allergy Clin Immunol 2002;110:797-804.)

Molecular and immunological characterization of a novel timothy grass (Phleum pratense) pollen allergen, Phl p 11.

Allergy to grass pollen is typically associated with serum IgE antibodies to group 1 and/or group 5 allergens, and additionally often to one or several less prominent allergens. Most of the grass pollen allergens identified to date have been characterized in detail by molecular, biochemical and immunological methods, timothy grass being one of the most thoroughly studied species. However, a 20-kDa allergen frequently recognized by IgE antibodies from grass pollen allergics has so far escaped cloning and molecular characterization. To clone and characterize the 20 kDa timothy grass pollen allergen Phl p 11. Phl p 11 cDNA was cloned by PCR techniques, utilizing N-terminal amino acid sequence obtained from the natural allergen. Phl p 11 was expressed as a soluble fusion protein in Escherichia coli, purified to homogeneity and used for serological analysis and to study Phl p 11 specific induction of histamine release from basophils and skin reactivity in sensitized and control subjects. Phl p 11 cDNA defined an acidic polypeptide of 15.8 kDa with homology to pollen proteins from a variety of plant species and to soybean trypsin inhibitor. The sequence contained one potential site for N-linked glycosylation. Serological analysis revealed that recombinant Phl p 11 shared epitopes for human IgE antibodies with the natural protein and bound serum IgE from 32% of grass pollen-sensitized subjects (n = 184). Purified recombinant Phl p 11 elicited skin reactions and dose-dependent histamine release from basophils of sensitized subjects, but not in non-allergic controls. As the first representative of group 11 grass pollen allergens, Phl p 11 has been cloned and produced as a recombinant protein showing allergenic activity. One-third of grass pollen-sensitized subjects showed specific IgE reactivity to recombinant Phl p 11, corresponding in magnitude to a significant proportion of specific IgE to grass pollen extract.

IgG-Mediated Histamine Release from Canine Mastocytoma-Derived Cells

Background: Recent data suggest that normal tissue mast cells can express functional receptors for IgG under certain conditions. However, little is known about IgG receptor expression and functional consequences in mast cell neoplasms. Methods: In this study, neoplastic mast cells were obtained from a dog with cutaneous mastocytoma (CM-MC) and from a dog with visceral mastocytoma (VI-MC). Both cell populations were characterized morphologically and functionally. Results: Most cells proliferated constantly in suspension without particular supplements. Doubling times of CM-MC and VI-MC were 52.2 and 27.5 h, respectively. Both cell types were sensitive to formalin fixation, did not contain heparin and were tryptase and chymase positive. Electron microscopy showed fine granules with electron-dense content in both cell populations. The total histamine content of CM-MC and VI-MC was 0.25 and 0.10 pg/cell, respectively. Calcium ionophore A23187 and substance P induced dose-dependent histamine release, whereas compound 48/80 had no effect. Most significantly, both cell types, when sensitized with monomeric dog IgG, released histamine upon stimulation by anti-dog IgG. Conclusions: Dog mastocytoma-derived cells may be useful to study the regulation of neoplastic mast cell growth and differentiation, as well as IgG receptor-mediated activation in neoplastic mast cells. Further research is required to clarify the pathophysiological significance of constitutive expression of IgG receptors in neoplastic (canine) mast cells.

The dose-dependent release of histamine from placental mast cells after administration of atrial natriuretic peptide.

The dose-dependent release of histamine from placental mast cells after administration of atrial natriuretic peptide.

α-Melanocyte Stimulating Hormone Acts as a Selective Inducer of Secretory Functions in Human Mast Cells

In the present study, we have investigated the pro-opiomelanocortin (POMC)-derived neuropeptide α-MSH for its ability to modulate activation of human mast cells. The in vitro ability of purified human skin mast cells to secrete various types of mast cell mediators was monitored in response to α-MSH at the mRNA and at the protein level. Picomolar concentrations of α-MSH induced a dose-dependent release of histamine from isolated human skin mast cells and from skin punch biopsies. However, no effect of α-MSH was seen regarding the expression of IL-1, IL-6, IL-8, TGF-β, and TNF-α. Melanocortin receptor MC-1 was identified at the transcriptional level by RT-PCR analysis but not at the protein level, whereas, in leukemic human mast cells (HMC-1), the mRNAs and the proteins for the MC-1 and MC-5 receptor were identified. These results suggest that α-MSH may selectively induce acute inflammary effects via secretion of histamine.

Histamine release from mast cells of EAE rats by Gi protein-dependent and IgE-dependent pathways.

We investigated both Gi protein-dependent and IgE-dependent pathways that control release of histamine by PMCs derived from EAE or Complete Freund's Adjuvant (CFA) immunized rats. The number and histamine content of MCs per rat were the same between normal and EAE rats. Activation of Gi pathway by substance P (SP), DSA, 48/80, and mastoparan resulted in a dose-dependent increase in release of histamine by PMCs in normal, EAE-, and CFA-immunized rats. In EAE and CFA rats, however, the induction was decreased by 10-20% compared to normal rats. The histamine release induced by MP was decreased at a concentration of 3 microM, but not at 10 microM in severe active EAE rats. Activation of the IgE pathway by MAM and concanavalin A (Con A) in the presence of phosphatidylserine led to dose-dependent histamine release in normal rats, and a 10-25% lower level of induction was observed in EAE rats. In CFA rats, the induction of histamine release was equivalent to normal rats. There was an increase in intracellular calcium stores following activation of both pathways in normal rats, whereas depletion of calcium stores by ryanodine reduced the level of induction by 48/80 and MP by 9-11% in normal rats. In EAE rats, 48/80, Con A, and MAM induced a smaller increase, but SP and MP induced larger or similar increases in calcium stores compared to normal rats. It was unlikely that the calcium stores of the PMCs from EAE rats were depleted, because MP stimulated calcium movement subsequent to the release of histamine. These results suggested that the Gi pathway may not be correlated to clinical manifestation of EAE, but cold be involved in the inflammatory process, and that the IgE pathway is better associated with clinical symptoms of EAE and may be more directly related to disease outcome.

The identification and characterization of umbilical cord blood-derived human basophils

Cross-linking allergen-specific immunoglobin E on human peripheral blood basophils results in the release of histamine and other inflammatory mediators that initiate allergy and asthma. The signaling pathways leading from IgE binding to mediator release have not been well established, mainly due to the difficulty in obtaining adequate numbers of highly purified basophils. It was the goal of this study to easily obtain Fc epsilonRI-positive human basophils in high yield and purity for studies of signal transduction pathways. We describe an in vitro culture system in which pulsing normal human cord blood leukocytes with interleukin-3 (IL-3) for 3-4 h followed by incubation in medium with fetal bovine serum generates a cell population that is predominately Fc epsilonRI positive between 14 and 28 days of culture. These cells resemble peripheral blood basophils when examined by light and electron microscopy. Like normal blood basophils, they express the integrins, CD11b, CD18, CD29, and CD49d. A majority of the IL-3-pulsed cells also express a marker recognized by the basophil-specific antibody, 2D7. Fc epsilonRI cross-linking results in a time and dose-dependent release of histamine. Fc epsilonRI cross-linking also stimulates protein-tyrosine phosphorylation, thought to be the first event leading to the IgE-mediated activation of peripheral blood basophils. These studies establish cord blood as an accessible source from which basophil-like cells can be developed to examine Fc epsilonRI-mediated signal transduction.

Effect of radiographic contrast media on histamine release from human mast cells and basophils.

Radiographic contrast media (RCM) cause histamine-dependent allergic-like reactions. The direct effects of diatrizoate (high osmolar ionic monomer), ioxaglate (low osmolar ionic dimer), iopromide (low osmolar non ionic monomer) and iotrolan (iso-osmolar non ionic dimer) at the concentration of 200 mgI ml-1 (60 min exposure) on the release of histamine from human basophils, human lung mast cells (HLMC), and human skin mast cells (HSMC) were investigated. Diatrizoate induced 48 +/- 4% histamine release in basophils, 15 +/- 3% in HLMC and 25 +/- 6% in HSMC. The remaining RCM were relatively ineffective activators of histamine release in both HLMC and HSMC (ioxaglate 4 +/- 1% and 4 +/- 1%, iopromide 5 +/- 1% and 7 +/- 2%, iotrolan 7 +/- 2% and 10 +/- 3%, respectively). Both iotrolan and ioxaglate were effective in basophils inducing 21 +/- 3% and 24 +/- 6% histamine release, respectively, whereas iopromide was relatively ineffective (7 +/- 4%). Diatrizoate induced histamine release from all three cell types with optimal levels of histamine release after a 2-4 h incubation although significant levels occurred within 15 min. Dose-dependent histamine release from HLMC occurred in all four types of RCM, the largest response (37 +/- 3%) being produced by diatrizoate. The effect of osmolality on histamine release was investigated using different concentrations of mannitol solutions (0.25, 0.5 and 1 M). Histamine release from HLMC, HSMC and basophils after 90 min exposure to mannitol (1 M) was 24 +/- 2% (p < 0.05), 9 +/- 3% (p = 0.06) and 49 +/- 1% (p < 0.05), respectively, suggesting that hyperosmolality per se can induce histamine release from basophils and mast cells. Diatrizoate-induced histamine release in all three cell types was significantly reduced by lowering the temperature to 0 degree C and partially attenuated by the metabolic inhibitors antimycin A (1 microM) and 2-deoxyglucose (5 mM), and by the omission of glucose from the buffer solution. Diatrizoate-induced histamine release was not dependent on extracellular calcium. These data suggest that diatrizoate induces histamine release at least in part by non-cytotoxic mechanisms.

Epigallocatechin gallate-induced histamine release in patients with green tea-induced asthma.

Epigallocatechin gallate is the causative agent of green tea-induced asthma. To determine whether an IgE-mediated mechanism plays a pathogenetic role in this disorder, we measured histamine release after in vitro exposure to epigallocatechin gallate. Subjects included eight patients (four men and four women) with green tea-induced asthma, who had been diagnosed by skin test and inhalation challenge, and eight controls (four asthmatic subjects with no previous exposure tea dust and four healthy volunteers). Heparinized whole blood samples were taken and incubated with epigallocatechin gallate at various concentrations (final concentration range, 0.003 to 300 micrograms/mL) for 30 minutes at 37 degrees C. After centrifugation, histamine was measured in the cell-free supernatants by radioimmunoassay. Histamine release was expressed as a percentage of total histamine. A result higher than 10% was considered positive. In one of the tea-sensitive patients, epigallocatechin gallate did not cause histamine release. Five of the other seven patients (71%) demonstrated a positive, dose-dependent histamine release to epigallocatechin gallate. In asthmatic and normal controls, histamine release was not observed at any epigallocatechin gallate concentration. Furthermore, a significant correlation was noted between the maximum percentage histamine release and the threshold epigallocatechin gallate concentration for intradermal skin testing. These results indicate that an IgE-mediated response is the basis for green tea-induced asthma.

Adriamycin-induced histamine release from heart tissue in vitro.

It has been proven that the anthracyclines induce an important, noncytotoxic histamine release from rat peritoneal mast cells. As mast cells derived from different tissues exhibit marked heterogeneity, the effect of Adriamycin in comparison with other antineoplastic agents was tested on fragments of the right heart auricle, which contain a great number of mast cells. In this experimental model, Adriamycin induced a dose-dependent histamine release that was significantly limited by the antiexocytotic drug sodium cromoglycate. The antineoplastic agents cisplatin and 5-fluorouracil, in contrast, did not provoke any comparable histamine release. In the formulation employed in clinical settings, paclitaxel was also capable of inducing a histamine release comparable with that of Adriamycin; the exocytotic activity, however, was also evident when the tissue fragments were treated with Cremophor EL alone, without the addition of paclitaxel, whereas treatment of samples with paclitaxel dissolved in ethanol did not induce any releasing action. These data thus suggest that the secretory activity should be ascribed to the solvent Cremophor EL and not to paclitaxel. The release of histamine induced by paclitaxel in Cremophor EL/ethanol was also limited by sodium cromoglycate. These results again indicate that histamine release from mast cells derived not only from the peritoneal cavity but also from the cardiac tissue could play a role in the cardiotoxicity of anthracyclines and of paclitaxel in the clinically employed formulation.

Gastrin Stimulates Histamine Release from the Isolated Pig Stomach

Background: Gastrin has been shown to give an immediate and dose-dependent histamine release preceding acid secretion in the totally isolated, vascularly perfused rat stomach. Methods: In the present study we prepared isolated, vascularly perfused stomachs taken from pigs and examined the effect of pentagastrin in a concentration of 520 pM on the histamine release to the vascular bed. Pentagastrin was given for three 5-min periods at 10-min intervals, and histamine was determined by a radioimmunoassay method. Results: Each pentagastrin dose resulted in stimulation of histamine release in the three pig stomachs examined. The various histamine concentrations increased to levels previously shown to stimulate aminopyrine accumulation in isolated pig parietal cells. Conclusion: The present study shows for the first time that gastrin induces histamine release to the vascular bed in the pig, as previously shown for the rat and dog.

High-Level Expression inEscherichia coliand Purification of Recombinant Plant Profilins: Comparison of IgE-Binding Capacity and Allergenic Activity

Because of their structural similarity and ubiquituous distribution as actin binding proteins, plant profilins represent important cross-reactive allergens for almost 20% of patients suffering from Type I allergy to pollen and other plant products. The cDNAs coding for three birch profilin variants (Tyr44, Glu47, and Asn47), timothy grass profilin, and three tobacco profilin isoforms (ntprof1-3) were expressed at high levels inEscherichia colias non-fusion proteins. The recombinant plant profilins were purified to homogeneity by poly (L-proline) affinity chromatography and showed comparable capacity to bind IgE-antibodies from profilin allergic patients. All recombinant plant profilins elicited dose-dependent histamine release from basophils of a profilin allergic patient and induced immediate type skin reactions. It is concluded that profilins from different plant species share IgE-epitopes and allergenic properties. Plant profilins therefore constitute a family of functional pan-allergens which may substitute each other for diagnosis and specific immunotherapy.