An automated fluorimetric assay for the rapid determination of histamine in biological fluids

Peptidomics and genomics analysis of novel antimicrobial peptides from the frog, Rana nigrovittata

Much attention has been paid on amphibian peptides for their wide-ranging pharmacological properties, clinical potential, and gene-encoded origin. More than 300 antimicrobial peptides (AMPs) from amphibians have been studied. Peptidomics and genomics analysis combined with functional test including microorganism killing, histamine-releasing, and mast cell degranulation was used to investigate antimicrobial peptide diversity. Thirty-four novel AMPs from skin secretions of Rana nigrovittata were identified in current work, and they belong to 9 families, including 6 novel families. Other three families are classified into rugosin, gaegurin, and temporin family of amphibian AMP, respectively. These AMPs share highly conserved preproregions including signal peptides and spacer acidic peptides, while greatly diversified on mature peptides structures. In this work, peptidomics combined with genomics analysis was confirmed to be an effective way to identify amphibian AMPs, especially novel families. Some AMPs reported here will provide leading molecules for designing novel antimicrobial agents.

Two novel antimicrobial peptides from centipede venoms

Centipede venoms are complex mixtures of biochemically and pharmacologically active components such as peptides and proteins. Very few are known about their pharmacological actions. The present work reports the structural and functional characterization of two antimicrobial peptides (scolopin 1 and -2) identified from centipede venoms of Scolopendra subspinipes mutilans by Sephadex gel filtration and reverse-phase high-performance liquid chromatography (RP-HPLC). The amino acid sequences of scolopin 1 and -2 were FLPKMSTKLRVPYRRGTKDYH and GILKKFMLHRGTKVYKMRTLSKRSH determined by Edman degradation and matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). Both scolopin 1 and -2 showed strong antimicrobial activities against tested microorganisms including Gram-positive/negative bacteria and fungi. They also showed moderate hemolytic activity against both human and rabbit red cells. This is the first report of antimicrobial peptides from centipedes.

Anti-infection peptidomics of amphibian skin

Peptidomics and genomics analyses were used to study an anti-infection array of peptides of amphibian skin. 372 cDNA sequences of antimicrobial peptides were characterized from a single individual skin of the frog Odorrana grahami that encode 107 novel antimicrobial peptides. This contribution almost triples the number of currently reported amphibian antimicrobial peptides. The peptides could be organized into 30 divergent groups, including 24 novel groups. The diversity in peptide coding cDNA sequences is, to our knowledge, the most extreme yet described for any animal. The patterns of diversification suggest that point mutations as well as insertion, deletion, and "shuffling" of oligonucleotide sequences were responsible for the diversity. The diversity of antimicrobial peptides may have resulted from the diversity of microorganisms. These diverse peptides exhibited both diverse secondary structure and "host defense" properties. Such extreme antimicrobial peptide diversity in a single amphibian species is amazing. This has led us to reconsider the strong capability of innate immunity and molecular genetics of amphibian ecological diversification and doubt the general opinion that 20-30 different antimicrobial peptides can protect an animal because of the relatively wide specificity of the peptide antibiotics. The antimicrobial mechanisms of O. grahami peptides were investigated. They exerted their antimicrobial functions by various means, including forming lamellar mesosome-like structures, peeling off the cell walls, forming pores, and inducing DNA condensation. With respect to the development of antibiotics, these peptides provide potential new templates to explore further.

Two families of antimicrobial peptides with multiple functions from skin of rufous-spotted torrent frog, Amolops loloensis

There are around 27 species of Amolops amphibian distributed in South-east of Asia. Seven antimicrobial peptides (AMPs) belonging to two different families were purified from skin of rufous-spotted torrent frog, Amolops loloensis, and designated brevinins-ALa, b, c, and d, and temporins-ALa, b, and c. The brevinins-AL family which is structurally related to brevinins-1 from skin secretions of the European frog, Rana brevipoda, is composed of 24 amino acids and has an intra-disulfide bridge at the C-terminus. The temporins-AL family, composed of 13 or 16 amino acid residues, is related with temporins from the skin secretions of R. temporaria. The findings of this study will facilitate the solutions to the taxonomic questions of the ranid genus Amolops and Staurois. In the work of this paper, both brevinins-ALb and temporin-Ma induced mast cell degranulation and histamine release, and had cytotoxic activity toward solid tumor cell line HepG(2). Brevinins-ALb also exerted strong hemolytic activity while temporin-Ma had no such activity.

The contribution of histamine to the action of bradykinin in the human nasal airway

Bradykinin, 10 to 1000 micrograms given by aerosol into the nasal cavity of normal, healthy volunteers, produced a dose-related increase of nasal airway resistance. Bradykinin also reduced the minimal nasal cross-sectional area (Amin), increased albumin release into nasal lavage fluid and increased the symptoms of nasal inflammation. Pretreatment with cetirizine (10 mg orally) reduced the fall in Amin induced by bradykinin, 300 micrograms, but not by bradykinin, 100 micrograms. Pre-treatment of the subjects with the H1 histamine receptor antgonist cetirizine (10 mg, orally) or terfenadine (60 mg, orally) 3 h before bradykinin administration caused significant reduction of the bradykinin-induced increase in nasal airway resistance in the upper range of bradykinin doses (300-1000 micrograms) but not in the lower range (10-100 micrograms). Cetirizine reduced the albumin release into the nasal airway and the symptoms induced by bradykinin, 1000 micrograms. Following nasal challenge with bradykinin 300 micrograms or 1000 micrograms, no increase could be detected in the histamine content of nasal lavage fluid. Isolated human nasal cells released histamine in response to bradykinin, 33 and 100 microM, anti-IgE and calcium ionophore, A23187. We conclude that the actions of bradykinin in the human nasal airway are, in part, accounted for by the release of histamine.

Some anti-allergic and anti-inflammatory actions of 2-N-carboxamidinonormianserin (FCC5)

The aims of these studies were to examine the effects of FCC5 (2-carboxamidino-1,2,3,4,10,14b-hexahydrodibenzo (c,f) pyrazino (1,2,-a) azepine HCl), an analogue of mianserin, on immediate type hypersensitivity reactions in-vitro. The actions of FCC5 were examined on the Schultz-Dale reaction of guinea-pig ileum and on histamine and leukotriene release from human- and guinea-pig-sensitized lung fragments. FCC5 (applied topically) was assessed for anti-inflammatory activity in-vivo against phorbol-12-myristate-13-acetate (PMA)-induced oedema in the mouse ear. FCC5 (IC50 = 0.17 microM) was a potent inhibitor of the Schultz-Dale reaction in-vitro, as assessed by a concentration-dependent attenuation of egg albumin-induced contractions of sensitized guinea-pig isolated ileum. Using human and guinea-pig isolated sensitized lung fragments, FCC5 (1-100 microM) attenuated antigen-induced release of sulphidopeptidoleukotrienes and histamine. FCC5 (50 micrograms topically) resembled mianserin and indomethacin in attenuating PMA-induced mouse ear inflammation. These properties together with previously published evidence of long lasting antihistamine properties in-vivo, suggest that FCC5 has therapeutic potential as an anti-allergic agent, especially in pathological conditions where an inflammatory component is present.

Serum histamine and the elicitation of murine contact sensitivity

We report that challenge of previously contact-sensitized mice results in a significant increase in the concentration of serum histamine. In an attempt to determine whether this phenomenon might form the basis of an alternative method for the evaluation of elicitation reactions in experimental contact sensitivity, we have compared challenge-induced increases in ear thickness with elevations in serum histamine. Challenge of sensitized mice revealed that both ear thickness changes and increases in the serum level of histamine were dependent upon the concentration of oxazolone used for sensitization. The kinetics of changes in serum histamine concentration were found to be biphasic, with a small increase measurable 2 h following challenge and the maximal response at 24 or 48 h. In contrast, increases in ear thickness were monophasic, although maximum responses were also observed at 24 h. It is concluded that, although they do not exactly parallel increases in ear thickness, changes in histamine concentration may provide a useful serological correlate of the challenge reaction in contact sensitivity.

Structural and secretory characteristics of bovine lung and skin mast cells: evidence for the existence of heterogeneity

We have examined cells dispersed enzymatically from three different sites in the bovine lung (tracheal mucosa, bronchial mucosa and parenchyma) and the skin, in order to ascertain whether the bovine model could be used to study mast cell heterogeneity. Histochemically there were two sub-populations of mast cells present in both lung and skin (on the basis of toluidine blue staining and the sensitivity to formalin fixation), but their proportions were similar in all sites studied. Skin mast cells contained approximately twice the amount of histamine than their counterparts in the lung (P less than 0.05). Functional heterogeneity was examined by in vitro release of histamine following secretagogue challenge. Calcium ionophore induced a substantial release of histamine; skin mast cells releasing significantly more histamine than any of the lung mast cells (at 10 microM ionophore, 37.1% and 20.7% net histamine release, respectively, P less than 0.05), although the time-course of release from the two tissues was similar. The neuropeptides vasoactive intestinal peptide and somatostatin induced a modest but statistically significant release of histamine from both skin and lung mast cells, whilst substance P only induced histamine secretion from skin mast cells. A range of other potential immunological and non-immunological secretagogues was unsuccessful in eliciting histamine release from mast cells in any of the tissues. We conclude that there were no convincing histochemical differences between mast cells from the sites examined in the lung or skin. Additionally, there was no discernable functional heterogeneity between mast cells within the lung, but functional differences were evident between mast cells of the bovine lung and skin. However, in the absence of a suitable immunological stimulus the bovine model cannot be regarded as a good model of mast cell heterogeneity.

Affinity-purified soluble Fc epsilon RII/CD23 derived from RPMI-8866 cells induces histamine release from human nasal polyp mast cells through a non-IgE-mediated mechanism

Soluble Fc epsilon RII/CD23 (IgE-binding factor) is released spontaneously from activated B cells and most EBV-immortalised B cell lines. We have purified soluble Fc epsilon RII/CD23 from culture supernatants of RPMI-8866 cells on an IgE Sepharose column, and studied its ability to release histamine from human nasal polyp mast cells. Soluble Fc epsilon RII/CD23 induces release of a significant amount of histamine from nasal polyp mast cells in a dose-dependent manner. IgE, and a monoclonal antibody specific for the soluble form of this receptor, were shown to neutralise this effect. It was found that soluble Fc epsilon RII/CD23 was still capable of triggering histamine release from nasal polyp mast cells from which IgE had been eluted by incubation in a low pH buffer, suggesting that a non-IgE mediated mechanism was responsible for this effect.

The determination of histamine in challenged human leukocyte preparations by high-performance liquid chromatography

A highly sensitive and rapid method was developed for the determination of histamine in challenged human leukocyte preparations by high-performance liquid chromatography. The assay is based on the Shore's OPT-reaction of the unpurified sample and on a specific separation of the derivate with analytical reversed phase phenyl column combined with spectrofluorometric detection. The detection limit of histamine by this method was 0.07 pmol (signal to noise ratio 2:1) and the within-day variation for peak height was 3.6% and for retention time 0.8%. A good linear standard curve ranging from 12.5 pg to 500 pg (0.07 pmol-2.7 pmol) was obtained with correlation coefficient of 0.998. The histamine release from human basophils in mixed leukocyte preparation was induced by the calcium ionophore A 23187. A concentration of 0.4 micrograms/ml ionophore was required for 50% histamine release with a Ca2(+)-concentration of 1.8 mmol/l. The measured total histamine content was 1.5 pg/basophil.

Immediate contact reactions to chemicals in the fragrance mix and a study of the quenching action of eugenol

In this study, the nature of non-immune immediate contact reactions (NIICR) produced by cinnamic aldehyde, benzoic acid and sorbic acid were investigated, with particular interest in the 'quenching' ability of eugenol. Three groups of human subjects were studied, and the guinea-pig ear was also used as a model of NIICR. Cinnamic aldehyde, benzoic acid and sorbic acid were all able to produce NIICR in the majority of subjects studied. There was a strong correlation between the susceptibility of each subject to each urticant, but no correlation between the susceptibility to NIICR and age, atopic status or tanning ability. Eugenol caused a reduction in NIICR induced by all three urticants. This 'quenching' effect was apparent even when the eugenol was applied up to 60 min prior to application of cinnamic aldehyde, and its effect was not eliminated by washing. In the guinea-pig-ear model, ear thickening was induced by all three urticants, and this response was inhibited by eugenol.

Platelet activating factor does not release histamine from human dispersed cutaneous mast cells

Histamine H1-antagonists inhibit the weal-and-flare responses to the intradermal injection of platelet activating factor (PAF) in humans, and PAF response is reduced in histamine-depleted skin sites. This indicates that mast cell histamine release is likely to be the mechanism of this response. We have therefore studied the interaction of PAF with cutaneous mast cells by observing whether it releases histamine directly from human dispersed foreskin mast cells, potentiates the activity of known mast cell stimulants or liberates histamine releasing factors (HRFs) from human platelets and leucocytes to release mast cell histamine by an indirect mechanism. At a concentration of 100 microM both PAF C18 and PAF C16 caused near maximal release (83.5 +/- 4.3% and 88.2 +/- 4.5% respectively) of the total histamine content of the cell. This release was not inhibited in the absence of extracellular Ca2+, by the lack of metabolic energy or in the presence of the PAF antagonists WEB 2086 (100 nM-3 microM) or BN 52021 (100 nM-10 microM). These results indicate a cytotoxic mechanism of histamine release by PAF 100 microM. PAF (10 nM-1 microM) failed to potentiate the mast cell-stimulating activity of anti-IgE, calcium ionophore A23187 or substance P and it did not induce the release of HRFs for skin mast cells when incubated with platelets and leucocytes in concentrations up to 1 microM.

Nedocromil sodium inhibits antigen-induced contraction of human lung parenchymal and bronchial strips, and the release of sulphidopeptide-leukotriene and histamine from human lung fragments

1. The effects of nedocromil sodium on antigen-induced release of sulphidopeptide-leukotrienes and histamine from passively sensitized fragments of human lung, and on antigen-induced contraction of sensitized strips of human lung parenchyma and bronchus, have been studied. 2. Nedocromil sodium 0.1 and 1 microM inhibited leukotriene release from fragments of human lung by 30% and 38% respectively, and histamine release by 43% for both concentrations, but 10 microM was ineffective. The lung fragments, which were passively sensitized to house dust mite, Dermataphagoides pteronyssinus, in control experiments released leukotrienes (6.58 +/- 0.12 nmol equiv. leukotriene C4 per g, n = 6) and histamine (10.3 +/- 1.8 of total tissue histamine, n = 5) when challenged with house dust mite extract. 3. Isolated strips of human lung parenchyma, passively sensitized to D. pteronyssinus, contracted when treated with house dust mite extract to a mean value of 40% of the maximal histamine response for each strip. Nedocromil sodium 0.1 and 1 microM inhibited these contractions by 50% and 70% of the control response, but 10 microM had no inhibitory effect. 4. Isolated rings from human bronchus, also passively sensitized to D. pteronyssinus, contracted when treated with house dust mite extract to a mean value of 86% of the maximal histamine response. Nedocromil sodium 1 microM, but not 0.1 or 10 microM, inhibited contractions by 48% of the control response. 5. The therapeutic effects of nedocromil sodium in allergic asthma may depend, partly, on its inhibition of antigen-induced release of leukotrienes and histamine in human lung and its consequent inhibition of antigen-induced contractions of parenchymal and bronchial tissue.

A comparison of the effects of chlorpromazine and more selective histamine and 5-hydroxytryptamine antagonists on human IgG synthesis in vitro

We have shown previously that chlorpromazine, a drug associated with immunological abnormalities in vivo, significantly potentiates pokeweed mitogen (PWM)-stimulated IgG synthesis by human peripheral blood mononuclear cells (PBMC) in culture. Chlorpromazine is a pharmacological antagonist of histamine and 5-hydroxytryptamine (5-HT) and thus may exert its immune-enhancing effects by competing with these amines for their respective receptors, which are known to be present on lymphocytes. In this report we show that histamine and 5-HT are present at micromolar concentrations in PBMC cultures. To examine the role of histamine and 5-HT in chlorpromazine-induced enhancement of IgG synthesis we incubated PWM-treated cells with a range of selective histamine and 5-HT antagonists, and with the amines added to cultures either alone or in combination with chlorpromazine. The H1 antagonists mepyramine and promethazine and the H2 antagonist cimetidine had no significant effect on IgG synthesis. The combined 5-HT1/5-HT2 antagonists methysergide and methiothepin also failed to modulate synthesis. Neither histamine nor 5-HT at concentrations up to 100 microM modulated IgG synthesis, nor did they abrogate the enhancement of IgG synthesis induced by chlorpromazine. We conclude that the modulation of IgG synthesis in vitro by chlorpromazine cannot be attributed to an interaction of this drug with lymphocyte receptors for histamine and 5-HT. Other possibilities for the mechanism of action of this drug on immune function are discussed.

The release of histamine from nasal polyp tissue and peripheral blood when challenged with antihuman IgE, house dust mite extract and mixed grass pollen extract and compared with positive skin tests

Nasal polyps are a condition of uncertain aetiology but are associated with diseases of the lower respiratory tract, in particular, asthma and cystic fibrosis. Asthma may be mediated by mast cell reactions and the commonest allergen to degranulate mast cells is house dust mite. Mast cells have been shown to be degranulated in nasal polyps. This study looks at thirty-six patients who had nasal polypectomy and of whom fourteen were asthmatic to see if histamine was released from polyp tissue and peripheral blood when they were challenged with antihuman IgE and extracts of house dust mite and mixed grass pollens. These results were compared with skin tests to these allergens. A release of above 15 per cent of the total histamine was considered positive. Eight patients released histamine from polyp tissue but only three patients released histamine with both anti IgE and allergen extracts. The release from blood compared well with positive skin tests (p greater than 0.05 corrected chi square). Although allergy may cause mast cell degranulation in polyp tissue, this study suggests that it is unlikely to be a common cause of nasal polyps.

Synergistic enhancement of histamine release from rat peritoneal mast cells by the phorbol ester 12-O-tetradecanoylphorbol 13-acetate is not reflected by corresponding changes in phospholipid turnover

In an attempt to elucidate further the relationship between changes in phospholipid metabolism in, and histamine secretion from, purified rat peritoneal mast cells, the effects of the phorbol diester 12-O-tetradecanoylphorbol 13-acetate (TPA) on these responses in stimulated and unstimulated cells was investigated. TPA caused a dose-dependent increase in the incorporation of 32PO4(3-) into the mast cell phospholipids; phosphatidic acid (PA) and phosphatidylcholine (PC), but not phosphatidylinositol (PI). TPA synergistically enhanced histamine release from cells stimulated by anti-immunoglobulin E (IgE) and the calcium ionophore A23187, reducing its ED50 from 150 nM to 40 nM, but did not alter histamine release from cells stimulated by compound 48/80. The effect of TPA on the changes in 32PO4(3-) incorporation into phospholipids associated with the above secretagogues did not, however, correlate well with the observed effects on histamine secretion induced by the same secretagogues. These observations are discussed in relation to the known effects of phorbol esters upon both secretory processes and phospholipid metabolism in other tissues.

Characterization of neuropeptide-induced histamine release from human dispersed skin mast cells

1. Human skin mast cells, unlike other human mast cells so far studied, released histamine in a concentration-related manner in response to substance P, vasoactive intestinal peptide (VIP) and somatostatin (1 microM to 30 microM). In contrast, eledoisin, physalaemin, neurokinin A, neurokinin B, calcitonin gene-related peptide (CGRP), neurotensin, bradykinin and Lys-bradykinin induced negligible histamine release. 2. The low histamine releasing activity of physalaemin, eledoisin, neurokinin A and neurokinin B relative to substance P suggests that the human skin mast cell activation site is distinct from the tachykinin NK-1, NK-2 or NK-3 receptors described in smooth muscle. 3. The relative potencies of substance P and its fragments SP2-11, SP3-11, SP4-11 and SP1-4 in releasing histamine from human skin mast cells suggests that both the basic N-terminal amino acids and the lipophilic C-terminal portion of substance P are essential for activity. 4. Peptide-induced histamine release, like that induced by compound 48/80, morphine and poly-L-lysine, is rapid, reaching completion in 10-20 s, is largely independent of extracellular calcium but requires intact glycolysis and oxidative phosphorylation. 5. The substance P analogue, [D-Pro4,D-Trp7,9,10] SP4-11 (SPA), not only reduced substance P-induced histamine release in a concentration-related manner but also inhibited that induced by VIP, somatostatin, compound 48/80, poly-L-lysine and morphine but not anti-IgE. 6. The similar characteristics of histamine release induced by substance P, VIP, somatostatin, compound 48/80, poly-L-lysine and morphine suggest that they share a common pathway of activation-secretion coupling distinct from that of IgE-dependent activation. Furthermore, the ability of human skin mast cells to respond to basic non-immunological stimuli including neuropeptides may reflect a specialised function for these cells.

Theophylline's inhibition of antigen-induced contraction of human parenchymal strips is independent of adenosine antagonism

The effects of theophylline, and adenosine antagonist, and enprofylline, reported to lack adenosine antagonism, were studied using antigen-induced contraction of sensitized human lung parenchymal strips. Cumulative addition of adenosine usually resulted in a small concentration-dependent contraction, which was antagonized by theophylline, 100 microM. Antigen-induced contraction was reduced by pretreatment with adenosine, 10 microM, but not by adenosine addition after antigen challenge. Dipyridamole, 2 microM, pretreatment did not change adenosine's effect. Theophylline, 100 microM, caused relaxation of the lung strips and reduced their response to antigen. It did not affect the response to adenosine. Enprofylline, 100 microM, caused a relaxation of parenchyma greater than that of theophylline. It reduced the contractile response to antigen and potentiated the reduction caused by adenosine. Thus, neither drug antagonized the effect of adenosine on antigen-induced contraction. Antigen-induced histamine release from the lung parenchymal strip was not modified by any of these drugs.

Analysis of the interaction between rat immunoglobulin E and rat mast cells using anti-peptide antibodies

Polyclonal antisera with pre-determined specificities for a range of rat IgE epitopes were produced by immunizing rabbits with KLH-conjugates of five different synthetic peptides representing sequences 378-396, 414-428, 491-503, 522-535 and 560-571 in the CH3 and CH4 domains of rat IgE. Each rabbit elicited peptide-specific antibodies which were capable of binding affinity-purified rat IgE (IR162) (titres 1/1000-1/10,000) and IgE in rat immunocytoma serum (IR162) either immobilized on microtitre-plates or in free-solution as assessed by ELISA. Heating a solution of rat IgE at 56 degrees C for 1 hr, a treatment known to abolish the cytophilic activity of rat IgE and also induce irreversible conformational changes in the CH3 and CH4 domains, resulted in enhanced binding of the immunoglobulin to antibodies directed against IgE sequences represented by two of the synthetic peptides 414-428 and 491-503, but not to the three other peptides. The five anti-peptide sera together with two previously studied antisera specific for rat IgE sequences 459-472 and 542-557 were tested in functional assays designed to investigate the mode of interaction between rat IgE and its receptor on rat mast cells. Each anti-peptide serum was capable of inhibiting the binding of IgE to mast cells and furthermore, able to initiate the secretion of histamine from cells sensitized with rat IgE in an "anti-IgE"-induced manner. In view of the evidence implicating the CH3 and/or CH4 domains as the location of the mast cell receptor-site on rat IgE, we propose a model to describe the mode of interaction between IgE and its mast cell receptor.

Inhibition of immunological and nonimmunological histamine release from human basophils by adenosine analogues that act at P-sites

2',5'-Dideoxyadenoside (DDA) inhibited both anti-IgE and ionophore A23187 induced histamine secretion from human basophils. Whereas DDA inhibited IgE-dependent histamine secretion when added at all times prior to challenge, release induced by A23187 was inhibited only with simultaneous addition of DDA and secretagogue. Dipyridamole, but not theophylline, abrogated DDA mediated inhibition of histamine release suggesting an intracellular mechanism of action of DDA. The observations that 2'-deoxyadenosine and 9-beta-D-arabinofuranosyladenine also inhibited release suggest that the its inhibitory effect was enhanced by manganese and reversed by islet activating protein from Bordetella pertussis suggest that DDA inhibits basophil histamine release by interacting with a guanine nucleotide binding protein which may be linked to either adenylate cyclase or other second messenger system(s).

Inhibition of mast cell sensitization in vitro by a human immunoglobulin epsilon-chain fragment synthesized in Escherichia coli

An immunoglobulin epsilon-chain fragment was synthesized in E. coli by cloning and expression of the gene coding for the second, third and fourth constant domains of the human IgE heavy chain. The bacterial CH2-4 polypeptide product was assembled by oxidation into a covalently linked dimeric epsilon-chain molecule presumably analogous to the Fc region of native IgE. This bacterial Fc epsilon preparation, within the concentration range 0.01-10 micrograms/ml, inhibited sensitization of human lung mast cells, determined as histamine released upon challenge with specific antigen. Monomer CH2-4 epsilon-chain polypeptide, prepared by reduction and alkylation of the active bacterial Fc epsilon fragment, was inactive as an inhibitor of sensitization. The molar potency of the active bacterial Fc epsilon product was approximately one fourth of that of native IgE. Since the bacterial Fc epsilon is nonglycosylated, carbohydrate does not make an essential contribution to the Fc receptor binding activity of IgE. These results show that a functionally active immunoglobulin molecule can be synthesized by gene cloning and expression in E. coli.

The effects of non-steroidal inhibitors of phospholipase A2 on leukotriene and histamine release from human and guinea-pig lung

The effects of chloroquine and mepacrine were determined on the release of slow reacting substances (leukotrienes) from lung fragments in vitro. These drugs have been shown in a variety of tissues to inhibit phospholipase A2, and thus to reduce the availability of arachidonate, which is a substrate for leukotriene biosynthesis. Leukotriene and histamine release from unsensitized human lung was stimulated by calcium ionophore A23187, and from actively sensitized guinea-pig lung, by ovalbumin. Chloroquine (10 microM and 100 microM) significantly inhibited leukotriene release in lung from both species, and at 100 microM also inhibited histamine release. Mepacrine (10 microM) inhibited leukotriene release in human lung and at 100 microM in guinea-pig lung. The effects of chloroquine (100 microM) on leukotriene release were counteracted by the presence of arachidonic acid (10 microM), which suggests that chloroquine had impaired the availability of arachidonate. It seems probable that chloroquine and mepacrine inhibit leukotriene release by inhibition of phospholipase A2 in lung.

The effect of methyltransferase inhibitors on histamine release from human dispersed lung mast cells activated with anti-human IgE and calcium ionophore A23187

Inhibitors of adenosylmethionine (AdoMet)-dependent methyltransferases reduce histamine release from enzymatically dispersed human lung mast cells activated with either anti-human IgE or calcium ionophore A23187. The IC25 values for adenosine and 3-deazaadenosine (DZA) inhibiting anti-IgE-induced histamine release were 395 microM and 301 microM respectively. The addition of homocysteine thiolactone (Hcy) potentiated the effects of adenosine and DZA, reducing their IC25 values to 32 microM and 10.5 microM respectively. The adenosine deaminase (adenosine aminohydrolase EC 3.5.4.4) inhibitors erythro-9-(2-hydroxy-3-nonyl)-adenine (EHNA) inhibited anti-IgE-induced histamine release with an IC50 of 162 microM. This inhibition was not potentiated by Hcy. The combination of DZA and Hcy effectively inhibited histamine release induced by concentrations of A23187 which released a similar amount of histamine to anti-IgE. However the combination was 17 times less potent against A23187-compared with anti-IgE-induced release. These observations suggest that AdoMet-dependent methyltransferases play an important role in IgE-dependent histamine release from human lung mast cells but their role in A23187-induced release is less clear.

Histamine and its release from nasal polyps: preliminary communication

Two hundred consecutive patients admitted for polypectomy had no evidence of an increased incidence of allergic disorders. Mast cell degranulation was found on transmission electron microscopy and this resulted in considerable quantities of histamine in polyp extracellular fluid (124-7300 ng/ml). RAST levels of allergen-specific IgE to house-dust mite and mixed-grass pollens were raised in 4 out of 28 cases in polyp fluid, and in only one matched serum. In vitro challenge of polyp tissue with allergen extract and anti-IgE suggested an IgE-mediated response in only 4 of 36 patients.

The effect of tartrazine on histamine release from rat peritoneal mast cells

The release of histamine from purified rat peritoneal mast cells induced by specific antigen (egg albumin), compound 48/80 and calcium ionophore A23187 was modified by tartrazine. Histamine release induced by 48/80 and antigen was inhibited by the presence of 10(-5) to 10(-2)M tartrazine. The inhibitory effect on egg albumin induced histamine release was maximal when the tartrazine was added simultaneously with egg albumin, and was reduced by increased preincubation of the cells with tartrazine. Tartrazine had a small inhibitory effect on ionophore induced release at high concentrations, but augmented histamine release at tartrazine concentrations of 10(-3) and 10(-4)M. Augmentation of ionophore induced release was maximal at between 0-5 min preincubation of the cells with tartrazine.

Safety evaluation of thaumatin (Talin protein)

Thaumatin, the sweet proteinaceous extract of the arils of Thaumatococcus daniellii (Benth.) has been studied for its subacute toxicity in rats and dogs and its ability to produce anaphylactic antibodies following oral administration to rats and normal human subjects. Thaumatin was readily digested prior to absorption in rats and no adverse effects resulted from its continuous administration to rats and dogs at dietary concentrations of 0, 0.3, 1.0 and 3.0% for 13 wk. It was not teratogenic when administered orally to rats at 0, 200, 600 and 2000 mg/kg body weight/day from day 6 to 15 of gestation and was without effect on the incidence of dominant lethal mutations when administered on five consecutive days to male mice at 200 and 2000 mg/kg/day. The lack of mutagenic potential was confirmed in bacterial mutagenic assays with Salmonella typhimurium (strains TA1535, TA1537, TA1538, TA98 and TA100) and Escherichia coli WP2, at levels of addition of 0.05-50 mg/plate. In rats, thaumatin was found to be a weak sensitizer, comparable with egg albumen, when administered systemically but to be inactive when administered orally. Prick testing of laboratory personnel who had been intermittently exposed by inhalation to thaumatin for periods up to 7 yr showed that 9.3% (13/140) responded positively to commercial thaumatin, while 30.7% were positive to Dermatophagoides pteronyssinus (house dust mite). None of the subjects who gave a positive skin reaction to commercial thaumatin responded to the plant components remaining after removal of the specific sweet Thaumatin proteins. Challenge tests in man did not demonstrate any oral sensitization. The results indicate that thaumatin when used as a flavour modifier and extender, and partial sweetener, is unlikely to be hazardous at the anticipated level of consumption.

Effect of fenoterol on immunological release of leukotrienes and histamine from human lung in vitro: selective antagonism by beta-adrenoceptor antagonists

The inhibitory effects of fenoterol, a beta 2-adrenoceptor agonist, on the release of SRS-A leukotrienes and histamine from chopped human lung tissue were measured and selective beta-adrenoceptor antagonists used to investigate the nature of the receptors involved. Fenoterol 0.01-1.0 microM inhibited the antigen-induced release of SRS-A and histamine, but not the release induced by the calcium ionophore A23187. Propranolol 0.1 and 1.0 microM and butoxamine 10 and 100 microM significantly antagonized the effects of fenoterol 0.1 microM on SRS-A and histamine at concentrations which affect (beta 2-adrenoceptors, while atenolol 0.1 to 10 microM showed no antagonism at concentrations which affect beta 1-adrenoceptors. These results suggest that adrenoceptors in human lung which modulate the immunological release of SRS-A leukotrienes are of the beta 2-subtype as for histamine release.

The effect of ribose and purine modified adenosine analogues on the secretion of histamine from rat mast cells induced by ionophore A23187

The purine nucleosides adenosine and 2',5'-dideoxyadenosine (2',5'ddAdo) enhance and inhibit respectively the anti-IgE-induced secretion of histamine and transient rise in cellular levels of cyclic AMP in rat mast cells. These findings have provided evidence for a role for cyclic AMP in the activation of mast cell secretion. It has been generally accepted that the nucleosides mediate their effects on mast cells by altering adenylate cyclase activity. We have investigated the effect of various purine and ribose modified analogues of adenosine on secretion of histamine from rat mast cells induced by ionophore A23187 for which there is no associated elevation in cyclic AMP and no evidence for the activation of adenylate cyclase in its mechanism of action. Adenosine and N6, phenylisopropyladenosine (0.01-1000 microM) (activators of adenylate cyclase in many tissues) enhanced the secretion of histamine induced by ionophore A23187 and anti-IgE. Two inhibitors of adenylate cyclase had differential effects on secretion. 2',5'ddAdo (100-1000 microM) inhibited both A23187-and anti-IgE-mediated secretion; whilst 9-beta-D-arabinofuranosyladenine had no effect on secretion. These results suggest that the ability of these nucleosides to modulate histamine secretion is unrelated to their effects on adenylate cyclase.

A high-sampling-rate automated continuous-flow fluorometric technique for the analysis of nanogram levels of histamine in biological samples

An automated continuous-flow technique of the modified fluorometric method of Shore was devised to obtain a high sampling rate (60/h) and a sensitive measurement of the histamine content of biological samples. The volumes of samples range from 50 to 500 microliter. A linear relationship is obtained from 0 to 5 micrograms/ml (histamine base) with a good specificity. The limit of detection is 25 pg (actual amount). The coefficient of variation is less than or equal to +/- 5% for concentrations of less than 2 ng/ml and from +/- 0.2 to +/- 2% for higher concentrations. With this technique more sensitive, more specific, and twice as fast as similar ones, histamine content in 350-400 unknowns can be measured routinely in a working day. It has been used for more than 4 years and has proven to be a reliable and useful tool for the numerous research studies in which histamine is involved: immunology, allergy, pharmacology, dermatology, cancer, nutrition.

Photochemotherapy (PUVA) in the treatment of urticaria pigmentosa

Eight patients received PUVA for mastocytosis. Five women had typical adult-onset urticaria pigmentosa, without evidence of systemic disease. Another woman had suspected hepatic involvement while the remaining female had early-onset familial urticaria pigmentosa with morphologically atypical mast cells. The only male patient had cirrhosis with hepatic deposits of mast cells in addition to polycythaemia rubra vera. In all patients, except the man with systemic disease, there was reduced pruritus and wealing and partial to almost complete fading of the macules. The manifestations of urticaria pigmentosa recurred after treatment was discontinued. In both lesional and uninvolved skin there was no significant change in either the mean mast cell counts or mast cell ultrastructure after an average of twenty-seven PUVA exposures. In addition, PUVA did not cause a significant alteration in the histamine content of the skin. The beneficial effect of PUVA in urticaria pigmentosa therefore does not appear to be directly related to a change in mast cell numbers or morphology, or to the histamine concentration in the skin.

Changes in cellular levels of cyclic AMP in rat mast cells during secretion of histamine induced by immunoglobulin E decapeptide and ACTH(1-24) peptide. Comparison with immunological and ionophore triggers

The role of cyclic AMP in the secretory mechanism of mast cells has been investigated by comparing the time course of changes in cellular levels of this cyclic nucleotide with the kinetics of secretion induced by basic peptides, antigen, anti-IgE and calcium ionophore. ACTH(1-24) peptide and a synthetic decapeptide representative of the sequence 497-506 within the C epsilon 4 domain of human IgE induced a transient rise in cyclic AMP which reached approx. 150% of the resting levels by 10 s. Peptide-induced secretion of histamine was also rapid, reaching a maximum after 5-10 s. Immunological triggering of mast cells with antigen and anti-IgE raised levels of cyclic AMP to 150% of resting levels within 15 s, accompanying secretion of histamine which reached a maximum after 30 s. A relatively slower release of histamine induced by the calcium ionophore A23187 was paralleled by a significant reduction in cyclic AMP to 50% of the resting levels after 300 s. These data suggest a relationship between the accumulation of cyclic AMP in mast cells and secretion of histamine mediated by the C epsilon 4 decapeptide and the ACTH(1-24) peptide as well as by IgE-dependent mechanisms. However, the simultaneous increase in cyclic AMP and secretion of histamine suggests that the two events may not be causally related.

Antigen sensitization does not alter response of guinea-pig lung strips to noradrenaline

Guinea-pigs were sensitized to ovalbumin by an intraperitoneal injection, followed 3 weeks later by daily aerosol exposure for 4 weeks. Noradrenaline-induced contractions of peripheral lung strips from sensitized and unsensitized guinea-pigs were compared. There were no differences in sensitized or unsensitized strips with respect to maximal tension generated, concentration of noradrenaline for threshold or maximal responses or EC50. These results suggest that any changes in the population of alpha-adrenoceptors consequent upon immunological sensitization did not influence contractile responses to noradrenaline.

Latent anaphylactic sensitivity of infants to cow's milk proteins. Histamine release from blood basophils

Approximately 25% of infants tested released greater than 9% of their blood basophil histamine content in the presence of cow's milk proteins, indicating a degree or level of latent anaphylactic sensitivity to these allergens. Approximately 10% of infants show a considerably higher level of sensitivity (14-63% histamine release). These findings fulfil an essential tenet of the modified anaphylactic hypothesis for cot-death.

Food intolerance: a major factor in the pathogenesis of irritable bowel syndrome

Specific foods were found to provoke symptoms of irritable bowel syndrome (IBS) in 14 of 21 patients. In 6 patients who were challenged double blind the food intolerance was confirmed. No difference was detected in changes in plasma glucose, histamine, immune complexes, haematocrit, eosinophil count, or breath hydrogen excretion produced after challenge or control foods. Rectal prostaglandin E2 (PGE2), however, increased significantly, and in a further 5 patients rectal PGE2 correlated with wet faecal weight. Food intolerance associated with prostaglandin production is an important factor in the pathogenesis of IBS.

Basophils, histamine and gastric acid secretin in chronic myeloproliferative disorders

Fourteen patients with polycythaemia rubra vera (PRV) and four with chronic granulocytic leukaemia (CGL) were studied to examine the relationship between basophil counts, blood histamine, gastric acid secretion and dyspepsia or peptic ulceration. Basophil counts and blood histamine were markedly raised in untreated CGL but only marginally increased in other cases. Blood histamine and basophil counts were well correlated. Gastric acid secretion was normal in 10 out of 11 cases, and did not correlate with blood histamine values. The previously reported high incidence of dyspepsia and peptic ulceration is examined and its mechanisms are discussed.

The role of basophils in asthma. I. Sodium cromoglycate on histamine release and content

The increased plasma-histamine levels observed after provocation of asthmatic subjects with antigen or exercise may result from the release of this granule-associated mediator from either mast cells or basophil leucocytes. In this preliminary study, designed to ilucidate the source and role of mediators in asthma, the effects of sodium cromoglycate on basophil-histamine release has been assessed. Basophil histamine-release in vitro was not inhibited by 0.01-100 microgram/ml sodium cromoglycate. When administered by inhalation at a dose of 20 mg every 8 hr to six subjects, the drug did not modify the ability of basophils to synthesize and store histamine or to release histamine on incubation with antigen. As sodium cromoglycate reduces IgE-dependent histamine release from human mast-cells, these results suggest that lung mast-cells, rather than circulating basophils, are source of mediators in exacerbations of asthma and following exercise or antigen bronchial-provocation in asthmatic subjects.

Dissociation of histamine release and clinical improvement following treatment of acquired cold urticaria by prednisone

1 Corticosteroids are known to suppress evoked histamine release from human skin in vitro. Therefore the effect of prednisone, on cold evoked histamine release and clinical response was studied in six patients with acquired cold urticaria. 2 Following cold challenge all six patients developed an immediate urticarial response of the forearm and elevation of histamine levels, measured by superfusion cascade bioassay of the venous blood draining the forearm. 3 After treatment with prednisone, in an oral dose of 20-25 mg for 1 to 5 days, a suppression of evoked histamine release occurred in all but one patient. However, there was no corresponding decrease of erythema or oedema, though pruritus was improved in most patients. 4 The lack of clinical improvement in erythema and oedema, despite reduction in histamine levels, suggests that histamine may not be the principal mediator of the vascular response to cold challenge in acquired cold urticaria.

The effects of nonidet P40 on the function of rat peritoneal mast cells in vitro

1 Treatment of purified rat peritoneal mast cells at 37 degrees C with concentrations of the non-ionic detergent nonidet P40 (NP40) up to 0.005% (v/v) failed to reduce their viability. 2 There was a marked reduction in the histamine releasing capacity of NP40-treated mast cells upon challenge with a variety of selective (adrenocorticotrophic hormone 1-24 (Synacthen), rabbit anti-rat IgE antiserum, adenosine triphosphate (ATP) and the calcium ionophore, A 23187) and non-selective (rabbit anti-rat mast cell antiserum plus complement) histamine liberators. 3 Nonidet P40 (0.005%) was found to reduce the activity of a mast cell membrane 'ecto-enzyme', calcium-activated ATPase, by about 45% when presented at the time of its assay.

An in vivo demonstration of the antianaphylactic effect of terbutaline

Allergen-mediated histamine release was measured on small samples of blood in atopic subjects before and following ingestion of two tablets of terbutaline (5 mg) or placebo. No significant variation of histamine release was observed in the placebo group whereas a statistically significant decrease (maximally 45% of basal value) was found in four of the five patients receiving terbutaline. The mean reduction was about 25% of basal allergen-mediated histamine release. The inhibition was observed 1 hr after taking the drug and persisted for at least 5 hr. Twenty-four hours later the amount of histamine released by antigen was again at its basal value. These data indicate that terbutaline, at what are considered therapeutic doses, has an antianaphylactic action which might be of interest in the treatment of atopic disorders.

Further studies on histamine release from rat mast cells in vitro induced by peptides. Characteristics of a synthetic intermediate with potent releasing activity

Previous studies on histamine release by corticotropin peptides and melittin peptides were extended, leading to the identification of a synthetic peptide intermediate, Lys(Z)-Arg(NO2)-Arg(NO2)OMe, (I) as an active non-cytolytic histamine releaser from rat mast cells. However, significant differences in the releasing capacity of optical isomers of this compound, and of Lys-Lys-Arg-ArgOMe [methyl ester of corticotropin-(15-18)-tetrapeptide; 'basic core'] were observed, with the L-forms being markedly more active. A study of various analogues of the tripeptide compound (I) indicated that the structural basis for mast-cell triggering by such peptidic agents was highly specific. The relevance of these observations to the immunologically induced histamine-release processes is discussed.

The activity of sodium cromoglycate analogues in human lung in vitro: a comparison with rat passive cutaneous anaphylaxis and clinical efficacy

1 Eleven analogues of sodium cromoglycate have been tested for their ability to suppress histamine release induced by anti-IgE from passively sensitized human lung fragments in vitro. 2 With the exception of WY 16922, which released histamine at high concentrations, all inhibited histamine release in a linear dose-related manner. 3 The analogues were 30 to 1500 times more potent than sodium cromoglycate. However, their regression slopes of activity upon log-concentration were only one-third as steep as that for sodium cromoglycate, indicating a possible difference in their mechanism of action. 4 In comparison with sodium cromoglycate, the analogues were more potent in human lung than in rat passive cutaneous anaphylaxis (PCA); there was no quantitative correlation between potencies in the two tests. 5 The human lung model is not predictive of anti-asthmatic activity in man as the six analogues tested clinically are less effective than sodium cromoglycate. 6 These results throw doubt on the use of models of mast cell degranulation in the search for anti-allergic drugs and, possibly, on the relative importance of mast cell degranulation in the pathogenesis of asthma.

An improved automated fluorimetric method for determination of histamine

The automated continuous flow system for the extraction and fluorimetric analysis of histamine based on the principle of Shore et al. (1959) has been improved. With lower consumption of reagents and further simplification of the working conditions, histamine can be determined quantitatively in a routine fashion in aqueous samples, with or without protein content, up to a concentration of approximately 0.1 ng/ml. The rate of analysis is 30 samples/h.

Inhibition of histamine release from human lung in vitro by antihistamines and related drugs

1 A series of cationic, lipophilic histamine H1-receptor antagonists, neuroleptics, antidepressants and monoamine oxidase inhibitors were tested for their effects on anti-IgE-induced histamine release from human lung fragments in vitro. 2 They had a biphasic effect: at low concentrations a dose-related inhibition of histamine release was observed whereas, at higher concentrations, the drugs liberated histamine even in the absence of antigen. 3 Mepyramine, a much less lipophilic drug than the others tested, was only weakly active on mast cells at pharmacological concentrations. 4 The potency of the drugs as release inhibitors was not related quantitatively to their histamine liberating potency. 5 There was no; correlation between activity on mast cells and histamine H1-receptor antagonism. 6 Mast cell stabilization may play a part in the activity of these drugs as anti-allergic agents.

Human leukocyte histamine release assays with whole ragweed and Alternaria antigens using Technicon autoanalyzer II

A simple and commercially available automated technique for fluorometric analysis of histamine is described. It is applicable to histamine release experiments utilizing washed leukocytes, and analyzes 15 samples/h at histamine concentrations between 1 and 1000 ng/ml with a mean variance between 0.5% and 18%. This technique is applied to a cross sectional study of leukocytes from 14 ragweed sensitive patients (7 on and 7 off immunotherapy) as well as five normals. It was also applied to 17 Alternaria-sensitive patients (4 on and 12 off immunotherapy) in addition to six normals. While antigen induced in histamine release clearly separated the sensitive group from the normals, it did not correlate with immunotherapy, and a considerable variation was seen in the sensitive patients of both the treated and untreated groups.

Induction of histamine secretion by polycations

Poly(arginine), poly(lysine) and poly(ornithine) induce histamine secretion from human basophil leukocytes in the concentration range 1--100 nmol/l. Histamine secretion induced by poly(arginine) requires extracellular calcium at 0.1--1 mmol/l. Strontium (1--10 mmol/l) will substitute for calcium. Lanthanum (30--90 nmol/l) inhibits histamine release induced by poly(arginine). Histamine secretion induced by poly(arginine) is inhibited by 1--30 mumol/l N-ethyl-maleimide, 0.3--3 mmol/l 2-deoxy-D-glucose, 0.3--3 mmol/l dibutyryl cyclic AMP, 0.3--3 mmol/l, adenosine 3'5'-cyclicphosphorothioate. The action of poly(arginine) is inhibited by pretreatment of basophils at 47 degrees C or with neuraminidase. 10 microgram/ml heparin inhibits the response to poly(arginine). Histamine releasing potency of the polymer amino acids is dependent on chain length of the peptide. Succinylated poly(lysine) is inactive. Monomer amino acids do not release histamine and do not inhibit the action of the polymers. Histones and protamine do not release histamine, nor do the peptides eledoisin and tuftsin. Putrescine, cadaverine, spermine and spermidine do not release histamine. Poly(glutamic acid), poly(aspartic acid) and poly(tyrosine) are also inactive. The IgE-mediated release of histamine appears to be independent of that mediated by poly(arginine).

Modulation of the rate of histamine release from basophils by cyclic AMP

Rates of histamine release from human basophil leukocytes have been studied in response to three different stimuli: antigen, ionophore A23187 and strontium ions. Dibutyryl cycle AMP and other agents which are assumed to cause a rise in intracellular levels of cyclic AMP accelerate the release of histamine induced by all of the stimuli. In addition, dibutyryl cyclic AMP caused an inhibition of the maximum release obtainable with antigen stimulation but no inhibition of the maximum release obtainable with ionophore A 23187 or with strontium ions alone.

Oxatomide: inhibition and stimulation of histamine release from human lung and leucocytes in vitro

Oxatomide is a very potent inhibitor of histamine release induced by anti-1gE and Timothy pollen extract in passively sensitized human lung fragments and that induced by anti-1gE from human leucocytes. Its spectrum of activity is different from sodium cromoglycate-like drugs. In high concentrations oxatomide, like other antihistamines and related structures, induced histamine release from both lung and leucocytes. However, oxatomide induced histamine release far more effectively from sensitized lung than non-sensitized lung. Inhibition of immunologically induced histamine releast by oxatomide may play a part in its action as an anti-hay fever and, possibly, an anti-asthmatic drug.