Effect of ecdysterone on histamine release from rat peritoneal mast cells.

Ecdysterone dose-dependently inhibited anti-IgE-induced histamine release from mast cells. Moreover, the rate and extent of histamine release from mast cells induced by Concanavalin A (Con A) are significantly diminished in samples incubated with ecdysterone. Ecdysterone inhibited both the initial and gradual rise in fluorescent response by anti-IgE and Con A. The effects of ecdysterone on the fluorescence response was correlated with the inhibition of histamine release. These results suggest the possibility that the inhibition of histamine release from rat mast cells by ecdysterone might be due to inhibition of Ca2+ mobilization from intracellular Ca2+ storage.

Anti-interferon gamma treatment blocks the ability of glutaraldehyde-polymerized allergens to inhibit specific IgE responses.

The lymphokines interleukin 4 and interferon gamma (IFN-gamma) have been shown to play an important role in regulation of polyclonal immunoglobulin E (IgE) and IgG2a responses in vitro and in vivo. We demonstrate here that treatment with chemically modified ovalbumin (OA) results in long-lived, 97-99% inhibition of allergen-specific murine IgE responses and 10(3)-10(4)-fold increases in anti-OA IgG2a. Responses to unrelated antigens are not affected. Treatment with unmodified OA under the same conditions fails to inhibit primary or secondary IgE responses or to increase IgG2a but does lead to pronounced increases in OA-specific IgG1 production. Glutaraldehyde-polymerized ovalbumin (OA-POL)-induced changes in IgE and IgG2a responses are abrogated by in vivo treatment with purified monoclonal anti-IFN-gamma antibody (XMG 1.2), a finding indicative of preferential IFN-gamma production upon exposure to chemically modified, but not native, allergen. The results suggest the possibility that the pattern of cytokine synthesis elicited after exposure to protein antigens, and the resulting immune response, may be dependent upon the form of antigen to which the individual is exposed and consequently may be subject to manipulation.

Inhibition of phospholipid methylation by an anti-allergic agent, NCO-650, during histamine release.

Antigen, anti-IgE and concanavalin A (Con A) induced an increase in both the incorporation of the 3H-methyl moiety into phospholipids and histamine release. Maximal incorporation of the 3H-methyl moiety into the lipid fraction of the cells was observed within 15 sec and 1 min after being challenged with antigen (100 micrograms/mL) and anti-IgE (200 micrograms/mL) respectively. However, the methylated phospholipid decreased rapidly. The addition of Con A (10 micrograms/mL) also increased phospholipid methylation, which reached a maximum at 5 min after challenge. Trans-4-guanidinomethylcyclohexanecarboxylic acid p-tert-butylphenyl ester hydrochloride (NCO-650; 27 microM) strongly inhibited the incorporation of the 3H-methyl moiety into phospholipid by antigen, anti-IgE and Con A. The IC50 values of NCO-650 for phospholipid methylation in response to antigen, anti-IgE and Con A were 1.5, 4.7 and 1.1 microM respectively. Although the Ca2(+)-ionophore A23187 did not induce phospholipid methylation, it caused histamine release.

Proyecciones y estrategias actuales en la búsqueda y desarrollo de nuevos medicamentos antiasmáticos y antialérgicos profilácticos / Current strategies and projections in the search for and development of new prophylactic antiasthmatic and antiallergic drugs

Se analizan las nuevas estrategias a seguir para el descubrimiento y desarrollo de nuevos y mejores medicamentos antiasmáticos. Los resultados obtenidos han conllevado a una reevaluación crítica de los métodos farmacológicos que se han utilizado hasta el presente en este campo. Los antagonistas del factor activador plaquetario y los leucotrienos al igual que los inmunomoduladores que ejercen efecto inhibitorio en la producción de la inmunoglobulina E (IgE), constituyen los principales avances para el logro de este objetivo

Inhibition of IgE-mediated N-acetylglucosaminidase and serotonin release from rat basophilic leukemia cells (RBL-2H3) by tenidap: a novel anti-inflammatory agent.

Tenidap [(Z)-5-chloro-2,3-dihydro-3-(hydroxy-2-thienylmethylene)-2-oxo-1H- indole-1-carboxamide] is a novel anti-inflammatory compound of the oxindole class that currently is undergoing clinical evaluation in man. Here we demonstrate that tenidap inhibits (IC50 = approximately 10 microM) IgE-mediated secretion of granule constituents from the rat mast cell tumor line RBL-2H3. The inhibitory effect is rapid in onset, readily reversible, and appears to be unique when compared to a representative selection of other acidic (carboxylic acids, pyrazoles and oxicams) nonsteroidal anti-inflammatory compounds.

IgE suppressor factor induced by phytohemagglutinin.

Suppression of IgE response induced by phytohemagglutinin (PHA) inoculation near the time of immunization is studied. Donor spleen cells injected with PHA on day -1 before transfer were either depleted from Lyt 1+ or Lyt 2+ T cells and inoculated to isogenic recipients. Animals were immunized with ovalbumin in aluminum hydroxide gel 1 h later. IgE response was determined by passive cutaneous anaphylactic (PCA) reaction and ELISA. Results show that suppression of the IgE response caused by PHA only affects PCA reaction. In contrast, IgE response measured by ELISA is not modified. Depletion of Lyt 1+ T cell abolished the PHA effect. Thus, as a provocative notion, we propose the generation of an IgE suppressor factor which inhibited the PCA reaction. It was present in the sera of treated animals. IgM and/or IgG production was not affected.

Modulation of mediator release from human basophils and pulmonary mast cells and macrophages by auranofin.

Auranofin, a new orally absorbable gold compound, inhibits IgE-(anti-IgE) and non-IgE-mediated (f-met-peptide and the Ca2+ ionophore A23187) histamine release from human basophils. Auranofin inhibits the release of histamine induced by phorbol myristate (TPA) and bryostatin 1 both in the presence and absence of extracellular Ca2+. Increasing the Ca2+ concentrations in the extracellular medium does not reduce the inhibitory effect of auranofin on anti-IgE- or A23187-induced secretion. Auranofin inhibits the de novo synthesis of sulfidopeptide leukotriene C4 (LTC4) induced by anti-IgE from basophils and mast cells purified from human lung. However, in both systems auranofin has a significantly greater inhibitory effect on LTC4 release than on histamine secretion. Finally, auranofin induces a concentration-dependent inhibition of A23187-induced leukotrine B4 (LTB4) release from purified human lung macrophages. These data suggest that auranofin modulates the release of preformed (histamine) and de novo synthesized (LTC4 and LTB4) chemical mediators from human inflammatory cells isolated from peripheral blood and human lung tissues.

Modulation of human leukocyte histamine release by sn-1,2-isopropylidene-3-decanoyl-glycerol and decanoic acid cyclopentyl methylester in comparison with effects of synthetic diacylglycerols and a phorbol ester.

Previous studies have shown that the glyceride derivative, sn-1,2-isopropylidene-3-decanoyl-glycerol (IpOCOC9), can trigger human leukocyte histamine release. Approximately 25% of the total cellular histamine content is extruded in the presence of 206 microM of IpOCOC9; at 69 microM, however, the secretagogue action of the compound is marginal. The characteristics of the release induced by IpOCOC9 are closely similar to those reportedly recorded at hyperosmolar triggering of basophils with mannitol, and in many respects they also mimic those observed at phorbol ester-induced histamine release. The compound decanoic acid cyclopentyl methylester (DACPME), a structural analogue of IpOCOC9, fails to induce histamine release. IpOCOC9, but not DACPME, stimulates human polymorphonuclear leukocyte cytosolic Ca2+- and phospholipid-dependent histone III-S kinase activity (unpublished observations). The secretagogue action of IpOCOC9 has therefore tentatively, at least partly, been attributed to a direct protein kinase C activation. In the present studies, we examined the influence of IpOCOC9 and DACPME on histamine release triggered by an ensuing exposure to anti-IgE, the calcium ionophore A23187, formyl-methionyl-leucyl-phenylalanine (FMLP), or 4 beta-phorbol 12-myristate 13-acetate (PMA). It is shown that IpOCOC9-treatment of cells results in either enhancement or reduction of the release induced by anti-IgE or by A23187, whereas FMLP-induced release is consistently reduced and PMA-induced release consistently enhanced by such a treatment. Treatment of cells with DACPME enhances but does not reduce anti-IgE-triggered release, whereas FMLP-induced release is not affected. Pretreatment of the cells with other putative protein kinase C activators like PMA, sn-1-oleoyl-2-acetyl-glycerol (OAG), 1,2-dioctanoyl-glycerol (DiC8) or the glycerol derivative sn-1,2-diacetyl-3-decanoyl-glycerol (DiC2OCOC9) affects secretagogue-induced basophil histamine release according to specific patterns similar to but not identical with those recorded for IpOCOC9 and DACPME. Thus, e.g., DiC2OCOC9 consistently reduces but does not enhance anti-IgE-triggered release. These data show that limited structural changes of IpOCOC9 may qualitatively affect its modulating properties in the human basophil histamine release system.

Soybean flour asthma: detection of allergens by immunoblotting.

A 43-year-old woman developed asthma 6 years after beginning work in a food-processing plant in which soybean flour was used as a protein extender. Symptoms of sneezing, coughing, and wheezing would begin within minutes of exposure to soybean flour and resolve 2 hours after exposure ceased. Skin tests were positive to a soy extract prepared from the flour. Airway hyperreactivity was confirmed by a positive bronchial challenge to methacholine. Bronchial challenge with soybean flour produced an immediate increase in specific airway resistance from 5.0 to 22.7 L. cm of H2O/L/sec. There was no response to challenge with lactose. The patient's allergic response to soy-flour extract was further characterized by several immunologic methods. IgE binding to soy-flour protein by direct RAST was 5.98 times that of a normal control serum. The soy-flour extract was separated by dodecyl sulfate-polyacrylamide gel electrophoresis. Twenty-four protein bands were detected in the crude soy-flour extract. After immunoblotting and subsequent autoradiography, nine proteins with molecular weights ranging from 54,500 to 14,875 were found. Cross-reactivity studies with other legumes demonstrated apparent immunologic identity between a component in green pea extract and a soybean protein with a molecular weight of 17,000. The clinical significance of this cross-reactivity is not known. We conclude that in this case of occupational asthma to soybean flour, multiple allergens were involved. Immunoblotting may be useful in identifying the allergens involved in occupational asthma.

IgE FAST inhibition: a rapid technique for the standardization of pollen allergen extract potency.

An IgE FAST(TM) inhibition protocol has been developed as a rapid in vitro method for determining relative potencies of in vivo allergenic extracts. Results are obtained within one day and correlate well with those of the RAST inhibition protocol (r = .96), making the FAST assay a preferable procedure for inprocess potency determination during the manufacture of standardized allergenic extracts.

A comparison of nedocromil sodium and sodium cromoglycate on human lung mast cells obtained by bronchoalveolar lavage and by dispersion of lung fragments.

Bronchoalveolar lavage (BAL) mast cells provide a useful tool with which to screen potential therapeutic agents for human airway diseases. This study was therefore designed to compare the activity of nedocromil sodium and sodium cromoglycate in inhibiting anti-IgE induced histamine release from human mast cells obtained by BAL and from dispersed lung (DL) fragments. After 10 min pre-incubation with the mast cell preparations, both drugs displayed greater inhibition of histamine release from BAL than from DL mast cells. Under optimal conditions of 10 min pre-incubation with BAL and none with DL mast cells, nedocromil sodium showed significantly more activity than sodium cromoglycate on both BAL and DL mast cells.

IgG is not the only inhibitor of IgE in the RAST test.

Blocking phenomenon of the RAST test was studied in the sera of 50 different patients. Specific levels of IgE and IgG against 11 common foods were evaluated by ELISA. Results showed that decreases in IgG levels by protein-A were not always followed by IgE increases. In this regard, we found three different combinations in the levels of IgE and IgG: (1) an IgG decrease followed by IgE increase (29%); (2) an IgG increase followed by IgE decrease (18%); and (3) both IgG and IgE decrease (28%). From these results we concluded that IgG is not the only inhibitor of the RAST test.

Basophil releasability in the newborn: factors limiting immunoglobulin E-mediated histamine release.

Cord basophil preparations from 53 term neonates were studied for various factors affecting immediate hypersensitivity reactions including: basophil IgE receptor density and histamine releasability following incubation with calcium ionophore A23187, zymosan-activated serum (C5a), and anti-IgE. Basophil histamine content (geometric mean, 0.4 pg/basophil, with content in 14/28 cord blood samples below 0.2 pg/cell) is considerably below that of atopic and nonatopic individuals (geometric mean, 2.3 pg/basophil). Histamine release is normal with both A23187 (range 33% to 88%) and C5a (range 11% to 58%). Normal release with anti-IgE was shown in five of nine cord blood samples (range 13% of 52%), but four of five cell preparations required IgE preincubation. Indirect evidence indicates that basophils from newborns contain less than 30,000 total IgE receptors/cell. IgE-mediated histamine release in basophils from newborns is minimized by suboptimal IgE binding. Optimal IgE binding is not favored in basophils from neonates because of low serum IgE and low IgE receptor density. Serum IgE and IgE receptors increase to a variable degree as the child grows older and may determine the clinical onset of allergic disease.

Inhibition of IgE binding to tissue culture cells and leucocytes by pentapeptide.

The specific binding of radiolabelled IgE to a tissue culture lymphoblastoid cell line (Wil-2WT) was confirmed. The binding of IgE and Hamburger's IgE-derived pentapeptide Asp-Ser-Asp-Pro-Arg (HEPP) to Wil-2WT cells and to human leucocytes was compared. HEPP inhibition of IgE binding to leucocytes averaged 24% but with Wil-2WT cells only 12% inhibition was observed with double the amount of HEPP. Using myeloma IgE to inhibit the binding of tritiated HEPP to leucocytes and Wil-2WT cells confirmed the specificity of the peptide binding as well as the greater affinity of HEPP for leucocytes (basophils) compared to Wil-2WT lymphoblastoid cells. Based upon the extent of binding and the maximum inhibition attainable with HEPP it is suggested that the receptors for IgE on Wil-2WT cells, basophilic leucocytes and mast cells are not identical but that they share specificities in common. A new hypothesis for the mechanism of action of HEPP is proposed.

New orally effective chromosome derivatives for the treatment of asthma.

Two new chromone derivatives have been identified which possess oral anti-allergic activity in the rat PCA model of immediate hypersensitivity. They may have a wider spectrum of anti-allergic activity than disodium cromoglycate (SCG) since they are effective in in vitro tests involving sensitized basophils, in which SCG is inactive. Both compounds, when given orally, provide relief from experimental and clinical asthma in man.

Ammonium and sulfate ion release of histamine from lung fragments.

In vitro studies with guinea pig lung fragments incubated with 10- to 200-mM concentrations of ammonium ion demonstrated the release of substanial quantities of histamine. Of the anions tested with ammonium ion, sulfate was the most potent, while nitrate and acetate ions were of intermediate potency and chloride was less potent. An osmotic effect is unlikely since equal concentrations of sodium chloride failed to release histamine. Isoproterenol, known to decrease anaphylactic histamine release, and acetycholine, known to increase histamine release, had no effect on the ammonium sulfate-mediated release of histamine. N-6 2'-O-Dibutyryladenosine 3',5' monophosphate (dibutyryl c-AMP) was also ineffective. These studies suggest that the inhalation irritation associated with certain sulfate and other salts, may be a function of their ability to release histamine in the presence of amonium ion.

Histamine release from human leukocytes: modulation by a cytochalasin B-sensitive barrier.

Cytochalasin B, a metabolic product of several fungi, enhances up to 10-fold the sensitivity and reactivity of human leukocytes to antigen E or anti-IgE-mediated histamine release. The effect of cytochalasin B is a result of its action on the second, antigen-independent, stage of histamine release. These data suggest that normally, antigen-triggered histamine release is modulated by a cytochalasin-sensitive barrier (CSB). This CSB modulation of histamine release can be separated from the modulating effect of cyclic adenosine monophosphate (AMP).

Naturally occurring human antiglobulins with specificity for E.

Human sera have been examined for antibodies with specific reactivity for gammaE using the tanned cell hemagglutination test. Cells tanned with three different gammaE myeloma proteins provided a reproducible test system. Inhibition of agglutination reactions by gammaE proteins, but not by gammaG, gammaA, gammaM, or gammaD confirmed the specificity of these reactions. 8.5% of 304 serial serum samples obtained from miscellaneous hospitalized patients showed clear-cut anti-gamma-globulins with specificity for gammaE. In most of these instances no definite clinical history of concomitant allergic disorders could be obtained. 53% of 73 patients with well-established allergic disorders (hay fever, extrinsic asthma) showed serum anti-gamma-globulins with reactivity for gammaE. Some patients studied before and after desensitization to Bermuda grass allergen showed an increase in titer or a conversion from negative to positive reactions for anti-gammaE antibodies following several month courses of progressive desensitization. Gradient and gel filtration studies indicated that anti-gammaE globulins were 19S gammaM in all instances. No clear correlation was noted between quantitative serum gammaE levels and titer of anti-gammaE antibodies.19S serum fractions with anti-gammaE antibody activity did not release histamine from normal human peripheral blood leukocytes, whereas specific rabbit anti-gammaE antisera consistently induced leukocytic histamine release. Moreover, macroglobulin fractions with anti-gammaE activity did not block allergen-specific leukocyte histamine release induced by in vitro leukocyte challenge with allergens such as Bermuda grass and leukocytes from allergic donors. In some instances 19S human serum fractions with anti-gammaE activity appeared to potentiate histamine release when incubated concomitantly with specific allergen and leukocytes from allergic individuals.

Mast cells from human respiratory tissue and their in vitro reactivity.

Human respiratory mast cells, which were obtained coincidentally with diagnostic bronchial brush biopsy, were maintained under conditions for short-term tissue culture. Most mast cells were viable and degranulated on exposure to antibody to immunoglobulin E or to the mast cell degranulating agent compound 48-80. The degranulation of human mast cells is characteristically an intracellular process with no extracellular extrusion of granules.