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PubMed1981

Modulation of histamine release from human basophils in vitro by physiological concentrations of zinc.

Zinc, at physiologic concentrations, inhibits in vitro histamine release from human basophils induced by several immunologic (i.e., antigen and anti-immunoglobulin E (IgE) and nonimmunologic [Ca++ ionophore A23187 and formylated tripeptide formyl-methionyl-leucyl-phenylalanine (f-met peptide)] stimuli in a dose-dependent manner. Inhibition begins at about 10(-6) (ionophore A23187, anti-IgE and antigen) or 10(-5) M (f-met peptide) and is maximum at 10(-4) M (80--100% inhibition of histamine release). The activity of zinc is about 25-fold greater with respect to ionophore A23187 (ID50 = 1.1 x 10(-6) M) than to f-met peptide-induced (ID50 = 4 x 10(-5) M) histamine release. Its activity on IgE-mediated histamine release is intermediate between these two extremes (ID50 = 9.7 x 10(-6) M). Zinc does not affect the first stage of histamine release but acts on the calcium-dependent second stage. It is a competitive antagonist of the action of Ca++ in histamine secretion induced by antigen, anti-IgE and f-met peptide (but not by A23187) with a dissociation constant of about 1.2 x 10(-5) M. The addition of colchicine with zinc fails to increase the inhibition caused by the ion alone, suggesting the two compounds work via a common mechanism of action. Deuterium oxide reversed, in a dose-dependent manner, the inhibition of histamine release caused by zinc. These results suggest that the effect of zinc on histamine release from human basophils may be related to its influence on the microtubule system, directly or via its interaction with calcium.

Allergens↗
PubMed1981

[The value of the basophil degranulation test on the study of hypersensitivity reactions to iodinated contrast media].

The ability of basophils and tissue mastocytes activated by sensitised IgE antibodies to release mediators in the presence of the specific antigen underlies immediate hypersensitivity reactions. This phenomenon can be explored by the in vitro basophil degranulation test adopted not only in experimental pathology, but in human allergological pathology and in the study of post-streptococcal and lupus glomerulonephritis. The test has been carried out to analyse sensitisation to iodate contrast media in 71 patients already submitted to contrastography, 37 of whom had given evidence of allergic reactions. All patients with a previous history of sensitisation presented, in vitro, a positive reaction (56 + 15.3% degranulation) in the presence of the contrast medium. Against this, none of the patients with negative test presented an allergic reaction during contrastography. Stress is laid on the practical importance of the test prior to performance of contrastography so as to predict possible sensitisation and select the most suitable medium.

Basophils↗
PubMed1980

The role of histamine H-receptors in the anaphylactic histamine release from human basophilic leukocytes.

The effect of two recently synthetized selective histamine H2-receptor agonists on anaphylactic histamine release from human basophilic leukocytes was investigated. It was found that both agonists tested, partially inhibited histamine release induced either by antigen or by human anti-IgE. Cimetidine, the histamine H2-receptor antagonist, generally antagonized this effect. It is concluded that anaphylactic basophil histamine release can be modulated by stimulation of histamine H2-receptors.

Anaphylaxis↗
PubMed1981

Inhibition of IgE-mediated histamine release from rat basophilic leukemia cells and rat mast cells by inhibitors of transmethylation.

This study evaluated the effect of inhibitors of transmethylation on histamine release from rat mast cells and rat basophilic leukemia cells. IgE-mediated histamine release from rat basophilic leukemia cells (RBL-2H3 cells) was inhibited by 3-deazaadenosine (DZA) in the presence of L-homocysteine thiolactone (Hcy) or the combination of adenosine, erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA), and Hcy in a dose-dependent fashion. There were no significant changes in the cellular cAMP levels by these inhibitors. Histamine release induced by anti-IgE or dextran from normal rat mast cells was also blocked by DZA plus Hcy in a dose-dependent manner. DZA at 10(-3) M in the presence of 10(-4) M Hcy or the combination of 10(-3) M adenosine, 10(-4) M EHNA, and 10(-3) M Hcy inhibited lipid (perhaps phospholipid) methylation into RBL-2H3 cells without affecting choline incorporation. In the presence of 10(-3) M DZA plus 10(-4) M Hcy there was a 170-fold increase in [35S]AdoHcy with the concomitant appearance of 3-deaza-AdoHcy when the cells were incubated with [35S]methionine, thus indicating that these drugs inhibited methylation reaction(s) through the intracellular accumulation of AdoHcy and 3-deaza-AdoHcy. In contrast, histamine release from rat mast cells induced by the calcium ionophore A23187, compound 48/80, polymyxin B, or ATP was not inhibited by these compounds. These results suggest that IgE- or dextran-mediated histamine release involves methylation reactions(s), whereas the other secretagogues bypass this early step.

Adenine↗
PubMed1981

Qualitative characteristics of histamine release from human basophils by covalently cross-linked IgE.

We have studied the effects of permanent oligomers of human IgE produced using the cross-linking reagent, dimethyl suberimidate, on histamine release from human basophils. IgE dimers were found to be sufficient stimuli for both release and desensitization of these cells; monomeric IgE had no effect. Histamine release was augmented by deuterium oxide (D2O) in the medium, but D2O was not an absolute requirement to observe release. Desensitization by the dimeric IgE was specific in that the response to anti-IgE was not affected by preincubation of the leukocytes with the IgE dimer under suboptimal releasing conditions. IgE trimers and higher oligomers of IgE also caused both release and desensitization. IgE trimers were 3- to 4-fold more effective than IgE dimers with regard to the amount required for 50% histamine release. Dilution studies with monomeric IgE suggested that the difference was due to the presence of more "active" dimers in the trimeric IgE fractions. We conclude that dimeric IgE, by juxtaposing 2 receptors on the basophil membrane, is the "unit signal" for both release and desensitization of these cells.

Animals↗
PubMed1981

The transition from specific to nonspecific desensitization in human basophils.

Human basophils can be desensitized to IgE-mediated stimuli either specifically (to the desensitizing antigen only) or nonspecifically (to all antigens). It has been suggested that the specificity of desensitization depends on the number of membrane-bound, antigen-specific IgE antibody molecules per basophil. We have varied the number of IgE antibody molecules/basophil by passive sensitization of mixed leukocyte preparations with increasing concentrations of purified IgE anti-penicillin (BPO) antibody. The cells were then desensitized with penicillin-human serum albumin (BPO-HSA). Desensitization was specific (lack of response to BPO-HSA only) with 1000 specific antibody molecules/basophil, and increasingly nonspecific (greater than 70% desensitization to rechallenge with anti-IgE and ragweed antigen E as well as lack of response to BPO-HSA) as the number of antibody molecules was increased to 14,000. This formally established that the number of specific IgE antibody molecules/basophil determines the mode of desensitization.

Basophils↗
PubMed1982

Variants of the rat basophilic leukemia cell line for the study of histamine release.

Cloning of the rat basophilic leukemia (RBL) cell lines demonstrates variability in cell chromosome number (approximately 44-70) and in their capacity to release histamine following an IgE- or Ca2+-ionophore stimulus. After IgE activation there is increased phospholipid methylation, Ca2+ influx, arachidonic acid, and histamine release. On Ca2+ ionophore A23187 stimulation, phospholipid methylation is not increased, but Ca2+ influx, arachidonic acid, and histamine release occur. Variants of the RBL-cloned sublines defective at different stages in the release process were obtained and used to sequence the different events in the release process: IgE activation is followed by methylation, Ca2+ influx, arachidonic acid, and histamine release. However, there are other variants with defects in intermediate steps in the pathway, e.g., increased phospholipid methylation that is not followed by Ca2+ influx or arachidonic acid release not followed by histamine release. Isolating variants carrying drug-resistance markers made hybridization (reconstitution) experiments possible. Two variants were recognized, each of which was deficient in one of the two phospholipid methyltransferase enzymes. Neither of these two variants released histamine; hybrids formed by fusion of these two cell lines have both phospholipid methyltransferase enzymes and release histamine. By other complementation experiments, groups of variants with defects at different steps in the histamine release sequence were recognized. Clearly, these basophilic leukemia cell lines provide a unique system for the study of the mechanism of histamine release.

Animals↗
PubMed1982

Quantification of ultrastructural variations in enriched blood basophils: correlation of morphological changes and antigen-induced histamine release.

Highly purified preparations of human basophils have been studied ultrastructurally to delineate quantifiably those alterations associated with immunologically-induced histamine release. Of six characteristic variations of basophil morphology, totally degranulated cells, those with some exteriorized granules and those with some extracellular vesicles were almost exclusively associated with antigen challenge. Of these, total degranulation without extracellular granules or vesicles was most frequent. A correlation was found between percentage histamine released and percentage totally degranulated cells present in the samples incubated with antigen. In addition, increased plasma membrane folding and irregularity were more prevalent in stimulated samples than in controls and their mean frequency was related quantifiably to the percentage of histamine released in each group. Cells with empty vesicles or electronlucent intracellular granules or both occurred to the same extent in experimental and control aliquots. The possible of histamine release is discussed.

Antigens, Fungal↗
PubMedDate not supplied

In vitro histamine release from human basophils triggered by a purified allergen from Dermatophagoides farinae: bimodal aspect of the dose response curve.

Histamine release experiments were performed over a 10(6)-fold range of allergen concentrations on basophils of patients sensitive to Dermatophagoides farinae. Two extracts of D. farinae were used, a partially purified one (Df 80d) containing several allergens and a highly purified component (Ag11). This histamine release patterns obtained with the complex allergen mixture Df 80d gave broad histamine release curves presenting an initial increase, followed by a decrease or a plateau, with occasionally a small dip. The Ag11-induced histamine release curves presented two peaks (bimodal pattern), separated by a more or less pronounced inhibition dip. No non-specific histamine releasing activity was observed with the basophils of two controls. The possible theoretical models for the bimodal histamine release patterns are discussed.

Allergens↗
PubMed1983

Studies of antigen binding on human basophils. I. Antigen binding and functional consequences.

We developed an assay to study simultaneously antigen binding and its functional consequences on human basophils. Using a 125iodine-labeled penicillin-human serum albumin conjugate, we were able to detect as few as 100 molecules of antigen bound to purified basophils. We found that histamine release could be initiated with fewer than 100 molecules of antigen and that the optimum for histamine release occurred at a concentration at which 10 to 15% of the available antibody-binding sites were occupied. Analysis of the binding kinetics in the presence of monovalent hapten allowed a calculation of the affinity constant for the antibody:hapten association; the value of 2 to 3 X 10(6)/Msec confirmed an earlier independent calculation. Binding data also suggested a 25% fraction of the bound antigen was binding in monogamous bivalent form. It is anticipated that studies of this kind will delineate the nature of the antibody-antigen reaction on cell surfaces.

Antigens↗
PubMed1983

Studies of antigen binding on human basophils. II. Continued expression of antigen-specific IgE during antigen-induced desensitization.

We previously postulated that desensitization of human basophils was due to endocytosis or shedding of IgE and/or its Fc receptor. We report here, however, that during a 3-hr desensitization of purified basophils, there was no loss of cell surface antigen-specific IgE. The specific desensitization induced by antigen persists for at least 24 hr whereas simultaneously occurring nonspecific desensitization can recover during the same time interval. Therefore, we suggested that specific desensitization may result from a permanent modification of the Fc receptor or some closely associated protein. On the basis of elution studies of 125I-labeled BPO-HSA, we also suggest the antigen antibody reaction matures to aggregates of increasing size, and we propose that these large aggregates, unable to initiate a release signal, cause an additional component of desensitization.

Antigen-Antibody Reactions↗
PubMedDate not supplied

[Correlation between serum IgE level and human basophil degranulation by anti-IgE antibodies].

The human basophil degranulation test (HBDT) by anti-IgE antibodies was applied in 3 groups of subjects: 20 controls, 26 patients with helminthiasis and 28 allergic patients. Mean degranulation was higher in patients with helminthiasis than in the two other groups. A correlation was found between IgE serum level and HBDT results by anti-IgE (r = 0.373; p less than 0.02) with Spearman's rank correlation test. Therefore, degranulation with anti-IgE antibodies would appear to depend on the quantity of cell-bound IgE rather than on intrinsic basophil sensitivity.

Antibodies, Anti-Idiotypic↗
PubMed1983

Mast cells and basophils: models for studying the antianaphylactic potency of drugs.

Disodium chromoglycate, an antiasthmatic drug, which is effective in inhibiting mediator release from bronchial mast cells, failed to inhibit allergen-induced histamine release in vitro from actively sensitised basophils of grass pollen sensitive children and adults. In contrast, ketotifen, a drug that has been demonstrated in a number of placebo controlled studies to be of lower efficacy in vivo, inhibits histamine release. Our data support the concept that human basophils and mast cells respond differently to antianaphylactic drugs.

Adult↗
PubMed1978

Colonic basophil hypersensitivity.

Contact hypersensitivity reactions were elicited by intraluminal application of DNCB to the colon of guinea pigs and were found sometimes to contain large infiltrates of basophils. These colonic basophil hypersensitivity reactions were accompanied by systemic sensitization and were not seen in nonspecific colonic inflammatory responses induced by croton oil. The heterogenous immune inflammatory responses induced in the colon by DNCB contact sensitivity may serve as a model for the study of inflammatory bowel disease.

Animals↗
PubMed1982

Lipid hapten containing membrane targets can trigger specific immunoglobulin E-dependent degranulation of rat basophil leukemia cells.

We have studied the binding of liposomes containing dinitrophenylated lipid to rat basophil leukemia cells armed with monoclonal anti-dinitrophenyl IgE. The liposomes were either "fluid" at 37 degrees C (dimyristoylphosphatidylcholine or an equimolar binary mixture dipalmitoylphosphatidylcholine and cholesterol) or "solid" (dipalmitoylphosphatidylcholine, distearoylphosphatidylcholine, or dibehanoylphosphatidylcholine). We have also studied the immune mediated degranulation of these cells induced by the above lipid membrane targets. In some cases both studies were carried out with liposomes containing various surface densities of lipid haptens. From these studies we conclude that freely mobile nonaggregated lipid haptens in bilayer membrane targets can trigger efficient serotonin release from rat basophil leukemia cells in the presence of specific antihapten IgE. Solid target membranes are also effective as stimulators of serotonin release. The release of serotonin depends strongly on the surface density of lipid haptens over a narrow range of surface densities. These studies with lipid membrane targets having well defined physical properties indicate the need for generalized molecular models of receptor-mediated cell triggering.

Animals↗
PubMed1983

Comparative studies of human basophils and mast cells.

Atopic disease in humans results primarily from the activity of tissue mast cells and circulating basophils. These two very similar cell types have recently been purified to near homogeneity and studies have begun to identify the biochemical mechanisms of mediator release, to explore the effects of pharmacologic manipulation of the response, and to determine unambiguously which mediators are derived from mast cells and basophils. This report will review studies examining various parameters of histamine release, the role of cyclic AMP in histamine release, and the production of arachidonic acid metabolites and their pharmacologic modulation.

Animals↗
PubMed1977

Measurement of IgE on human basophils: relation to serum IgE and anti-IgE-induced histamine release.

The number of IgE molecules bound to human basophils was calculated from direct measurements of the IgE dissociated after exposing leukocytes to pH 3.7 acetate buffer in the cold. In 18 donors studied, cell-bound IgE ranged from 4000 to 500,000 molecules/basophil and correlated with the serum IgE concentration (r = 0.89, p less than 0.001) which ranged from 5 to 3,000 ng/ml. Sensitivity of these cells to anti-IgE was tested to explore the relationship between cell-bound IgE and the concentration of anti-IgE required for histamine release. Cells from some nonatopic donors (4000 to 100,000 IgE molecules/basophil) were as sensitive as cells from allergic donors (100,00 to 500,000 IgE molecules/basophil). Moreover, cells from donors having approximately the same cell-bound IgE concentration varied widely in their sensitivity to anti-IgE. We conclude that an intrinsic property of human basophils ("releasability") is an important parameter in determing mediator release.

Acetates↗