Search

Background Allergy can be diagnosed using basophil tests. Several methods measuring basophil activation are available. This study aimed at comparing basophil activation test ( BAT), histamine release assay ( HR), and passive sensitization histamine release assay (passive HR) in the diagnosis of peanut allergy. Methods BAT, HR, and passive HR were performed on 11 peanut-allergic and 14 nonallergic subjects. Blood was incubated with peanut extract or anti-IgE and tests were performed as follows: BAT- CD63 upregulation was assessed by flow cytometry; HR-released histamine was quantified by a glass fiber-based fluorometric method; passive HR-IgE-stripped donor basophils were incubated with participants' serum and histamine release was quantified as HR. Results CDsens, a measure of basophil allergen sensitivity, was significantly higher for BAT (80.1±17.4) compared to HR (23.4±10.31) and passive HR (11.1±2.0). BAT, HR, and passive HR had a clinical sensitivity of 100%, 100%, and 82% and specificity of 100%, 100%, and 100%, respectively, when excluding inconclusive results. BAT identified 11 of 11 allergic patients, HR 10, and passive HR 9. Likewise, BAT recognized 12 of 14 nonallergic subjects, HR 10, and passive HR 13. However, the tests' diagnostic performances were not statistically different. Interestingly, nonreleasers in HR but not in BAT had lower basophil count compared to releasers (249 vs 630 counts/min). Conclusion BAT displayed a significantly higher CDsens compared to HR and passive HR. The basophil tests' diagnostic performances were not significantly different. Still, BAT could diagnose subjects with low basophil number in contrast to HR. [ABSTRACT FROM AUTHOR]

Background: Patent Blue V (PBV) is injected in order to map sentinel nodes during cancer staging procedures. Anaphylactic reactions, allegedly IgE antibody mediated, have been reported. The aim of the study was to explore the immunological mechanism of anaphylaxis to PBV. Methods: PBV allergen threshold basophil sensitivity, CD-sens, was performed on cells from nine patients diagnosed as having had adverse reactions to PBV. The mechanisms of the CD-sens were studied by immunological and immuno-chemical methods. Results: Five of the nine patients had a positive CD-sens to PBV which was completely eliminated by washing the cells in phosphate buffered saline before allergen challenge. However, the positive CD-sens was completely reconstituted by incubating the cells in plasma or serum of that patient or the other PBV-anaphylactic patients for 15 min at room temperature. In some patients the factor mediating CD-sens was completely or partially destroyed by heating at +56°C for 30 min or being exposed to the low pH used for elution from anti-Ig columns. A 1000-fold excess of monoclonal IgE blocked the reconstitution by approximately 50%. Conclusion: Anaphylactic reactions to PBV are mediated by IgE antibodies giving a classical CD-sens reaction. However, the allergenic configuration seems to constitute a structure completely dependent on PBV, as a hapten, linked to a, so far, unknown carrier that seems to be unique for patients having experienced a PBV-induced reaction. Further studies are needed to characterize the postulated carrier. [ABSTRACT FROM AUTHOR]

Basophils of some individuals do not release histamine upon activation of their high-affinity immunoglobulin E (IgE) receptor (Fc εRI), but do so if this receptor is circumvented for cell activation. This so-called nonresponder phenomenon is clinically relevant, because in various studies atopy was less frequent or absent in nonresponder individuals. So far, it is unknown if this phenomenon is acquired during adulthood or exists from birth on. Histamine release was determined from isolated leucocytes stimulated with anti-IgE or calciumionophor. Also, random primed cDNA was synthesized and the open reading frame (ORF) of the Fc εRI β-subunit amplified and sequenced. In the first part of our study, we examined the role of atopic status, type of atopy, and age in a random population of 95 children of whom we found 22% to be nonresponder. None of these parameters correlated with the nonresponder status. Except for food allergy, no specific type of atopy correlated with histamine release. The mechanism underlying the nonresponder phenomenon is assumed to occur early in the signalling cascade. We hypothesized that mutations in the Fc εRI β-chain may be associated with the nonresponder status, and in the second part of our study sequenced the β-subunit in 20 responders and 20 nonresponders. Two conservative and two nonconservative heterozygous one base mutations (Thr179Thr, Asp216Asp, Ile147Leu and Glu237Gly) were found in two nonresponders and one responder. Three of these mutations have not been described so far. The nonresponder phenomenon is present from birth on and genetically determined. In our population, it was not associated with age or the presence of atopy, and appeared not to be caused by mutations in the Fc εRI β-chain. [ABSTRACT FROM AUTHOR]

To date, very little data are available about the nature of tomato allergens. Immunoglobulin E (IgE) cross-reactive profilins have been suggested to account for allergic symptoms in patients suffering from tomato allergy. The cDNA of tomato profilin was amplified by reversely transcribed polymerase chain reaction (RT-PCR) from total RNA extracted from ripe tomato fruit. The gene was cloned into the pET101D expression plasmid and the protein was produced in Escherichia coli BL21. Purification was performed via poly- l-proline (PLP) affinity chromatography. IgE reactivity of recombinant tomato profilin was investigated by immunoblot and enzyme-linked immunosorbent assay. IgE-inhibition studies were performed to analyse cross-reactivity with other profilins. To determine the allergenic activity of the recombinant protein, basophil histamine release assays using sera of patients with adverse reactions to tomato were performed. Profilin was identified as a new minor allergen in tomato fruits. The recombinant tomato profilin comprises 131 amino acids and high sequence identity to other allergenic food and pollen profilins. It was shown to be IgE-reactive with a prevalence of 22% (11/50) in tomato-allergic patients. In patients with tomato allergy and multiple sensitization to other foods and birch pollen, IgE directed against tomato profilin showed a strong cross-reactivity with profilins from plant food sources and birch pollen. The tomato profilin was able to induce mediator release from human basophils. The tomato profilin is a minor allergen in tomato fruit. Thus, it shows biological activity, as confirmed by in vitro histamine release assays with human basophils and thereby has the potential to account for clinical symptoms in tomato-allergic patients. [ABSTRACT FROM AUTHOR]

Background: The aim of the study was to examine the diagnostic value of skin prick test (SPT), scratch-chamber test (SCT), histamine release (HR) and specific immunoglobulin E (IgE) in birch-allergic patients with oral allergy syndrome to apple. Methods: Ten birch-allergic patients with oral allergy syndrome to apple and 10 control subjects were included. All were tested with SPT, SCT, HR and specific IgE [CAP, Pharmacia, Sweden and Magic Lite (ML), ALK-ABELLÓ, Denmark]. Results: The SPT with apple, acetone extract of apple (A72) and commercial apple extract showed sensitivities of 0.80, 0.90 and 0.10, respectively. The SCT with the same extracts showed sensitivities of 0.30, 0.50 and 0.20, respectively. The sensitivity of specific IgE to apple were 0.90 (CAP) and 0.10 (ML). The sensitivity of the HR test was 90% (A72), and 25% using the commercial extract. Conclusion: The SPT and HR test with apple and A72 showed a good diagnostic value with a sensitivity of more than 70% and a specificity of 100%. The SCT showed a poor sensitivity to apple, A72 and commercial apple extract. The ML test was not suitable in detecting specific IgE to apple compared with the CAP test. In daily practice a detailed case history about symptoms of oral allergy syndrome combined with a SPT with fresh apple peel or A72 will be useful. [ABSTRACT FROM AUTHOR]

The diagnosis of allergic reactions in clinical practice is based on both clinical history and the determination of specific immunoglobulin E (IgE), either in the serum or on skin mast cells. However, for various reasons, identification of the causative factors is not possible in all the cases. Moreover, not all allergies are IgE-dependent. In an attempt to find sensitive, specific and cost-effective methods to investigate hypersensitivity reactions, in vitro tests were developed at a very early stage. Allergen-induced mediator release assays analyze the mediator released from effector cells, mainly peripheral blood cells, when stimulated in vitro with serial dilutions of the putative allergens. Described initially as research tools, they could well become diagnostic tests. However, relatively few high quality reports have been published so far. In this review, we will detail allergen-dependent histamine, tryptase, arachidonic acid metabolite, e.g. cysteinyl leukotrienes and 15-hydroxyeicosatetraenoic mediator release tests. [ABSTRACT FROM AUTHOR]

Background: The diagnosis of allergic reactions to drugs is difficult. Most skin tests are not standardized, and in vitro tests are needed to avoid provocation tests. Cross-linking of IgE on basophils is known to cause the release of both cysteinyl leukotriene (Cys-LT) and histamine. We aimed to evaluate the diagnostic utility (sensitivity, specificity, and efficiency) of measurement of sulfidoleukotrienes in drug allergy. Methods: We performed a prospective study in 55 patients with proven immediate adverse reactions to drugs (30 to β-lactams, six to acetaminophen, and 19 to aspirin) and 64 drug-exposed nonallergic controls. Positive diagnosis was established by history, skin tests, and, if needed, oral provocation tests. Cys-LT release was determined after drug-allergen stimulation by the cellular antigen stimulation test (CAST®) technique. Histamine release was also assessed on the same samples by enzyme immunoassay. Spontaneous and anti-FcεRIα-induced mediator release was also studied in all subjects. Sensitivity, specificity, and efficiency were calculated. Results: Net Cys-LT release was over the maximal threshold given by the manufacturer in 19/55 patients and in 9/64 controls. Net histamine release was over 5% of total histamine content in 28/55 patients and 34/64 controls. The efficiency of both tests was low. Conclusions: Thus, in most cases, the in vitro Cys-LT test has little or no diagnostic utility and is not superior to histamine release. [ABSTRACT FROM AUTHOR]

Background: Patients with birch and grass allergy often suffer from oral allergy symptoms when ingesting cross-reacting fresh fruits and vegetables. However, fruit and vegetable allergen extracts are often readily degradable or contain clinically irrelevant cross-reacting epitopes, resulting in diagnostic discrepancies when fruit and vegetable allergic reactions are evaluated. The risk of using nonstandardized fresh food extracts for skin testing may also be of concern. The objective was to compare and evaluate the clinical utility of selected recombinant grass and birch cross-reacting food allergens with fresh and commercial melon, hazelnut, and apple extracts. Methods: Thirty-six grass- and or birch-allergic patients and 17 control subjects consented to participate in the study. All subjects were skin prick tested and had basophil histamine-release tests done with fresh fruits and various extracts of hazelnut, apple, and melon. The diagnosis of oral allergy syndrome was confirmed by oral challenges. In addition, histamine release to recombinant Bet v 1 and Bet v 2, and recombinant Phl p 1 and Phl p 2, Phl p 5 was performed. Results: The skin prick test with fresh hazelnut, apple, and melon showed sensitivities of 0.97, 0.92, and 0.89, respectively. The corresponding specificities were 0.78, 0.72, and 0.82, respectively. In contrast, the histamine-release test with hazelnut, apple, and melon gave sensitivities of 0.87, 0.71, and 1.00, respectively. The corresponding specificities were 0.65, 0.93, and 0.43. The skin prick test showed excellent negative predictive value (>90%). No added value of recombinant allergen testing was noted. Oral challenge did not result in severe systemic reactions, and no systemic reactions were observed with skin prick tests with fresh fruits. Conclusions: The skin prick test showed an almost optimal diagnostic value with a satisfactory sensitivity (>89%) and excellent negative predictive value with fresh fruits. When the skin prick test with fresh nut and apple cannot be performed, histamine release is a diagnostic alternative. Histamine release with melon showed lack of specificity. This was probably due to extensive IgE cross-reactivity with pollen, since these patients also responded to recombinant Phl p 1 and Bet v 1. Skin testing and challenges with fresh fruits were safe. [ABSTRACT FROM AUTHOR]

Chronic spontaneous urticaria ( CSU) significantly impacts the quality of life of those affected through symptoms of pruritus and recurrent skin lesions. In active CSU disease, reduced IgE-mediated basophil histamine release ( HR) and basopenia are observed. We sought to examine the relationship between interval changes in basophil measures and shifts in patient-reported disease impairment. Simultaneous symptom and basophil evaluations were completed at two sequential study visits, and interval changes in measures were compared between visits for each subject ( n = 38). These measures included Skindex-29, current itch and hives scores, total leukocyte histamine content (an indirect measure of blood basophil presence), and basophil HR in response to anti-IgE and formyl-methionine-leucine-phenylalanine. Overall, interval improvements in disease measures in CSU subjects were associated with increased basophil numbers (total leukocyte histamine content) and IgE-mediated HR. This suggests these measures are potential biomarkers for CSU disease improvement and further implicates a role for basophils in CSU. [ABSTRACT FROM AUTHOR]

Background: The diagnosis of immediate allergic reactions to drugs is difficult, requiring in vitro test development. Basophils are likely to be involved in these reactions, and to evaluate the sensitivity, the specificity, and the predictive values of the histamine‐release test, we performed a prospective study in 68 patients tested for suspected drug allergy. Methods: Positive diagnosis was established by history, skin tests, and, if needed, oral provocation tests. Histamine release in the presence of the drug was assessed on heparinized whole blood by enzyme immunoassay (Immunotech, France), and the cutoff value was set at 5% of total histamine content. Spontaneous and anti‐IgE‐induced histamine release was also studied in all subjects. Results: All patients presented to our clinic with reactions ranging from maculopapular exanthema to anaphylactic shock. Thirty‐five patients had proven drug allergy; 33 were not allergic to drugs and served as a control group together with 40 other subjects with no history of drug allergy. Net histamine release was positive in 18/35 allergics and 27/73 nonallergics, giving poor sensitivity (51.4%), specificity (63.0%), and positive predictive value (29.3%), but valuable negative predictive value (81.1%). Conclusions: The usefulness of the in vitro histamine‐release test for the diagnosis of drug allergy appears to be insufficient. [ABSTRACT FROM AUTHOR]

Background The aim of this study was to evaluate the in vivo and ex vivo effects of the H1-antagonist loratadine on histamine release. Methods The study was designed as a double-blind, crossover trial. Ten patients with allergic rhinitis due to Dermatophagoides pteronyssinus were treated with loratadine (10 mg daily p.o.) and with placebo for 1 week, with a 2-week interval between the two treatments. Nasal lavages with saline solution were done before and after challenge with the relevant allergen at the end of treatments with loratadine and placebo. Venous blood was taken after treatments, and basophil histamine release induced by anti-IgE (10 µg/ ml), N-formyl-methionyl-leucyl-phenylalanine (fMLP, 1 µM), and Ca2+ ionophore A23187 (1 µM) was evaluated by an automated fluorometric method. Results Treatment with loratadine attenuated early antigen-induced nasal obstruction, rhinorrhea, and itching. Nasal symptoms were accompanied by a significant histamine release in the nasal lavages collected 5 min after stimulation when the patients received placebo (median 4 ng/ml, range 1-28; P<0.05). After treatment with loratadine, histamine release in the 5-min postchallenge lavages was almost abrogated (median 0.5 ng/ml, range 0-3; P<0.01 vs placebo). Median anti-IgE-induced histamine release from basophils was 41.9% (range 27.8-79.2) after placebo and 30.0% (range 1.7- 73.3, P 0.05) after loratadine. Active treatment exerted an inhibitory effect also on basophil histamine release induced by fMLP and Ca2+ ionophore A23187. Conclusions Treatment for 1 week with loratadine reduces allergen-induced nasal symptoms and inhibits in vivo and ex vivo histamine release in patients with allergic rhinitis. [ABSTRACT FROM AUTHOR]

The article discusses the general rule concerning the interactions between allergen and cell-bound immunoglobulin E (IgE) antibody. It highlights the differences between carbohydrate epitopes and peptide epitopes in terms of structures and immunologic recognition. It also discusses the modifying effects of IgE antibodies and its structural variability in glycosylation patterns through chemical analysis of myeloma proteins and of reactivity to lectins.

Identification of factors influencing histamine release from purified and cultured basophil leukocytes is important for proper interpretation of results obtained on histamine release. This paper describes factors that influence spontaneous histamine secretion from human basophil leukocytes purified on Percoll gradients, followed by negative selection with Dynabeads. Anti- IgE and recombinant human interleukin-3 were used as model stimulants, and the purified basophil leukocytes were stimulated for 10 min and 6 h. The effect of the following conditions was examined: Percoll temperature, cell-suspension density, and serum in the media. The results showed that low Percoll temperature, high cell-suspension density, and the presence of serum in the media decreased spontaneous histamine release and increased maximal net histamine release upon stimulation. [ABSTRACT FROM AUTHOR]

The effects of interleukin-3 (IL-3) on histamine release from cord and adult blood basophils were evaluated. Leukocyte suspensions, obtained from adult patients with respiratory allergy (n = 15), normal adult subjects (n = 15), and neonates with (n=15) and without (n=19) atopic disposition, were stimulated with anti-IgE, fMLP, and IL-3. IgE-mediated histamine release was significantly higher in adult patients, either allergic or normal, than in neonates with or without atopic disposition. A trend toward higher fMLP-induced histamine release was found in allergic adult subjects. IL-3 had a weak direct histamine-releasing activity in allergic adult subjects and in neonates, but not in normal adult donors. A significant enhancing effect of IL-3 on histamine release induced by anti-IgE was observed in neonates with and without atopic disposition and in normal adult subjects, but not in atopic adult patients. IL-3 exerted a priming effect also when basophils were stimulated with fMLP, without any significant difference between neonates and adult subjects. Passive sensitization with IgE-rich serum resulted in a significant increase in anti-IgE-induced, but not in IL-3-induced, histamine release from cord-blood basophils. In conclusion, IL-3 primes cord-blood as well as adult blood basophils for a consecutive anti-IgE- or fMLP-induced histamine release, and its activity is not limited by the low density of membrane IgE in cord-blood basophils. [ABSTRACT FROM AUTHOR]

A number of investigations have indicated that cholinergic agonists release histamine from isolated mast cells and suggested that cholinergic stimulation releases histamine in vivo. The purpose of this study was to investigate whether the cutaneous wheat-and-flare reaction induced by methacholine challenge in human skin involves histamine release as measured by the skin microdialysis technique. Five hollow dialysis fibers were inserted intradermally in forearm skin in eight healthy subjects. Each fiber was perfused with Kreb's-Ringer bicarbonate at a rate of 3 μ/min. Dialysates were collected in 2-min fractions before skin challenge and for 20 min after intradermal injection of methacholine 10-3-10-1 M, the vehicle, and a positive control, codeine phosphate 0.3 mg/ml. Histamine was assayed spectrofluorometrically. Methacholine caused a statistically significant dose-related wheal-and-flare reactions the flare reaction to methacholine 10-1 M being comparable with that seen with codeine 0.3 mg/ml. No significant histamine release was observed with methacholine, cumulative histamine release of 16 ± 8 nM by methacholine 10-1 M being similar to vehicle responses of 15 ± 9 nM. Histamine release by codeine was 2524 ± 435 nM. In conclusion. methacholine-induced wheat-and-flare reactions in human skin appeared not to involve histamine release from skin mast cells. [ABSTRACT FROM AUTHOR]

Experiments were done to clarify the mechanisms associated with releasability of histamine. First, washed leukocytes from 23 asthmatic patients sensitive to mite allergen were challenged with Der p 1, a major allergen isolated from Dermatophagoides pteronyssinus, or anti-IgE. A significant correlation was observed between the ratio of Der p 1-specific IgE titer to total IgE level (S,T) in the patient's plasma and either the reactivity (maximal percentage of histamine release: rs = 0.514, P= 0.016, n = 23) or the sensitivity (the minimum allergen concentration required to achieve 25% histamine release: rs = -0.790, P = 0.0002) to Der p 1. Additionally, the reactivity to Der p 1 was significantly correlated with that to anti-IgE (rs = 0.690, P = 0.0012), indicating that an intrinsic cellular property may be one of the contributing factors in immunologic histamine release. In a second series of experiments, sinus mast cells were passively sensitized with immunoglobulins prepared from the patient's plasma. A statistically significant correlation was found between either the reactivity or the sensitivity to Der p 1 and S T, thus indicating that S.T is an indicator of the releasability of histamine. When basophils or mast cells were passively sensitized with mouse IgE and subsequently stimulated with antimouse IgE, the reactivity to antihuman IgE was significantly correlated with that to antimouse IgE (rs 0.966, P = 0.0023, n = 11). These observations suggest that an intrinsic cellular property regulates reactivity in immunologic histamine release. Taken together, our results suggest that an intrinsic cellular property, as well as specific IgE antibody levels on the cell surface. is an important factor in determining histamine release in response to IgE-dependent activation. [ABSTRACT FROM AUTHOR]

The major allergen from birch pollen, Bet v I, and the cross-reacting 18-kDa major allergen from Golden Delicious and Granny Smith applies were isolated by micropreparative SDS-PAGE followed by electroelution. In the case of apples, highly active, low-temperature extracts were used. The purity of the allergens was checked by analytic SDS-PAGE and immunoblotting with allergic patients' sera, as well as by N-terminal amino acid microsequencing, and the allergens were found to be very pure. The strong immunologic activity of the isolates was determined by the enzyme allergosorbent test (EAST) and EAST inhibition assays; this activity was, in the case of Bet v I, similar to that of a preparation obtained by monoclonal antibody affinity chromatography. The allergenic potency of Bet v I and of the cross-reactive apple allergen was determined by EAST inhibition and dose-related histamine release. With both assay systems, the allergenic reactivity of Bet v I was considerably higher than that of the major apple allergen. Furthermore, skin prick tests with the purified allergens and with whole allergenic extracts were performed on a group of 33 patients suffering from birch-pollen and apple hypersensitivity, and on a control group of 10 patients. The frequency of positive prick test results in the allergic patient group ranged from 73% for the major allergen from Golden Delicious apples to 97% with Bet v I and whole birch pollen extract, respectively. In contrast to our low-temperature extracts, commercial prick test solutions of four different manufacturers were found to be unreliable for the diagnosis of apple allergy. The skin test results again indicated the strong immunologic activity of the allergen isolates and the predominance of the major allergens in context with birch-pollen and apple hypersensitivity. Taken together, the results support the view that the 18-kDa major allergen represents most of the allergenicity of the the apple fruit, and that all allergenic epitopes of the apple proteins are present on Bet v I. [ABSTRACT FROM AUTHOR]

We investigated the effects of stem cell factor (SCF) on histamine release (HR) from human bronchoalveolar lavage (BAL) mast cells. BAL cells were recovered from lavage performed in patients undergoing clinical bronchoscopy. SCF (0.02-20 ng/ml), which is by itself a poor secretagogue (mean ± SEM HR: 3.7 ± 0.9%; n = 27), strongly enhanced HR induced by anti-IgE in a concentration-related manner. Significant potentiation began at 0.2 ng/ml (30 ± 10%; P< 0.05; n = 12) and reached a plateau at 2 ng/ml (40 ± 10%; P< 0.01 at 2 ng/ml and 45 ± 10%; P< 0.01 at 20 ng/ml; n = 12). In contrast, SCF failed to enhance HR induced by calcium ionophore A23187. Among the BAL cell samples initially unresponsive to anti-IgE (55% of samples), 36% (10/28) were converted to responders if the cells were shortly preincubated with SCF. In 25% of samples (7/27), SCF (20 ng/ml) caused direct HR of 10 ± 2.1%. The mast cells which released histamine when challenged with SCF also secreted higher levels of histamine in response to anti-IgE and calcium ionophore than those nonresponsive to SCF. While interleukin (IL)-3 and IL-5 (20 ng/ml) were unable to modulate immunologic HR, GM-CSF (20 ng/ml) produced significant potentiation (P< 0.05), which was, however, smaller than that observed with SCF. The rate of responders to anti-IgE in atopic asthma (47%) was greater than that in control (9%) and intrinsic asthma (10%) but not different from that in some other respiratory diseases such as chronic bronchitis (44%c), lung cancer (47%). or interstitial disease (68%). The potentiation of HR afforded by SCF did not differ significantly among the several disease groups. We conclude that, whatever the underlying respiratory disease, SCF selectively enhances IgE-mediated HR from human BAL mast cells. Furthermore, this cytokine is sometimes necessary to render mast cells able to release histamine in... [ABSTRACT FROM AUTHOR]

We report the effect of interleukin-3 (IL-3) and of other cytokines on antigen-induced basophil histamine release in wasp-venom-allergic subjects. Leukocytes from 12 patients with documented anaphylactic sensitivity to wasp venom were preincubated in the presence or absence of IL-3, granulocyte/macrophage-colony stimulating factor (G M-CSF), IL-5, IL-8, or stem cell factor (SCF). Washed cells were then exposed to venom and to other secretagogues and histamine release in the supernatant was measured fluorometrically. Preincubation of leukocytes with IL-3, GM-CSF, or IL-5 (0.02-2 ng/ml) but not with IL-8 and SCF, caused a dose-dependent enhancement of antigen-induced basophilic histamine release in all subjects tested. Mean, maximum increase was about 100% for IL-3, IL-5, and GM-CSF. The priming effect of IL-3 was rapid, persisted up to 12 h, and was not accompanied by a change in cellular histamine. IL-3 had a comparable enhancing effect when basophils were triggered with anti-IgE or N-formylmethionylphenylalanine (FMP). By contrast, IL-3 had no effect on substance-P-induced histamine release. The significant enhancement of basophil releasability to antigen in wasp-venom allergy by very low concentrations of IL-3, GM-CSF, and IL-5 suggests that cytokines in the basophil (mast-cell?) microenvironment could be critical factors in determining the variability of sting reactions in Hymenoptera-venom-allergic subjects. [ABSTRACT FROM AUTHOR]

High levels of IgE and eosinophilia are found in both allergy and helminth infections, but allergic symptoms are rare in naturally acquired helminth infections. The interrelation of specific IgE antibodies and in vitro basophil histamine release (HR) induced by exoantigens from the larva! stages (L2/L3) of the nematodes Toxocara canis and Ascaris suum was examined in 148 patients visiting an outpatient clinic for parasitic diseases The antigen sensitivity of the basophils was found to be dependent not only on the absolute amount of antigen-specific IgE present in patient plasma but also on the ratio between specific and total IgE. Thus, large HR was observed an some patients in response to helminth antigens despite low levels of both specific and total IgE content in plasma. Patients with eosinophilia showed greater IgE-mediated HR than the other patients examined In contrast, only thee patients showed HR after challenge with antigen-specific IgG4, despite the presence of high levels of antigen-specific IgG4 and lgG 1 in all patients showing specific IgG4 and IgG1 in all patients showing specific lgE antibodies. [ABSTRACT FROM AUTHOR]

Low-temperature, acetone powder extracts were prepared from mature fruit of 16 apple strains. SDS--PAGE and immunoblot analysis revealed great variation in the relative amounts of the 18-kDa apple allergen in these extracts. EAST (RAST) scores, measured with individual and pool sera from patients allergic to birch pollen and apples, ranged from 0.2 to 4.0 and were related to the relative amount of the 18-kDa protein. These findings were confirmed by ELISA-inhibition assays, dose-related histamine release, semiquantitative evaluation of immunoblots by absorption/reflection densitometry, and skin prick tests with extracts of Golden Delicious, Boskoop, and Jamba apples (corresponding to a high, low, and very low 18-kDa allergen content). Additional open oral challenge tests were performed with two apple-allergic patients and 15 and 16 apple strains. With all methods, the deduced allergenic potency decreased in the following order: Golden Delicious > Boskoop > Jamba. Therefore, we concluded that the IgE-binding potency of apple strains depends on the occurrence of the 18-kDa allergen. [ABSTRACT FROM AUTHOR]

A microfiberglass-based histamine assay (HRM) was compared with an automated fluorometric histamine assay (HRA). Twenty-four subjects with and 24 without a case history (CH) of milk and/or egg allergy were tested by HRM and HRA, skin prick test (SPT), and specific serum IgE (RAST). Six different concentrations of milk, egg, and anti-IgE were used to stimulate washed leukocytes (250 μl for HRA) and whole blood samples (25 μl for HRM) in parallel. When we compared scores representing basophil sensitivity, correlation coefficients (rs) were positive (r(anti-IgE) = 0.88, r(egg) = 0.95, r(milk) = 0.88, P < 0.001), but no significant correlations were found after exclusion of the negatives in both tests. In some individual dose-response curves, the scores obtained by HRM were shifted to higher allergen and anti-IgE concentrations. A high degree of concordance was found in positive and negative responses between the two tests: anti-IgE 91%, egg 92%, milk 86%. Finally, we found a good concordance between, on one side, HRM and, on the other, CH, SPT, and RAST (HRM vs. CH/SPT/RAST): egg 92/82/82%; milk 89/74/67%. We conclude that HRM is in good qualitative, but poor quantitative, agreement with the autoanalyzer-based fluorometric histamine assay. [ABSTRACT FROM AUTHOR]

The main objective of this study was to test the effectiveness of astemizole in vitro in blocking the release of histamine from blood of patients with allergic rhinitis. The results of this investigation indicated that astemizole inhibited allergen-mediated histamine release from blood basophils of patients with this allergic disorder The inhibition by astemizole (33-156 μmol) was immediate, requiring no pre-incubation of the cells, and was dose-dependen, with maximal inhibition of about 91% . The relatively high potency of astemizole in inhibiting the immunologic release of histamine may provide an additional measure in the treatment of allergic rhinitis with this Hl-receptor antagonist. [ABSTRACT FROM AUTHOR]

Histamine release (HR) studies were performed in 40 birch pollen-allergic patients (positive case history, positive SPT, positive birch pollen-specific serum lgE RAST≥3) with (n = 20, A) and without (n = 20, B) fruit hypersensitivity, and 10 nonatopic volunteers (C) Several fruit allergens were used and characterized by protein determination and immunoblot techniques. Dose-dependent HR (apple peel = apple pulp > peach = cherry) was demonstrated in both allergic groups, but to a higher extent in patients with fruit allergy (P<0.01) Increased basophil sensitivity to birch pollen was found in the group with fruit, allergy (P<0.001) Strong correlations between the mediator response induced by several fruits indicate common allergens within the extracts. We conclude that fruit-related symptoms require not only high specific serum IgE, but a strong cellular sensitization to birch pollen allergens together with an increased cellular reactivity to fruit allergens. [ABSTRACT FROM AUTHOR]

Histamine as an important mediator of the allergic reaction has been measured by a number of methods both in whole blood and cell supernatants after in vitro release. We compared the fluorometric histamine assay with two radioimmunoassays and studied detection limit, recovery, cross-reactivity and accuracy in buffer-based standards as well as the sensitivity after IgE-mediated in vitro release from washed cells and whole blood. Our data indicate that the double-antibody RIA (Pharmacia) can be used for studies of basophil histamine release in both whole blood and cell supernatants. Due to significant cross-reactivity to N-methyl-histamine it cannot be used for histamine determinations in plasma. The second radioimmunoassay using succinyl-glycine as an acylating reagent and monoclonal antibodies, which have been raised to acylated histamine, is the most sensitive assay without any cross-reactivity with methylhistamine. [ABSTRACT FROM AUTHOR]

Histamine release from human basophil leukocytes from allergic patients or controls was induced by specific antigens, anti-IgE or calcium ionophore A23187. Influenza A virus, S. aureus and lipopolysaccharide from S.typhimurium increased the maximum release of histamine and caused a shift to the left of the dose-response curves showing increased cell sensitivity and lowering of the threshold to these stimuli. The mechanism of action was elucidated by examining the mediator release as a function of increasing extracellular concentration of calcium. In these experiments the dose-response curves were changed by the microorganisms and lipopolysaccharide as before. This indicates that the microorganisms and lipopolysaccharide as before. This indicates that the microorganisms and lipopolysaccharide change the basophil cell response to IgE-dependent and non-immunological stimuli by causing a change in the subcellular handling of calcium. [ABSTRACT FROM AUTHOR]

Histamine release induced by Staphylucoccus aureus was examined in cells obtained by bronchoalveolar lavage (BAL) in non-atopic mdividuals. Approximately half of the individuals responded with mediator release to the bacterium, and the release was found to be time- and concentration dependent. No difference was found between the patients who responded and those who did not respond in regard to age, sex, smoker/non smoker, % recovery of BAL-fluid, total cell count, differential cell counts, histamine content per mast cell, or diagnoses. Also stimulation of the BAL-cells with the calcium-ionophore A23187 resulted in histamine release, S. aureus-induced histamine release from basophil was examined in leukocyte suspensions obtained from the same individuals, and in all experiments release was found. The dose-response curves were similar to those obtained with BAL cells- The bacteria-induced mediator release from superficially lying cells in the airways epithelium might be of importance for the precipitation or exacerbation of bronchial asthma in respiratory tract infections. [ABSTRACT FROM AUTHOR]

We followed a number of in vitro parameters in nine adult patients with atopic dermatitis for a period of 3 weeks during which the patients took herbal drugs that are claimed to improve chronic eczema. The following investigations were performed weekly: blood leucocytes, circulating eosinophils, serum IgE, mitogen responsiveness of lymphocytes, interleukin 1 release, soluble interleukin 2 receptor levels in serum, and in vitro histamine release from basophils in blood. The study demonstrated increased levels of IgE in six patients, increased levels of soluble interleukin 2 receptor in six patients, and a significant correlation between the amount of IgE in serum and the maximal release of histamine from basophils in blood. In this open study five patients experienced a clinical worsening of their disease during the intake of herbal medicine. All other parameters were within normal levels. There was no significant change in the in vitro parameters during the observation period. [ABSTRACT FROM AUTHOR]

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

Histamine release caused by anti-IgE, specific antigens and calcium ionophore A23187 was examined in leukocyte suspensions from healthy individuals and patients allergic to house dust mite and birch pollen. Staphylococcus aureus and LPS from Salmonella typhimurium were found to cause a synergistic enhancement of the release. The potentiation of mediator release by the bacteria and the endotoxin depends on a binding to the basophilocyte, followed by a non-transient event, since the potentiating effect persists after preincubation of the cells with the LPS followed by washout and leaving the cells for 30 min at 37 °C before stimulation with anti-IgE. The potentiation was abolished or reduced by galactose (10-7 and 10-6 M) and N-acetylglucosamine (10-6 and 10-5 M), acting by a binding to the basophil cell membrane, demonstrated by the persistence of effect after preincubation and washout of unbound sugar. [ABSTRACT FROM AUTHOR]

Influenza A virus was found to enhance basophil histamine release induced by Escherichia coli, Salmonella enteritidis, Staphylococcus aureus, Streptococcus pneumoniae and Streptococcus sanguis, but did not per se release histamine. This potentiating effect of the virus was seen both when the bacteria-induced mediator release was IgE-dependent (i.e. patient allergic to bacterium) and when the bacterium caused histamine release by a non-immunological mechanism independent of IgE (putative sugar-lectin mediated). Also histamine release induced by other immunological and non-immunological stimuli, such as anti-IgE, calcium ionophore or agarose beads was enhanced in the presence of the virus. The potentiating effect of the virus on bacteria-induced mediator release might be of importance for the conversion from latent to manifest asthma in upper respiratory tract infections. [ABSTRACT FROM AUTHOR]

The aim of the study is to compare the glass fibre-based basophil histamine release test with skin test (Phazet®), RAST (Phadebas®) and bronchial provocation test in children with allergic asthma. The study comprised 68 selected children with a case history of extrinsic allergic asthma to danders (cat and dog) and house-dust mite. Skin prick test, RAST, and histamine release were performed in all children and the bronchial provocation test was used as a reference of "true allergic asthma". A total of 81 allergen bronchial challenges were performed and 44 children experienced 49 positive provocations. In 2.994 (2/68) of the children histamine release could not be performed due to technical difficulties (low histamine release with anti-IgE). Concordances in the range 76-87 % were observed with no significant difference between the tests. The highest concordance (87%) was found between histamine release and bronchial provocation test' followed by skin prick test vs bronchial provocation (84%) and RAST vs bronchial provocation (80 %). The sensitivity and specificity were calculated for each test. All tests showed sensitivities in the range 90-94 % and no significant difference between them was observed. The specificity of histamine release, skin prick test, and RAST was 0.78, 0.69, and 0.63, respectively. The specificity of histamine release was better than RAST demonstrated by 95 % confidence intervals. In conclusion, it was found that the histamine release test is a convenient diagnostic method and the study indicates a diagnostic value comparable to the common diagnostic methods in clinical allergy. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the diagnostic value of common allergy tests with basophil histamine release in 124 children with symptoms of asthma. The patients were evaluated by case history, skin prick test, RAST-analysis, and basophil histamine release using a glass fibre-based histamine assay to 10 common inhalant allergens. The bronchial provocation test was used as a reference of "true" IgE-mediated asthma. To compare the various diagnostic parameters each absolute test value was classified into a scoring system. The concordance between the tests varied between 85-97%. In general, the best concordance was found between basophil histamine release and RAST, Sensitivity, specificity and predictive values were calculated on the basis of 104 bronchial provocation tests. It was found that histamine release was the best single analysis, followed by RAST and prick testing. The sensitivity of RAST and histamine release was very high (1.00) for pollen and house dust mites. Histamine release showed a predictive value between 0.91. and 1.00 for pollen and house dust mites, thus indicating the possibility of omitting the bronchial provocation test. In the dander group histamine release gave the best sensitivity (0.91), however at the expense of specificity (0.64) whereas RAST and skin prick test gave a specificity of 1.00. In the mould group histamine release also showed the best diagnostic value. The combination of skin testing with histamine release or RAST was of no additional diagnostic help. It is concluded that the glass fibre-based histamine analysis, which makes routine histamine release testing possible. is a reliable diagnostic test in children. [ABSTRACT FROM AUTHOR]

Forty-six adult asthmatics allergic to D. pteronyssinus (Dp) participated in a 2-year study. Thirty-one underwent hyposensitization (HS-group). Fifteen were treated with Dp-extract (Dp-group), and 16 with a similar extract modified by monomethoxypolyethylene glycol with reduced allergenicity (mPEG-Dp-group). Fifteen patients served as controls. Dp-specific antibodies and histamine release from blood basophils were determined and compared with Dp-sensitivity in lungs and skin. In addition, IgG and IgE against the major allergen Der p I were followed in a subgroup. Dp-specific IgG, IgG1, and IgG4 increased significantly in both HS-treated groups after 1 and 2 years (median: 2.5- to 11.6-fold). IgG4 was not induced if maintenance dose during the first year was less than 20,000 BU. Median skin sensitivity decreased 4.4- to 8.2-fold after 1 year and 7.4- to 21.4-fold after 2 years. Der p I specific IgG response was unrelated to the occurrence or change in IgE with the same specificity. The mPEG-Dp-extract tended to have less effect on skin sensitivity and immunological parameters, differences reaching statistical significance for skin sensitivity only. In the HS-group, the decrease in bronchial sensitivity was significantly correlated to a decrease in IgE (r = 0.36), IgG1/IgG4 (r = 0.49), Dp-specific histamine release (r = 0.58), and to an increase in Dp-specific IgG4 (r = -0.36) and IgG4/IgE (r = -0.48). In patients improving clinically, Dp-specific IgG4/IgE increased, and median Dp-specific IgE was reduced to 80% compared with an increase to 150-160% seen in the unchanged or deteriorated group (P< 0.05). Findings indicate an improvement of effect, if the allergen dose is sufficient to reduce specific IgE and/or induce an IgG and especially IgG4 response. [ABSTRACT FROM AUTHOR]

Haemophilus influenza and its extracellular products (EP) did not release histamine from basophil leukocytes in cell suspensions from normal individuals, patients with chronic bronchitis or patients allergic to either house dust mite, grass pollen, eat dander or to their own bacteria. However, the EP was found to enhance their basophil histamine release. IgE-mediated histamine release was examined by stimulation of the cells with anti-IgE or the specific allergens, and non-immunological histamine release by stimulating the cells with the calcium ionophore A23187 or Staphylacoccus aureus. In all the experiments EP caused a significant increase in the histamine release. When H. influenzae endotoxins were removed from the EP, the potentiating effect of EP was completely abolished, whereas heating (80°C, 30 min) or treatment of EP with proteinase did not influence the potentiating effect. These results indicate that H. influenzae endotoxin potentiates histamine release caused by IgE-mediated reactions or by non-immunological mechanisms. [ABSTRACT FROM AUTHOR]

The in vitro histamine release response of human intestinal mast cells and basophils challenged with anti-IgE, Concanavalin A, ionophore A23187 and food extracts was compared with skin prick test, RAST analysis and open food challenge. It was not possible to perform food challenge in all patients; however, seven children underwent open food challenge and in five the clinical diagnosis of ‘true’ food allergy was confirmed. The intestinal mast cells were pooled from enzymatically dispersed duodenal biopsies obtained by duodenoscopy from 15 selected children suspected of food allergy, and five age-matched controls. In nine of 10 patients classified as ‘food allergic’ intestinal mast ceils released histamine m various food extracts in a dose-dependent fashion. From the mast cells of the nine food-allergic patients compared with non- allergies, the anti-IgE mediated mast cell histamine release was increased. Additionally, at 1000 U/ml anti-IgE the mast cell histamine release was increased compared with their corresponding basophils. However, in non-allergic subjects the histamine release of basophils was increased compared with their corresponding mast cells. Histamine release from basophils was positively correlated to the test scores of the RAST analysis, skin prick test, and food challenge. No apparent correlation between tests scores obtained from histamine release of intestinal mast cell and the other tests was demonstrated, except in children with diarrhoea as only symptom. However, the study gives evidence that duodenal mast cells actually are sensitized with specific IgE and thus may play a pathophysiological role in food hypersensitivity. In addition, the study shows that the ability of different stimuli, including food extracts, to trigger basophil histamine release does not correlate with their potency to induce histamine release from mast cells. [ABSTRACT FROM AUTHOR]

To study the human intestinal mast cell of children and adults, we combined a sensitive glassfibre-based histamine assay with the enzymatic and mechanical dispersion of surgical specimens or mucosal biopsies. The method yields between 1.2 × 103 to 4.6 × 103 mast cells/mg tissue constituting 1.2 % to 5.3 % of total cell count. The mast cell yield, however, depends on the intestinal tissue specimen used for dispersion. Aliquots containing 1500 mast cells per sample are sufficient for measuring significant amounts of histamine (≥ 0.15 ng histamine per sample), thus making it possible, to carry out approximately 75 tests for four mucosal biopsies of 10 mg each. The intestinal mast cell releases histamine in a dose-dependent manner on challenge with anti-lgE (6–600 U/ml), ionophore A23187 (0.25–1.0 μM), and Concanavalin A (0.7–25.0 μg/ml). The histamine release shows interindividual variation with a net histamine release between 0 to 2.5 ng/samples dependent on the secretatogue. In general, it is not necessary to passively sensitize the mast cells to obtain a sufficient histamine release response to anti-IgE challenge, indicating the presence of intact and functional cell-bound IgE. However, it is shown that four of 10 non-atopic intestinal mast cell samples could be passively sensitized with human plasma containing either mite- or grass-specific IgE without stripping nit the IgE first. This indicates the presence of free and preserved Fc-receptors on the dispersed mast cells in some subjects. In addition, it is found that the phorbolester TPA increases die histamine release response to A23187 and turns anti-IgE non-responding mast cells into responding mast cells, but TPA alone at 2 to 16 ng/ml has no histamine releasing effect. In patients with anti-IgE responding mast cells no additional effect of TPA is seen. Finally, no substantial differences between mast cells of children and adults are demon- strated. [ABSTRACT FROM AUTHOR]

AIDS patients in contrast to healthy individuals show basophil histamine release by stimulation in vitro of their blood leukocytes with Candida albicans (CA) and Herpes simplex virus Type 1 (HSV-I). Passive sensitization of cells from healthy individuals with the patient serum or surface immunoglobulins (Ig) derived from leukocytes of AIDS patients caused histamine release by the following stimulation of the cells with CA or HSV-i. When IgE was removed from the surface Ig no response was obtained, whereas a removal of IgG did not diminish the response. In contrast, no passive sensitization was obtained by serum derived from healthy individuals. The results show that IgE is responsible for the histamine release caused by CA and HSV-1 in AIDS patients. [ABSTRACT FROM AUTHOR]

We investigated the effect of rush and long-term venom immunotherapy on histamine release parameters in bee venom allergic patients. Ten patients received rush venom immunotherapy, and histamine release data were obtained immediately before and after treatment. 17 patients were assessed by histamine release 24 to 63 months after termination of long-term venom immunotherapy. A control group of 10 non-allergic subjects was included in this study Histamine released from whole blood was determined in a sensitive radio-enzymatic assay using a single isotope technique. Bee venom phospholipase A-induced histamine release from whole blood proved to be a test procedure of high specificity and sensitivity. Eight of 10 untreated patients and no control subject showed significant antigen-induced histamine release. Results obtained from patients immediately after successful rush venom immunotherapy showed an important decrease (mean 45.9%) of total histamine content of basophil leukocytes in all patients. Antigen-induced maximum histamine release was found to be increased in one, decreased in two and unchanged in seven patients. In patients who received long-term immunotherapy cell sensitivity to phosopholipase A was significantly lower than in a group of untreated patients (P &les; 0.002). These results suggest that even years after discontinuation of immunotherapy, histamine release parameters reflect patients' protection from systemic sting reactions as assessed by sting challenges. Histamine depiction of basophils induced by rush immunotherapy may play an important role in patients' protection immediately after termination of the rush regimen. [ABSTRACT FROM AUTHOR]

Histamine release tests using whole blood were applied in testing in vitro Type I birch allergic reaction in two patients with allergic rhinitis. Heparinized blood was incubated with varying dilutions of allergen for 30 min at +37°C. After centrifugation of the blood, plasma was separated and the liberated histamine was analysed by histamine radio enzyme assay (REA), high performance liquid chromatography (HPLC) with post-column derivatization system or radio immuno assay (RIA), and the results obtained by these methods were compared. REA and HPLC gave similar results, while RIA gave somewhat higher values, but was less sensitive. [ABSTRACT FROM AUTHOR]

Rat mast cells were challenged with compound 48/80 or calcium ionophore A23187, and protein kinase C activity in the cell pellets and the amount of histamine release into the supernatant were measured . After stopping the reaction, rat mast cells were lysed in a medium which prevents alterations in phosphorylation and dephosphorylation during sample processing. Histamine was significantly released from compound 48/80-stimulated mast cells at 30 s after the stimulation. In parallel with this, protein kinase C activity in the cell pellets increased at 30 s and 1 min and returned to basal value 3 min after the stimulation. When mast cells were incubated with various concentrations of 48/80 for 30 s, the amount of histamine release and protein kinase C activity increased dependently on the concentration of 48/80. Significant histamine release from A23187-stimulated mast cells was found at 1 min after the stimulation. Also protein kinase C activity in the cell pellets increased at 1 min and returned to basal value 5 min after the stimulation. A reduction of cytosolic protein kinase C activity was observed upon 48/80 treatment in a time- and concentration-dependent manner. Further, staurosporine, a potent inhibitor of protein kinase C, inhibited 48/80-induced histamine release in parallel with the inhibition of protein kinase C activity. These findings suggest that transient increase of protein kinase C activity may be involved in the mast cell activation process. [ABSTRACT FROM AUTHOR]

Histamine release was examined in leukocyte suspensions from patients allergic to house dust mite, grass pollen, birch pollen or cat dander. Influenza A virus was found to enhance the antigen-induced mediator release, but did not cause release of histamine from the cells per se. Also histamine release induced by anti-IgE in cell suspensions from normal individuals was enhanced by virus. The potentiating effect of influenza A virus might be due to neuraminidase on the surface of virus, since a similar effect was caused by a purified neuraminidase obtained from Vibrio cholerae, and the effect of virus as well as the neuraminidase was completely abolished by a potent neuraminidase inhibitor. The synergistic enhancement in IgE-mediated histamine release by virus could be of significance for the conversion from latent to manifest asthma. [ABSTRACT FROM AUTHOR]

Influenza A virus was found to enhance Staphylococcus aureus-induced histamine release in human leukocyte suspensions, but did not per se release histamine. This potentiating effect was found to be similar in cells from normal individuals and from patients with intrinsic asthma. The enhancement of mediator release could be due to viral neuraminidase on the surface of the virus, since a similar potentiating effect was caused by a purified neuraminidase preparation obtained from Vibrio cholerae, and the effect of virus as well as of the purified neuraminidase was completely abolished by a potent neuraminidase inhibitor. The potentiating effect of virus on bacteria-induced mediator release might be of importance for the conversion from latent to manifest asthma in upper respiratory tract infections. [ABSTRACT FROM AUTHOR]

Basophil histamine release was examined in 26 children suspected of having cow milk allergy (CMA). Following oral challenge with cow milk, the initial adverse reaction reappeared in 20 children, the majority developing urticaria. The urticaria patients showed a high degree of correlation between the results of histamine test, RAST and skin test. Children with gastrointestinal symptoms reacted to milk challenge, but only a few showed a positive histamine test, RAST and skin test. Among the patients with atopic dermatitis, the tests gave mostly negative results, which was in accordance with the lack of response to a milk challenge. The results obtained by removal from and fixation to the cell surface of IgE indicate an IgE-mediated reaction in CMA, which, in connection with the correlation between histamine test and RAST or skin test, suggests basophil histamine release as a suitable method for testing Type I allergy in children suspected of CMA. [ABSTRACT FROM AUTHOR]

The interrelation of in vitro IgE-mediated parameters, i.e. serum-specific IgE (RAST), basophil cell-bound specific IgE, and histamine release from basophil leucocytes was investigated in a 1-year placebo-controlled, double-blind Cladosporium immunotherapy study involving 22 adult asthmatics. The intense and early burst (within 6 weeks of immunotherapy) of serum-specific IgE did not result in a corresponding increased binding of specific IgE molecules to basophils. Cell-bound IgE increased in the Cladosporium season in both groups at the same time as serum levels of specific IgE declined in the Cladosporium group. In the placebo group histamine release from circulating basophils paralleled changes in basophil-bound IgE. In Cladosporium-treated patients, histamine release cell sensitivity after a lag phase (during immunotherapy dose-increase) declined two log steps, i.e. the cells became less responding in spite of a significant increase in cell-bound IgE. To further evaluate the sensitizing capacity of circulating specific IgE, passive sensitization studies were performed using basophils from a single donor. Although sera taken at the maximal IgE-response showed an enhanced capacity of passive sensitization, the ratio between RAST and passive sensitization capacity increased significantly in Cladosporium-treated patients, implying a less than expected sensitization capacity of immunotherapy-induced specific IgE. The lack of active binding of IgE to basophils might be explained by a reduced Fc-affinity of immunotherapy-induced IgE in contrast to the Cladosporium-seasonally induced IgE. Regarding the decrease in histamine release in Cladosporium-treated patients in spite of an increased amount of cell-bound specific IgE, immunotherapy may initiate a decrease in mediator releasibility which is not caused by a reduction in the number of Fc-receptors but rather some yet unknown subcellular mechanisms regulating the histamine release. The described changes in IgE-mediated parameters do not seem to be caused by interference with either specific IgG1 or IgG4. Changes in histamine release in the Cladosporium season were the only IgE-mediated parameter significantly related to the graded clinical efficacy of immunotherapy. [ABSTRACT FROM AUTHOR]

Basophil leukocytes from a non-atopic donor, who responded well to anti-IgE, were depleted of their native membrane-bound IgE by acid treatment and passively sensitized with plasma containing either Phleum pratense-, Dermatophagoides pteronyssinus- or dog dander- specific IgE obtained from 18 allergic children. Histamine release was then performed on the passively sensitized cells and the results were compared with those of bronchial provocation test (BPT), allergen-specific serum IgE (RAST), skin prick test (SPT), and conventional histamine release test (HR). A high coincidence rate was found between BPT, RAST and histamine release after passive sensitization (HR-PS), but compared to HR, it was lower. This could be because several of the patients had nonresponding basophils (i.e. no release after challenge with anti-IgE) in the conventional histamine release asssay. The lower rate was not related to a lack of antigen-specific IgE, since after passive sensitization of basophils, anti-IgE and allergen provocation could induce release. It is concluded that plasma from allergic children with non-responding basophil leukocytes contain antigen-specific IgE capable of binding to Fc-receptors on the basophils of a non-atopic donor. In addition it was found that the plasma could change the cell reactivity (maximal histamine release) of the donor cells, since the amount of histamine released varied according to the plasma used for passive sensitization. The lack of histamine release response in some patients could be because their own membrane-bound IgE is unable to induce mediator release or, more likely, activation of one or more of the subcellular steps involved in the release is impaired. [ABSTRACT FROM AUTHOR]