Allergen-induced basophil activation: CD63 cell expression detected by flow cytometry in patients allergic to Dermatophagoides pteronyssinus and Lolium perenne

Precision Medicine in House Dust Mite-Driven Allergic Asthma

House dust mites (HDMs) are the allergenic sources most frequently involved in airway allergy. Nevertheless, not every sensitized patient develops respiratory symptoms upon exposure to HDM, and there is a clinical need to differentiate allergic asthmatics (AAs) from atopic non-allergic asthmatics with HDM sensitization. This differentiation sometimes requires in vivo provocations like the bronchial allergen challenge (BAC). Interestingly, recent data demonstrate that non-atopic patients with asthma can also develop positive BAC results. This novel phenotype has been termed local allergic asthma (LAA). The interest in identifying the allergic triggers of asthma resides in the possibility of administering allergen immunotherapy (AIT). AIT is a disease-modifying intervention, the clinical benefit of which persists after therapy discontinuation. Recently, new modalities of sublingual tablets of HDM immunotherapy registered as pharmaceutical products (HDM-SLIT tablets) have become commercially available. HDM-SLIT tablets have demonstrated a robust effect over critical asthma parameters (dose of inhaled corticosteroids, exacerbations, and safety), thus being recommended by international guidelines for patients with HDM-driven AA. In this review, we will summarize the current knowledge on the phenotype and endotype of HDM-driven AA, and LAA, address the difficulties for BAC implementation in the clinic, and discuss the effects of AIT in AA and LAA.

Genetically engineered fusion of allergen and viral-like particle induces a more effective allergen-specific immune response than a combination of them

Chimeric virus-like particles (VLPs) were developed as a candidate for allergen-specific immunotherapy. In this study, hepatitis B core antigen (HBcAg) that genetically fused to Chenopodium album polcalcin (Che a 3)-derived peptide was expressed in E. coli BL21, purified, and VLP formation was evaluated using native agarose gel electrophoresis (NAGE) and transmission electron microscopy (TEM). Chimeric HBc VLPs were characterized in terms of their reactivity to IgE, the induction of blocking IgG and allergen-specific IgE, basophil-activating capacity, and Th1-type immune responses. Results from IgE reactivity and basophil activation test showed that chimeric HBc VLPs lack IgE-binding capacity and basophil degranulation activity. Although chimeric HBc VLPs induced the highest level of efficient polcalcin-specific IgG antibody in comparison to those induced by recombinant Che a 3 (rChe a 3) mixed either with HBc VLPs or alum, they triggered the lowest level of polcalcin-specific IgE in mice following immunization. Furthermore, in comparison to the other antigens, chimeric HBc VLPs produced a polcalcin-specific Th1 cell response. Taken together, genetically fusion of allergen derivatives to HBc VLPs, in comparison to a mix of them, may be a more effective way to induce appropriate immune responses in allergen-specific immunotherapy. KEY POINTS: • The insertion of allergen-derived peptide into major insertion region (MIR) of hepatitis B virus core (HBc) antigen resulted in nanoparticles displaying allergen-derived peptide upon its expression in prokaryotic host. • The resultant VLPs (chimeric HBc VLPs) did not exhibit IgE reactivity with allergic patients' sera and were not able to degranulate basophils. • Chimeric HBc VLPs dramatically improved protective IgG antibody response compared with those induced by allergen mixed either with HBc VLPs or alum. • Chimeric HBc VLPs induced Th1 responses that were counterparts of Th2 responses (allergic). • Chimeric HBc VLPs increased IgG2a/ IgG1 ratio and the level of IFN-γ compared to those induced by allergen mixed with either HBc VLPs or alum. Graphical Abstract.

Coexistence of nasal reactivity to allergens with and without IgE sensitization in patients with allergic rhinitis

BACKGROUND

Allergic rhinitis (AR) and local allergic rhinitis (LAR) are defined by nasal reactivity to aeroallergens with and without positive skin prick test (SPT), respectively. In this study, we aimed to investigate whether both types of allergen-specific reactivity can coexist in the same individual.

METHODS

Forty-eight patients with perennial rhinitis symptoms and positive SPT with seasonal allergens only (discrepant group) were subjected to consecutive nasal allergen challenges (NAC) with seasonal (NAC-S) and perennial allergens (NAC-P). A nasal lavage was collected before and after the NACs to measure eosinophil cationic protein (ECP). A basophil activation test (BAT) with seasonal and/or perennial allergens was performed in ten patients from the discrepant group and in six seasonal allergic rhinitis (SAR), eight perennial local allergic rhinitis (LAR), six nonallergic rhinitis (NAR), and six healthy control (HC) individuals.

RESULTS

All patients in the discrepant group tested positive in the NAC-S, and 41 of them (85.4%), also in the NAC-P (group A). Conversely, seven patients tested negative in the NAC-P (group B). ECP in the nasal lavage increased after the NAC-P in the group A (P = .004), but not in the group B. The BAT with seasonal allergens was positive in 100% of SAR and group A cases, whereas the BAT with perennial allergens was positive in 37.5% and 60% of LAR and group A cases, respectively. All NAR and HC subjects tested negative for the BAT.

CONCLUSION

This study shows that nasal reactivity to aeroallergens with and without positive SPT can coexist in the same patient. We propose the term dual allergic rhinitis for this rhinitis phenotype.

IgE Contributes to Atherosclerosis and Obesity by Affecting Macrophage Polarization, Macrophage Protein Network, and Foam Cell Formation

OBJECTIVE

By binding to its high-affinity receptor FcεR1, IgE activates mast cells, macrophages, and other inflammatory and vascular cells. Recent studies support an essential role of IgE in cardiometabolic diseases. Plasma IgE level is an independent predictor of human coronary heart disease. Yet, a direct role of IgE and its mechanisms in cardiometabolic diseases remain incompletely understood. Approach and Results: Using atherosclerosis prone Apoe^-/- mice and IgE-deficient Ige^-/- mice, we demonstrated that IgE deficiency reduced atherosclerosis lesion burden, lesion lipid deposition, smooth muscle cell and endothelial cell contents, chemokine MCP (monocyte chemoattractant protein)-1 expression and macrophage accumulation. IgE deficiency also reduced bodyweight gain and increased glucose and insulin sensitivities with significantly reduced plasma cholesterol, triglyceride, insulin, and inflammatory cytokines and chemokines, including IL (interleukin)-6, IFN (interferon)-γ, and MCP-1. From atherosclerotic lesions and peritoneal macrophages from Apoe^-/-Ige^-/- mice that consumed an atherogenic diet, we detected reduced expression of M1 macrophage markers (CD68, MCP-1, TNF [tumor necrosis factor]-α, IL-6, and iNOS [inducible nitric oxide synthase]) but increased expression of M2 macrophage markers (Arg [arginase]-1 and IL-10) and macrophage-sterol-responsive-network molecules (complement C3, lipoprotein lipase, LDLR [low-density lipoprotein receptor]-related protein 1, and TFR [transferrin]) that suppress macrophage foam cell formation. These IgE activities can be reproduced in bone marrow-derived macrophages from wild-type mice, but muted in cells from FcεR1-deficient mice, or blocked by anti-IgE antibody or complement C3 deficiency.

CONCLUSIONS

IgE deficiency protects mice from diet-induced atherosclerosis, obesity, glucose tolerance, and insulin resistance by regulating macrophage polarization, macrophage-sterol-responsive-network gene expression, and foam cell formation.

Update on the Management of Nonsteroidal Anti-Inflammatory Drug Hypersensitivity

The clinical phenotypes of nonsteroidal anti-inflammatory drug (NSAID) hypersensitivity are heterogeneous with various presentations including time of symptom onset, organ involvements, and underlying pathophysiology. Having a correct diagnosis can be challenging. Understanding their respective mechanisms as well as developing a comprehensive classification and diagnostic algorithm are pivotal for appropriate management strategy. Treatment modalities are based on the subtypes and severity of hypersensitivity reactions. Insights into the phenotypes and endotypes of hypersensitivity reactions enable personalized management in patients with suboptimal control of disease. This review updated the recent evidence of pathophysiology, classification, diagnostic algorithm, and management of NSAID hypersensitivity reactions.

Efficacy and Safety of Sublingual Immunotherapy in Elderly Rhinitis Patients Sensitized to House Dust Mites

PURPOSE

This study aims to determine the efficacy and safety of house dust mite (HDM)-sublingual immunotherapy (SLIT) in elderly patients with AR.

METHODS

A total of 45 patients aged ≥ 60 years with HDM-induced AR who had ≥ 3 A/H ratio on skin prick test and/or ≥ 0.35 IU/L to both Dermatophagoides farinae and Dermatophagoides pteronyssinus by ImmunoCAP were enrolled in 4 university hospitals. To evaluate additional effects of HDM-SLIT, they were randomized to the SLIT-treated group (n = 30) or control group (n = 15). Rhinoconjunctivitis total symptom score (RTSS), rhinoscopy score, Korean rhinoconjunctivitis quality of life questionnaire, rhinitis control assessment test, asthma control test scores, and adverse reactions, were assessed at the first visit (V1) and after 1 year of treatment (V5); for immunological evaluation, serum levels of HDM-specific immunoglobulin A/IgE/IgG1/IgG4 antibodies and basophil response to HDMs were compared between V1 and V5 in both groups.

RESULTS

There were no significant differences in demographics, RTSS, skin reactivity to HDMs, or serum total/specific IgE levels to HDMs (P < 0.05, respectively) between the 2 groups. Nasal symptom score and RTSS decreased significantly at year 1 in the 2 groups (P < 0.05). There were no significant differences in percent decrease in nasal symptom score and RTSS at year 1 between the 2 groups (P < 0.05); however, rhinoscopic nasal symptom score decreased significantly in the SLIT-treated group (P < 0.05). Immunological studies showed that serum specific IgA levels (not specific IgE/IgG) and CD203c expression on basophils decreased significantly at V5 in the SLIT-treated group (P = 0.011 and P = 0.001, respectively), not in the control group. The control group required more medications compared to the treatment group, but there were no differences in adverse reactions.

CONCLUSIONS

It is suggested that HDM-SLIT for 1 year could induce symptom improvement and may induce immunomodulation in elderly rhinitis patients.

Prueba de activación de basófilos: aspectos técnicos, metodológicos y su utilidad clínica

Introducción. La prueba de activación de basófilos (PAB) se considera una técnica confiable y segura para el diagnóstico de problemas alérgicos.Objetivo. Profundizar en el estado del arte de la PAB y su utilidad clínica.Materiales y métodos. Se realizó una revisión narrativa de la literatura mediante la búsqueda electrónica en las bases de datos y metabuscadores Ovid Medline, Google Scholar y PubMed, sin limitar la búsqueda por fecha, idioma o tipo de artículo. Se buscaron artículos sobre los detalles técnicos de la PAB y su utilidad clínica en el manejo de las enfermedades alérgicas.Resultados. De los marcadores de activación, CD63 ha sido el más estudiado y es el que mejor representa un evento de degranulación anafiláctica, mientras que CD203c es representativo de varias formas de degranulación. La superioridad de uno sobre otro como prueba diagnóstica depende del problema alérgico estudiado. En cuanto a los métodos de detección de basófilos, su selección con un único marcador, CCR3, se propone como una opción con buena relación de costo-efectividad.Conclusiones. La PAB es una herramienta prometedora para evaluar en clínica las reacciones alérgicas de forma segura. Es necesario una mayor estandarización de protocolos para obtener resultados más reproducibles.

International Consensus Statement on Allergy and Rhinology: Allergic Rhinitis

BACKGROUND

Critical examination of the quality and validity of available allergic rhinitis (AR) literature is necessary to improve understanding and to appropriately translate this knowledge to clinical care of the AR patient. To evaluate the existing AR literature, international multidisciplinary experts with an interest in AR have produced the International Consensus statement on Allergy and Rhinology: Allergic Rhinitis (ICAR:AR).

METHODS

Using previously described methodology, specific topics were developed relating to AR. Each topic was assigned a literature review, evidence-based review (EBR), or evidence-based review with recommendations (EBRR) format as dictated by available evidence and purpose within the ICAR:AR document. Following iterative reviews of each topic, the ICAR:AR document was synthesized and reviewed by all authors for consensus.

RESULTS

The ICAR:AR document addresses over 100 individual topics related to AR, including diagnosis, pathophysiology, epidemiology, disease burden, risk factors for the development of AR, allergy testing modalities, treatment, and other conditions/comorbidities associated with AR.

CONCLUSION

This critical review of the AR literature has identified several strengths; providers can be confident that treatment decisions are supported by rigorous studies. However, there are also substantial gaps in the AR literature. These knowledge gaps should be viewed as opportunities for improvement, as often the things that we teach and the medicine that we practice are not based on the best quality evidence. This document aims to highlight the strengths and weaknesses of the AR literature to identify areas for future AR research and improved understanding.

Basophil activation test for inhalant allergens in pediatric patients with allergic rhinitis

OBJECTIVE

Flow cytometric quantification of in vitro basophil activation can be quite performant and reliable tool to measure IgE-dependent allergen-specific responses in allergic patients. Current study aimed to evaluate the clinical relevance of basophil activation test (BAT) for the diagnosis of pediatric grass pollen and house dust mite (HDM) allergies.

METHODS

Forty-seven patients suffering from allergic rhinitis with HDM and grass pollen co-sensitization with clinical history of allergic rhinitis and/or asthma and 15 non-allergic healthy subjects were enrolled. BAT was determined by flow cytometry upon double staining with anti-IgE/anti-CD63 mAb.

RESULTS

Regarding HDM with cut-off point greater than 12.5% for CD63⁺ basophils sensitivity and specificity of the BAT were 90% and 73%, with positive predictive value (PPV) and negative predictive value (NPV) as 0.70 and 0.91, respectively. The analysis of concordance of being either allergic or healthy in comparison to BAT results for HDM revealed a substantial concordance (κ index = 0.61, p < 0.001). Grass pollen with cut-off point greater than 11%, BAT attained a sensitivity, specificity, PPV, and NPV of 96%, 93%, 0.98, and 0.88, respectively. The analysis of concordance of being either allergic or healthy in comparison to BAT results for grass pollen revealed an almost perfect concordance (κ index = 0.87, p < 0.001).

CONCLUSION

Our findings concluded that BAT is reliable technique in the diagnosis of sensitization to grass pollen and HDM. The sensitivity of BAT in pollen allergic children was found to be remarkably higher in our cohort compared to other studies.

Assessing basophil activation by using flow cytometry and mass cytometry in blood stored 24 hours before analysis

BACKGROUND

Basophil activation tests (BATs) have promise for research and for clinical monitoring of patients with allergies. However, BAT protocols vary in blood anticoagulant used and temperature and time of storage before testing, complicating comparisons of results from various studies.

OBJECTIVE

We attempted to establish a BAT protocol that would permit analysis of blood within 24 hours of obtaining the sample.

METHODS

Blood from 46 healthy donors and 120 patients with peanut allergy was collected into EDTA or heparin tubes, and samples were stored at 4°C or room temperature for 4 or 24 hours before performing BATs.

RESULTS

Stimulation with anti-IgE or IL-3 resulted in strong upregulation of basophil CD203c in samples collected in EDTA or heparin, stored at 4°C, and analyzed 24 hours after sample collection. However, a CD63^hi population of basophils was not observed in any conditions in EDTA-treated samples unless exogenous calcium/magnesium was added at the time of anti-IgE stimulation. By contrast, blood samples collected in heparin tubes were adequate for quantification of upregulation of basophil CD203c and identification of a population of CD63^hi basophils, irrespective of whether the specimens were analyzed by means of conventional flow cytometry or cytometry by time-of-flight mass spectrometry, and such tests could be performed after blood was stored for 24 hours at 4°C.

CONCLUSION

BATs to measure upregulation of basophil CD203c and induction of a CD63^hi basophil population can be conducted with blood obtained in heparin tubes and stored at 4°C for 24 hours.

Immunotherapy in allergy and cellular tests: state of art

The basophil activation test (BAT) is an in vitro assay where the activation of basophils upon exposure to various IgE-challenging molecules is measured by flow cytometry. It is a cellular test able to investigate basophil behavior during allergy and allergy immunotherapy. A panoply of critical issues and suggestive advances have rendered this assay a promising yet puzzling tool to endeavor a full comprehension of innate immunity of allergy desensitization and manage allergen or monoclonal anti-IgE therapy. In this review a brief state of art of BAT in immunotherapy is described focusing onto the analytical issue pertaining BAT performance in allergy specific therapy.

Impact of allergic rhinitis and specific subcutaneous immunotherapy on peripheral blood basophils of patients sensitized to Dermatophagoides pteronyssinus

Background

Basophils are important effectors cells in allergic rhinitis (AR) since they are involved in immunoglobulin (Ig) E – mediated inflammation and in the release of pro-inflammatory mediators. Specific subcutaneous immunotherapy (SCIT) provides clear immunologic modulation in some immune cells, however its systemic effects on basophils are not well known.

Methods

Peripheral blood (PB) samples from 43 patients with allergic rhinitis mono-sensitized to Dermatophagoides pteronyssinus (Dpt) [33 of them under SCIT with allergoid Dpt extract, in maintenance dose (SCIT), with evaluation just before SCIT injection (SCIT-T0) and 4 hours later (SCIT-T4) and the other 10 Dpt allergic patients never having, in the past, undergone specific immunotherapy treatment (NSIT)], and 15 healthy age- and gender-matched controls (HG), were analyzed. For each sample, the total (t-IgE) and specific IgE (s-IgE) was performed, as well as, the relative frequency and absolute number of PB basophils and receptor-bound IgE and IgG expression were evaluated by flow cytometry and the Histamine N-methyltransferase (HNMT) and tryptase α/β1 (TPSAB1) gene expression was assessed by real-time PCR.

Results

Higher levels of receptor-bound IgE were observed in SCIT patients, which are correlated with the levels of serum t-IgE and s-IgE, whereas no significant differences were observed for receptor-bound IgG. Regarding HNMT mRNA expression, significantly lower expression levels were detected in AR patients compared to HG, independently of type of therapy. Moreover a negative correlation was found between HNMT gene expression and time under SCIT. Conversely, tryptase gene expression was significantly up-regulated in NSIT when compared to HG; however in SCIT patients, tryptase gene expression was significantly decreased than in NSIT patients. No differences were found for any parameter between SCIT-T0 and SCIT-T4 with exception of a transient increased expression of tryptase in SCIT-T4.

Conclusion

PB basophils from patients with AR show altered functional features, which seems to be influenced by SCIT, suggesting that these cells could be useful to clarify the SCIT triggered mechanisms at a systemic level.

Cold-induced urticaria: challenges in diagnosis and management

Cold-induced urticaria (CU) is a chronic physical urticaria that can be hard to diagnose and manage. Symptoms of CU can vary from mild localised urticaria, angio-oedema to anaphylaxis. CU may be induced by a wide range of cold triggers from aquatic activities to ingestions of cold substances. This exemplifies the importance of accurate diagnosis and management of patients with CU. We present three cases of CU that demonstrate the variability in triggers and clinical presentation.

Analysis of mite allergic patients in a diverse territory by improved diagnostic tools

BACKGROUND

There are few studies comparing the sensitization with mite allergens from different mite species which could potentially be the cause of allergy.

OBJECTIVE

To improve the diagnosis of mite allergic patients from a diverse territory in which D. pteronyssinus/D. farinae mites together with storage mites could be present in the environment.

METHODS

Four hundred and seventy-seven patients (both children and adults) from different regions, covering the main mite prevalent areas of Spain, were recruited. sIgE to eight allergens was measured together with SPT to whole mite extracts, level of mite allergen exposure, and specific IgG(4) . BAT and CAST was performed in a subgroup of patients.

RESULTS

D. pteronyssinus and L. destructor were more prevalent in Atlantic areas, whereas D. farinae predominate in Mediterranean areas. About 90% of patients were sensitized to group 1 and/or group 2 allergens. Group 2 was the most prevalent, and the IgE response/intensity of sensitization in BAT was higher. sIgE to Der p 2/Der f 2 was almost fully cross-reactive, but no cross-reactivity was detected with Lep d 2. Group 1 allergens were also cross-reactive, but in some patients a species-specific response was observed. sIgE to Lep d 2 was associated with SPT results to storage mites. Sensitization to Der p 1 was more frequent in children, whereas Lep d 2 sensitization was more frequent in adults. A higher ratio IgE/IgG(4) to Der p 2 was associated with the presence of allergic asthma.

CONCLUSION

An improved diagnosis algorithm has been established. Group 2 allergens seem to have a leading role in mite allergy, but as group 1 sensitization could be species-specific in some patients and its prevalence is higher in children, an adequate balance on major mite species and major allergens must be consider in the design of mite allergy vaccines.

CD 63 Cell Expression Detected by Flow-Cytometric Determination and Basophil Activation in Allergic Patients

Flow cytometry analysis of in vitro activated basophils (BATs) based on the detection of CD63 up-regulation on basophil membrane provides the physician and the clinical laboratory with a novel diagnostic approach, proposed as a promising alternative method for in vitro diagnosis of IgE and non-mediated reactions. We performed an optimized flow cytometric procedure to assess CD63 expression on activated basophils on twenty allergic patients, and compared the results with specific IgE determination (RAST) and skin testing (Prick test).

Reliability of basophil activation test using CD203c expression in diagnosis of pollen allergy

BACKGROUND

CD203c is a basophil surface marker and its expression is rapidly up-regulated after cross-linking of high-affinity immunoglobulin E (IgE) receptor (FcepsilonR1) by an allergen. CD203c basophil activation tests have been studied for the in vitro diagnosis of several allergic conditions. However, there is limited data about its diagnostic usefulness. The optimum allergen concentrations for stimulation and allergen specific cutoff values remain unknown for a number of allergens. This study was designed to investigate the efficacy of basophil activation test via CD203c in the diagnosis of pollen allergy.

METHODS

The CD203c basophil activation was determined in 31 allergic rhinitis patients with pollen allergy and 9 healthy nonatopic controls during the off-season. CD203c expression was evaluated using three-color staining protocol by flow cytometry.

RESULTS

After an in vitro stimulation with grass pollen extract, the CD203c assay clearly discriminated pollen-allergic patients from controls (p < 0.001). A dose-dependent increase in the percentages of CD203c-activated basophils was shown in rhinitis patients with pollen allergy (p < 0.001). The sensitivity and specificity was 100% and optimal cutoff values were 14.05 and 10.05% with 45.1 and 4.5 μg/mL Phl p 5 stimulation, respectively. Although the specificity was also 100%, the sensitivity was 93 and 87% and the cutoff values were 5.40 and 5.35% with 4.5 × 10(-4) and 4.5 × 10(-5) micrograms/mL Phl p 5 stimulation, respectively.

CONCLUSION

The CD203c basophil activation test seems to be a reliable tool in the diagnosis of grass pollen allergy. It could be used when conventional diagnostic tests fail or can not be performed.

A mutant of the major melon allergen, Cuc m 2, with reduced IgE binding capacity is a good candidate for specific immunotherapy

Hypoallergenic mutants with reduced IgE-binding capacity but which show a similar T-cell response to the corresponding natural allergen are ideal tools for immunotherapy, for preventing a possible anaphylactic shock. An IgE conformational epitope has been identified in Cuc m 2, the major allergen and profilin from melon. Since this epitope is highly conserved in most pollen profilins, it may contribute to an explanation of cross-reactivity between pollen and food profilins. Mutants (Mut 1 and Mut 2) were generated by changing specific residues of the Cuc m 2 epitope to alanine, produced in Escherichia coli, and purified by chromatographic methods. Mut 1 showed a slight reduction in IgE binding but an allergenic activity that was similar to recombinant Cuc m 2, as measured by basophil activation test (BAT) and skin prick test (SPT). By contrast, Mut 2 displayed a substantial reduction in IgE-binding capacity (57%) and positive responses, as determined by BAT (33%) and SPT (50%), when compared to those of rCuc m 2. However, the T-cell proliferation and cytokine production induced by Mut 2 and rCuc m 2 were similar. Thus, this mutant represent potential candidate for immunotherapy of profilin allergies.

Clinical and laboratory parameters of mast cell activation as basis for the formulation of diagnostic criteria

Mast cell (MC) activation occurs in a number of different pathologic conditions. Acute activation is commonly seen in patients with allergic reactions, with consecutive massive release of vasoactive and proinflammatory mediator substances from MCs, leading to the clinical signs and symptoms of anaphylaxis. In these patients, serum tryptase concentrations usually increase subtantially above baseline levels. Chronic MC activation is more difficult to diagnose, especially when symptoms are mild or atypical, and no underlying disease is found. In these patients, serum tryptase levels usually are normal. In a smaller group of patients, tryptase levels are constantly elevated and may point to an occult form of mastocytosis. These patients have to be examined for MC monoclonality, other criteria of a primary MC disease, non-MC hematopoietic neoplasms, and reactive disorders producing chronic MC activation or MC accumulation. In most patients in whom MC activation is found, histamine-induced symptoms can be documented and usually respond to treatment with histamine receptor antagonists or MC stabilizers. If this is not the case, alternative explanations for symptoms and differential diagnoses have to be considered.

Immunoglobulin-E reactivity to wine glycoproteins in heavy drinkers

N-glycans from plant and invertebrate allergens can induce extensive immunoglobulin-E (IgE) cross-reactivity in vitro. IgE antibodies against these N-glycans, also termed cross-reactive carbohydrate determinants or CCDs, are prevalent in alcohol drinkers. This study investigated the prevalence and biological significance of IgE antibodies to N-glycans from wine glycoproteins in heavy drinkers. A structured questionnaire, skin prick tests, serum IgE levels, IgE-immunoblotting to wine extracts, and basophil activation tests were used to characterize 20 heavy drinkers and 10 control subjects. Eleven heavy drinkers (55%) showed IgE binding to proteins in wine extracts. The proteins were identified by mass spectrometry as grape-derived vacuolar invertase and thaumatin-like protein. Immunoblot reactivity was closely associated with the presence of IgE to CCDs and was inhibited by preincubation with a glycoconjugate containing bromelain-type N-glycans. The same conjugate, CCD-bearing allergens, and wine extracts activated basophils in patients with high-titer CCD-specific IgE but not in healthy controls. There was no relationship between immunoblot reactivity and consumption of any specific type of wine. No patient reported symptoms of hypersensitivity to Hymenoptera venom, food, or wine. In conclusion, heavy drinkers frequently show IgE reactivity to the N-glycans of wine glycoproteins. Glycans and wine glycoprotein extracts can induce basophil activation in sensitized alcoholics. The clinical significance of these findings remains to be elucidated.

Evaluation of basophil activation in mastocytosis with Hymenoptera venom anaphylaxis

BACKGROUND

Basophil activation tests (BATs) have been demonstrated to be useful in detecting IgE-mediated sensitization by measuring basophil activation surface markers (CD63 and CD203c). Hymenoptera venom is one of the best known mediators-release trigger in patients with systemic mastocytosis (SM). The aim of this study was to investigate the use of BATs as an additional diagnostic tool in patients with mastocytosis suffering from hymenoptera venom anaphylaxis (HVA).

METHODS

A total of 22 patients with history of HVA and SM, together with a group of 11 patients with HVA in whom SM was ruled out after a complete bone marrow study, were analyzed.

RESULTS

Among 11 SM patients who had specific serum IgE (sIgE) against hymenoptera venom and an evaluable BAT, a positive BAT was found in nine. Additionally, a positive BAT was detected in three of seven patients who had no sIgE. These three patients had low levels of total IgE compared with control population (mean of 20 vs. 78 IU/mL); one had discontinued immunotherapy after 5 years, when sIgE levels had turned negative, and, in the other two patients, BAT identified the culprit insect.

CONCLUSIONS

BAT is a useful complementary diagnostic tool to sIgE in mastocytosis patients with HVA, and it may contribute to predict or confirm these nearly fatal reactions, especially before discontinuing venom immunotherapy in patients who are negative for skin tests or sIgE or display low total IgE levels; in such cases, it also provides evidence on the culprit insect prompting HVA.

Validation of basophil CD164 upregulation for pollen allergy diagnosis

The aim of the study was to evaluate the sensitivity and specificity of allergen-induced basophil CD164 upregulation in patients with seasonal allergic rhinitis caused by allergy to grass pollens. This study was performed in 24 patients with allergy to grass pollens, and in 25 healthy controls. The protocol for allergen-induced basophil CD164 upregulation consisted of whole blood samples processing and staining with anti-CCR3/anti-CD164 antibodies added to a buffer at the beginning of stimulation. We observed dose-dependent allergen-induced basophil CD164 upregulation with 100% of specificity in both used allergen concentrations (12 and 1.2 ng/ml). Higher allergen concentration resulted in 100% and lower concentration in only 70.83% sensitivity. We have observed in the patients statistically significant correlations between anti-IgE stimulation and both allergen concentrations (for 12 ng/ml, r = 0.71, p < 0.0001; and for 1.2 ng/ml, r = 0.64, p < 0.001). We conclude that assessment of allergen-induced basophil CD164 upregulation is a very useful method for in vitro determination of allergy to grass pollens. This method seems to be a very promising tool in laboratory testing of allergies to other allergens.

The basophil activation test in the diagnosis of allergy: technical issues and critical factors

BACKGROUND

The basophil activation test (BAT) is a widely validated and reliable tool especially for the diagnosis of hymenoptera venom allergy. Nevertheless, several pitfalls have to be considered and outcomes may differ because of diverse in-house protocols and commercially available kits. We aimed to identify the factors that may influence results of the CD63-based BAT.

METHODS

Basophil responses to monoclonal anti-IgE (clone E124.2.8) and bee and wasp venom were determined by BAT based on CD63. The effect of stimulating factors such as, IL-3, cytochalasin B and prewarming of the samples was investigated. Furthermore, we compared two different flow cytometer systems and evaluated the influence of storage time, different staining protocols and anti-allergic drugs on the test results.

RESULTS

Interleukin-3 enhanced the reactivity of basophils at 300 pM, but not at 75 and 150 pM. Prewarming of samples and reagents did not affect basophil reactivity. CD63 expression assayed after storage time of up to 48 h showed that basophil reactivity already started to decline after 4 h. Basophils stained with HLA-DR-PC5 and CD123-PE antibodies gated as HLA-DR(neg)/CD123(pos) cells showed the highest reactivity. No effect on test outcomes was observed at therapeutic doses of dimetindene and desloratadine. Finally, slight differences in the percentage of activated basophils, depending on the cytometer system used, were found.

CONCLUSION

Basophil activation test should be performed as early as possible after taking the blood sample, preferably within 4 h. In contrast to the skin test, BAT can be performed in patients undergoing treatment with antihistamines. For reasons of multiple influencing factors, BAT should be performed only at validated laboratories.

Analysis of basophil activation by flow cytometry in pediatric house dust mite allergy

Detection of allergen-induced basophil activation by flow cytometry has been shown to be a useful tool for allergy diagnosis. The aim of this study was to assess the potential of this technique for the diagnosis of pediatric house dust mite allergy. Quantification of total and specific IgE and basophil activation test were performed to evaluate mite allergic (n = 24), atopic (n = 23), and non-allergic children (n = 9). Allergen-induced basophil activation was detected as a CD63-upregulation. Receiver operating characteristics (ROC) curve analysis was performed to calculate the optimal cut-off value of activated basophils discriminating mite allergic and non-allergic children. ROC curve analysis yielded a threshold value of 18% activated basophils when mite-sensitized and atopic children were studied [area under the curve (AUC) = 0.99, 95% confidence interval (CI) = 0.97-1.01, p < 0.001] with a sensitivity and specificity of 96% for 16 microg/ml mite extract. Analysis of the data obtained with 1.6 microg/ml mite extract defined a cut-off value of 8% activated basophils (AUC = 0.96, 95% CI = 0.91-1.01; p < 0.001) with a sensitivity of 82% and specificity of 100%. Comparison between mite allergic and non-allergic children produced a cut-off of 8% activated basophils (AUC = 1.0) with 16 microg/ml allergen extract and a sensitivity and specificity of 100%. The same threshold and specificity values were obtained with 1.6 microg/ml extract (AUC = 97%, 95% CI = 0.92-1.02; p < 0.001) but sensitivity decreased to 83%. Two atopic children showed negative skin prick and basophil activation tests and high specific IgE (>43 kU/l) values for Dermatophagoides pteronyssinus allergen. They also showed positive prick (wheal diameter >1.0 cm) and basophil activation (>87%) tests and high specific IgE (>100 kU/l) with shrimp allergen. Shrimp sensitization was demonstrated by high levels of Pen a 1-specific IgE (>100 kU/l). Cross-reactivity between mite and shrimp was confirmed by fluorescence enzyme immunoassay (FEIA-CAP) inhibition study in these two cases. This study demonstrated that the analysis of allergen-induced CD63 upregulation by flow cytometry is a reliable tool for diagnosis of mite allergy in pediatric patients, with sensitivity similar to routine diagnostic tests and a higher specificity. Furthermore, this method can provide additional information in case of disagreement between in vivo and in vitro test results.

Anaphylaxis to vecuronium: the use of basophil CD63 expression as a possible screening tool to identify a safe alternative

A 29-year-old woman with a history of anaphylaxis during anesthesia required diagnostic laparoscopic surgery for investigation of infertility. Previous laboratory investigations suggested that she had reacted to vecuronium, but she also had a specific IgE antibody to succinylcholine. The use of the basophil activation marker CD63 as a screening tool in selecting a safe muscle relaxant is presented.

Two different profiles of peach allergy in the north of Spain

BACKGROUND

Peach allergy has two different patterns: central Europe with oral allergy syndrome (OAS) related to a primary sensitization to birch pollen Bet v 1 and profilins and southern Europe with mostly systemic symptoms, in many cases due to sensitization to lipid-transfer proteins.

METHODS

Thirty peach-allergic patients with positive skin and food challenge tests and 29 control subjects were included. Skin prick tests (SPT) with inhalant allergens, commercial peach and apple extracts and native Pru p 3 were performed. In vitro specific immunoglobulin (Ig) E to grass pollen, birch pollen, peach, apple, rBet v 1, rBet v 2 and rPhl p 12 was determined by CAP, and rBet v 1, rMal d 1, rMal d 4, rMal d 3 and rPru p 3 using the ADVIA-Centaur platform. Basophil activation test (BAT) with commercial peach extract, commercial apple extract, nPru p 3, rMal d 3, rMal d 1 and rMal d 4 was also performed.

RESULTS

Pru p 3 was the major allergen in the patient group from northern Spain. Sensitization to this allergen was found in 100% of the patients with systemic symptoms or contact urticaria. Only 60% of OAS patients were sensitized to Pru p 3, being all of them sensitized to profilins and 60% of them to allergens of the Bet v 1 family. Specific IgE determination and BAT using recombinant allergens (rPru p 3) show specificity and sensitivity values close to 100%.

CONCLUSIONS

Most peach-allergic patients coming from the north of Spain present systemic symptoms after ingestion of peach, Pru p 3 being the main allergen. Patients with OAS present profilin-Bet v 1-related sensitization. Thus, in the north of Spain our patients show a mixed central-south Europe pattern with LTP-profilin-Bet v 1 sensitization depending on the symptoms presented. The use of natural and recombinant plant allergens, allows establishing the sensitization patterns to the different allergens studied.

Flow cytometry for basophil activation markers: the measurement of CD203c up-regulation is as reliable as CD63 expression in the diagnosis of cat allergy

The flow cytometric basophil activation test (BAT), based on the detection of allergen-induced CD63 expression, has been proved effective in the diagnosis of various IgE-mediated allergies. However, there is not yet consensus about the suitability of CD203c expression as a specific basophil activation marker and its diagnostic reliability. The goal of the present study was to compare measurement of CD63 and CD203c expression using BAT in a model of cat allergy and to determine optimal experimental conditions for both markers. Heparinized whole blood samples from 20 cat allergic patients and 19 controls were incubated with Fel d1 (relevant allergen) or anti-FcepsilonRI (positive control) either in IL-3 or IL-3-free conditions. An optimal gating of basophils was achieved in triple staining protocols: anti-IgE PE/anti-CD45 PerCP/anti-CD63 FITC or anti-IgE FITC/anti-CD45 PerCP/anti-CD203c PE. We demonstrated that IL-3 significantly enhanced CD63-induced expression by basophils obtained from cat allergic patients in response to Fel d1. Sensitivity was found to be 100%. The CD203c protocol, when performed under IL-3-free conditions, also demonstrated 100% sensitivity. Only one of the control subjects was positive in both tests. In conclusion, using well-defined experimental conditions, the measurement of CD203c up-regulation on basophils in response to specific allergens is as reliable as CD63-BAT for the in vitro diagnosis of patients with IgE-mediated allergy.

Potential food allergens in wine: Double-blind, placebo-controlled trial and basophil activation analysis

OBJECTIVE

Recent Australian and international legislation requires labeling of wines made by using the potentially allergenic food proteins casein, milk, egg white, or isinglass (fish-derived) where "there is a detectable residual processing aid." We investigated whether wines fined using these proteins or non-grape-derived tannins (tree-nut derived) can provoke significant clinical allergic reactions (anaphylaxis) in patients with confirmed immunoglobulin E-mediated relevant food allergy.

METHODS

A double-blind, placebo-controlled trial was performed to determine whether allergic reactions followed consumption of Australian commercial wines fined using one or more of the legislation-targeted food proteins. In addition, allergenicity of a larger panel of these wines was evaluated by blood basophil activation.

RESULTS

No anaphylaxis was induced by wine consumption. Three mild clinical reactions to protein-fined wine and two mild reactions to unfined wine occurred, but there was no statistically significant difference in reaction parameters between subject groups or between processing aids. No pattern of basophil activation correlated with wine type, processing aid, or subject group.

CONCLUSION

Wines fined with egg white, isinglass, or non-grape-derived tannins present an extremely low risk of anaphylaxis to fish-, egg-, or peanut-allergic consumers. Although consumption of milk protein-fined wine did not induce anaphylaxis, there were insufficient subjects to determine statistically whether wines fined with milk proteins present a risk to the very rare milk-allergic consumers. In summary, the observed lack of anaphylaxis and basophil activation induced by wines made using the legislation-targeted food proteins according to good manufacturing practice suggests negligible residual food allergens in these wines.

Flow-assisted allergy diagnosis: current applications and future perspectives

Physicians predominantly rely upon quantification of serum-specific immunoglobulin E (IgE) and/or skin test to confirm clinically suspected IgE-mediated allergy. However, for various reasons, identification of the offending allergen(s) and potentially cross-reactive structures is not always straightforward. Flow-assisted allergy diagnosis relies upon quantification of alterations in the expression of particular basophilic activation markers. Actually, upon challenge with a specific allergen, basophils not only secrete quantifiable bioactive mediators but also upregulate the expression of different markers which can be detected efficiently by flow cytometry using specific monoclonal antibodies. Currently, the technique has been applied in the investigation of IgE-mediated allergy caused by classical inhalant allergens, food, Hevea latex, hymenoptera venoms and drugs. It is also appreciated; the technique proves valuable in the diagnosis of non-IgE-mediated (anaphylactoid) reactions such drug hypersensitivity and the detection of autoantibodies in certain forms of chronic urticaria. This review will not address immunologic features, characteristics and general pitfalls of flow-assisted analysis of in vitro-activated basophils as summarized elsewhere. After a recapitulation of the principles and some specific technical issues of flow-assisted analysis of in vitro-activated basophils, we principally focus on the current clinical and research applications of the basophil activation tests. Personal experience of both research groups is provided, where appropriate. Finally, a viewpoint on how the field might evolve in the following years is provided.

Comparision of two-flow cytometry methods for basophil degranulation in patients sensitized to grass pollen

BACKGROUND

Two-flow cytometry methods for quantification of degranulated basophil after allergen-specific activation were discussed. The methods are discerned by used membrane receptors--FcepsilonRI or IL-3Ralpha Our goal was to evaluate the diagnostic potential of the methods and to correlate them to allergen-specific IgE detection and skin prick test (SPT).

METHODS

Patient's and control's groups were studied with Bulgarian grass pollen allergen B1 simultaneously by flow cytometry kits: Basotest and BD FastImmune test. Allergy diagnosis was based on clinical history and SPT. The determination of specific IgE was performed by ELISA--RIDASCREEN.

RESULTS

There were no significant differences between the patient's results from Basotest and FastImmune (P>0.05). A significant correlation between values, analyzed by Basotest and by FastImmune was found (r=0.88). The sensitivity and specificity of the Basotest, FastImmune, specific IgE and SPT were 85%, 72%, 92% and 92% sensitivity and 100%, 92%, 100% and 85% specificity respectively. The efficiency was between 82% and 97%. There were a significant correlation between the specific IgE and flow cytometry tests: tau=0.92 (Basotest) and tau=0.71 (FastImmune) and a moderate significant correlation between the SPT and the in vitro tests: tau=0.26 (Basotest) and tau=0.31 (FastImmune).

CONCLUSION

The successful use of the Bulgarian grass pollen allergen B1 and both flow cytometry tests was presented. These methods could be as specific tools for IgE-mediated diagnosis especially FastImmune in the case of low IgE receptor expression.

Significant correlation between the CD63 assay and the histamine release assay in chronic urticaria

BACKGROUND

Antibodies directed to the alpha subunit of the high affinity IgE receptor and the IgE molecule are proposed to be of pathogenetic relevance in a group of patients with chronic urticaria (CU). The diagnosis of autoimmune chronic urticaria (ACU) is difficult; the autologous serum skin test (ASST) seems to be a useful screening test, but reliable, additional confirmatory methods are needed.

OBJECTIVES

To assess the diagnostic value of a modified serum-induced basophil activation test, the CD63 expression assay, in the diagnosis of ACU by comparing the results of the CD63 assay with the results of the histamine release (HR) test, the ASST and serum levels of soluble CD40 ligand (sCD40L).

METHODS

Using basophils from an atopic (DA) and a nonatopic (DNA) donor the activity of sera of 72 patients with CU were measured in HR assay by enzyme-linked immunosorbent assay and in CD63 expression assay by flow cytometry. An ASST was carried out in all patients; in 30 of the 72 patients sCD40L was detected and correlations were derived between the different assays. Sera of 20 normal controls and 26 patients with systemic autoimmune diseases were also tested in the HR assay and in the CD63 expression assay.

RESULTS

Histamine-releasing activity was detected in the sera of 51% (DA) and 32% (DNA) of CU patients and 57% (DA) and 28% (DNA) of sera upregulated CD63 expression on the surface of basophils from the different donors. There was a significant correlation between the HR and the CD63 assays carried out on both donors, but the ASST showed a strong correlation with the HR assay only for basophils from the DA. The serum level of sCD40L was significantly higher in patients with CU compared with controls, but the difference between the autoimmune and the nonautoimmune groups was not significant.

CONCLUSIONS

The CD63 expression assay seems to be a reliable functional test in the diagnosis of ACU, particularly if highly sensitive donor basophils are used, but the determination of the sCD40L serum level was not sufficient to differentiate between the autoimmune and the nonautoimmune patient groups.

Basophil Activation Test and specific IgE measurements using a panel of recombinant natural rubber latex allergens to determine the latex allergen sensitization profile in children

There are no documented studies that describe natural rubber latex (NRL) sensitization in children with a history of surgical intervention but without any congenital malformation (urogenital anomalies, spina bifida, etc.), although some authors have studied NRL allergy in children without a history of surgical intervention. The aim of this work was to evaluate the sensitization profile to single NRL allergens in children without spina bifida and without repeated surgical interventions, by using different recombinant and natural latex allergens in two analytical techniques: specific serum immunoglobulin E (IgE) quantification and flow cytometry determination of activated basophils expressing CD63, after stimulating cells from patients with NRL allergens. A total of 23 patients and 10 healthy children were selected. Conjunctival and in-use NRL provocation tests were carried out, as well as specific IgE determination in all patients' and controls' sera with the recombinant NRL allergens: rHev b 1, rHev b 2, rHev b 3, rHev b 5, rHev b 6.01, rHev b 6.02, rHev b 8, rHev b 9 and rHev b 11 and with NRL (k82) using appropriate ImmunoCAPs. The Basophil Activation Test (BAT) was performed with whole latex extract and with the recombinant allergens rHev b 5 and rHev b 6.01, as well as with the natural allergen Hev b 6.02. The sensitivity and the specificity of NRL-specific IgE (k82) were 100%. Positive IgE responses to rHev b 5 were found in sera of 10 children, to rHev b 6.01 in 16 and for rHev b 6.02 in 15 children's sera. Specific IgE to rHev b 8 was found in four sera of the children. We only found significant differences in sensitization to rHev b 5 in children with two or more surgical interventions compared with the non-intervened group or those with only one intervention. Specific IgE in sera of children with latex-fruit syndrome recognized rHev b 6.02, but not to rHev b 11. The patients sensitized to Hev b 8, Hev b 9 and/or Hev b 11 were atopic. The four patients presenting a positive response to the NRL profilin Hev b 8 were allergic to pollen. The BAT against whole NRL extract was positive in 22 of 23 children; against rHev b 5 in 14 of the patients studied; against rHev b 6.01 in seven cases and against nHev b 6.02 in 19 children. In all the control subjects, the results using this technique were negative. If combined rHev b 5, rHev b 6.01 and nHev b 6.02 together, BAT could detect 20 of the 23 children with latex allergy. The combined use of ImmunoCAP with all the recombinant NRL allergens and BAT with rHev b 5, rHev b 6.01 and nHev b 6.02, enabled the identification of NRL allergy in 22 of 23 patients. There is a positive and significant correlation between sensitization to Hev b 5 and the number of interventions. BAT and allergen-specific IgE determination could be used as first-line in vitro diagnostic tests in patients with NRL allergy.

Anaphylaxis to GelofusineR confirmed by in vitro basophil activation test: a case series*

The plasma expander Gelofusine (succinylated gelatin) is a recognised cause of peri-operative anaphylaxis. Current diagnosis of Gelofusine sensitivity is by skin testing, a procedure that itself carries a risk of allergic reaction. We evaluated the reliability of the in vitro basophil activation test as a diagnostic assay for Gelofusine sensitivity in subjects with a clinical history highly suggestive of Gelofusine allergy. Six patients with peri-operative anaphylaxis clinically attributed to Gelofusine were skin tested to confirm sensitivity. Control subjects included three healthy subjects and five subjects allergic to a neuromuscular blocking drug, all negative on Gelofusine skin testing. Whole blood basophil activation to Gelofusine was analysed by flow cytometry for CD63 surface expression. All of the Gelofusine sensitive patients and one of the control allergic subjects showed positive basophil activation to Gelofusine. In this series of subjects, the basophil activation test for Gelofusine allergy had a sensitivity of 100% and a specificity of 87.5%. Our findings suggest that basophil activation testing is a safe and reliable in vitro assay for prediction or confirmation of Gelofusine sensitivity in patients with high clinical suspicion of Gelofusine-induced anaphylaxis.

Detection of Anisakis simplex-induced basophil activation by flow cytometry

BACKGROUND

Laboratory diagnosis of anisakidosis is based on specific serum IgE detection. Recently, detection of allergen-induced basophil activation by flow cytometry has been proposed as a valuable tool for allergy diagnosis.

OBJECTIVE

To evaluate if detection of Anisakis-induced basophil activation by flow cytometry is a useful tool in the diagnosis of Anisakis allergy.

METHODS

Patients with Anisakis allergy (A.s.+, n = 37), patients reporting chronic urticaria or abdominal pain unrelated to fish ingestion (A.s.-, n = 51), and healthy controls (n = 12) were studied. Specific IgE to Anisakis simplex (A. simplex) was quantified with CAP-FEIA method, and basophil activation test was performed with three different concentrations of an Anisakis crude extract. Basophil gating was performed with CD123 and HLA-DR, and cellular activation was measured with CD63.

RESULTS

A.s.+ patients showed significantly higher age and total IgE levels than did the A.s.- patients. Specific IgE to A. simplex correlated with the activated basophil percentages obtained with 15 microg/mL (r = 0.80; P < 0.001), 1.5 microg/mL (r = 0.84; P < 0.001), and 0.15 microg/mL (r = 0.82; P < 0.001) of A. simplex crude extract. Nine individuals (3 in the A.s.+ group and 6 in the A.s.- group) were nonresponders to basophil stimulation with anti-IgE. Five A.s.- patients showed positive IgE values to A. simplex while the basophil activation test was negative. According to the receiver operating characteristics curves performed between A.s.+ vs. A.s.- and A.s.+ vs. healthy controls, the cutoff for a positive basophil activation test was >or=21% (specificity = 96%, sensitivity = 100%), and 16% (sensitivity and specificity of 100%) respectively. When nonresponders were included in the A.s.+ vs. A.s.- analysis, sensitivity decreased to 95%. Multivariate logistic analysis showed that the specific basophil activation was a factor independently associated with clinical symptoms of A. simplex allergy.

CONCLUSIONS

Detection of A. simplex-induced basophil activation by flow cytometry is a useful laboratory technique for the diagnosis of anisakidosis, supplementing specific IgE determinations.

Polysorbate 80 in medical products and nonimmunologic anaphylactoid reactions

BACKGROUND

Polyoxyethylene-sorbitan-20-monooleate (also known as polysorbate 80 and Tween 80) is a solubilizing agent ubiquitously used in nutritives, creams, ointments, lotions, and multiple medical preparations (e.g., vitamin oils, vaccines, and anticancer agents) and as an additive in tablets. Whereas its relevance as a contact allergen has declined during the past decades, it is of current relevance as a "hidden" inductor of anaphylactoid reactions.

OBJECTIVE

To identify polysorbate 80 (generally believed to be an inert vehicle) as an inductor of a severe anaphylactoid reaction.

METHODS

Skin prick testing, enzyme-linked immunosorbent assay, IgE immunoblotting, and flow cytometric detection of basophil activation were performed in controls and in a patient with a medical history of anaphylactic shock due to intravenous administration of a multivitamin product during pregnancy.

RESULTS

Polysorbate 80 was identified as the causative agent for the anaphylactoid reaction of nonimmunologic origin in the patient. Polysorbate specific IgE antibodies were not identified in enzyme-linked immunosorbent assay and immunoblot examinations, confirming the nonimmunologic nature of the anaphylactoid reaction.

CONCLUSIONS

Polysorbate 80 is a ubiquitously used solubilizing agent that can cause severe nonimmunologic anaphylactoid reactions.

Functional analysis of cross-reactive immunoglobulin E antibodies: peanut-specific immunoglobulin E sensitizes basophils to tree nut allergens

BACKGROUND

Peanut and tree nuts are a major cause of food-induced anaphylaxis with an appreciable mortality. Co-sensitization to peanuts and tree nuts is a common clinical observation and may be because of peanut-specific serum IgE antibodies that cross-react with tree nut allergens. It is, however, unclear whether these cross-reactive IgE antibodies are involved in effector-cell activation.

OBJECTIVE

To determine if cross-reactivity of peanut-specific IgE antibodies with tree nuts can cause effector cell activation using an in vitro basophil activation assay.

METHODS

Two peanut allergic subjects with positive specific IgE for peanut and tree nuts (as measured by CAP-FEIA) were studied. Basophil activation to peanut and tree nuts, as indicated by CD63 expression, was assessed by flow cytometry to confirm co-sensitization to peanut and tree nuts. Inhibition ELISA using sera from the subjects was performed to detect peanut-specific IgE antibodies that cross-reacted with tree nut proteins. To determine whether cross-reactive tree nut allergens can induce effector-cell activation, peanut-specific antibodies were affinity purified from the subject sera and used to resensitize non-peanut/tree nut allergic donor basophils stripped of surface IgE. Basophil activation was then measured following stimulation with peanut and tree nut extracts.

RESULTS

The two peanut allergic subjects in this study showed positive basophil activation to the peanut and tree nut extracts. Inhibition ELISA demonstrated that pre-incubation of the peanut allergic subject sera with almond, Brazil nut and hazelnut extracts inhibited IgE binding to peanut extract. IgE-stripped basophils from non-peanut/tree nut allergic subjects resensitized with affinity-purified peanut-specific antibodies from the peanut allergic subject sera became activated following stimulation with peanut, almond and Brazil nut extracts, demonstrating biological activity of cross-reactive IgE antibodies.

CONCLUSION

Peanut-specific IgE antibodies that cross-react with tree nut allergens can cause effector-cell activation and may contribute to the manifestation of tree nut allergy in peanut allergic subjects.

Lysis with Saponin improves detection of the response through CD203c and CD63 in the basophil activation test after crosslinking of the high affinity IgE receptor FcepsilonRI

BACKGROUND

The basophil activation test (BAT), in which translocation of markers to the surface of blood basophils is measured in response to allergen by flow cytometry, is a rapid assay that is gaining popularity. Two markers are currently being evaluated for the BAT; CD63 and the lineage-specific CD203c. In a recent report, detection of CD203c after lysis with Saponin was shown to be superior to detection of CD63 after lysis with formic acid. We wanted to compare a) lysis with formic acid and lysis with Saponin, b) the response through CD203c and CD63, and c) the definition 10% activated cells above background with the probability binning metric T(chi) > 4, on sets of data generated with blood basophils stimulated with varying concentrations of anti-FcepsilonRI antibody.

METHODS

Blood from volunteers was incubated with serial logarithmic dilutions of anti-FcepsilonRI and subsequently with antibodies to CD203c PE and CD63 FITC. Sets of samples set up in parallel were lysed with either Saponin based Whole Blood Lysing reagent or with formic acid based Immunoprep/Q-prep. Samples were acquired on a FACS Calibur, but were compensated and analysed offline. Responders were defined as persons who had 10% or more activated basophils above background, or a T(chi) > 4, for two consecutive dilutions of anti-FcepsilonRI antibody.

RESULTS

More basophils (median 1164 vs. median 397) and better discrimination of upregulated CD203c and CD63 amongst responders were obtained after lysis with Saponin than after lysis with formic acid. We suggest that CD203c may be a more sensitive marker for the BAT than CD63, as 6/11 responders were found with CD203c, compared with 3/11 with CD63. Most responders (7/11) were identified with probability binning.

CONCLUSION

A combination of lysis with Saponin and the markers CD203c and CD63 computed by probability binning may be the most sensitive method of detecting activation of basophils after stimulation through FcepsilonRI.

The basophil activation test by flow cytometry: recent developments in clinical studies, standardization and emerging perspectives

The diagnosis of immediate allergy is mainly based upon an evocative clinical history, positive skin tests (gold standard) and, if available, detection of specific IgE. In some complicated cases, functional in vitro tests are necessary. The general concept of those tests is to mimic in vitro the contact between allergens and circulating basophils. The first approach to basophil functional responses was the histamine release test but this has remained controversial due to insufficient sensitivity and specificity. During recent years an increasing number of studies have demonstrated that flow cytometry is a reliable tool for monitoring basophil activation upon allergen challenge by detecting surface expression of degranulation/activation markers (CD63 or CD203c). This article reviews the recent improvements to the basophil activation test made possible by flow cytometry, focusing on the use of anti-CRTH2/DP2 antibodies for basophil recognition. On the basis of a new triple staining protocol, the basophil activation test has become a standardized tool for in vitro diagnosis of immediate allergy. It is also suitable for pharmacological studies on non-purified human basophils. Multicenter studies are now required for its clinical assessment in large patient populations and to define the cut-off values for clinical decision-making.

Flow cytometric investigation of peri-anaesthetic anaphylaxis using CD63 and CD203c

The investigation of anaphylactic reactions in the peri-operative period is difficult. Elevation of serum tryptase levels is a good indicator of an anaphylactic event but the ability of subsequent investigations to identify the drug(s) responsible for the reaction is still potentially unreliable. The aim of this study was to examine basophil activation as an investigative tool. We performed flow cytometric analysis of the expression on the cell surface of the basophil activation markers CD63 and CD203c and measured histamine release in 21 patients who were referred with possible peri-operative anaphylaxis. The sensitivity of CD63, CD203c, basophil histamine release and skin prick for the muscle relaxants was found to be 79%, 36%, 36% and 64%, respectively; the specificity was found to be 100%. These results demonstrate the difficulty in investigating the cause of an unexpected clinical event following drug administration, but the higher sensitivity of neo-expression on the cell surface of CD63 suggests that flow cytometric analysis of its neo-expression on basophils in vitro may be a diagnostic aid.

The flow-cytometric determination of basophil activation induced by aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) is useful for in vitro diagnosis of the NSAID hypersensitivity syndrome

BACKGROUND

Hypersensitivity reactions to non-steroidal anti-inflammatory drugs (NSAIDs), manifested by cutaneous symptoms and/or airway manifestations represent 20-25% of all hypersensitivity reactions to drugs. Today, it is still claimed that no in vitro diagnostic tests exist for that condition and that the only way to confirm the diagnosis is a provocation challenge.

OBJECTIVE

The objective of this study was to assess whether NSAIDs may provoke blood basophil activation in vitro in such patients, as detected by a flowcytometric technique.

METHODS

Sixty NSAID hypersensitive patients (38 with cutaneous, 20 with airway and two with cutaneous and airway symptoms) and 30 control patients (15 asthmatics) were selected. Their hypersensitivity was confirmed by documented history indicating at least two clinical episodes to two or more different NSAIDs or by positive oral provocation challenge. Isolated buffy coat leukocytes were stimulated in vitro with aspirin, paracetamol, metamizol, diclofenac, and naproxen. The percentage of activated basophils was evaluated by an anti-CD63.

RESULTS

Aspirin showed a sensitivity of 43.3%, a specificity of 100%, a positive predictive value of 100% and a negative predictive value of 99.4%. For the other NSAIDs, the sensitivity and specificity values were: for paracetamol 11.7% and 100%, for metamizol 15% and 100%, for diclofenac 43.3% and 93.3% and for naproxen 54.8% and 74.1%. When considering the first four NSAIDs, the global sensitivity raised to 63.3% and specificity to 93.3%. If the number of tests is to be limited for practical reasons, the combination of acetylsalicylic acid and diclofenac at two concentrations yields a sensitivity of 58.3% and a specificity of 93.3%.

CONCLUSIONS

Flowcytometric determinations of basophil activation following stimulation with NSAIDs show a high sensitivity (60-70%) with specificity above 90%. So this test may help avoiding some cumbersome and dangerous provocation challenges.