Basophil Allergen Threshold Sensitivity Research Articles

Basophil allergen threshold sensitivity to casein (casein-specific CD-sens) predicts allergic reactions at a milk challenge in most but not all patients.

The basophil activation test is an emerging clinical tool in the diagnosis of cow's milk allergy (CMA). The aim was to assess the association between the basophil allergen threshold sensitivity to the major milk protein casein (casein-specific CD-sens), the levels of milk- and casein-specific Immunoglobulin E antibodies (IgE-ab), and the severity of allergic reactions at milk challenges. We enrolled 34 patients aged 5-15 (median 9) years who underwent a double-blind placebo-controlled milk-challenge (DBPCMC) as screening before inclusion in an oral immunotherapy study for CMA. The severity of the allergic reaction at the DBPCMC was graded using Sampson's severity score. Venous blood was drawn before the DBPCMC. Milk- and casein-specific IgE-ab were analyzed. Following in vitro stimulation of basophils with casein, casein-specific CD-sens, was determined. Thirty-three patients completed the DBPCMC. There were strong correlations between casein-specific CD-sens and IgE-ab to milk (rs = 0.682, p < .001), and between casein-specific CD-sens and IgE-ab to casein (rs = 0.823, p < .001). There was a correlation between the severity of the allergic reaction and casein-specific CD-sens level (rs = 0.395, p = .041) and an inverse correlation between casein-specific CD-sens level and the cumulative dose of milk protein to which the patient reacted at the DBPCMC (rs = -0.418, p = .027). Among the 30 patients with an allergic reaction at the DBPCMC, 67% had positive casein-specific CD-sens, 23% had negative casein-specific CD-sens, and 10% were declared non-responders. Two thirds of those reacting at the DBPMC had positive casein-specific CD-sens, but reactions also occurred despite negative casein-specific CD-sens. The association between casein-specific CD-sens and the severity of the allergic reaction and cumulative dose of milk protein, respectively, was moderate.

Basophil Activation Test Utility as a Diagnostic Tool in LTP Allergy.

Plant-food allergy is an increasing problem, with nonspecific lipid transfer proteins (nsLTPs) triggering mild/severe reactions. Pru p 3 is the major sensitizer in LTP food allergy (FA). However, in vivo and in vitro diagnosis is hampered by the need for differentiating between asymptomatic sensitization and allergy with clinical relevance. The basophil activation test (BAT) is an ex vivo method able to identify specific IgE related to the allergic response. Thus, we aimed to establish the value of BAT in a precise diagnosis of LTP-allergic patients. Ninety-two individuals with peach allergy sensitized to LTP, Pru p 3, were finally included, and 40.2% of them had symptoms to peanut (n = 37). In addition, 16 healthy subjects were recruited. BAT was performed with Pru p 3 and Ara h 9 (peanut LTP) at seven ten-fold concentrations, and was evaluated by flow cytometry, measuring the percentage of CD63 (%CD63+) and CD203c (%CD203chigh) cells, basophil allergen threshold sensitivity (CD-Sens), and area under the dose–response curve (AUC). Significant changes in BAT parameters (%CD63+ and %CD203chigh) were found between the controls and patients. However, comparisons for %CD63+, %CD203chigh, AUC, and CD-Sens showed similar levels among patients with different symptoms. An optimal cut-off was established from ROC curves, showing a significant positive percentage of BAT in patients compared to controls and great values of sensitivity (>87.5%) and specificity (>85%). In addition, BAT showed differences in LTP-allergic patients tolerant to peanut using its corresponding LTP, Ara h 9. BAT can be used as a potential diagnostic tool for identifying LTP allergy and for differentiating peanut tolerance, although neither reactivity nor sensitivity can distinguish the severity of the clinical symptoms.

Evaluation of the basophil activation test as diagnostic method in pediatric peanut allergy

Peanut allergy diagnosis relies on various tests including the oral food challenge (OFC), which is potentially associated with severe symptoms such as anaphylaxis. An alternative has emerged, the basophil activation test (BAT), which allows to determine the basophil allergen threshold sensitivity in vitro. We aimed to determine the discriminative ability of BAT between, first, OFC reactive and non-reactive patient, and secondly low or high cumulative dose-reactive patients in comparison with other diagnostic tools for peanut allergy. The ability of BAT to discriminate patient with mild or severe OFC clinical reactions was also evaluated. We performed a prospective study, from February 2018 to October 2020, evaluating in 79 peanut allergic children the basophils allergen reactivity (CDmax) and the basophils allergen sensitivity [CDsens or area under the curve (AUC)] in BAT (CD63+ or CD203c+) as well as specific IgE level and skin prick-test in relation to OFC performed the same day. Based on ROC curve analyses, optimal cutoff of CDmax, CDsens and AUC to peanut and Ara h 2 were defined by the Youden index. Among the 79 children included, ROC curve analysis showed that f13- or Ara h 2-CDmax and AUC appeared to be the best markers associated with reactivity on OFC. We defined positive cutoff [i.e. Closet to 100% positive predictive value (PPV)] and demonstrated that 21% of the OFC could have been avoided. Also, by discriminating peanut-reactive patients according to low (< 200 mg) or high (> 200 mg) cumulative dose of peanut proteins in OFC [corresponding to effective dose 50 (ED50)], basophils allergen sensitivity monitored with AUC to f13 and Ara h 2 were the best biomarkers predicting cumulative dose with 92% and 88% specificity and 88% and 91% sensitivity, respectively. BAT to f13 and Ara h 2 may be a useful diagnostic tool to predict the allergic status and could reduce dangerous OFC. Then, BAT may be useful for risk assessment of clinical reactions during OFC and could significantly improve management by integrating a personalized approach.

Nasal upregulation of CST1 in dog-sensitised children with severe allergic airway disease.

The clinical presentation of children sensitised to dog dander varies from asymptomatic to severe allergic airway disease, but the genetic mechanisms underlying these differences are not clear. The objective of the present study was to investigate nasal transcriptomic profiles associated with dog dander sensitisation in school children and to reveal clinical symptoms related with these profiles. RNA was extracted from nasal epithelial cell brushings of children sensitised to dog dander and healthy controls. Blood sample analyses included IgE against dog dander, dog allergen molecules, other airborne and food allergens, basophil activation and white blood cell counts. Clinical history of asthma and rhinitis was recorded, and lung function was assessed (spirometry, methacholine provocation and exhaled nitric oxide fraction). The most overexpressed gene in children sensitised to dog dander compared to healthy controls was CST1, coding for Cystatin 1. A cluster of these children with enhanced CST1 expression showed lower forced expiratory volume in 1 s, increased bronchial hyperreactivity, pronounced eosinophilia and higher basophil allergen threshold sensitivity compared with other children sensitised to dog dander. In addition, multi-sensitisation to lipocalins was more common in this group. Overexpression of CST1 is associated with more severe allergic airway disease in children sensitised to dog dander. CST1 is thus a possible biomarker of the severity of allergic airway disease and a possible therapeutic target for the future treatment of airborne allergy.

The basophil activation test differentiates between patients with alpha-gal syndrome and asymptomatic alpha-gal sensitization

Galactose-alpha-1,3-galactose (alpha-gal) syndrome is characterized by the presence of serum specific IgE antibodies to alpha-gal and delayed type I allergic reactions to the carbohydrate alpha-gal after consumption of mammalian (red) meat products and drugs of mammalian origin. Diagnostics currently rely on patient history, skin tests, determination of serum specific IgE antibodies, and oral food or drug challenges. We sought to assess the utility of different basophil parameters (basophil reactivity and sensitivity, the ratio of the percentage of CD63+ basophils induced by the alpha-gal-containing allergen to the percentage of CD63+ basophils after stimulation with anti-FcεRI antibody [%CD63+/anti-FcεRI], and area under the dose-response curve [AUC]) as biomarkers for the clinical outcome of patients with alpha-gal syndrome compared with subjects with asymptomatic alpha-gal sensitization. In addition to routine diagnostics, a basophil activation test (Flow CAST) with different concentrations of alpha-gal-containing allergens (eg, commercially available alpha-gal-carrying proteins and pork kidney extracts) was performed in 21 patients with alpha-gal syndrome, 12 alpha-gal-sensitized subjects, and 18 control subjects. Alpha-gal-containing allergens induced strong basophil activation in a dose-dependent manner in patients. Basophil reactivity at distinct allergen concentrations, the %CD63+/anti-FcεRI ratio across most allergen concentrations, the AUC of dose-response curves, and basophil allergen threshold sensitivity (CD-sens) with pork kidney extract were significantly higher in patients with alpha-gal syndrome compared with those in sensitized subjects. All parameters were negative in control subjects. The basophil activation test should be considered as an additional diagnostic test before performing time-consuming and potentially risky oral provocation tests. The %CD63+/anti-FcεRI ratio for all allergens and AUCs for pork kidney were the best parameters for distinguishing patients with alpha-gal syndrome from subjects with asymptomatic alpha-gal sensitization.

Exploratory analysis of CD63 and CD203c expression in basophils from hazelnut sensitized and allergic individuals.

BackgroundSensitization to hazelnut (HN) is frequent and requires clarification to determine whether this sensitization is clinically relevant. The aim of this study was to investigate basophil activation profiles in HN-sensitized and allergic subjects.MethodsBasophil activation was determined by flow cytometric analyses of CD63 and CD203c expression using several HN allergen concentrations. Depending on their clinical reaction pattern, an oral allergy symptom group (OAS, n = 20), a systemic reaction group (n = 12) and a sensitized group without clinical symptoms (n = 20) were identified. Additionally, 10 non-allergic and non-sensitized individuals served as controls.ResultsCD63 and CD203c expression differed between allergic (OAS and systemic group) and sensitized subjects. The HN concentration required to activate 30% of CD203c+ basophils [effective concentration (EC)30] was significantly higher in sensitized versus the allergic group (p = 0.0089). This was more pronounced when the basophil allergen threshold sensitivity (CD-sens) was calculated (CD63: p = 0.018; CD203c: p = 0.009).ConclusionOur data indicate that the basophil activation test may provide information to better distinguish between sensitized and allergic subjects if several allergen concentrations are considered. CD203c expression displayed a better discrimination compared to CD63; therefore, its diagnostic value might be superior compared with CD63.Electronic supplementary materialThe online version of this article (doi:10.1186/s13601-016-0134-7) contains supplementary material, which is available to authorized users.

Evaluation of basophil allergen threshold sensitivity (CD-sens) to peanut and Ara h 8 in children IgE-sensitized to Ara h 8.

BackgroundDiagnosing peanut allergy properly is important and can be achieved by combining clinical history with various diagnostic methods such as IgE-antibody (IgE-ab) measurements, skin-prick test, basophil allergen threshold sensitivity (CD-sens) and food challenge. We aimed to evaluate CD-sens to peanut, Ara h 8 and Gly m 4 in relation to an oral peanut challenge in children IgE-sensitized to birch, peanut and Ara h 8 avoiding peanuts.MethodsTwenty children IgE-sensitized to birch pollen and Ara h 8, but not to Ara h 1, Ara h 2 or Ara h 3 were challenged orally with roasted peanuts. Blood samples were drawn for IgE-ab and CD-sens analysis. To measure CD-sens, basophils were stimulated in vitro with decreasing doses of allergens until threshold sensitivity was reached.ResultsAll children passed challenge without objective symptoms, but mild oral allergy syndrome (OAS) symptoms were reported in 6/20 children. Nineteen of twenty children were negative in CD-sens to peanut but 17/20 were positive to rAra h 8. Eleven of twenty children were positive in CD-sens to rGly m 4.ConclusionPositive CD-sens to rAra h 8 show that the Ara h 8 IgE-ab sensitized basophils can be activated by a rAra h 8 allergen and initiate an allergic inflammation despite a negative challenge. Hence, children sensitized to Ara h 8 but not to peanut storage proteins may be at risk for systemic allergic reaction when eating larger amounts of peanuts but most likely don’t have to fear smaller amounts.Electronic supplementary materialThe online version of this article (doi:10.1186/s12948-014-0007-3) contains supplementary material, which is available to authorized users.

Distinct parameters of the basophil activation test reflect the severity and threshold of allergic reactions to peanut

BackgroundThe management of peanut allergy relies on allergen avoidance and epinephrine autoinjector for rescue treatment in patients at risk of anaphylaxis. Biomarkers of severity and threshold of allergic reactions to peanut could significantly improve the care for patients with peanut allergy.ObjectiveWe sought to assess the utility of the basophil activation test (BAT) to predict the severity and threshold of reactivity to peanut during oral food challenges (OFCs).MethodsThe severity of the allergic reaction and the threshold dose during OFCs to peanut were determined. Skin prick tests, measurements of specific IgE to peanut and its components, and BATs to peanut were performed on the day of the challenge.ResultsOf the 124 children submitted to OFCs to peanut, 52 (median age, 5 years) reacted with clinical symptoms that ranged from mild oral symptoms to anaphylaxis. Severe reactions occurred in 41% of cases, and 57% reacted to 0.1 g or less of peanut protein. The ratio of the percentage of CD63+ basophils after stimulation with peanut and after stimulation with anti-IgE (CD63 peanut/anti-IgE) was independently associated with severity (P = .001), whereas the basophil allergen threshold sensitivity CD-sens (1/EC50 × 100, where EC50 is half maximal effective concentration) value was independently associated with the threshold (P = .020) of allergic reactions to peanut during OFCs. Patients with CD63 peanut/anti-IgE levels of 1.3 or greater had an increased risk of severe reactions (relative risk, 3.4; 95% CI, 1.8-6.2). Patients with a CD-sens value of 84 or greater had an increased risk of reacting to 0.1 g or less of peanut protein (relative risk, 1.9; 95% CI, 1.3-2.8).ConclusionsBasophil reactivity is associated with severity and basophil sensitivity is associated with the threshold of allergic reactions to peanut. CD63 peanut/anti-IgE and CD-sens values can be used to estimate the severity and threshold of allergic reactions during OFCs.

Basophil activation test in the diagnosis and monitoring of mastocytosis patients with wasp venom allergy.

Background: There is need for an accurate diagnostic test in mastocytosis patients with wasp venom allergy (WVA) and monitoring of these patients during immunotherapy (IT). In this study, we aimed to evaluate sensitivity and specificity of the Basophil Activation Test (BAT) as a diagnostic and monitoring test in patients with mastocytosis and WVA. Methods: Seventeen patients with mastocytosis and WVA and 6 mastocytosis patients without WVA were included. BAT was performed before the start of IT (1st visit) and at 6 weeks (2nd visit) and 1 year (3rd visit), after reaching the maintenance dose. Of 17 patients included, 11 complerted the 3rd visit.In mastocytosis patients with WVA, dose-dependent wasp-venom induced upregulation of CD63 and CD203c expression on basophils was observed compared to mastocytosis patients without WVA. Serum specific IgE, IgG4 and tryptase levels were measured in all patients. Results: BAT had a sensitivity of 87% and specificity of 100% in diagnosing WVA in mastocytosis patients. Basophil allergen threshold sensitivity with respect to CD63 and CD203c was significantly decreased in the second visit compared to the first visit and increased significantly in the third visit compared to the second visit. Specific IgE levels increased significantly in the 2nd visit compared to first and decreased significantly in the third visti compared to the second. Specific IgG4 levels rose significantly in the 2nd visit compared to the 1st and on the 3rd visit compared to the 2nd . Tryptase levels did not change significantly during the study. Conclusions: BAT can represent a diagnostic test in allergic patients with mastocytosis and these patients are better to be monitored for a longer period during IT. © 2013 Clinical Cytometry Society.

Relationship of IgE to basophil phenotypes in peanut-sensitized adults

Relationship of IgE to basophil phenotypes in peanut-sensitized adults

Basophil activation test in the diagnosis and monitoring of mastocytosis patients with wasp venom allergy on immunotherapy

There is need for an accurate diagnostic test in mastocytosis patients with wasp venom allergy (WVA) and monitoring of these patients during immunotherapy (IT). In this study, we aimed to evaluate sensitivity and specificity of the Basophil Activation Test (BAT) as a diagnostic and monitoring test in patients with mastocytosis and WVA. Seventeen patients with mastocytosis and WVA and six mastocytosis patients without WVA were included. BAT was performed before the start of IT (first visit) and at 6 weeks (second visit) and 1 year (third visit), after reaching the maintenance dose. Of 17 patients included, 11 completed the third visit. In mastocytosis patients with WVA, dose-dependent wasp-venom induced upregulation of CD63 and CD203c expression on basophils was observed compared with mastocytosis patients without WVA. Serum specific IgE, IgG4, and tryptase levels were measured in all patients. BAT had a sensitivity of 87% and specificity of 100% in diagnosing WVA in mastocytosis patients. Basophil allergen threshold sensitivity with respect to CD63 and CD203c was significantly decreased in the second visit compared with the first visit and increased significantly in the third visit compared with the second visit. Specific IgE levels increased significantly in the second visit compared with first and decreased significantly in the third visit compared with the second. Specific IgG4 levels rose significantly in the second visit compared with the first and on the third visit compared with the second. Tryptase levels did not change significantly during the study. BAT represents a diagnostic test with 100% specificity in allergic patients with mastocytosis and these patients are better to be monitored for a longer period during IT.

Basophil Activation Test in the diagnosis and monitoring of mastocytosis patients with wasp venom allergy.

Background: There is need for an accurate diagnostic test in mastocytosis patients with wasp venom allergy (WVA) and monitoring of these patients during immunotherapy (IT). In this study, we aimed to evaluate sensitivity and specificity of the Basophil Activation Test (BAT) as a diagnostic and monitoring test in patients with mastocytosis and WVA. Methods: Seventeen patients with mastocytosis and WVA and 6 mastocytosis patients without WVA were included. BAT was performed before the start of IT (1st visit) and at 6 weeks (2nd visit) and 1 year (3rd visit), after reaching the maintenance dose. Of 17 patients included, 11 complerted the 3rd visit.In mastocytosis patients with WVA, dose-dependent wasp-venom induced upregulation of CD63 and CD203c expression on basophils was observed compared to mastocytosis patients without WVA. Serum specific IgE, IgG4 and tryptase levels were measured in all patients. Results: BAT had a sensitivity of 87% and specificity of 100% in diagnosing WVA in mastocytosis patients. Basophil allergen threshold sensitivity with respect to CD63 and CD203c was significantly decreased in the second visit compared to the first visit and increased significantly in the third visit compared to the second visit. Specific IgE levels increased significantly in the 2nd visit compared to first and decreased significantly in the third visti compared to the second. Specific IgG4 levels rose significantly in the 2nd visit compared to the 1st and on the 3rd visit compared to the 2nd . Tryptase levels did not change significantly during the study. Conclusions: BAT can represent a diagnostic test in allergic patients with mastocytosis and these patients are better to be monitored for a longer period during IT. © 2013 Clinical Cytometry Society.

Treatment of life-threatening food allergy

Background Food allergy may be life-threatening and affected individuals have impairment in quality of life. Children with multiple and severe food allergies usually have other allergic manifestations like allergy to furry animals and pollen, causing eczema and asthma. Treatment with the anti-IgE (omalizumab) is indicated for severe allergic asthma. Oral immunotherapy (OIT) has been performed in studies, but has shown to be associated with allergic side-effects. Basophil allergen threshold sensitivity (CD-sens) is suggested to mirror the patient’s allergen sensitivity.

Combining Analyses of Basophil Allergen Threshold Sensitivity, CD-sens, and IgE Antibodies to Hydrolyzed Wheat, ω-5 Gliadin and Timothy Grass Enhances the Prediction of Wheat Challenge Outcome

Background: Wheat is a common food causing allergy which has implications on the quality of life. The diagnosis of IgE-mediated wheat allergy is based on the clinical history and presence of IgE antibodies (IgE-Ab) in skin or blood, and the results of an oral food challenge which is time consuming and associated with risks. An improved diagnostic workup is needed for wheat allergy. The objective was to examine the relationship between wheat challenge, CD-sens and IgE-Ab to related allergens in wheat-allergic children and investigate if a combination of different markers could enhance the prediction of challenge outcome. Method: Twenty-four children (aged 1-15 years) with a wheat allergy diagnosis underwent an open wheat challenge. CD-sens and IgE-Ab to wheat, hydrolyzed wheat protein (HWP), ω-5 gliadin and timothy grass were analyzed and related to the challenge outcome. Results: A positive challenge was seen in 12/24 children. Children reacting to the challenge had higher IgE-Ab concentrations to wheat, ω-5 gliadin and HWP (p < 0.01) and a tendency to higher wheat CD-sens values (p = 0.08) than nonreacting children. Combining wheat CD-sens >150 and IgE-Ab to wheat >20 kU_A/l, or ω-5 gliadin >0.1 kU_A/l predicted the challenge outcome in 83% of the patients. Most children with IgE-Ab to wheat also had IgE-Ab to timothy. Seven of 9 challenge-positive children had a positive CD-sens to HWP and IgE-Ab to HWP >8 kU_A/l. Conclusion: Combining CD-sens and IgE-Ab to wheat or wheat components could be useful in the diagnosis and follow-up of wheat-allergic children.

Basophil Allergen Threshold Sensitivity, CD-Sens, and IgE Antibodies to Wheat, Hydrolysed Wheat, ω-5 Gliadin and Timothy Grass in Relation to Wheat Challenge Outcome

Wheat is one of the six most common foods causing allergy, requires a wheat free diet and has implications on the quality of life. The diagnosis of IgE-mediated immediate wheat allergy is currently based on oral food challenges which are time consuming, associated with risks and not frequently performed. An improved diagnostic workup is needed for wheat allergy.

Oral Peanut Challenge Identifies an Allergy but the Peanut Allergen Threshold Sensitivity Is Not Reproducible

BackgroundDouble-blind placebo-controlled food challenge, DBPCFC, the gold standard for diagnosing food allergy, is time-consuming and potentially dangerous. A basophil allergen threshold sensitivity test, CD-sens, has shown promising results as a diagnostic tool in food allergy.ObjectivesTo evaluate the reproducibility of oral peanut challenge and compare the outcome to CD-sens in peanut-sensitized children.MethodsTwenty-seven children (4–19 years) underwent a DBPCFC followed by a single-blind oral food-challenge. The peanut challenges (1 mg to 5 g) were evaluated by severity scoring. Blood samples were drawn for CD-sens before the two first challenges.ResultsThirteen children (48%) did not react at any of the challenges. Fourteen reacted at both peanut challenges but not to placebo. Only two of these children reacted at the same threshold dose and with the same severity score. All other children scored differently or reacted at different doses. For children with a positive challenge the geometric mean of the ratio of the doses was 1.834 (p = 0.307) and the arithmetic mean of the difference between the severity scores was 0.143 (p = 0.952). No association was obtained between the two peanut challenges regarding severity score (rs = 0.11, p = 0.71) or threshold dose (rs = 0.35, p = 0.22). Among the children positive in peanut challenge, 12 were positive in CD-sens. Two were low-responders and could not be evaluated. Geometric mean of the ratio of CD-sens values in children with a positive challenge was 1.035 (p = 0.505) but unlike for the severity score and the threshold dose the association between the two CD-sens values was strong (rs = 0.94, P<0.001).ConclusionsFor a positive/negative test the reproducibility is 100% for both peanut challenge and CD-sens. However, a comparison of the degree of allergen threshold sensitivity between the two tests is not possible since the threshold dose and severity scoring is not reproducible.

False-positive penicillin immunoassay: An unnoticed common problem

False-positive penicillin immunoassay: An unnoticed common problem

CD-Sens Can Be a Reliable and Easy-to-Use Complement in the Diagnosis of Allergic Rhinitis

Background: A reproducible standard for a graded allergen response in allergic rhinitis is lacking. The aim was to evaluate basophil allergen threshold sensitivity, CD-sens, as a diagnostic complement to nasal allergen challenge. Methods: Twenty-six patients with a history of allergic rhinitis due to grass pollen were intranasally challenged and nasal symptom score and peak nasal inspiratory flow (PNIF) changes were determined after 15 min. A 20% decrease in PNIF or a symptom score ≥2 were considered a positive test. A blood sample for CD-sens was drawn before each challenge. Eighteen patients were tested twice. Results: CD-sens agreed with the positive or negative nasal symptom score in 22/26 and PNIF in 24/26 patients. After the second challenge, 14/18 patients had the same symptom, 17/18 the same PNIF, while all had identical CD-sens classification. Conclusion: CD-sens appears to be a reproducible test for diagnosis of allergic rhinitis with great advantages also for follow-up of disease development and treatment effects.

Intravenous fluorescein as a cause of immunoglobulin E‐mediated anaphylactic shock

We report a patient with severe anaphylactic shock immediately after injection of i.v. fluorescein. The patient recovered without sequela. Immunoglobulin E (IgE) mechanism was highly suggestive with significant increase in serum tryptase, positive basophil allergen threshold sensitivity (CD-sens) and histamine release tests towards fluorescein. This is, to our knowledge, the first report where CD-sens has been used to aid in diagnosing an IgE-mediated anaphylactic shock caused by fluorescein.

High basophil allergen sensitivity (CD‐sens) is associated with severe allergic asthma in children

Children with problematic severe asthma (PA) have persistent symptoms and/or severe exacerbations despite treatment with several drugs. Classification of asthma severity is currently based on level of treatment and assessment of asthma control, but objective biomarkers of asthma severity are needed. To investigate the clinical relevance of basophil allergen threshold sensitivity (CD-sens) as a measure of allergen sensitivity in a well-characterized cohort of children with different manifestations of persistent allergic asthma. Cat-allergic children (6-18 yr) with problematic severe asthma (n = 11) according to GINA were compared with eleven age-matched children with controlled, but persistent asthma (CA). The protocol included standardized questionnaires, asthma control test (ACT), spirometry, methacholine challenges, measurement of FE(NO,) IgE, cat IgE and IgG antibodies, and analysis of CD-sens (CD63-expression) by flow cytometry. The 11 cat-allergic children with PA had a significantly lower ACT score (p < 0.001), reduced FEV(1) (p = 0.04), and increased numbers of blood eosinophils (p = 0.03) compared with the 11 children with CA. The former exhibited a higher CD-sens to cat (p = 0.02). No significant differences were detected with respect to FE(NO) (p = 0.17), IgE (p = 0.84), cat IgE (p = 0.12), and the major cat-allergen rFel d 1 (p = 0.30). CD-sens significantly correlated with ACT (p = 0.002, r = -0.63) and FE(NO) (p = 0.01, r = 0.55). No significant differences between PA and CA were found regarding IgG antibodies to rFel d 1. Cat-allergic children with problematic severe asthma have higher sensitivity to cat allergen, as measured by CD-sens, compared with children with controlled asthma. This suggests that CD-sens could be used as an additional marker for identifying children with the most severe allergic asthma.