Individually dosed omalizumab: an effective treatment for severe peanut allergy.

BACKGROUND: Treatment with omalizumab has shown a positive effect on food allergies, but no dosages are established. Basophil allergen threshold sensitivity (CD-sens) can be used to objectively measure omalizumab treatment efficacy and correlates with the outcome of double-blind placebo-controlled food challenge to peanut. OBJECTIVE: To evaluate whether individualized omalizumab treatment monitored by CD-sens could be an effective intervention for suppression of allergic reactions to peanut. METHODS: Severely peanut allergic adolescents (n = 23) were treated with omalizumab for 8 weeks, and CD-sens was analysed before and after. Based on whether CD-sens was suppressed after 8 weeks, the patients either were subject to a peanut challenge or received eight more weeks with increased dose of omalizumab, followed by peanut challenge or another 8-week cycle of omalizumab. IgE and IgE-antibodies to peanut and its components were analysed before treatment. RESULTS: After individualized omalizumab treatment (8-24 weeks), all patients continued with an open peanut challenge with no (n = 18) or mild (n = 5) objective allergic symptoms. Patients (n = 15) needing an elevated omalizumab dose (ED) to suppress CD-sens had significantly higher CD-sens values at baseline 1.49 (0.44-20.5) compared to those (n = 8) who managed with normal dose (ND) 0.32 (0.24-5.5) (P < 0.01). Median ratios for Ara h 2 IgE-ab/IgE were significantly higher in the ED group (17%) compared to the ND group (11%). CONCLUSIONS AND CLINICAL RELEVANCE: Individually dosed omalizumab, monitored by CD-sens, is an effective and safe treatment for severe peanut allergy. The ratio of IgE-ab to storage protein Ara h 2/IgE as well as CD-sens to peanut may predict the need of a higher omalizumab dose. Clinical trials numbers: EudraCT; 2012-005625-78, ClinicalTrials.gov; NCT02402231.

The clinical utility of basophil activation testing in diagnosis and monitoring of allergic disease.

The basophil activation test (BAT) has become a pervasive test for allergic response through the development of flow cytometry, discovery of activation markers such as CD63 and unique markers identifying basophil granulocytes. Basophil activation test measures basophil response to allergen cross-linking IgE on between 150 and 2000 basophil granulocytes in <0.1 ml fresh blood. Dichotomous activation is assessed as the fraction of reacting basophils. In addition to clinical history, skin prick test, and specific IgE determination, BAT can be a part of the diagnostic evaluation of patients with food-, insect venom-, and drug allergy and chronic urticaria. It may be helpful in determining the clinically relevant allergen. Basophil sensitivity may be used to monitor patients on allergen immunotherapy, anti-IgE treatment or in the natural resolution of allergy. Basophil activation test may use fewer resources and be more reproducible than challenge testing. As it is less stressful for the patient and avoids severe allergic reactions, BAT ought to precede challenge testing. An important next step is to standardize BAT and make it available in diagnostic laboratories. The nature of basophil activation as an ex vivo challenge makes it a multifaceted and promising tool for the allergist. In this EAACI task force position paper, we provide an overview of the practical and technical details as well as the clinical utility of BAT in diagnosis and management of allergic diseases.

Basophil allergen threshold sensitivity and component-resolved diagnostics improve hazelnut allergy diagnosis.

BACKGROUND: IgE sensitization to hazelnut is common, especially in birch endemic areas. However, its clinical significance often needs to be confirmed by a food challenge. OBJECTIVE: To evaluate the clinical significance of IgE antibodies to hazelnut components and basophil allergen threshold sensitivity (CD-sens) to hazelnut, in relation to double-blind placebo-controlled food challenge (DBPCFC) in children with a suspected hazelnut allergy. METHODS: Forty children underwent a DBPCFC. CD-sens to hazelnut as well as IgE antibodies to hazelnut and its components Cor a 1, Cor a 8, Cor a 9 and Cor a 14 were analysed. Serum tryptase was measured before, during and after DBPCFC. RESULTS: Eight children had a positive DBPCFC, and all of them had a high CD-sens value to hazelnut. Of the 32 children that passed the DBPCFC, 31 were very low or negative in CD-sens. A positive DBPCFC corresponded with significantly higher CD-sens values (median 8.9, range 3.3-281) compared to children negative in challenge (median 0.05, range 0-34.7, P < 0.0001). Children positive in challenge also had higher levels of IgE-ab to Cor a 9 and Cor a 14 (P < 0.01 and P < 0.001, respectively) compared with those with a negative challenge. In relation to the results from DBPCFC, the sensitivity of CD-sens and IgE-ab to Cor a 14 was excellent (100%) and the specificity was very high (> 97% and > 94%, respectively). Five of the eight patients positive at challenge showed an increase in tryptase > 20% compared to tryptase baseline levels. CONCLUSIONS AND CLINICAL RELEVANCE: CD-sens and component-resolved diagnostics to hazelnut, used separately or in combination, may improve the diagnostic accuracy and safety and reduce overdiagnosis of hazelnut allergy.

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 kUA/l, or ω-5 gliadin >0.1 kUA/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 kUA/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.

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.

Basophil allergen threshold sensitivity, CD-sens, IgE-sensitization and DBPCFC in peanut-sensitized children.

BACKGROUND: Immunoglobulin E (IgE)-sensitization to peanut is common and can indicate an allergy. A positive test needs to be confirmed by a double-blind, placebo-controlled food challenge (DBPCFC), which is regarded as 'the gold standard'. The aim of the study was to evaluate the basophil allergen threshold sensitivity (CD-sens) and antibodies to peanut allergen components in relation to DBPCFC in the diagnoses of peanut allergy in children. METHODS: Thirty-eight children with suspected peanut allergy underwent a DBPCFC. CD-sens to peanut and Ara h 2 were analysed as well as IgE-antibody to peanut and some of its allergen components (Ara h 1, 2, 3, 8 and 9). RESULTS: Twenty-five children had a positive DBPCFC, and 92% of these were positive in CD-sens to peanut and Ara h 2. Two children with a positive DBPCFC were classified as 'low-responders' and were not further evaluated. Children positive in DBPCFC had higher CD-sens values to peanut (median 1.3; range 0.4-29, n = 21) compared with children negative in DBPCFC (median 0; range 0-0.5, n = 13) (P < 0.0001). A positive DBPCFC correspond with increased levels of IgE-antibody to Ara h 1, 2 and 3 compared with those with a negative challenge (P < 0.0001 for all). All children with a negative CD-sens were negative in DBPCFC. CONCLUSION: In this study, a negative CD-sens to peanut excluded peanut allergy. Both tests, CD-sens to peanut and immunoassay for IgE-antibody to the peanut components, appear to be safe, time saving and cost-effective complements to DBPCFC.

Basophil allergen threshold sensitivity, CD-sens, is a measure of allergen sensitivity in asthma.

BACKGROUND: Allergic asthma is IgE-mediated and the IgE-sensitisation is usually demonstrated by skin prick tests (SPT) and IgE antibody determinations in serum. The SPT and IgE-antibody values do not directly predict if the allergy clinically contributes to the asthma. There is therefore a need for new objective tests that may indicate the clinical importance of an IgE-sensitisation. OBJECTIVE: To evaluate basophil allergen threshold sensitivity (CD-sens) as a measure of allergen sensitivity in allergic asthma. METHODS: Twenty-six subjects with stable, intermittent allergic asthma were tested with SPT and spirometry, and methacholine and allergen inhalation challenges to determine methacholine PD(20) (provocative dose causing a 20% drop in forced expiratory volume in 1 s) and allergen PD(20) . The results were compared with CD-sens and serological parameters, i.e. IgE- and IgG4 antibodies to the relevant allergens. RESULTS: A significant correlation was found between CD-sens and allergen PD(20) (P = 0.01; r = 0.49; n = 26) as well as between CD-sens and the ratio of allergen PD(20) to methacholine PD(20) (P = 0.007; r = 0.52; n = 26). In patients with a moderate to low degree of bronchial hyperresponsiveness there was an excellent correlation (P = 0.0001; r = 0.88, n = 13) between CD-sens and allergen sensitivity. No relation to either allergen PD(20) or the ratio was found for basophil allergen reactivity measured as CD63 up-regulation at high concentrations of the respective allergen. CONCLUSIONS AND CLINICAL RELEVANCE: CD-sens was found to be an objective marker of airway allergen sensitivity in stable allergic asthmatics, that may be used to predict airway responsiveness when bronchial challenge tests cannot be performed.

Xolair is effective in allergics with a low serum IgE level.

BACKGROUND: Two atopic patients suffering from severe allergy difficult to handle by conventional medication were given Xolair despite an IgE level <30 kU/l. METHODS: Increasing dosages were given and monitored by clinical evaluation and CD-sens to clinically relevant allergens. The patients' IgE antibody fractions were 11-14%. RESULTS: Xolair dosages extrapolated from a recommended dose for IgE of 30-75 kU/l were adapted to the patients' IgE body pool but had very little effect. The double dose resulted in some clinical improvement and a decrease in CD-sens. However, not until the dose was doubled again did the patients become symptom free, although 1 patient needed some additional drugs but no oral steroids. CD-sens turned negative to 5 of the 7 tested allergens. CONCLUSIONS: Xolair is most useful also in atopics with an IgE level <30 kU/l. The dose must be adjusted to the size of the IgE antibody fraction adding all non-cross-reacting, clinically relevant specificities.

Anaphylaxis to Patent Blue V. I. Clinical aspects.

BACKGROUND: The dye Patent Blue V (PBV) is increasingly used for staging procedures in operable breast cancer, but is reported to cause adverse reactions. The aim of this study was to present the clinical features and the results of follow-up examinations in patients with such reactions. METHODS: We studied nine patients with hypersensitivity reactions to PBV between 1999 and 2006 who were identified through the Norwegian network for reporting and investigating allergic reactions during anesthesia. RESULTS: We observed incidences of 0.5% (7/1418) for all kinds of PBV reactions and 0.4% (5/1418) for anaphylaxis. Typical clinical features included: (i) cardiovascular and/or cutaneous symptoms, (ii) a delay in symptoms, compared to the time of dye injection, (iii) poor response to ephedrine and intravenous fluid, and (iv) need for adrenaline administration, sometimes prolonged, for circulatory stabilization. Cutaneous manifestations were noted in five of the seven patients with anaphylaxis and two additional patients without circulatory instability. During anaphylactic reactions, serum tryptase was increased in six patients and normal in one. Serum tryptase was normal in one patient with skin symptoms only. Skin prick tests to PBV were positive in all eight patients tested, including the two with skin manifestations only. CONCLUSION: The clinical features and the results of follow-up studies strongly suggest that these reactions are IgE mediated.

Anaphylaxis to Patent Blue V. II. A unique IgE-mediated reaction.

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

The size of the disease relevant IgE antibody fraction in relation to 'total-IgE' predicts the efficacy of anti-IgE (Xolair) treatment.

BACKGROUND: Some patients with allergic asthma treated with anti-IgE (Xolair) do not become symptom free. Better criteria for response assessment than allergy skin tests or IgE determination are needed. The impact of the size of the disease relevant allergen-specific IgE antibody fraction, i.e. the percentage of IgE antibody of total IgE, was evaluated in cat allergic patients treated with the recommended doses of Xolair. Results were measured as changes in basophil allergen threshold sensitivity (CD-sens). METHODS: In a double-blind placebo controlled trial 20 patients with a high (>3.8%) and 18 with a low (<1%) percentage of IgE antibodies to cat were given Xolair for 16 weeks and the change in CD-sens was compared to 11 and 10 patients, respectively, in each group receiving placebo. RESULTS: The CD-sens dropped significantly in both the high (P < 0.001) and low (P < 0.001) group on Xolair but did not change significantly after placebo. For Xolair-treated patients, at the end of the trial there was a highly significant (P < 0.001) difference in CD-sens between the high group, where no patients, and the low group, where 13/18 patients, had become negative. CONCLUSIONS: The currently recommended doses of Xolair very efficiently eliminate IgE antibodies if the IgE antibody fraction is <1% of total IgE but has not enough effect on allergen sensitivity if the fraction is >3-4%. Further studies will show if increased doses of Xolair would help also these patients, who seem to represent about 1/3 of the patient population.

CD-sens: a biological measure of immunological changes stimulated by ASIT.

BACKGROUND: Allergen-specific immunotherapy (ASIT) in allergic rhinitis and asthma is the only treatment that effects the long-term development of these diseases. Basophil allergen threshold sensitivity, CD-sens, which is a valuable complement to resource-demanding clinical challenge tests, was used to monitor the initiation of ASIT induced allergen 'blocking activity'. METHODS: Patients IgE-sensitized to timothy (n = 14) or birch (n = 19) pollen were started on conventional (8-16 weeks) or ultra rush ASIT, respectively, and followed by measurements of CD-sens, allergen binding activity (ABA) and serum IgG4- and IgE-antibody concentrations. RESULTS: CD-sens decreased during the early phase of ASIT-treatment. In parallel, ABA increased and correlated significantly with the increasing levels of IgG4 antibody concentrations. High dosages of allergen were more effective while mode of dosing up did not seem to matter. No change was seen in basophil reactivity. CONCLUSION: CD-sens and ABA, in contrast to basophil reactivity, seem to be promising tools to monitor protective immune responses initiated by ASIT.

CD-sens and clinical changes during withdrawal of Xolair after 6 years of treatment.

BACKGROUND: Many clinical trials with omalizumab, Xolair, have been reported but the treatment period has always been short, i.e. <12 months. After withdrawal, the clinical symptoms tend to return. A group of patients who stopped treatment after approx. 6 years allowed studies of the long-term effects of Xolair. METHODS: The patient's cat or mite allergen sensitivity was quantitated as basophil allergen threshold sensitivity, CD-sens, and immunoglobulin E (IgE) and IgE- and IgG4-antibodies were determined before start and during treatment withdrawal. Asthma severity was evaluated from forced expiratory volume (FEV), peak expiratory flow (PEF) and a questionnaire. RESULTS: At 6-14 months without Xolair 13 of the 18 cat and mite allergic asthmatics had either improved or remained the same as on treatment. Most of the patients were in a stable clinical condition reporting high quality of life, no increased nightly asthma attacks, no emergency visits as well as little or no increase in medication. The CD-sens to cat showed a peak 4 months after withdrawal but then decreased to levels below those of untreated patients with allergic asthma and at 12 months six of 14 had nonreactive basophils. Cat IgG4 antibody levels were higher than in cat allergics in general. CONCLUSION: Most of the patients 12-14 months had, after closing of 6-year Xolair treatment, a surprisingly mild asthma. Interestingly, and probably contributing to the clinical results, a downregulation of basophil, and presumably also mast cell, reactivity, was seen.

No consumption of IgE antibody in serum during allergic drug anaphylaxis.

BACKGROUND: The general understanding is that a blood sample for analysis of immunoglobulin (Ig) E antibodies to an allergen suspected to cause an anaphylaxis cannot be drawn until several weeks after the reaction. As this is most unpractical, the changes in IgE antibody levels during anaphylaxis were studied to evaluate the possibility of using samples drawn at the time of the reaction. METHODS: Immunoglobulin E antibodies to suxamethonium were quantitated with ImmunoCAP before, during and after an anaphylactic reaction occurring during anaesthesia using neuromuscular blocking agents. RESULTS: Serum IgE antibody concentrations against suxamethonium in blood samples collected up to 6 h after the reaction were not different from those in samples drawn before or days and weeks after the anaphylaxis. CONCLUSIONS: A serum sample intended to trace the drug involved in an IgE-mediated anaphylactic reaction can be drawn in direct relation to the reaction.

The importance of IgE antibody levels in anti-IgE treatment.

BACKGROUND: Dosages of anti-immunoglobulin (Ig)E in treatment of allergic asthma is based on total IgE body pool assuming that IgE antibodies responsible for the disease are evenly distributed among patients. This assumption was evaluated. METHODS: Median and quartile concentrations of IgE and IgE antibodies to cat and mite in 6461 sera submitted to an allergy laboratory during 2003-2005 were calculated and expressed in groups of different IgE levels. RESULTS: Of 3872 (60%) samples from adults with a serum IgE level of 30-700 kU/l, 22.2% had IgE antibodies (>or=0.35 kU(A)/l) to mite, 36.0% to cat and 8.1% to both. The relative concentration of IgE antibody of IgE decreased with increasing IgE, indicating a more specific response in patients with slightly elevated serum IgE. At a hypothetical serum IgE level of 10 kU/l, the threshold recommended for anti-IgE treatment, 25% of the originally mite- and/or cat-positive population in the <75 kU/l IgE group still would have detectable IgE antibodies. CONCLUSIONS: Sera from patients sensitized to mite and cat with moderate serum IgE levels have a high proportion of IgE antibodies; in the 30-74 kU/l group, as much as 10% of the IgE could be specific to one allergen. An increase of the anti-IgE dosage given to such patients should be considered, especially because IgE antibodies with different, relevant specificities have an additive effect in triggering inflammatory cells.