Patch testing with the European baseline series and 10 added allergens: Single-centre study of 748 patients.

BACKGROUND: The European baseline series (EBS) of contact allergens is subject to change. An allergen is considered for inclusion when routine patch testing of patients with suspected contact dermatitis results in ≥0.5% prevalence rate. OBJECTIVES: We aimed to determine the frequency of sensitizations to 30 EBS allergens and 10 locally added allergens. Additionally, we assessed the strength and evolution of reactions to all tested allergens and co-reactivity of additional allergens. METHODS: Patch testing with our baseline series of 40 allergens was done in 748 consecutive adults. Tests were applied to the upper back and removed by patients after 48 h. Readings were done on Day 3 (D3) and D6 or D7 (D6/7). Positive reactions fulfilled the criteria of at least one plus (+) reaction. A retrospective analysis was done. RESULTS: Eight allergens not listed in the EBS had ≥0.5% prevalence rate (i.e., cocamidopropyl betaine, thiomersal, disperse blue mix 106/124, 2-bromo-2-nitropropane-1,3-diol, diazolidinyl urea, propylene glycol, Compositae mix II and dexamethasone-21-phosphate), and 16.6% of positive reactions would have been missed without D6/7 readings. CONCLUSION: We propose further studies to evaluate whether cocamidopropyl betaine, disperse blue mix 106/124, 2-bromo-2-nitropropane-1,3-diol, diazolidinyl urea and Compositae mix II need to be added to the EBS.

Biomarkers of the Severity of Honeybee Sting Reactions and the Severity and Threshold of Systemic Adverse Events During Immunotherapy.

BACKGROUND: A biomarker that could identify individuals at high risk for severe honeybee sting allergic reaction and/or systemic adverse events (SAEs) during venom immunotherapy (VIT) would improve the management of patients with honeybee (HB) venom allergy. OBJECTIVE: To identify biomarkers for risk of severe sting reactions or SAEs during VIT. METHODS: We recruited 332 patients undergoing HB VIT. We ascertained predictors of the severity of the field-sting reaction and the severity and threshold of SAEs during VIT. We assessed the use of cardiovascular medications; baseline serum tryptase (BST) levels; specific IgEs to HB venom, rApi m 1, and rApi m 10; and basophil activation test (BAT) response. RESULTS: Significant and independent predictors of a severe HB field-sting reaction were age (P = .008), an absence of skin symptoms (P = .001), BST (P = .014), and BAT response at an HB venom concentration of 0.1 µg/mL (P = .001). Predictors of severe SAEs during HB VIT were age (P = .025), BST (P = .006), and BAT response (P = .001). BAT response was also an individual and significant predictor of any SAEs and SAEs at a low cumulative allergen dose (median, 55 µg) during VIT build-up (P < .001). The use of ß-blockers and angiotensin-converting-enzyme inhibitors and specific IgE levels were not associated with the severity of HB field-sting reactions or VIT SAEs. CONCLUSIONS: BST and basophil activation are independent risk factors for severe HB sting anaphylaxis and SAEs during HB VIT. BAT response was the best biomarker for any SAEs and a lower threshold of SAEs during HB VIT. These risk factors can help guide recommendations for VIT and overcome systemic reactions to HB VIT.

Routine KIT p.D816V screening identifies clonal mast cell disease in patients with Hymenoptera allergy regularly missed using baseline tryptase levels alone.

BACKGROUND: Clonal mast cell disorders and elevated basal serum tryptase (BST) levels with unknown cause(s) are associated with severe Hymenoptera venom-triggered anaphylaxis (HVA). However, some individuals with clonal disease have a normal BST level (<11.4 ng/mL). OBJECTIVE: Our aim was to evaluate whether screening for KIT p.D816V in the blood is a useful clinical tool to risk-stratify patients with venom allergy. METHODS: We prospectively recruited 374 patients with Hymenoptera allergy and no overt signs of mastocytosis who were referred to our center during the years 2018 and 2019. KIT p.D816V was determined in their peripheral blood by quantitative PCR, and tryptase genotyping was performed by droplet digital PCR. RESULTS: In all, 351 patients (93.9%) had normal levels of BST, and KIT p.D816V was detected in 8% of patients (28 of 351), predominantly in patients with the most severe Mueller grade IV anaphylaxis (18.2% [24 of 132] vs 1.8% in patients with lower grades [4 of 88 with grade III and 0 of 131 with other grades]; P < .001). In grade IV patients with a normal BST level, KIT p.D816V was associated with more severe symptoms, including a significantly higher frequency of loss of consciousness (58.3% [14 of 24] vs 34.3% [37 of 108]; P = .03) and absence of skin symptoms (41.7% [10 of 24] vs 15.7% [17 of 108]; P = .004). Among patients with a normal BST level, KIT p.D816V (OR = 10.25 [95% CI = 3.75-36.14]; P < .0001) was the major risk factor associated with severe HVA. Hereditary α-tryptasemia (HαT) due to increased germline copies of TPSAB1 encoding α-tryptase was the most common cause (65.2% [15 of 23]) of elevated BST level in patients with HVA, and together with KIT p.D816V, it accounted for 90% of BST level elevations (20 of 23) in patients with HVA. CONCLUSION: These results indicate that routine KIT p.D816V screening identifies clonal disease in high-risk patients with HVA who are regularly missed when BST level is used alone.

Clinical and immunological differences between asymptomatic HDM-sensitized and HDM-allergic rhinitis patients.

BACKGROUND: Confirmation of the clinical relevance of sensitisation is important for the diagnosis of allergic rhinitis. OBJECTIVE: To investigate the usefulness of an in vitro basophil activation test and component-resolved diagnosis in distinguishing between symptomatic allergic rhinitis patients and asymptomatic sensitization to house dust mites (HDMs). METHODS: Thirty-six subjects with a positive skin prick test (SPT) for HDM were divided into a symptomatic (n = 17) and an asymptomatic (n = 19) group on the basis of their clinical history and a nasal provocation test. A basophil CD63 response to in vitro stimulation with Dermatophagoides pteronyssinus whole allergen extract and the IgE reactivity profiles for Der p 1, 2, 4, 5, 7, 10, 11, 14, 15, 18, 21, 23 were evaluated. Serum IgE and IgG specific to D pteronyssinus whole allergen extract and total IgE were measured. RESULTS: There were no statistically significant differences in the levels of IgE (IgE levels were higher in symptomatic patients with P = 0.055) and IgG specific to D pteronyssinus and total IgE. Symptomatic patients showed a lower threshold for in vitro basophil activation (3.33 ng/mL vs 33.3 ng/mL), a higher area under the curve (AUC) of basophil activation (171 vs 127) (P = 0.017), a higher response to positive control with anti-FcεRI stimulation (97% vs 79%) (P < 0.001), a recognition of more HDM allergens (4 vs 2) and more frequent sensitization to rDer p 7 (P = 0.016) and rDer p 23 compared to asymptomatic subjects (P = 0.018). There was a positive correlation (r = 0.63; P < 0.001) between the number of recognized allergens and the AUC of basophil activation. CONCLUSION AND CLINICAL RELEVANCE: In the subjects studied, the differences in the basophil response to D pteronyssinus allergen extract, number of recognized HDM allergens and reactivity to rDer p 7 and rDer p 23 distinguish symptomatic from asymptomatic HDM sensitisation better than SPT or allergen extract-specific IgE. Information regarding the clinical relevance of sensitization is important for the prescription of allergen-specific immunotherapy.

Omalizumab in chronic urticaria: our experience and literature review.

INTRODUCTION: Chronic urticaria (CU) severely affects quality of life. If symptoms are not controlled by antihistamines, patients need immunomodulatory drugs. Recent studies show a tremendous effect of omalizumab, a monoclonal antibody against human IgE in refractory CU. METHODS: We report on the use of omalizumab in four patients with CU. By reviewing medical files, we estimated the proportion of CU patients that are candidates for such treatment. We reviewed the literature to compare the dosing schedules and outcome measures used in different studies. RESULTS: Up to 14% of CU patients referred to a tertiary center are candidates for omalizumab. Four of our CU were patients treated with doses of 150 mg/month or less, and all responded with nearly complete remission of symptoms. In the literature, 90% of patients respond to treatment, the response being obvious in days. Half of patients were able to stop all other medications, including antihistamines. More than half of patients responded well to doses of 150 mg of omalizumab every 4 to 8 weeks. In the majority of patients, the disease relapsed after discontinuation of omalizumab. CONCLUSIONS: Omalizumab should be offered to patients with refractory CU. The duration of treatment is not known.

Clinical routine utility of basophil activation testing for diagnosis of hymenoptera-allergic patients with emphasis on individuals with negative venom-specific IgE antibodies.

BACKGROUND: Previous reports suggest the usefulness of basophil activation testing (BAT) in Hymenoptera-allergic patients with negative venom-specific IgE antibodies. We sought to evaluate the diagnostic utility of this testing in a routine clinical laboratory setting. MATERIALS AND METHODS: Twenty-one patients with anaphylactic reactions to Hymenoptera sting (median grade III) and negative venom-specific IgE were routinely and prospectively tested with BAT. RESULTS: We were able to diagnose 81% (17 of 21) of patients with BAT and 57% (12 of 21) with intradermal skin testing. Three wasp venom-allergic patients showed IgE positivity to rVes v 5. Four patients (19%) were negative for all tests. In the case of double-positive BAT, the culprit insect correlated with the venom that induced a significantly higher basophil response. CONCLUSIONS: BAT allows the identification of severe Hymenoptera-allergic patients with negative specific IgE and skin tests. The routine use of this cellular test should facilitate prescription of venom immunotherapy in complex cases with inconclusive diagnostic results.

Acetylsalicylic acid-triggered 15-HETE generation by peripheral leukocytes for identifying ASA sensitivity.

BACKGROUND: Exposure to acetylsalicylic acid (ASA) may exacerbate respiratory or skin diseases or induce anaphylactoid reactions in apparently healthy individuals. We wanted to evaluate the clinical and diagnostic utility of measuring ASA-induced 15-hydroxyeicosatetraenoic acid (15-HETE) generation. METHODS: We performed a prospective single-blind study with 26 subjects undergoing clinical evaluation and/or ASA provocation testing. We also included 12 control subjects. Peripheral blood leukocytes were incubated with 500 µM ASA and 15-HETE release was measured by competitive ELISA. RESULTS: We found that 18 subjects were ASA-tolerant and 8 were ASA-intolerant. The mean increase in 15-HETE in intolerant subjects was 34% and this was comparable to the mean increase of 30% observed in ASA-tolerant subjects. A similar mean increase was also observed in control subjects. The ROC calculation showed that the optimal diagnostic threshold would be an increase of greater than 33%. However, the sensitivity of this increase was only 63% and the specificity was 50%. CONCLUSIONS: Our data suggest that further studies are needed before the ASA-induced 15-HETE test can be used in clinical practice.

Basophil responsiveness and clinical picture of acetylsalicylic acid intolerance.

BACKGROUND: Exposure to acetylsalicylic acid (ASA) may exacerbate respiratory or skin diseases or induce anaphylactoid reactions in apparently healthy individuals. We wanted to evaluate specific responsiveness of basophils to ASA in correlation with the clinical picture. METHODS: We performed a prospective single-blind study of 59 subjects involved in clinical evaluation and/or ASA provocation testing. Whole blood basophils were stained with anti-CD63/CD123/HLA-DR mAbs after stimulation with 0.25 or 1 mg/ml ASA. RESULTS: We found that 40 subjects were ASA tolerant and 19 were ASA intolerant. Both groups had comparable manifestations of asthma and/or rhinitis (13 in the tolerant and 9 in the intolerant group). Intolerant subjects showed significantly higher basophil responsiveness to ASA in comparison to tolerant subjects, which was concentration-dependent in both groups. The ratio between responses at 1 mg/ml of ASA and at baseline (activation index) was analyzed according to the clinical picture. We demonstrate that the activation index was higher only in the intolerant subjects with anaphylactoid reactions, but not in a subgroup of subjects with asthma/rhinitis. The ROC calculations show that the optimal threshold activation index was more than 2.18. The sensitivity was 80% and the specificity was 83% in the subgroup with anaphylactoid reactions. In the asthma/rhinitis subgroup, the sensitivity was 78% and the specificity was 50%. CONCLUSIONS: Our study demonstrates that there is a significantly higher in vitro basophil response to ASA in intolerant as compared to tolerant subjects. ROC analyses suggest that this measurement might only have a diagnostic value in subjects without asthma and/or rhinitis.

Diagnostic value of the basophil activation test in evaluating Hymenoptera venom sensitization.

BACKGROUND: Diagnosis of allergy to Hymenoptera venom is usually confirmed with skin testing and measurement of specific serum IgE antibody, tests which are sometimes inconclusive. In these cases, additional in vitro tests are necessary. The aim of this study was to show the applicability of the basophil activation test in detecting sensitization to Hymenoptera venom and to compare the test sensitivity and clinical positive-predictive value with skin prick tests and measurement of allergen-specific serum IgE. METHODS: This prospective study was conducted between June 2004 and December 2007 and included a large group of 204 patients. All patients had a history of at least one systemic allergic reaction of Müller grades II-IV after a Hymenoptera sting. We compared results of the basophil activation test, specific serum IgE and skin prick tests with patients' clinical history and data on culprit insects. RESULTS: The overall clinical sensitivities of the basophil activation test, specific serum IgE and skin prick tests were 90%, 76% and 64%, respectively; the clinical positive-predictive values of the three tests were 79%, 73% and 78% for bee venom, 86%, 59% and 43% for wasp venom; and 84%, 77% and 22% for both venoms. CONCLUSIONS: Our results revealed a higher clinical sensitivity and comparable or better clinical positive-predictive value of basophil activation tests than skin prick tests and allergen-specific serum IgE in the detection of allergy to Hymenoptera venom.

The local and systemic side-effects of venom and inhaled-allergen subcutaneous immunotherapy.

BACKGROUND: Although immunotherapy is effective in allergic rhinitis, conjunctivitis, asthma and stinging insect hypersensitivity, it carries a risk of anaphylactic reactions. METHODS: In a 4-year retrospective survey, we investigated 1257 adult patients who had received venom or inhaled-allergen subcutaneous immunotherapy. The dose-increase phase was performed as the 2-day rush protocol for venom immunotherapy and the 6-week protocol for inhaled-allergen immunotherapy. RESULTS: A total of 904 patients received venom immunotherapy and 353 patients inhaled-allergen immunotherapy. The prevalence of systemic reactions was 13.6%. The frequency of systemic reactions was higher during the maintenance phase than in the dose-increase phase (9.6% vs. 5.9%) and was highest in both phases of treatment with honeybee venom (P < 0.001). The majority of systemic reactions were mild. Five (0.4%) patients had reaction with a fall of blood pressure and were treated with adrenaline. There was no fatal outcome. The systemic side-effects during the dose-increase phase of venom immunotherapy occurred at a median dose of 46 microg (range 2-100 microg). Large local reactions occurred in 13.9% of patients without any significant difference between the allergens. CONCLUSIONS: We have shown that systemic reactions are not rare even during maintenance phase in patients with a well tolerated dose-increase phase of treatment. The most prominent risk factor for systemic reactions was immunotherapy with honeybee extract.

Aspirin-induced COX-2 overexpression in monocytes of aspirin-intolerant patients.

BACKGROUND: We hypothesize that alternate regulation of cyclooxygenase-2 (COX-2) may predispose patients to aspirin-induced exacerbations.Therefore, we want to examine the dynamics of COX-2 up-regulation in whole blood monocytes in the presence and absence of aspirin. METHODS: COX-2 expression was evaluated by flow cytometry through intracellular staining of whole blood monocytes with anti-COX-2 antibodies. Enzyme up-regulation was monitored after in vitro stimulation with lipopolysaccharide (LPS) and/or aspirin in 19 aspirin-intolerant (AI) patients (8 aspirin-sensitive asthmatics and 11 urticaria-angioedema patients) and 14 healthy controls. RESULTS: We found significantly higher COX-2 expression levels after stimulation with LPS and aspirin (mean 78.8, range 44.9-92.3; p = 0.0002) in comparison to LPS alone (mean 65.9%, range 33.6-82.6) in AI patients. A comparable, but lower up-regulation was also observed after aspirin stimulation alone (median 2.1%, range 0.5-15.9; p = 0.004) in comparison with baseline values (median 1%, range 0.1-5.4). There was no significant difference in COX-2 expression between LPS and aspirin stimulation (mean 61.8%, range 26.8-89.2; p = 0.09) and LPS stimulation (mean 55.5%, range 28.1-74.3) nor between aspirin stimulation alone (median 0.5%, range 0-8.6; p = 0.8) and baseline values (median 0.4%, range 0-5.4) in healthy control subjects. CONCLUSIONS: The main finding of this study is that COX-2 appears to be differentially regulated in aspirin-sensitive patients. What is really new is the observation that aspirin and LPS increase COX-2 expression on blood monocytes of AI asthmatics, a finding in contrast with the lack of an effect of the same stimuli on COX-2 expression on monocytes from healthy subjects.