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.

Mast cell activation test in the diagnosis of allergic disease and anaphylaxis.

BACKGROUND: Food allergy is an increasing public health issue and the most common cause of life-threatening anaphylactic reactions. Conventional allergy tests assess for the presence of allergen-specific IgE, significantly overestimating the rate of true clinical allergy and resulting in overdiagnosis and adverse effect on health-related quality of life. OBJECTIVE: To undertake initial validation and assessment of a novel diagnostic tool, we used the mast cell activation test (MAT). METHODS: Primary human blood-derived mast cells (MCs) were generated from peripheral blood precursors, sensitized with patients' sera, and then incubated with allergen. MC degranulation was assessed by means of flow cytometry and mediator release. We compared the diagnostic performance of MATs with that of existing diagnostic tools to assess in a cohort of peanut-sensitized subjects undergoing double-blind, placebo-controlled challenge. RESULTS: Human blood-derived MCs sensitized with sera from patients with peanut, grass pollen, and Hymenoptera (wasp venom) allergy demonstrated allergen-specific and dose-dependent degranulation, as determined based on both expression of surface activation markers (CD63 and CD107a) and functional assays (prostaglandin D2 and ß-hexosaminidase release). In this cohort of peanut-sensitized subjects, the MAT was found to have superior discrimination performance compared with other testing modalities, including component-resolved diagnostics and basophil activation tests. Using functional principle component analysis, we identified 5 clusters or patterns of reactivity in the resulting dose-response curves, which at preliminary analysis corresponded to the reaction phenotypes seen at challenge. CONCLUSION: The MAT is a robust tool that can confer superior diagnostic performance compared with existing allergy diagnostics and might be useful to explore differences in effector cell function between basophils and MCs during allergic reactions.

Basophils, high-affinity IgE receptors, and CCL2 in human anaphylaxis.

BACKGROUND: The role of basophils in anaphylaxis is unclear. OBJECTIVE: We sought to investigate whether basophils have an important role in human anaphylaxis. METHODS: In an emergency department study we recruited 31 patients with acute anaphylaxis, predominantly to Hymenoptera venom. We measured expression of basophil activation markers (CD63 and CD203c); the absolute number of circulating basophils; whole-blood FCER1A, carboxypeptidase A3 (CPA3), and L-histidine decarboxylase (HDC) gene expression; and serum markers (CCL2, CCL5, CCL11, IL-3, and thymic stromal lymphopoietin) at 3 time points (ie, during the anaphylactic episode and in convalescent samples 7 and 30 days later). We recruited 134 patients with Hymenoptera allergy and 76 healthy control subjects for comparison. We then investigated whether the changes observed during venom-related anaphylaxis also occur during allergic reactions to food in 22 patients with peanut allergy undergoing double-blind, placebo-controlled food challenge to peanut. RESULTS: The number of circulating basophils was significantly lower during anaphylaxis (median, 3.5 cells/µL) than 7 and 30 days later (17.5 and 24.7 cells/µL, P < .0001) and compared with those in patients with venom allergy and healthy control subjects (21 and 23.4 cells/µL, P < .0001). FCER1A expression during anaphylaxis was also significantly lower than in convalescent samples (P ≤ .002) and control subjects with venom allergy (P < .0001). CCL2 levels (but not those of other serum markers) were significantly higher during anaphylaxis (median, 658 pg/mL) than in convalescent samples (314 and 311 pg/mL at 7 and 30 days, P < .001). Peanut-induced allergic reactions resulted in a significant decrease in circulating basophil counts compared with those in prechallenge samples (P = .016), a decrease in FCER1A expression (P = .007), and an increase in CCL2 levels (P = .003). CONCLUSIONS: Our findings imply an important and specific role for basophils in the pathophysiology of human anaphylaxis.

Distinct Contributory Factors Determine Basophil-Allergen Sensitivity in Grass Pollen Rhinitis and in Anaphylactic Wasp Venom Allergy.

BACKGROUND: We sought to determine whether basophil-allergen sensitivity could be transferred to donor basophils by passive IgE sensitisation in allergic rhinitis and anaphylactic Hymenoptera venom hypersensitivity. METHODS: We studied 15 wasp venom-, 19 grass pollen- and 2 house dust mite-allergic patients, 2 healthy donors, and 8 wasp venom-allergic donors. In all subjects, we first evaluated the initial basophil response to wasp venom, grass pollen, or house dust mite allergen. Donor basophils were then stripped, sensitised with the different patients' serum IgE, and challenged with the corresponding allergen. The CD63 response of donor basophils was then compared with initial basophil responses. RESULTS: In wasp venom-allergic subjects, the IgE transfer did not reflect the initial basophil-allergen sensitivity, because the venom IgE of subjects with high or low basophil sensitivity induced comparable responsiveness in healthy donor basophils. Furthermore, vice versa, when we sensitised the donor basophils of wasp venom-allergic individuals with different wasp venom or house dust mite IgE, we demonstrated that their response was predictable by their initial basophil allergen sensitivity. In the rhinitis allergy model, the IgE transfer correlated with the patients' initial basophil responsiveness because the grass pollen IgE of the subjects with high basophil allergen sensitivity induced significantly higher responsiveness of donor basophils than the IgE of subjects with initially low basophil allergen sensitivity. CONCLUSIONS: Our results suggest that basophil allergen sensitivity evaluated by flow-cytometric CD63 analysis depends on two distinct contribution factors. In anaphylactic Hymenoptera allergy, the major factor was intrinsic cellular sensitivity, whereas in pollen allergy, the major factor was allergen-specific IgE on the cell surface.

8-isoprostane as Oxidative Stress Marker in Coal Mine Workers.

This study was to investigate whether working in conditions of elevated concentrations of mine gases (CO2, CO, CH4, DMS) and dust may result in oxidative stress. Coal miners (n=94) from the Velenje Coal mine who were arranged into control group and three groups according to a number of consecutive working days. 8-isoprostane as a biological marker of oxidative stress was measured in exhaled breath condensate (EBC). Miners who worked for three consecutive days had higher 8-isoprostane values in EBC compared to the control group. Gas/dust concentrations and exposure time of a single/two day shift seem too low to trigger immediate oxidative stress.

Stable phase post-MI patients have elevated VEGF levels correlated with inflammation markers, but not with atherosclerotic burden.

BACKGROUND: The role of vascular endothelial growth factor (VEGF) in patients in the stable phase after myocardial infarction (MI) has not yet been explored. Therefore, we compared the values of VEGF in post-MI patients with those obtained in healthy controls. Furthermore, we investigated whether the values of VEGF correlate to either inflammation markers or the atherosclerotic burden. METHODS: 41 male patients (on average 44 years old) in the stable phase after MI (on average 20.5 months after MI) were recruited, while 25 healthy age-matched males served as controls. Plasma levels of VEGF and several markers of inflammation were measured by standard procedures. The atherosclerotic burden was determined by the angiographic severity of coronary atherosclerosis, endothelial dysfunction (measured by ultrasound measurement of the flow mediated dilation of the brachial artery), the intima-media thickness of the common carotid artery and the ankle-brachial pressure index. RESULTS: VEGF values were significantly elevated in post-MI patients compared to the controls (53.8 ± 42.7 pg/ml vs. 36.3 ± 8.9 pg/ml, p = 0.014). The elevated VEGF values significantly correlated to the (increased) values of the inflammatory molecules interleukin 6 and 8 (r = 0.37, p = 0.017; and r = 0.45, p = 0.003; respectively). In contrast, no correlation was found between VEGF and the parameters of the atherosclerotic burden, although FMD and IMT were significantly impaired in patients. CONCLUSIONS: We found that plasma levels of VEGF are increased in the stable phase after MI and correlate with inflammation cytokines, but not with the atherosclerotic burden. Thus, this suggests that increased levels of VEGF are a part of ongoing inflammatory activity. Since VEGF in these patients stimulates neovascularization of inflamed plaques and induces their destabilization, the VEGF level can have an important negative prognostic value. Clearly, further studies are needed to clarify the role of VEGF as a prognostic marker.

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.

The relevance of basophil allergen sensitivity testing to distinguish between severe and mild peanut-allergic children.

BACKGROUND: Peanut sensitization is common in children. However, it is difficult to assess which children will react mildly and which severely. This study evaluated the relevance of basophil allergen sensitivity testing to distinguish the severity of peanut allergy in children. METHODS: Twenty-seven peanut-sensitized children with symptoms varying from mild symptoms to severe anaphylaxis underwent peanut CD63 dose-response curve analysis with the inclusion of basophil allergen sensitivity calculation (CD-sens) and peanut component immunoglobulin E (IgE) testing. RESULTS: Eleven children who had experienced anaphylaxis to peanuts showed a markedly higher peanut CD63 response at submaximal allergen concentrations and CD-sens (median 1,667 vs. 0.5; p < 0.0001) than 16 children who experienced a milder reaction. Furthermore, a negative or low CD-sens to peanuts unambiguously excluded anaphylactic peanut allergy. Children with anaphylaxis have higher levels of Ara h 1, 2, 3 and 9 IgE, but comparable levels of IgE to Ara h 8 and whole-peanut extract. The diagnostic specificity calculated with a receiver operating characteristic analysis reached 100% for CD-sens and 73% for Ara h 2. CONCLUSIONS: We demonstrated that severe peanut allergy is significantly associated with higher basophil allergen sensitivity. This cellular test should facilitate a more accurate diagnosis of peanut allergy.

House dust mite-specific immunotherapy alters the basal expression of T regulatory and FcεRI pathway genes.

BACKGROUND: Regulatory T (Treg) cells and IgE-mediated signaling pathways could play important roles in the induction of allergen tolerance during house dust mite-specific subcutaneous immunotherapy (HDM-SCIT). Our aim was to compare the basal expression levels of Treg, T helper 1 (Th1) and Th2 transcription factors and components involved in IgE-mediated signaling in healthy subjects with those in HDM-allergic patients both untreated and successfully treated with HDM-SCIT. METHODS: Thirty-nine HDM-allergic patients who completed a 3- to 5-year course of mite extract SCIT, 20 mite-allergic controls and 25 healthy controls participated in this study. The efficacy of SCIT was monitored using skin-prick tests (SPTs), total immunoglobulin E (tIgE), specific IgE (sIgE), sIgG(4), nasal challenge and visual analog scale (VAS) scores at several time points. The mRNA levels of forkhead box protein 3 (FOXP3), T-BET, GATA-3, FcεRI, spleen tyrosine kinase (Syk), phosphatidylinositol 3 kinase (PI3K) and SH2 domain-containing inositol phosphatase (SHIP) were quantified by real-time RT-PCR using nonstimulated whole blood samples. RESULTS: Decreased wheal sizes and VAS scores, negative challenges and increased sIgG(4) levels indicated that SCIT was effective in the treated patients. Basal expression levels of FOXP3 and GATA-3 decreased and T-BET levels increased in both treated patients and in healthy controls compared to untreated patients. The IgE-mediated pathway kinases Syk and PI3K exhibited reduced expression, whereas SHIP phosphatase levels were elevated in both treated patients and healthy controls relative to untreated patients. The expression levels of FcεRI were not significantly altered. CONCLUSIONS: Immunotherapy using HDM extracts results in a modification of the basal expression levels of several IgE-related signaling factors and induces a highly significant upregulation of Th1-response and downregulation of Th2-response transcription factors. Interestingly, this therapy also appears to reduce the basal expression of FOXP3.

Monitoring honeybee venom immunotherapy in children with the basophil activation test.

BACKGROUND: New in vitro methods are essential for developing better follow-up criteria for venom immunotherapy (VIT). METHODS: Thirty-one children with a history of honeybee venom-induced systemic anaphylaxis were included in this prospective, single-blinded study. The basophil CD63 activation test (BAT) was assessed before starting VIT, at the end of the build-up phase (day 5), 6 months later, and after 2-4 yr of VIT. RESULTS: Basophil CD63 activation test allowed identification of the culprit insect in 74% of honeybee venom-allergic children. In comparison, IgE reactivity was single positive in only 52% of children. Five days after starting VIT, BAT was highly comparable to before VIT. However, after 6 months and further after 2-4 yr of VIT, a significant and approximately fourfold decrease was demonstrated in CD63 response at sub-maximal 0.1 µg/ml allergen concentration, which mainly represents cellular sensitivity. No such differences were found at a higher 1 µg/ml of allergen concentration. Person-to-person analyses showed that after 2-4 yr of VIT, a marked CD63 decrease was evident in 85% of children. In addition, elevated basophil sensitivity measured before VIT was associated with the appearance of side effects observed during the build-up phase of VIT. CONCLUSION: Basophil CD63 allergen-specific sensitivity seems to be a promising tool for monitoring protective immune response in honeybee VIT.

Angiogenin and vascular endothelial growth factor expression in lungs of lung cancer patients.

BACKGROUND.: Lung cancer is the leading cause of cancer deaths. Angiogenesis is crucial process in cancer growth and progression. This prospective study evaluated expression of two central regulatory molecules: angiogenin and vascular endothelial growth factor (VEGF) in patients with lung cancer. PATIENTS AND METHODS.: Clinical data, blood samples and broncho-alveolar lavage (BAL) from 23 patients with primary lung carcinoma were collected. BAL fluid was taken from part of the lung with malignancy, and from corresponding healthy side of the lung. VEGF and angiogenin concentrations were analysed by an enzyme-linked immunosorbent assay. Dilution of bronchial secretions in the BAL fluid was calculated from urea concentration ratio between serum and BAL fluid. RESULTS.: We found no statistical correlation between angiogenin concentrations in serum and in bronchial secretions from both parts of the lung. VEGF concentrations were greater in bronchial secretions in the affected side of the lung than on healthy side. Both concentrations were greater than serum VEGF concentration. VEGF concentration in serum was in positive correlation with tumour size (p = 0,003) and with metastatic stage of disease (p = 0,041). There was correlation between VEGF and angiogenin concentrations in bronchial secretions from healthy side of the lung and between VEGF and angiogenin concentrations in bronchial secretions from part of the lung with malignancy. CONCLUSION.: Angiogenin and VEGF concentrations in systemic, background and local samples of patients with lung cancer are affected by different mechanisms. Pro-angiogenic activity of lung cancer has an important influence on the levels of angiogenin and VEGF.

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.

Recombinant allergen-based IgE testing to distinguish bee and wasp allergy.

BACKGROUND: The identification of the disease-causing insect in venom allergy is often difficult. OBJECTIVE: To establish recombinant allergen-based IgE tests to diagnose bee and yellow jacket wasp allergy. METHODS: Sera from patients with bee and/or wasp allergy (n = 43) and patients with pollen allergy with false-positive IgE serology to venom extracts were tested for IgE reactivity in allergen extract-based tests or with purified allergens, including nonglycosylated Escherichia coli-expressed recombinant (r) Api m 1, rApi m 2, rVes v 5, and insect cell-expressed, glycosylated rApi m 2 as well as 2 natural plant glycoproteins (Phl p 4, bromelain). RESULTS: The patients with venom allergy could be diagnosed with a combination of E coli-expressed rApi m 1, rApi m 2, and rVes v 5 whereas patients with pollen allergy remained negative. For a group of 29 patients for whom the sensitizing venom could not be identified with natural allergen extracts, testing with nonglycosylated allergens allowed identification of the sensitizing venom. Recombinant nonglycosylated allergens also allowed definition of the sensitizing venom for those 14 patients who had reacted either with bee or wasp venom extracts. By IgE inhibition studies, it is shown that glycosylated Api m 2 contains carbohydrate epitopes that cross-react with natural Api m 1, Ves v 2, natural Phl p 4, and bromelain, thus identifying cross-reactive structures responsible for serologic false-positive test results or double-positivity to bee and wasp extracts. CONCLUSION: Nonglycosylated recombinant bee and wasp venom allergens allow the identification of patients with bee and wasp allergy and should facilitate accurate prescription of venom immunotherapy.

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.

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.

C5a-induced in vitro basophil activation in patients with chronic urticaria: a pilot study.

BACKGROUND: Complement component 5a (C5a) might be involved in the formation of wheals in patients with chronic urticaria (CU). We sought to compare the in vitro responsiveness of basophils to C5a in patients with CU and in a control group. METHODS: Basophil surface expression of activation marker CD63 induced by C5a, anti-FcepsilonRI mAb or anti-IgE pAb was measured using flow cytometry in 17 patients with CU and in 10 healthy controls. RESULTS: Patients with CU showed significantly greater basophil CD63 surface expression induced by C5a (median [interquartile range]; 16.4% [13-25.1]; P = 0.011) than the group of healthy controls (10.7% [7.2-16.8]). In contrast, basophil CD63 response to anti-IgE and anti-FcepsilonRI was lower in the CU group (12.3% [6-36.3]; 25.9% [12.5-60.5]) than in the control group (51.7% [6.7-84.3]; 62.1% [9.7-89.2]), although not statistically significant. CONCLUSION: Results of this pilot study suggest that patients with CU might have an enhanced basophil response to stimulation with C5a, indicating that further studies in CU basophil responsiveness are needed.

Carbohydrate epitopes as a cause of cross-reactivity in patients allergic to Hymenoptera venom.

BACKGROUND: Among patients with allergy to insect stings, double positivity in tests for IgE antibodies specific to honey bee and wasp venoms is a frequent diagnostic problem. True double sensitization and possible cross-reactivity of venom hyaluronidases and with carbohydrate determinants must be considered in such patients. We studied the frequency of sensitization to carbohydrate determinants and the role of these in double positivity in tests for specific IgE antibodies. MATERIALS AND METHODS: A group of 66 patients (41 men, 25 women; 16-66 years) with double positivity for wasp and bee venoms were tested in the FEIA inhibition test in order to distinguish true double sensitization from cross-reactivity. Patients were tested for the presence of IgE antibodies specific to oilseed rape (OSR) pollen and MUXF3 allergens, both of which are rich in cross-reacting carbohydrate epitopes. RESULTS: Inhibition tests revealed true double sensitization in 37 patients (56.1%) and cross-reactivity in 29. Among those showing cross-reactivity, five were sensitized to honey bee venom and 24 to wasp venom. The median value of IgE specific for OSR pollen in patients sensitized to honey bee venom was 4.350 IU/ml, in patients sensitized to wasp venom 0.61 IU/ml, and in patients with double sensitization 0.25 IU/ml (P = 0.028, Kruskal-Wallis test). Findings for IgE specific for MUXF3 were similar. Discordance between OSR pollen positivity and MUXF3 positivity was found in 11.1% of the patients. CONCLUSION: The values of IgE specific for OSR pollen and MUXF3 in patients with primary sensitization to either honey bee venom or wasp venom were significantly higher than in patients with double sensitization. These results confirm that IgE antibodies against carbohydrates epitopes are a frequent cause of double positivity in tests for anti-venom IgE antibodies.

The specificity of tests for anti-beta-lactam IgE antibodies declines progressively with increase of total serum IgE.

BACKGROUND: Immediate allergic reactions to beta-lactam antibiotics are mediated by specific IgE antibodies. The Phadia CAP System FEIA is a commercial method for quantification of specific IgE. We wished to determine anti-beta-lactam IgE antibodies in patients without penicillin allergy but with high levels of total IgE. METHODS: Sera from 41 patients (31 with high total IgE, 10 with low total IgE) were analyzed for IgE antibodies specific to penicilloyl G, penicilloyl V, amoxicilloyl and ampicilloyl using the CAP FEIA((R)) method that was available up to 2006. Seven sera that tested positive were rechecked in a new improved system available after 2006. RESULTS: In patients without a history of penicillin allergy, the specificities of commercial tests for anti-beta-lactam IgE antibodies were 100%, 60%, 27% and 20% at total IgE levels of 8-263 kU/l, 500-664 kU/l, 1000-2000 kU/l and > 2000 kU/l, respectively. In seven retested sera, only 2 (28%) were still positive for penicillin-specific IgE antibody. CONCLUSION: Before 2006, tests for anti-beta-lactam IgE antibody in patients with total IgE > 500 kU/l were probably often false positive. Patients who were diagnosed as penicillin allergic before 2006 solely on the basis of a positive CAP FEIA test for specific IgE should be considered for diagnostic reevaluation.