Skin Tests versus Serology: Specific IgE May Suffice for Diagnosis of Vespid Venom Allergy and Follow-Up of Allergen Immunotherapy.

INTRODUCTION: In adults, allergic reactions to insect stings are among the most frequent causes of anaphylaxis, a potentially life-threatening condition. Recurrent anaphylaxis following vespid stings may be prevented by allergen immunotherapy (AIT). The aim of this study was to evaluate the benefit of measuring venom-induced wheal area in intracutaneous skin tests (ICT), in comparison to various serological and clinical parameters, for the diagnosis of severe vespid venom allergy and during follow-up of AIT. METHODS: We conducted a monocentric, retrospective evaluation of 170 patients undergoing AIT against vespid venoms. We scanned ICT wheals at baseline and at three time points after AIT initiation and measured wheal area using objective data analysis software. RESULTS: We found that ICT histamine-induced and venom-induced wheal areas did not correlate. In addition, the venom-induced wheal area was independent from the minimal venom concentration required to elicit a wheal in an ICT and all other parameters. No correlation was found between wheal area and the severity of anaphylaxis. Wheal area standardized to the application of 0.1 µg/mL venom inversely correlated with anaphylaxis severity and positively correlated with venom-specific IgE levels. During AIT, mean areas of venom-induced wheals did not change. In contrast, venom-specific IgG and IgG4 levels, and the minimal venom concentration required to induce a positive ICT result increased, while the venom wheal area standardized to 0.1 µg/mL venom application and specific IgE levels decreased over time. CONCLUSION: Wheal area evaluation did not provide additional information over specific IgE analysis. We therefore recommend that ICTs are used only as a secondary measure for confirming serological test results.

Intracutaneous Skin Tests and Serum IgE Levels Cannot Predict the Grade of Anaphylaxis in Patients with Insect Venom Allergies.

Background: Allergies against Hymenoptera venoms are a major cause of severe anaphylaxis. Risk assessment for subjects with suspected allergy is difficult because there are currently no biomarkers that predict the likelihood of high-grade anaphylaxis other than several associated comorbidities. Objective: We investigated the relationship between the severity of anaphylaxis and the results of intracutaneous skin tests (ICTs) together with serum levels of tryptase, total IgE, and venom-specific IgE, IgG, and IgG4. Methods: We performed a retrospective evaluation of 194 patients who presented to a single medical center with allergies to bee venoms (Apis mellifera, Bombus spp.; n=24, 12.4%), vespid venoms (Vespula spp., Vespa spp., Polistes spp.; n=169, 87.1%), or both (n=1, 0.5%). Results: Index bee stings occurred earlier in the year than vespid stings, although the latter were reported more frequently overall. On average, subjects who previously experienced grade IV anaphylaxis required higher dosages of venom to yield positive ICTs than those who exhibited lower grade responses. Patients diagnosed with grade IV anaphylaxis exhibited significantly lower levels of venom-specific IgE and IgG and trended toward elevated levels of tryptase. No significant differences in average levels of venom-specific IgG4 and total IgE were observed. Conclusion: Our findings reveal that intracutaneous skin testing and levels of venom-specific IgE do not predict the degree of anaphylaxis that develops in patients with venom allergy. Furthermore, the month of the index sting is not a reliable means to differentiate bee from vespid stings in patients presenting with an uncertain history.

Insulin allergy can be successfully managed by a systematic approach.

BACKGROUND: Type I insulin allergy can be a challenging condition, and there is no international consensus on how to establish the diagnosis. Measurement of specific IgE and skin testing have been cornerstones in the diagnostic work-up. However, these tests have limitations, mainly lack of correlation between test results and clinical findings. At the Allergy Centre, Odense University Hospital, patients with suspected insulin allergy have been evaluated since 2003. The aim of this study was to establish a systematic approach to diagnose and treat patients with insulin allergy. METHODS: The study was conducted retrospectively by retrieving data from the Allergy Centre database on patients with suspected insulin allergy evaluated from 2003 to 2017. The examination comprised a comprehensive medical history, specific IgE against insulin and intracutaneous tests (ICT) with different insulins. RESULTS: A total of 144 patients were examined on suspicion of insulin allergy of which 110 had negative specific IgE in serum. Of the remaining 34 patients, 33 had ICT performed; 2 had negative ICTs, while 31 had one or more positive ICT. All 34 patients had mild symptoms, and 4 could obtain symptom relief with antihistamines or local steroids, 9 could be managed with oral antidiabetics, and 7 were switched to other insulins. The final 14 patients were offered an insulin pump because of reactions to many different insulins, many positive ICTs, unmanageable diabetes, young age and compliance, or convenience. CONCLUSION: Insulin allergy can be managed by a systematic approach, and symptom relief is obtainable in most patients.

[Aeroallergen spectrum for patients with allergic rhinitis in Chongqing].

Objective:To determine the distribution characteristics of inhaled allergens and its influencing factors among allergic rhinitis (AR) patients in Chongqing. Method:Intracutaneous test was carried out in 2 474 AR patients. All the cases were divided into six groups according to age, 6-13 years old, >13-18 years old, >18-29 years old, >29-39 years old, >39-49 years old, >49 years old and four groups on the basis of season (spring, summer, autumn, winter). The correlations between the positive rates and gender, age, season were analyzed. Result:The most common allergens were dermatophagoides farin (71.26%), dermatophagoides pteronyssinus (73.61%) and polyvalent insect (60.79%). There was no significant correlation between most allergens and gender(P>0.05). Statistical analysis was conducted among different age groups, it showed that the positive rates of overwhelming majority allergens were highest in the group of 13-18 years old and higher in 6-13 years old group, and then gradually declined with age with a striking difference in each groups (P<0.05). Similar analysis was carried out among the groups in four seasons. It revealed that the prevalence rates of most allergens were higher in summer and autumn than that in spring and winter (P<0.05). Conclusion:Dermatophagoides and polyvalent insect are the most prevalent inhalant allergens in AR disease in Chongqing. Most AR patients had multiple allergens. The prevalence rates of most allergens were significantly different with age and season.

Is a positive intracutaneous test induced by penicillin mediated by histamine? A cutaneous microdialysis study in penicillin-allergic patients.

BACKGROUND: Diagnostic workup of penicillin allergy comprises skin testing with penicillins, and patients are deemed allergic if skin test is positive. However, the literature suggests that skin test-positive patients may be challenge-negative, indicating that the skin test may be falsely positive. OBJECTIVE: To investigate real-time histamine release from a positive intracutaneous test induced by penicillin in patients with positive and negative challenges to penicillin. METHODS: Skin microdialysis was performed in 21 penicillin-allergic patients with positive skin test, 13 non-allergic volunteers serving as negative controls, and 7 grass pollen-allergic patients serving as positive controls. Histamine was measured by microdialysis after skin test with penicillin/grass/NaCl. Penicillin challenge was subsequently performed in 12 of the patients. RESULTS: Only 10/21 patients (47.6%) were skin test positive at microdialysis. During microdialysis 13 single intracutaneous tests were positive and histamine was detected in 4/13 occurring in four challenge positive patients. Thirteen/21 patients (61.9%) were deemed allergic to penicillin; eight had positive skin test. Two patients with positive skin test were challenge negative. In grass pollen allergic patients, 7/7 had a positive intracutaneous test to grass and all released histamine in the wheals. All 13 negative controls had negative intracutaneous test to penicillin and no histamine release. CONCLUSION: Histamine was only detected in the minority of positive intracutaneous tests with penicillin in penicillin-allergic patients. Other mediators may be involved.

Allergenicity and safety of recombinant human C1 esterase inhibitor in patients with allergy to rabbit or cow's milk.

BACKGROUND: Recombinant human C1 inhibitor (rhC1INH) for on-demand treatment of hereditary angioedema is purified from milk of transgenic rabbits. It contains low amounts (<0.002%) of host-related impurities, which could trigger hypersensitivity reactions in patients with rabbit allergy (RA) and/or cow's milk allergy (CMA). OBJECTIVE: This study is an assessment of allergenicity and safety of rhC1INH in patients with RA and/or CMA. METHODS: Patients with CMA and/or RA underwent skin prick test (SPT), intracutaneous test (ICT), and, when results for both were negative, subcutaneous (SC) challenge with up to 2100U (14 mL) rhC1INH. The negative predictive value of the skin test protocol was calculated, defined as the ratio of patients without systemic symptoms of hypersensitivity following SC challenge, over the number of patients having tested negative for both the SPT and the ICT. Adverse events after exposure to rhC1INH were recorded. RESULTS: Twenty-six patients with RA and/or CMA were enrolled. Twenty-four had negative SPT and ICT results for rhC1INH, whereas 2 had negative SPT result but positive ICT result to rhC1INH (only the highest concentration). Twenty-two patients with negative SPT and ICT results underwent SC challenge. None developed allergic symptoms. Local treatment-emergent adverse events occurred in 7 patients (32%) after SC challenge. In 5 these were considered drug related. All were mild. CONCLUSIONS: None of the patients with negative SPT and ICT results for rhC1INH had allergic symptoms during rhC1INH challenge. The negative predictive value of the combination of SPT and ICT for the outcome of the SC challenge was 100% (95% CI, 84.6%-100%). SC administration of rhC1INH was well tolerated.

Allergic reactions to local anesthetics in dental patients: analysis of intracutaneous and challenge tests.

Some dental patients have histories of adverse reactions to local anesthesia. The aim of the present study was to investigate the frequency of allergy to local anesthetics of dental patients who had histories of adverse reactions to local anesthesia based on the results of allergy tests in our institute over a period of 5 years. We investigated the past medical records of dental patients retrospectively, and twenty patients were studied. Three of the 20 showed a positive or false-positive reaction in the intracutaneous test, and one patient showed a false-positive reaction in the challenge test. Our results suggest that the frequency of allergy to local anesthetics is low even if patients have histories of adverse reactions to local anesthesia. However, allergy tests of local anesthetics should be performed in patients in whom it is uncertain whether they are allergic.