Background Iodinated and gadolinium-based contrast media (ICM; GBCM) induce immediate hypersensitivity (IH) reactions. Differentiating allergic from non-allergic IH is crucial; allergy contraindicates the culprit agent for life. We studied frequency of allergic IH among ICM or GBCM reactors. Methods Patients were recruited in 31 hospitals between 2005 and 2009. Clinical symptoms, plasma histamine and tryptase concentrations and skin tests were recorded. Allergic IH was diagnosed by intradermal tests (IDT) with the culprit CM diluted 1:10, “potentially allergic” IH by positive IDT with pure CM, and non-allergic IH by negative IDT. Findings Among 245 skin-tested patients (ICM = 209; GBCM = 36), allergic IH to ICM was identified in 41 (19.6%) and to GBCM in 10 (27.8%). Skin cross-reactivity was observed in 11 patients with ICM (26.8%) and 5 with GBCM (50%). Allergy frequency increased with clinical severity and histamine and tryptase concentrations (p < 0.0001). Cardiovascular signs were strongly associated with allergy. Non-allergic IH was observed in 152 patients (62%) (ICM:134; GBCM:18). Severity grade was lower (p < 0.0001) and reaction delay longer (11.6 vs 5.6 min; p < 0.001). Potentially allergic IH was diagnosed in 42 patients (17.1%) (ICM:34; GBCM:8). The delay, severity grade, and mediator release were intermediate between the two other groups. Interpretation Allergic IH accounted for < 10% of cutaneous reactions, and > 50% of life-threatening ones. GBCM and ICM triggered comparable IH reactions in frequency and severity. Cross-reactivity was frequent, especially for GBCM. We propose considering skin testing with pure contrast agent, as it is more sensitive than the usual 1:10 dilution criteria.

Background: Flow cytometry (FCM) has been proposed for specific allergy in vitro testing. We investigated its biological significance for allergy to Hymenoptera venoms and compared it with the routinely performed basophil histamine release test (HRT).Methods: Blood samples from 26 allergic and 8 nonallergic donors were incubated with venom at serial concentrations. Basophils were analyzed with anti-CD45-PE-Cyanin 5, Anti-IgE-FITC, and Anti-CD63-Phycoerythrine. HRT was measured by radioimmunoassay.Results: FCM was as convenient as HRT for measuring basophil reactivity in at least 87% of allergic and 75% of nonallergic subjects. CD63 outer expression was specifically induced in 91% of releaser subjects (86% on HRT) and in 1 of 10 tests in nonallergic donors, or one of six tests (16% on HRT) in allergic patients tested with an irrelevant allergen. Both methods were concordant in 85.7% of the tests. The three discordant patients had low-grade reactions and borderline biological responses on FCM (n ‫؍‬ 2) or HRT (n ‫؍‬ 1).Conclusions: The dynamic, physiologic significance of CD63, the dose-response curve, and dependency on ethylene-diaminetetra acetic acid suggested that both tests reflect the same mechanism. Cytometry Part B (Clin. Cytometry) 52B:13-19, 2003.

Background: Skin exposure to chemicals may induce an inflammatory disease known as contact dermatitis (CD). Distinguishing the allergic and irritant forms of CD often proves challenging in the clinic. Methods:To characterize the molecular signatures of chemical-induced skin inflammation, we conducted a comprehensive transcriptomic analysis on the skin lesions of 47 patients with positive patch tests to reference contact allergens and nonallergenic irritants.Results: A clear segregation was observed between allergen-and irritant-induced gene profiles. Distinct modules pertaining to the epidermal compartment, metabolism, and proliferation were induced by both contact allergens and irritants; whereas only contact allergens prompted strong activation of adaptive immunity, notably of cytotoxic T-cell responses. Our results also confirmed that: (a) unique pathways characterize allergen-and irritant-induced dermatitis; (b) the intensity of the clinical reaction correlates with the magnitude of immune activation. Finally, using a machinelearning approach, we identified and validated several minimal combinations of biomarkers to distinguish contact allergy from irritation. Conclusion:These results highlight the value of molecular profiling of chemicalinduced skin inflammation for improving the diagnosis of allergic versus irritant contact dermatitis.

IntroductionVenom immunotherapy (VIT) is the only efficient prevention for sting-induced anaphylaxis, but its application is not without risks and needs precautions and standardization. European guidelines were proposed in 2005, but recent practice surveys and more recent knowledge raise the need for an update. The aim of this study was to analyze VIT practices in France, based on previous surveys in Europe but also extended to outcome event management.Material and methodsA paper questionnaire was sent widely to persons involved in venom treatment.ResultsEighty-six responses could be included from physicians actively involved in VIT induction evenly distributed in France. The survey shows that VIT was engaged from grade III down to grade I reactions, starting preferentially with the ultra-rush protocol. Premedication was used by 42% only and risks induced by co-treatment with β-blockers were well known but not with angiotensin-converting enzyme inhibitors. However, side effects were very variably managed from arrest to enhancement in doses, time-delay or duration. Similarly, we observed a large discrepancy in treatment evaluation (skin tests, biology, timing and interpretation), decision making for treatment termination (when and how long to be prolonged) and post-treatment follow-up (adrenaline kit, event record) as well as procedures in case of late relapse (new induction, different doses).ConclusionsOur study shows that most recommendations were fully or partially followed and may need reminding, but many points need to be completed or updated with new tools and knowledge acquired during the last 10 years.

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