Background: Immediate hypersensitivity reactions to clavulanic acid (CLV) seem to be on the increase. Diagnosis is mainly based on skin testing and the drug provocation test (DPT), procedures that are not risk free. The aim of this study was to evaluate whether the histamine release test (HRT) could help evaluate patients with selective hypersensitivity to CLV. Methods: Eighteen patients with immediate selective hypersensitivity reactions to CLV (positive skin tests to CLV but negative to the major and minor determinants of benzylpenicillin and amoxicillin; negative DPT to benzylpenicillin and amoxicillin) and 21 controls with tolerance to CLV were included. Direct and passive HRT, using patient whole blood or ‘IgE-stripped' donor blood sensitized by patient serum, respectively, were performed by stimulating the blood with CLV, and basophil histamine release was detected by fluorometric determination. Results: The clinical symptoms were anaphylaxis (n = 6), urticaria (n = 9) and urticaria-angioedema (n = 3). The median time interval between the reaction and the study was 225 days (interquartile range, IQR: 120-387.5) and between drug intake and the development of symptoms 30 min (IQR: 6.25-30). We obtained similar data for both the direct and passive HRT, with a sensitivity and specificity of 55 and 85%, respectively, a positive predictive value of 76% and a negative predictive value of 69%. Conclusions: The sensitivity of both the direct and passive HRT for diagnosing patients with immediate allergy to CLV is less than 60%. However, the passive HRT has the advantage that it is based on the testing of serum samples that can be handled more easily than fresh blood samples.

Background: The pathophysiological mechanism of eosinophilic esophagitis (EoE) is complex and is still being investigated. We believe that there is a group of patients with eosinophilic esophagitis which could be differentiated as having an allergic phenotype who exhibit a sensitization profile (aeroallergens, panallergens, foods and specific IgG4 levels) with significant differences compared to patients with conventional allergic disease without associated eosinophilic esophagitis and healthy controls. Method: We measured the prevalence of sensitization to aeroallergens, foods and panallergens by means of molecular diagnostic techniques (ImmunoCAP^TM ISAC) and determined the levels of specific IgG4 against foods and eosinophilic-derived neurotoxin (EDN) (ImmunoCAP technology) in patients with EoE of an allergic phenotype to study whether there are statistically significant differences with respect to the control groups (patients with different allergic pathologies without EoE and healthy patients without documented allergies). The total number of patients under study was 118, distributed among the different study groups. The case group (Allergic phenotype EoE patients) had 48 subjects. The food and respiratory allergy control groups had 30 subjects each. Finally, we included 10 in the healthy control group. Results: We were able to identify statistically significant differences when comparing levels of food-specific IgG4. Milk, egg, wheat, nuts, soy, cod, and Pru p3/LTP stood out. We did not observe significant differences in relation to sensitization to aeroallergens, foods, or panallergens. We also did not observe differences in EDN levels. Conclusions: We present a study in which statistically significant differences in IgG4 levels were observed in response to different types of food, comparing patients with eosinophilic esophagitis of allergic phenotype (case group) against subjects with allergic pathology without EoE and healthy subjects (control groups). Determining whether the detected foods are clinically relevant or not in these patients would be fundamental to establishing their usefulness as a treatment alternative in our patients.

Background: Eosinophilic esophagitis (EoE) pathophysiological mechanism is complex and it s still being investigated. We believe there is a group of patients with eosinophilic esophagitis which we could differentiate as having an allergic phenotype, who exhibit a sensitization profile (aeroallergens, panallergens, foods and specific IgG4 levels) with significant differences when compared to patients with conventional allergic disease without associated eosinophilic esophagitis and healthy controls. Method: We have measured the prevalence of sensitization to aeroallergens, foods and panallergens by means of molecular diagnostic techniques (ImmunoCAPTM ISAC) and determined the levels of specific IgG4 against foods and eosinophilic derived neurotoxin (EDN) (ImmunoCAP technology) in patients with EoE of allergic phenotype to study if there are statistically significant differences with respect to the control groups (patients with different allergic pathologies without EoE and healthy patients without documented allergies). The total number of patients under study was 118, distributed among the different study groups. The case group (Allergic phenotype EoE patients) has 48 subjects. The food and respiratory allergy control groups, 30 subjects each. Finally, we included 10 in the healthy control group. Results: We were able to identify statistically significant differences when comparing levels of food-specific IgG4. Milk, egg, wheat, nuts, soy, cod, and LTP stood out. We did not observe significant differences in relation to sensitization to aeroallergens, foods, or panallergens. We also did not observe differences in EDN levels. Conclusion: We present a study in which statistically significant differences in IgG4 levels were observed in response to different types of food, comparing patients with eosinophilic esophagitis of allergic phenotype (case group) against subjects with allergic pathology without EoE and healthy subjects (control groups). Determining whether the detected foods are clinically relevant or not in these patients would be fundamental to establishing their usefulness as a treatment alternative in our patients.