Oral challenge tests for soybean allergies in Japan: A summary of 142 cases.

BACKGROUND: Soybeans are one of causative foods for infantile onset allergies in Japan. This study aimed to analyze the results of soybean challenge tests that were conducted over approximately 7 years at our institution. Using the test data, we sought to identify the responses and clinical profiles of patients with soybean allergies, and to investigate the relationship between the responses and soybean sensitization status. METHODS: Between July 2004 and May 2010, 142 cases (125 patients) underwent food challenge tests (100 g of silken tofu) for the diagnosis of soybean allergy or confirmation of their tolerance. The patients' characteristics, soybean sensitization status, and responses to the challenge tests were retrospectively evaluated. RESULTS: Among the subjects who underwent the soybean challenge test, the male/female ratio was 1.6 (87/55), and the mean age at the test was 2.8 ± 1.7 years. The positive rate for the challenge test was 38.7%. Induced symptoms were observed in the skin (81.8%), respiratory system (50.9%), and gastrointestinal system/mucosal membrane/anaphylaxis (12.7%). Intramuscular epinephrine was administered to all 7 patients who experienced an anaphylactic reaction. The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic efficiency of soybean-specific IgE titers were low for predicting the responses to the challenge test. CONCLUSIONS: Soybean allergies were diagnosed in only 18% of the subjects with positive sensitization to soybeans. Therefore, soybean-specific IgE titers are not an effective predictor of a positive response to the challenge test.

Clinical studies in oral allergen-specific immunotherapy: differences among allergens.

Oral immunotherapy (OIT) is a significant focus of treatment of food allergy. OIT appears to be effective in inducing desensitization, however, patients receiving OIT frequently developmild/moderate symptoms during the therapy. It has not been clearly established whether the clinical tolerance induced by OIT resembles natural tolerance. According to our data, the efficacy of OIT is different among food antigens, and it is comparatively difficult to achieve the clinical tolerance in milk OIT. Moreover, the definitive evidence of efficacy and safety with long-term therapy is limited. Further studies need to be offered to patients in clinical practice. Recently, novel treatments for food allergy, sublingual and epicutaneous immunotherapy, and combination treatment with an anti-IgE monoclonal antibody (omalizumab), have been examined in some studies. OIT combined with omalizumab increased the threshold doses of food without adverse reactions and may be of benefit in food allergy treatment. More studies are needed to demonstrate long-term safety and treatment benefits in a larger patient cohort.

Basophil activation marker CD203c is useful in the diagnosis of hen's egg and cow's milk allergies in children.

BACKGROUND: The diagnosis of food allergy (FA) is usually based on oral food challenge tests (OFC). However, OFCs occasionally induce severe adverse reactions. CD203c expression on basophils is emerging as a potential diagnostic index. We evaluated whether CD203c expression on basophils would be a useful marker of OFC-associated symptoms in hen's egg and cow's milk allergies in children. METHODS: Seventy-one patients who had been diagnosed with FA based on OFCs or a convincing history of FA symptoms in the Department of Pediatrics, Sagamihara National Hospital, were recruited. CD203c expression was assessed after stimulation with antigens (egg white, ovomucoid, milk or casein) using allergenicity kits. The CD203c stimulation index (SI = the allergen-induced CD203c expression level divided by the baseline expression level) and the threshold of CD203c expression (the minimum concentration of antigen to induce CD203c SI >or=2) were analyzed in association with tolerance acquisition. RESULTS: For the CD203c SI, the areas under the receiver-operating characteristic curve were 0.72 for egg white, 0.82 for ovomucoid, 0.84 for milk and 0.67 for casein. The positive predictive value for the threshold of CD203c expression was 94.7% for egg white, 100% for ovomucoid, 85.7% for milk and 75.0% for casein. CONCLUSIONS: Assessment of food antigen-induced CD203c expression on basophils is useful to determine if children will outgrow FA as well as in decision making regarding whether or not to perform OFCs.