In this study, basophil activation test (BAT) established by the investigators' lab was evaluated for its sensitivity and specificity in child egg allergy diagnosis. Children with suspected IgE mediated allergy to egg will be recruited in the study. Specific IgE to egg allergen and BAT will be detected. The diagnostic accuracy of the BAT will be assessed against clinical diagnosis based on history, clinical symptoms and laboratory results.

In china, the prevalence of food allergy in in preschool children was about 7%. Diagnosis of food allergy is mainly based on a combination of clinical history, clinical manifestations and related supplementary examinations, including skin prick testing (SPT), serum specific IgE testing (sIgE), and oral food challenge (OFC). Although OFC is the gold standard for allergy diagnosis, it is rarely conducted in clinic for the low safety. Until now, serum specific IgE assays against allergen are the most commonly used in vitro diagnostic approach in China. However, specific-IgEs are sensitive, but not specific for diagnosis of food allergy. Moreover, food allergy could not be excluded when sIgE results are negative (<0.35KU/L). Thus, more accurate and safer test is needed. BAT was shown to have good accuracy for food allergy diagnosis. BAT is an ex vivo functional assay that measures by flow cytometry the degree of basophil activation after stimulation with an allergen. However, experimental strategies for BAT reported in the literatures are different. Some research even used 12 kinds of antibodies to identity basophils. In previous study, the investigators established BAT using 4 kinds of antibodies. Basophils could be distinguished well from other cells. In this study, children aged 4 months to 6 years who visit pediatric and emergency department, and are suspected with egg allergy will be included in study. Detailed information about clinical history and manifestations will be collected. Serum sIgE to food and BAT will be detected. The proposed study intends to analyze sensitivity and specificity of the established BAT according to the clinical comprehensive diagnosis results, and evaluate its efficacy to diagnose food allergy in children.

• 1.Children older than 4 months and younger than 6 years old
• 2.Suspected egg allergy with one or more of the following complaints after intake of egg: Skin or mucous symptoms (e. g. urticaria, increased eczema, or swollen lips) Respiratory symptoms (tight throat or shortness of breath with signs of bronchial obstruction) loss of consciousness Gastrointestinal symptoms (nausea, vomiting, abdominal pain, diarrhea) Ocular symptoms (conjunctival erythema, pruritus, tears) and other related symptoms
• 3. Sign informed consent by parents/guardians

Exclusion Criteria:

• 1.Patients with hematological tumors, autoimmune diseases, organ transplantation, and immunodeficiency diseases
• 2.Take immunosuppressants, immunomodulators, statins, and inject anesthetics within 3 weeks

Children with suspected egg allergy