Abstract
OBJECTIVE: To assess the clinical value of food-specific IgE (sIgE), IgG (sIgG), and IgG4 (sIgG4) in the diagnostic evaluation of allergic diseases in children. METHODS: A total of 149 pediatric patients with allergic diseases were retrospectively enrolled and categorized into three groups based on their predominant clinical manifestations: digestive symptoms, skin symptoms, and respiratory symptoms. Ninety-six age-matched healthy children were included as the control group. Serum total IgE and food-specific sIgE, sIgG, and sIgG4 levels were measured simultaneously. RESULTS: The overall positivity rates of food-specific sIgG and sIgG4 in the case group were significantly higher than those of sIgE (P<0.05). Substantial agreement was observed between sIgG and sIgG4 (0.4<κ<0.75), whereas both showed poor concordance with sIgE (κ<0.4). Among all food allergens, milk and eggs exhibited the highest positivity rates for sIgE, sIgG, and sIgG4. sIgE positivity was mainly concentrated in Grades I-II, while sIgG and sIgG4 were more frequently detected in Grades II-III. Across disease subgroups, total IgE levels were highest in children with respiratory symptoms. The positivity rates of sIgE in the digestive, skin, and respiratory groups were 69.4%, 44.0%, and 58.0%, respectively (P<0.05). For distinguishing allergic cases from healthy controls, sIgG demonstrated the best discriminatory performance (Youden index J=0.612), followed by sIgG4 (J=0.394), whereas sIgE showed relatively lower discriminative ability. Analysis of antibody grade distribution revealed that sIgG ≥ Grade II was most common for egg, milk, and wheat allergens (85.1%, 71.2%, and 69.0%, respectively). Similarly, sIgG4 levels were frequently elevated for milk and egg allergens (78.4% and 78.2%). In contrast, sIgE ≥ Grade II was most prominent for shrimp (57.7%). CONCLUSION: Food-related adverse reactions in children may involve distinct immune mechanisms. Comprehensive interpretation of sIgE, sIgG, and sIgG4 profiles is recommended in the clinical assessment of pediatric allergic diseases. Among these biomarkers, sIgG and sIgG4 may provide additional reference values for management of food allergies, particularly when antigen exposure is chronic or long-term.