D2.218 - ASSESSING THE DIAGNOSTIC VALUE OF SPECIFIC IgG4 IN KOREAN ADULT SHRIMP ALLERGY BASED ON SYMPTOM PRESENCE

Over the past two decades, food allergies have increased rapidly worldwide, affecting 2-10% of all age groups. Among Koreans who experienced the onset of food allergy symptoms for the first time at the age of 19 years or older, the most common cause was shellfish, with shrimp being the most prevalent. Desensitization to specific antigens in the gastrointestinal tract reduces mast cell and basophil activation and promotes IgG₄ production, which inhibits allergic symptoms by blocking specific IgE binding to allergens. The aim of this study is to verify the efficacy and accuracy of specific IgG₄ as an in vitro diagnostic tool for shrimp allergy.

Patients aged 19 years and older who visited the Department of Allergy at Severance Hospital in Seoul, South Korea, were enrolled. Subjects included those with (n=12) and without (n=5) allergy symptoms following shrimp exposure. All participants had shrimp-specific IgE (sIgE) levels measured by ImmunoCAP (>0.34 kU/L). The levels of total IgE(tIgE), specific-IgE(sIgE), specific IgG₄(sIgG₄) for shrimp and the sIgE/sIgG₄ ratio were compared to identify significant differences between the groups. The Mann-Whitney U test was used to analyze the significance of differences in each parameter between symptomatic and asymptomatic groups.

There were no significant differences between the symptomatic and asymptomatic groups in tIgE (1078.18±341.37 vs. 528.80±145.90, P=0.752), sIgE (6.18±1.58 vs. 3.92±2.58, p=0.460), and sIgE/sIgG₄ ratio (90.75±26.58 vs. 149.31±65.22, p=0.399). However, sIgG₄ level was significantly higher in the symptomatic group (0.11±0.03 vs. 0.02±0.01, p=0.019). In addition, no differences were observed in tropomyosin sIgE (0.04±0.04 vs. 0.14±0.41, p=0.886) and tropomyosin sIgE detection rate (10% vs. 25%, p=0.943) between two groups.

Even in the absence of allergic symptoms to shrimp, shrimp-specific IgE levels can exceed 0.34 kU/L, and in symptomatic individuals, levels may fall below 0.34 kU/L. In such cases, diagnosing shrimp allergy can be challenging. This study evaluated that shrimp-specific IgG₄ for shrimp may differ according to the presence or absence of allergic reactions to shrimp, suggesting the potential of these markers to improve the accuracy of shrimp allergy diagnosis. Further studies with larger sample sizes are planned to enhance statistical power and validate these findings.