Outcomes of Serum Food-Specific Immunoglobulin G4 to Guide Elimination Diet in Patients With Eosinophilic Esophagitis

INTRODUCTION: Eosinophilic esophagitis (EoE) is associated with atopy; however, recent studies have identified an association with food-specific immunoglobulin G(4) (FS-IgG(4)) rather than immunoglobulin E antibodies. This study aimed to evaluate the role of serum FS-IgG(4) in guiding an elimination diet and its outcomes. METHODS: Patients with and without EoE were enrolled in a prospective, controlled, single tertiary center trial. Serum FS-IgG(4) titers, esophageal eosinophil counts, and dysphagia symptom questionnaire scores were assessed, and participants with elevated FS-IgG(4) (ImmunoCAP, cutoff of 10 mgA/L) commenced 6-week targeted elimination diet. Repeat serum FS-IgG(4) and endoscopic and histologic examination were performed at 6-week follow-up. RESULTS: Twenty-two patients with active EoE and 13 controls were recruited. Serum FS-IgG(4) to milk, wheat, soy, eggs, and nuts was significantly higher in EoE (P = 0.0002, P = 0.002, P = 0.003, P = 0.012, and P < 0.001, respectively). Elevated serum FS-IgG(4) to 1 or more food groups (median 2) was identified in 21/22 (95.4%) patients with EoE; 20/21 underwent 6-week dietary elimination. Median reductions in dysphagia symptom questionnaire score and EoE endoscopic reference score after elimination were 8 (P = 0.0007) and 1 (P = 0.002), respectively. Nine (45%) patients had histological remission (<15 eosinophils per high-power field). Fall in median esophageal eosinophil count was not statistically significant (50 vs 23; P = 0.068). Serum FS-IgG(4) did not decline by 6-week follow-up. DISCUSSION: Serum FS-IgG(4) to milk, wheat, soy, egg, and nuts was present at higher levels in EoE, with targeted elimination resulting in 45% histologic remission rate. Serum FS-IgG(4) has potential as a noninvasive biomarker in EoE. When successful, FS-IgG(4)-led elimination diet can negate need for medications and be viewed more favorably by patients because of its smaller endoscopic burden compared with empirical elimination diets.