Food-Specific IgG4 Is Associated with Eosinophilic Esophagitis
Monday, March 7, 2016
South Exhibit Hall H (Convention Center)
Benjamin L. Wright, MD, Michael D. Kulis Jr., PhD, Rishu Guo, PhD, Kelly Orgel, BS, W. Asher Wolf, MD, A. Wesley Burks, MD FAAAAI, Brian P. Vickery, MD FAAAAI, Evan S. Dellon, MD MPH
Rationale: Current forms of allergy testing are unreliable for identifying triggers of eosinophilic esophagitis (EoE). Recent data suggests EoE is IgG4-associated.  We hypothesized that food-specific IgG4 (FS-IgG4) is associated with active EoE and may elucidate dietary triggers.

Methods:  Prospectively collected esophageal biopsies and plasma from 20 EoE subjects (newly diagnosed) and 10 non-EoE controls were tested for total IgG4 (T-IgG4) and FS-IgG4 using ELISA.  After 6-8 weeks of empiric dietary elimination, responder status in EoE subjects was determined by repeat biopsy {diet responders (DR) = 11, non-responders (NR) = 9}. Triggers were identified in DR by elimination, reintroduction, and biopsy.  Follow-up samples were available for 14 EoE subjects (DR = 8, NR = 6).  Comparisons were made between EoE subjects vs. non-EoE controls and DR vs. NR.

Results: Median esophageal T-IgG4 and FS-IgG4 (ng/ml) were significantly elevated in EoE subjects vs. controls (total: 1,847 vs. 469, p = 0.008; peanut: 4.05 vs. 0.01, p = 0.003; soy: 2.12 vs. 0.01, p < 0.001; egg white: 61.4 vs. 2.88, p < 0.001; casein: 55.8 vs. 0.67, p < 0.001; wheat: 19.9 vs. 1.1, p < 0.001).  Esophageal FS-IgG4 correlated with plasma FS-IgG4 for all foods (r > 0.5).  DR demonstrated significant decreases in esophageal T-IgG4 (p = 0.04) and had lower T-IgG4 following dietary elimination compared to NR (673.6 vs. 1,793, p = 0.03).  Importantly, esophageal FS-IgG4 to known triggers also declined significantly in DR (p = 0.02).

Conclusions: Elevated T-IgG4 and FS-IgG4 are associated with active EoE and decline in response to dietary elimination.