S466 Use of Immunoglobulin G and Immunoglobulin G4 as a Diagnostic Marker for Pediatric Eosinophilic Esophagitis

Abstract

Introduction: Eosinophilic esophagitis (EoE) is a chronic esophageal disease that is clinically characterized by esophageal dysfunction and histologically by eosinophil-predominate inflammation. Our aim is to study the use of IgG and IgG4 as a diagnostic marker for pediatric eosinophilic esophagitis and further help predicting responsiveness to proton-pump specific to EoE. Methods: We prospectively enrolled pediatric patients who are known to have EoE, and gastroesophageal reflux disease (GERD) and performed IgG and IgG4 immunostaining on esophageal epithelial biopsies. Enrolled patients were divided into 3 different groups: active EoE, remission EoE, and GERD. Active EoE was then subdivided into PPI-responsiveness (PPI-r) and PPI-non-responsiveness, based on the proceedings of the AGREE conference published in 2018. Demographic, clinical, histopathological data, IgG, IgG4 staining, Peak Eosinophil Count (PEC), EDN (eosinophil derived neurotoxin) level, endoscopic (EREFS) were collected and compared between the different groups using fisher t-test and Pearson correlation between the groups. Results: We enrolled 79 subjects (median age of 11, range 1-20 years with 72% were males). Patients’ characteristics shown in Table 1. IgG was significantly elevated in active EoE (n = 29, mean IgG staining 4.52 ± 4.50 per hpf) compared to EoE in remission, (n = 25, mean IgG staining 1.32 ± 1.72 P-value = 0.002), and GERD (n = 25, mean IgG staining 1.08 ± 2.87 per hpf, P-value = 0.000) (Figure 1). Within the active EoE group, IgG staining (hpf) was significantly higher in the PPI-responsiveness subgroup (n = 15, mean 6.4 ±4.9 )vs nonresponsive group (n = 11, mean IgG staining 3 ±2.6, P-value = 0.041). IgG staining correlated with peak eosinophil count (PEC) in active EoE patients (Pearson correlation of 0.56 with r2 of 0.314 with P-value of 0.002). Additionally, in the remission EoE group, there was a significant correlation between IgG staining and PEC with Pearson correlation of 0.55 (n = 25), P-value = 0.004. The EoE remission and GERD patients were not statistically different from each other for IgG staining. Prevalence of IgG4 positive staining in active EoE group was 24%, significantly higher than EoE in remission 8%, P-value = 0.04 and in subjects with GERD 3.8%, P-value = 0.01. Conclusion: IgG and IgG4 staining is higher in pediatric patients with active EoE compared to patients with EoE in remission and GERD. IgG staining might predict PPI-responsiveness in pediatric patients with active EoE.Table 1.: Demographics of active EoE, EoE in remission and GERDFigure 1.: IgG was significantly elevated in active EoE (n = 29, mean IgG staining 4.52 ± 4.50 per hpf) compared to EoE in remission, (n = 25, mean IgG staining 1.32 ± 1.72 P-value = 0.002), and GERD (n = 25, mean IgG staining 1.08 ± 2.87 per hpf, P-value = 0.000).