Specific IgG4 Antibodies to Cow’s Milk Proteins in Pediatric Patients With Eosinophilic Esophagitis

Purpose Of The Study: Although food protein causes eosinophilic esophagitis (EoE), the mechanism is not clear and appears not to be immunoglobulin E (IgE)–mediated. Cow's milk (CM) is among the most common causal foods in patients with EoE. Specific immunoglobulin G4 (sIgG4) antibodies to food extracts, including CM, have been found in sera and esophageal biopsies of adults with EoE. Is this true in children with EoE? Study Population: This study included data from 71 pediatric patients with EoE and 210 pediatric control subjects from an unselected birth cohort (Project Viva). Methods: Sera were assayed for sIgG4 and specific IgE to major CM proteins (α-lactalbumin, β-lactoglobulin, and caseins) as well as to wheat, soy, egg, and peanut. Results: In the EoE cohort, elevated levels of sIgG4 (>10 mg/mL) to CM proteins were more common than in control sera (odds ratios: 5.5–8.4). When adjusted for age and milk consumption, high-titer sIgG4 to CM proteins was strongly associated with EoE (odds ratios: 21.2–23.9 in boys and 2.7–9.3 in girls). Conclusions: Elevated levels of sIgG4 to CM proteins are common in children with EoE. Although the clinical relevance of these elevated levels it is not clear, results suggest that sIgG4 levels may be an important factor in EoE.