IgG4 is closely associated with eosinophilic esophagitis

Rosenberg et al.’s study (1) confirms the presence of abundant IgG4 in eosinophilic esophagitis (EoE) and has added important novel findings: that the abundant IgG4 is also present in pediatric EoE patients, that IgG4 content correlates with the degree of disease activity as measured by both eosinophil counts and by other histologic findings, and that IgG4 content also correlates with many, but not all, of the EoE mRNA markers. Of particular note is the correlation with IL-10, which induces expression of IgG4 rather than IgE (2). Together, these findings show that IgG4 is closely associated with EoE. This is an important confirmation and extension of the prior work. In contrast, relatively modest and variable IgG4 associations are seen in many other allergic and inflammatory diseases.