# Oral Immunotherapy-Induced Changes in IgE, IgG, and IgA: A Review of Antibody Isotype Shifts and Their Clinical Relevance in Food Allergy

## TL;DR

This review explores how oral immunotherapy changes antibody levels in food allergy patients, highlighting shifts in IgE, IgG4, and IgA that may help build tolerance.

## Contribution

The paper systematically reviews longitudinal changes in IgE, IgG4, and IgA during OIT, emphasizing their clinical relevance in food allergy treatment.

## Key findings

- OIT causes a temporary rise in IgE followed by a decline.
- IgG4 levels increase steadily and correlate with desensitization.
- Allergen-specific IgA, especially secretory IgA, rises, suggesting a role in mucosal tolerance.

## Abstract

Background: Food allergy is a growing public health concern, and oral immunotherapy (OIT) has emerged as a promising approach to induce desensitization and potentially sustained unresponsiveness to allergenic foods. Changes in humoral immunity, particularly in allergen-specific immunoglobulin levels, play a central role in the immunological mechanisms underlying OIT. This review aims to summarize the current evidence on how OIT modulates allergen-specific immunoglobulin E (IgE), G (IgG) and A (IgA) responses in individuals with food allergy. Methods: We conducted a review of original research articles reporting longitudinal data on allergen-specific IgE, IgG, and/or IgA in patients undergoing OIT for common food allergens. Results: OIT was consistently associated with a transient increase in allergen-specific IgE levels during early phases, followed by a gradual decline. In contrast, Allergen-specific IgG4 levels showed a robust and sustained increase, correlating with desensitization and proposed to function as blocking antibodies. Several studies also reported an increase in allergen-specific IgA, particularly secretory IgA at mucosal sites, suggesting a potential role in enhancing mucosal tolerance and immune exclusion of allergens. Conclusions: Humoral immune responses during OIT are characterized by distinct and dynamic changes in immunoglobulin patterns. In particular, the rise in IgG4 and, in some cases, IgA suggests a role in promoting tolerance. Monitoring these biomarkers may offer insights into treatment efficacy and support individualized approaches to OIT.