Early-Life IgG Patterns Linked to Childhood Food Allergy, With Julia Angkeow

A new study identified distinct IgG antibody patterns in early childhood, but not observed at birth.1 In an interview with HCPLive, investigator Julia W. Angkeow, a PhD candidate and former research technologist at Johns Hopkins Medicine, emphasized that the study was intended not to validate IgG as a diagnostic tool, but to map the broader IgG reactome in an unbiased way.

Using Phage ImmunoPrecipitation Sequencing (PhIP-Seq), a high-throughput antibody profiling platform developed in their laboratory, Angkeow and colleagues analyzed IgG responses to hundreds of thousands of peptides derived from allergens, viruses, toxins, and human proteins.

“It gives us a broad picture of what someone has been exposed to in their environment and how their immune system has responded to their past and ongoing immune exposures,” Angkeow told HCPLive. “What we found through this study is that we can use PhIP-Seq to identify IgG patterns that are distinct between allergic and allergic children, and they're also distinct in early childhood versus at birth.”

The prospective cohort included 458 children: 80 with food allergy, 151 with food sensitization, and 227 non-allergic controls without other atopic disease.1 Investigators profiled matched cord blood and early-childhood plasma samples. In early childhood, but not in cord blood, children with food allergy exhibited significantly greater diversity of IgG reactivity to allergen peptides (false discovery rate < 0.05).

Peanut-allergic children demonstrated greater IgG reactivity to 24 peanut peptides, while egg-allergic children showed increased responses to 17 egg peptides. Angkeow cautioned clinicians against overinterpreting these findings. She noted that elevated IgG likely reflects ongoing or repeated immune exposure and should not be interpreted as protective, pathogenic, or diagnostic. Professional societies have previously advised against IgG-based food sensitivity testing due to lack of clinical validity.2

One unexpected finding was lower cord blood IgG reactivity to milk peptides among children who later developed milk allergy. While this observation is consistent with the hypothesis that maternally transferred allergen-specific IgG could be protective, Angkeow emphasized that the study measured total IgG and did not distinguish subclasses with differing immunologic functions.

“There needs to be more mechanistic studies, such as profiling different IgG subclasses to test that directly,” she said.

References

1. Angkeow JW, Hong X, Thakar M, et al. Diverse food allergen IgG reactivities are associated with food allergies in the Boston Birth Cohort. Allergy. 2026. doi:10.1111/all.70246. https://pubmed.ncbi.nlm.nih.gov/41689198/

2. McGill University. Office for Science and Society. Published August 30, 2024. Accessed February 24, 2026. https://www.mcgill.ca/oss/article/medical-critical-thinking-health-and-nutrition/no-tolerance-igg-food-intolerance-tests