Blood antibody changes appear up to 10 years before Crohn's disease and ulcerative colitis are diagnosed
A study presented at UEG Week 2026 profiled antibodies in 2,000 blood samples and found differences up to 10 years before people were diagnosed with Crohn's disease or ulcerative colitis. It is a proof of principle, not yet a test.
Changes in the antibodies in people's blood can be seen up to 10 years before they are diagnosed with Crohn's disease or ulcerative colitis, according to a study presented at UEG Week 2026 in Barcelona, United European Gastroenterology said. The two conditions are the main forms of inflammatory bowel disease.
2,000 samples, 357,000 targets
The researchers analyzed 2,000 blood samples from 500 people: 200 who later developed Crohn's disease, 200 who later developed ulcerative colitis and 100 healthy people matched by age and sex. Samples had been taken at diagnosis and about 2, 4 and 10 years before. They profiled antibody responses against about 357,000 microbial, viral, food and immune-related targets.
People who later developed either disease had less diverse antibodies. Those who developed Crohn's showed stronger responses to herpesviruses and to flagellin, a bacterial protein, especially if their disease later became complicated. Those who developed ulcerative colitis showed rising responses to herpesviruses and to the body's own proteins. Machine-learning models separated future Crohn's patients from healthy people with an accuracy score (AUC) of 0.90, and future ulcerative colitis patients with 0.84.
“The next priority is to validate these signatures in independent, more diverse and prospectively followed populations.” — Dr Arno Bourgonje, lead author
What it means for patients now
There is no test to take yet. The authors describe the results as a proof of principle: the antibody signatures must be confirmed in other, more diverse groups of people followed over time, turned into an affordable test, and shown to improve outcomes before they could be used for screening. It is also not yet known how much they add to genetic, clinical and other blood markers.
The antibodies also distinguished complicated from non-complicated Crohn's disease with an AUC of 0.85, up to about 10 years before diagnosis. Bourgonje did the work during a postdoctoral fellowship at the Icahn School of Medicine at Mount Sinai in New York.
Not medical advice. This article reports on research and health programs for general information. Results from early studies often change in larger trials. Talk to a doctor before making decisions about your own health or treatment.
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