Changes in blood antibody profiles may reveal inflammatory bowel disease risk up to 10 years before diagnosis, according to findings presented at UEG Week 2026. The conditions studied, Crohn's disease and ulcerative colitis, involve abnormal immune responses that cause persistent intestinal inflammation and damage. Researchers examined 2,000 blood samples from 500 participants: 200 who later developed each condition and 100 healthy controls of comparable age and sex. Samples covered diagnosis and approximately two, four, and 10 years beforehand.
Participants who subsequently developed either condition showed reduced antibody diversity, alongside disease-specific immune signatures. Future Crohn's cases exhibited elevated responses to herpesviruses and bacterial flagellin, a protein involved in bacterial movement. Future ulcerative colitis cases showed increased responses to herpesviruses and components of the body's own tissues. Responses to bacteria with protective outer coatings declined as Crohn's diagnosis approached; responses to similarly protected pathogens also declined in ulcerative colitis. Machine-learning models distinguished future Crohn's cases from controls with an area under the curve, or AUC, of 0.90, compared with 0.84 for ulcerative colitis. On this measure, 0.5 represents chance performance and 1.0 perfect discrimination. Antibody patterns also distinguished future complicated Crohn's disease from less complicated disease approximately a decade before diagnosis, with an AUC of 0.85.
Although these findings suggest opportunities for earlier risk assessment and treatment planning, routine screening remains premature. Independent, more diverse populations must be followed prospectively to validate the signatures. Researchers also need to establish their added value beyond genetic information, clinical assessments, and other blood measurements. Any eventual test must be reproducible, affordable, accurate, and shown to improve patient outcomes.
