Immune sensitization to food, yeast and bacteria in Crohn's disease

Background: Complex food proteins and enteric flora may act as antigenic st imuli in Crohn's disease. This study assessed the prevalence and magnitude of lymphocyte priming to these antigens in Crohn's disease. Methods: A total of 31 Crohn's disease patients (median age 42 years, range 25-72 years) and 22 healthy controls (median 29 years, 23-43 years) were s tudied. Peripheral blood lymphocytes were collected and incubated with anti gens in hanging drop culture for 4 days. The antigens tested were cow's mil k, cereals, cabbage group, citrus group, peanut group, Saccharomyces (yeast ), Bacteroides, E. coli and Klebsiella. On the 4th day H-3-thymidine incorp oration was measured after a 4-h pulse. Responses to antigens were consider ed positive if mean proliferative values were above the 99% confidence inte rval for background proliferation. Results: The mean background and mitogen-stimulated proliferation did not d iffer between patients and controls. The mean proliferation to antigens was not above background in controls, but in Crohn's patients proliferative re sponses to all food and bacterial antigens were significantly higher than b ackground values. Twenty-three out of 31 Crohn's patients and five out of 2 2 controls (P=0.0003) responded to one or more antigens. Sixteen Crohn's pa tients and two controls responded to four or more antigens (P=0.001, Fisher 's exact test). Conclusion: The reactivity of peripheral lymphocytes to food, yeast and bac terial antigens, especially multiple antigens, is common in Crohn's disease . These sensitized lymphocytes may contribute to the inflammatory process.