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

Complex food proteins and enteric flora may act as antigenic stimuli in Crohn's disease. This study assessed the prevalence and magnitude of lymphocyte priming to these antigens in Crohn's disease.

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 studied. Peripheral blood lymphocytes were collected and incubated with antigens in hanging drop culture for 4 days. The antigens tested were cow's milk, cereals, cabbage group, citrus group, peanut group, Saccharomyces (yeast), Bacteroides, E. coli and Klebsiella. On the 4th day 3H-thymidine incorporation was measured after a 4-h pulse. Responses to antigens were considered positive if mean proliferative values were above the 99% confidence interval for background proliferation.

The mean background and mitogen-stimulated proliferation did not differ between patients and controls. The mean proliferation to antigens was not above background in controls, but in Crohn's patients proliferative responses to all food and bacterial antigens were significantly higher than background values. Twenty-three out of 31 Crohn's patients and five out of 22 controls (P=0.0003) responded to one or more antigens. Sixteen Crohn's patients and two controls responded to four or more antigens (P=0.001, Fisher's exact test).

The reactivity of peripheral lymphocytes to food, yeast and bacterial antigens, especially multiple antigens, is common in Crohn's disease. These sensitized lymphocytes may contribute to the inflammatory process.