Background: Food antigens may contribute to gut inflammation in Crohn's disease.
Aim: To assess in vivo sensitization to food antigens, ascertain whether sensitivity is gut specific, assess food sensitization in vitro, and correlate in vivo changes with histological and blood changes.
Methods: Skin testing and rectal exposure to six food antigens (cereal, cabbage, citrus, milk, yeast and peanut) and control saline were assessed double-blind by immediate and 3.5-h laser Doppler blood flowmetry, and rectal biopsies were taken. Peripheral blood lymphocyte proliferation was measured in response to the same antigens.
Results: Ten patients with Crohn's disease and 10 healthy controls were studied. Blood flow increased in 24 of 60 antigen sites in Crohn's disease patients and six of 60 antigen sites in controls (P < 0.0001) after 3.5 h. The Crohn's disease group demonstrated higher rectal blood flow than controls in response to all food antigens, and this was significantly different for the responses to yeast (P = 0.036) and citrus fruits (P = 0.038). Lymphocyte proliferation occurred in 32 of 60 tests in Crohn's disease patients and eight of 60 tests in controls (P < 0.0001). There were no skin responses. Submucosal oedema corresponded to increased mucosal flow.
Conclusions: Crohn's disease patients demonstrate in vivo and in vitro sensitization to food antigens, which is gut specific. Mucosal flowmetry allows the identification of sensitization to gut antigens.