CLINICAL-SIGNIFICANCE OF THE COLONOSCOPIC ALLERGEN PROVOCATION TEST

Background: To improve the diagnosis of intestinal allergy, we develop ed a colonoscopic allergen provocation (COLAP) test. Methods: The ceca l mucosa was challenged with three food antigen extracts, a buffer con trol and a positive control (histamine). The mucosal wheal and flare r eaction was registered semiquantitatively 20 min after challenge, and selected tissue biopsies were examined for mast cell and eosinophil ac tivation by immunohistochemistry and electron microscopy. The COLAP te st was performed on 70 adult patients with abdominal symptoms suspecte d to be related to food allergy and in 5 healthy volunteers. In parall el, skin prick tests were performed and IgE was measured in serum. Res ults: 97 out of 210 antigen challenges performed in the patient group induced a significant wheal and flare reaction of the mucosa (46%), wh ereas no reaction in response to antigen was observed in healthy volun teers. Antigen-induced wheal and flare reactions were dependent on pat ients' histories of adverse reactions to food, but not on serum levels of specific IgE or skin test results. Degranulation of mast cells was observed in almost all tissues in which food antigens caused a wheal and flare reaction. Eosinophil activation was also highly correlated w ith the extent of the wheal and flare reaction (r(s) = 0.86). Conclusi ons: The data suggest that the COLAP test may be a useful diagnostic m eans in patients with suspected intestinal food allergy and a new tool for the study of underlying mechanisms.