PEANUT INGESTION INCREASES RECTAL PROLIFERATION IN INDIVIDUALS WITH MUCOSAL EXPRESSION OF PEANUT LECTIN RECEPTOR

Background & Aims: The Thomsen-Friedenreich blood group antigen (galac tose beta 1,3-N-acetyl galactosamine alpha-) acts as an oncofetal anti gen in the colonic epithelium, with low expression in normal adult epi thelia but increasing to fetal levels of expression In hyperplasia or malignancy. Peanut lectin is one of the commonest dietary lectins that binds this antigen. The aim of this study was to determine whether pe anut ingestion can alter rectal epithelial proliferation. Methods: Thi rty-Six patients with normal colonic mucosa consumed 100 g of peanuts each day for 5 days. Rectal mitotic index was measured before and afte r ingestion, and changes in proliferation were correlated with immunoh istochemical detection of lectin receptor expression by colonocytes an d fecal lectin activity as measured by hemaglutination assay. Results: Peanut Ingestion caused a 41% increase in rectal mucosal proliferatio n in individuals with macroscopically normal mucose who express TF ant igen in their rectal mucosae (10 of 36 patients studied), The prolifer ative response correlated with fecal hemagglutinating activity, and pe anut lectin could be shown immunohistochemically within the rectal muc osa. Conclusions: The common expression of galactose beta 1,3-N-acetyl galactosamine alpha- by hyperplastic and neoplastic epithelia may the refore be functionally important because it allows interaction with mi togenic dietary lectins. This could be an important mechanism for the association between diet and colorectal cancer.