In vivo binding of the winged bean basic lectin labeled with iodo[2-14C]acetic acid to the intestinal epithelial cells of the rat.

Winged bean basic lectin was labeled with iodo[2-14C]acetic acid. The radiolabeling affected neither the antigenicity nor the hemagglutinating activity of the lectin. A liquid test meal consisting of [14C]lectin and an unabsorbable marker, [3H]polyethylene glycol (PEG), was administered to rats in order to investigate behavior of the lectin in the gastrointestinal tract. At 1 h after administration, 54% of the administered [14C]lectin was still in the stomach, 1% had reached the cecum, and 1-6% was found in the intestinal mucosa, indicating that the lectin was binding to the mucosa. In another experiment, rats were fed a commercial nonpurified diet for 3 d after administration of the test meal. About 87% of the administered lectin as well as 83% of [3H]PEG was recovered from the feces during these 3d. Lectin bound to the epithelial cells of the intestinal mucosa was recovered by liberating it from the cells with D-galactose. The recovered lectin showed both hemagglutinating activity and the antigenicity identical with those of the original lectin. These results clearly indicated that the lectin remained intact in the gastrointestinal tract while a part of it was bound to the intestinal mucosa, the rest being excreted directly into feces.