Lectin activity of axenic and xenic Giardia lamblia trophozoites.

The membrane bound lectin of Giardia lamblia is though to play an important role in the selective colonization of the proximal small intestine by the parasite. The lectin obtained from xenic lysetes of G.lamblia gave a titre of more than 1:2048 in the hemagglutination test with rabbit erythrocytes, whereas the axenic lysates required pre-treatment with proteases (trypsin and pronase) in order to obtain a titre of 1:32. Similar behavior was exhibited by enterocytes of the mouse small intestine when tested for agglutination. The activation of xenic trophofzoites by the intestinal proteases and the probable role of bacterial enzymes has been discussed.