Tk polyagglutination produced in vitro by an endo-beta-galactosidase.

After treatment with the culture supernatant of Bacteroides fragilis or with an endo-beta-galactosidase from Escherichia freundii, the human red blood cells are Tk-activated, i.e. agglutinable by BS II lectin and their blood group I and i activities are reduced. These results suggest that B. fragilis produces an endo-beta-galactosidase activity and that the main antigenic determinant of Tk polyagglutinable red cells is a terminal N-acetyl-glucosamine residue.