Lectin-induced agglutination of trophozoites of different species and strains of Entamoeba.

In vitro agglutinability of trophozoites of three Entamoeba histolytica strains, cultivated under axenic conditions in the presence of concanavalin A (Con A), was shown to be related to the degree of their pathogenicity for experimental animals and of the concentration of Con A. Seven strains of E. invadens tested also agglutinated in the presence of Con A, and the degree of agglutination was proportional to the concentration of the lectin. Three strains of E. histolytica-like "Laredo-type" amebae, a strain of E. terrapinae, and a strain of E. moshkovskii agglutinated very slightly, only in the presence of the highest concentration of Con A tested.