Entamoeba histolytica: erythrophagocytosis, collagenolysis, and liver abscess production as virulence markers.

High rates of erythrophagocytosis and collagenolysis in vitro have been regarded as indicative of virulence in vivo of Entamoeba histolytica trophozoites. In the present study, the erythrophagocytic index and the collagenolytic activity of 3 axenic lines of E. histolytica, strain HM1:IMSS, were measured. The 3 lines shared the same pathogenic zymodeme but showed clear-cut differences in the extent of liver damage induced in hamsters. A direct correlation between collagenolysis in vitro and the size of liver abscesses produced by each line of E. histolytica trophozoites was found. In contrast, the line with the highest erythrophagocytic index produced small amoebic abscesses in hamsters, whereas the line with a relatively low erythrophagocytic index produced the largest liver lesions. It is concluded that the extent of collagenolytic activity is a better marker of virulence of E. histolytica cultured under axenic conditions than is erythrophagocytosis.