N-Acetyl-D-galactosamine-inhibitable adherence lectin of Entamoeba histolytica. I. Partial purification and relation to amoebic virulence in vitro.

Adherence of axenic Entamoeba histolytica, strain HM1-IMSS, to Chinese hamster ovary (CHO) cells is mediated by an amoebic adhesin that is inhibited by N-acetyl-D-galactosamine (GalNAc). The in vitro virulence for CHO cells and human neutrophils (PMNs) of four strains of axenic amoebae was strain HM1-IMSS greater than H303-NIH = 200-NIH greater than nonvirulent Laredo (P less than .001). The HM1 strain had the greatest sensitivity to GalNAc-mediated inhibition of adherence (P less than .001). GalNAc (1.0 g/100 ml) inhibited the killing of CHO cells and PMNs by HM1 amoebae (P less than .001) and allowed PMNs to kill the amoebae (P less than .0047). Gel filtration chromatography of a soluble fraction of amoebic sonicate demonstrated a GalNAc-inhibitable amoebic lectin of 43,000-67,000 daltons that agglutinated CHO cells, erythrocytes, and PMNs. Strain HM1 contained greater specific lectin activity than did strains 303, 200, and Laredo amoebae (P less than .0016). The in vitro virulence of E. histolytica is associated with a GalNAc-inhibitable amoebic adhesin; this report is the first of a soluble GalNAc-inhibitable amoebic lectin.