N-Acetyl-D-Galactosamine-Inhibitable Adherence Lectin of Entamoeba histolytica. I. Partial Purification and Relation to Amoebic Virulence in Vitro

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Abstract
Adherence of axenicEntamoeba histolytica, strain HMI-IMSS, to Chinese hamster ovary (CHO) cells is mediated by an amoebic adhesin that is inhibited by N-acetyl-d-galactosamine (GaINAc). The in vitro virulence for CHO cells and human neutrophils (PMNs) of four strains of axenic amoebae was strain HMI-IMSS > H303-NIH = 200-NIH > nonvirulent Laredo (P < .001). The HMI strain had the greatest sensitivity to GalNAc-mediated inhibition of adherence (P < .001). GalNAc (1.0 g/l00 ml) inhibited the killing of CHO cells and PMNs by HMI amoebae (P < .001)and allowed PMNs to kill the amoebae (P < .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 HMI contained greater specific lectin activity than did strains 303, 200, and Laredo amoebae (P < .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.