Send to

Choose Destination
Parasitology. 1995 Dec;111 ( Pt 5):569-74.

Spontaneous release of cysteine proteinases but not of pore-forming peptides by viable Entamoeba histolytica.

Author information

Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.


Invasive properties of pathogenic Entamoeba histolytica have been postulated to depend on the secretion or release of cysteine proteinases and pore-forming peptides (amoebapores) by trophozoites. To establish whether such toxic molecules are released by viable trophozoites or upon cellular disintegration, amoebae were maintained in various culture media, and activities in supernatants were monitored over time in correlation to cellular integrity. By measuring the release of the cytoplasmic marker enzyme NADP(+)-alcohol dehydrogenase, it became apparent that release of amoebapore was accompanied by cellular disintegration. In contrast, considerable quantities of cysteine proteinases were found to be present in culture supernatants also when amoebae remained intact. Treatment of amoebae with concanavalin A, bacterial lipopolysaccharides or the calcium ionophore A23187 did not result in amoebapore secretion suggesting that here target cell contact is required as an essential stimulus.

[Indexed for MEDLINE]

Supplemental Content

Loading ...
Support Center