Chew on this: amoebic trogocytosis and host cell killing by Entamoeba histolytica

• Host cell killing is likely to underlie the pathogenesis of amoebiasis.
• Amoebic trogocytosis (from trogo-, ‘nibble’) by E. histolytica is a recently discovered mechanism for host cell killing.
• We place amoebic trogocytosis in the context of previous studies of cell killing by E. histolytica.
• Amoebic trogocytosis and phagocytosis are compared, and potential mechanistic differences are highlighted.
• ‘Nibbling’ processes by other organisms are discussed.

Entamoeba histolytica was named ‘histolytica’ (from histo-, ‘tissue’; lytic-, ‘dissolving’) for its ability to destroy host tissues. Direct killing of host cells by the amoebae is likely to be the driving factor that underlies tissue destruction, but the mechanism was unclear. We recently showed that, after attaching to host cells, amoebae bite off and ingest distinct host cell fragments, and that this contributes to cell killing. We review this process, termed ‘amoebic trogocytosis’ (trogo-, ‘nibble’), and how this process interplays with phagocytosis, or whole cell ingestion, in this organism. ‘Nibbling’ processes have been described in other microbes and in multicellular organisms. The discovery of amoebic trogocytosis in E. histolytica may also shed light on an evolutionarily conserved process for intercellular exchange.