Entamoeba histolytica: Target Cells Killed by Trophozoites Undergo DNA Fragmentation Which Is Not Blocked by Bcl-2

doi:10.1006/expr.1994.1107

Experimental Parasitology

Volume 79, Issue 3, November 1994, Pages 460-467

https://doi.org/10.1006/expr.1994.1107 Get rights and content

Abstract

Amebic destruction of neutrophils and macrophages is contact-dependent. Adherence is mediated by a galactose-specific surface lectin on the amebic membrane. The pathway by which contact-dependent cytolysis of the target cell occurs is unknown. We hypothesized that target cell death is due to the triggering of apoptosis (programmed cell death) by the amebae. The purpose of this study was to determine whether target cell DNA is fragmented into a ladder pattern characteristic of apoptosis and to test whether overexpression of Bcl-2, a protein that confers resistance to apoptotic death from some stimuli, blocks target cell killing. The murine myeloid cell line FDC-P1 transfected with a retrovirus construct expressing the Bcl-2 protein was shown to be resistant to the apoptotic death that the parental line undergoes upon growth factor deprivation. ⁵¹Cr-labeled FDC-P1 control or bcl-2-transfected cells were incubated with Entamoeba histolytica (4:1 cell/ameba ratio) and killing of the cells was assessed by ⁵¹Cr release. Both cell lines were susceptible to contact-dependent killing. Death induced by the amebae in the bcl-2-transfected cells resulted in a DNA ladder fragmentation pattern (using [¹²⁵I]iododeoxyuridine-labeled target cell DNA) identical to that seen in the control cells undergoing apoptosis upon growth factor withdrawal. Target cell DNA fragmentation was inhibited by blocking adherence with galactose. Our data suggest that target cell killing by E. histolytica can occur via Bcl-2-independent apoptotic mechanism.

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In conclusion, we developed a novel primate model of E. histolytica intestinal infection and demonstrated that a Gal-lectin-based intranasal synthetic peptide vaccine was highly efficacious in preventing experimental E. histolytica infection and colitis in baboons.

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Regular ArticleEntamoeba histolytica: Target Cells Killed by Trophozoites Undergo DNA Fragmentation Which Is Not Blocked by Bcl-2

Abstract

Regular Article
Entamoeba histolytica: Target Cells Killed by Trophozoites Undergo DNA Fragmentation Which Is Not Blocked by Bcl-2