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Analysis of the Epithelial Damage Produced by Entamoeba histolytica Infection
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Analysis of the Epithelial Damage Produced by Entamoeba histolytica Infection

Published on: June 12, 2014

Effect of Entamoeba histolytica toxins on isolated human polymorphonuclear leukocytes' phagocytic function

A S Al-Tuwaijri1

  • 1Department of Physiology, College of Medicine, King Saud University, Riyadh, Saudi Arabia.

Annals of Saudi Medicine
|July 1, 1992
PubMed

Insights

Entamoeba histolytica toxin from a virulent strain inhibits human immune cell (PMN) phagocytosis. This effect is irreversible and heat-stable, suggesting a potential mechanism in amebic infections.

Area of Science:

  • Immunology
  • Parasitology
  • Cell Biology

Background:

  • Entamoeba histolytica is an invasive parasite causing amoebiasis.
  • Human polymorphonuclear leukocytes (PMNs) are crucial immune cells for pathogen clearance.
  • Virulent strains of E. histolytica produce toxins that may modulate host immune responses.

Purpose of the Study:

  • To investigate the impact of Entamoeba histolytica toxin (Ehp/t) from a virulent strain (HM1:IMSS) on human PMN phagocytic function.
  • To compare the effects of Ehp/t from virulent (HM1:IMSS) and less virulent (NIH:200) strains.
  • To determine the reversibility and stability of Ehp/t's effect on PMNs.

Main Methods:

  • Isolation of Entamoeba histolytica toxin (Ehp/t).
  • Exposure of human polymorphonuclear leukocytes (PMNs) to Ehp/t from different strains.
  • Assessment of PMN phagocytic activity using yeast uptake and chemiluminescence assays.
  • Testing reversibility by washing PMNs post-toxin exposure.
  • Evaluating the effect of heat inactivation and N-acetyl-D-galactosamine (Ga1NAc) addition.

Main Results:

  • Toxin from the virulent HM1:IMSS strain significantly inhibited PMN phagocytic activity.
  • Toxin from the less virulent NIH:200 strain showed no significant effect on PMN phagocytosis.
  • The inhibitory effect of HM1:IMSS toxin on PMNs was irreversible upon washing.
  • Heat inactivation did not alter the toxin's effect on PMN function.
  • N-acetyl-D-galactosamine did not affect the toxin's activity.

Conclusions:

  • Entamoeba histolytica toxin (Ehp/t) from virulent strains can impair human PMN phagocytic function.
  • The observed inhibition is persistent and not easily reversed, indicating a stable interaction.
  • These findings suggest a potential mechanism by which E. histolytica evades the host immune system during infection.

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