Does the eosinophil have a protective role in amebiasis?

While normal human eosinophils are destroyed in vitro by virulent Entamoeba histolytica, notwhistanding the presence of antibodies and complement, activated eosinophils promptly destroy the parasite although dying also at the end of the process. To study the possible in vivo participation of eosinophils in evasive amebiasis, we compared the induction of experimental amebic abscess of the liver (AAL) in gerbils (Meriones unguiculatus) previously made eosinophilic through Toxocara canis antigen injection and in normal control gerbils. After intraportal inoculation of 105 ameba trophozoites (6 and 24 hr), the ratio of gerbils with AAL, as well as the number and size of the microabscesses was comparable in eosinophilic and control gerbils. However, at 9 hr the number and size of the microabscesses were significantly smaller (p<0.05) in eosinophilic gerbils. On the other hand, the actuarial AAL survival curve up to 45 days post-amebic inoculation was sugnificantly (p<0.05) shifted to the right in controls. These results suggest that antigen-induced eosinophilia may exert a protective effect agaisnt AAL in gerbils.

The ultrastructure of Entamoeba histolytica locomotion

This quantitative ultrastructural survery of E. histolytica locomotion in Boyden chambers supports the concept that this parasitis is capable of random, chemokinetic and chemotactic motility. An E. histolytica committed to chemotaxis will flatten over the filter, accumulate smaller vacuoles at the front of the cell, and will also project pseudopods and its polarized body towards and alongside the chemoattractant axis, respectively. Other cell features such as cell polarization, membrane ruffling, hyaline, total number of pseudopods and caudal displacement of the nucleus appear to be associated with the locomotion efforts as such, perhaps reflecting speed (chemokinesis) but irrespective of orientation (chemotaxis). Finally, only on of the 11 features that were analyzed (i.e., number of vacuoles) failed to be distinctly associated with any of the movement forms studied. E. histolytica appears to possess the full repertoire of locomotion modalities observed in free moving eukaryots, and its motility translates into ultrastructural landmarks that could be useful indicators of subcellular events related to locomotion