Does the eosinophil have a protective role in amebiasis?

RESUMO

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.