ANTIGEN-INDUCED EOSINOPHILIA PROTECTS GERBILS (MERIONES-UNGUICULATUS)AGAINST EXPERIMENTAL AMEBIC-ABSCESS OF THE LIVER

While the normal human eosinophil is destroyed in vitro by virulent En tamoeba histolytica, notwithstanding the presence of antibodies and co mplement, activated eosinophils promptly destroy the parasite even tho ugh succumbing in the process as well. To study the possible in vivo p articipation of eosinophils in invasive amebiasis, we compared the ind uction of experimental amebic abscess of the liver (EAAL) in gerbils ( Meriones unguiculatus) previously made eosinophilic (532 +/- 80 eosino phils/mm(3)) through Toxocara canis antigen injection and normal contr ol gerbils (101 +/- 15 eosinophils/mm(3)). Shortly (6 and 24 h) after intraportal injection of 10(5) virulentE. histolytica, the ratio of ge rbils with EAAL, as well as the number and size of the abscesses was c omparable in eosinophilic and control gerbils. At 96 h post-inoculatio n, the ratio of animals with EAAL was still the same in both groups, y et number and size of abscesses were significantly (p <0.05) smaller i n eosinophilic gerbils. The actuarial EAAL survival curve up to 45 day s post-amebic inoculation was significantly (p <0.05) shifted to the r ight in eosinophilic gerbils. No significant changes in IL-5 levels we re recorded throughout these experiments. The results suggest that ant igen-induced eosinophilia may exert a protective effect against EAAL i n gerbils. It is speculated that a less overwhelming EAAL strategy - m ore akin to human amebic abscesses may reveal this protective effect m ore clearly.