| Autor: |
Piedrafita, David, Estuningsih, Endah, Pleasance, Jill, Prowse, Rhoda, Raadsma, Herman W., Meeusen, Els N. T., Spithill, Terry W. |
| Zdroj: |
Infection and Immunity; April 2007, Vol. 75 Issue: 4 p1954-1963, 10p |
| Abstrakt: |
ABSTRACTIndonesian thin-tail (ITT) sheep resist infection by Fasciola giganticaby an immunological mechanism within 2 to 4 weeks of infection yet are susceptible to F. hepaticainfection. Studies of ITT sheep show that little liver damage occurs following F. giganticainfection, suggesting that the invading parasites are killed within the peritoneum or shortly after reaching the liver. We investigated whether cells isolated from the peritoneums of ITT sheep could kill newly excysted juvenile F. giganticain vitro and act as a potential mechanism of resistance against F. giganticainfection. Peritoneal cells from F. gigantica-infected sheep, rich in macrophages and eosinophils, mediated antibody-dependent cytotoxicity against juvenile F. giganticain vitro. Cytotoxicity was dependent on contact between the parasite and effector cells. Isolated mammary gland eosinophils of F. gigantica-infected sheep, or resident peritoneal monocytes/macrophages from uninfected sheep, also killed the juvenile parasites in vitro. By using inhibitors, we show that the molecular mechanism of killing in these assays was dependent on the production of superoxide radicals by macrophages and eosinophils. In contrast, this cytotoxic mechanism was ineffective against juvenile F. hepaticaparasites in vitro. Analysis of superoxide dismutase activity and mRNA levels showed that activity and gene expression were higher in F. hepaticathan in F. gigantica, suggesting a possible role for this enzyme in the resistance of F. hepaticato superoxide-mediated killing. We suggest that ovine macrophages and eosinophils, acting in concert with a specific antibody, may be important effector cells involved in the resistance of ITT sheep to F. gigantica. |
| Databáze: |
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