National Institute of Animal Health (NIAH)

Topics in Animal Health Research 2005

17. Enhanced erythrophagocytic activity of macrophages in anemic cattle experimentally infected with Theileria orientalis

  Anemia is the primary clinical manifestation of Japanese bovine theileriosis, which is caused by the intraerythrocytic protozoan parasite, Theileria orientalis, but anemia's precise mechanism remains unknown. To understand the pathogenesis of this anemia, we studied the erythrophagocytic activity of macrophages as an example of the destructive action of erythrocytes in cattle experimentally infected with Theileria orientalis. Before the T. orientalis infection, the erythrophagocytic activity of macrophages obtained from peripheral blood against both auto- and iso-erythrocytes was at a low level. However, during the onset of anemia, the level of the erythrophagocytic activity of macrophages increased remarkably. The erythrophagocytic activity of macrophages against auto-erythrocytes was especially intense compared to its activity against iso-erythrocytes. In general, the erythrophagocytosis of macrophages is one of the main contributors to a shortening of the life span of erythrocytes in the bloodstream. The actual function of phagocytic cells in T. orientalis-infected cattle is still unclear, but an increase in erythrophagocytosis could play an important role in the pathogenesis of anemia resulting from Japanese bovine theileriosis.
(Hokkaido Research Station, Research Team for Environmental/Enzootic Diseases TEL +81-11-851-5226)

References:

  • Shiono et al. (2002) Free Radic. Biol. Med. 33(Suppl. 1):S181-S182.
  • Shiono et al. (2003) Parasitol. Res. 89:228-234.
  • Shiono et al. (2004) J. Vet. Med. B 51:39-42.

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