Anemia is the major clinical symptom of Japanese bovine theileriosis caused by the intraerythrocytic protozoan Theileria orientalis, but the underlying pathogenesis of this anemia is still unknown. In order to clarify the mechanism of red blood cell (RBC) destruction in anemic cattle, we studied Heinz body formation in the RBC during the development of anemia in cattle experimentally infected with Theileria orientalis. Before the onset of anemia, Heinz body formation in the RBC was hardly seen; however, during the onset of anemia, the levels of Heinz body formation increased in proportion with the development of anemia and parasitemia. Heinz bodies cause membrane rigidity and affect global cellular deformability. Decreased RBC deformability tends to result in phagocytosis in the reticuloendothelial system by resident macrophages. This destructive phenomenon in RBC could play an important role in the onset of anemia in Japanese bovine theileriosis.
(Clinical Biochemistry Section, Hokkaido Research Station TEL +81-11-851-5226)
