Changes in peripheral leukocyte populations of weak calf syndrome of Japanese black calves.

To clarify the cellular immune condition in Japanese Black (JB) calves with a weak syndrome, peripheral leukocyte populations were analyzed by flow cytometry. Twenty JB calves were divided into two groups based on clinical observations; one group of calves was weak, because they had experienced an onset of diarrhea within 3 days after birth and needed treatment (Group 1 ;n=10), and the other group of calves was healthy (Group 2; n=10). With regard to leukocyte populations, CD8(+) cells and gamma delta T cells in Group 1 were markedly lower than those in Group 2 during the experimental periods. It is possible that immune-insufficiency might be based on T lymphocyte function in weak syndrome JB calves during the growth process.