Ecological Mechanism of Protection of Intestinal Bacterial Flora Against Salmonella typhimurium Infection

: Our results indicate that the responsiveness of the phagocytic and intracellular killing process of peripheral blood granulocytes and peritoneal phagocytic cells in infected germfree mice is due primarily to the OCl- (hypochloride ion) with myeloperoxidase involvement, while the response in infected conventional mice is brought about mainly by the O2- (superoxide anion). These facts are believed to be invaluable footholds in elucidating the quantitative and qualitative differences in phagocytic cell response depending upon the presence or absence of intestinal flora.