Immune Response of Bifidobacterium-Monoassociated Mice

Abstract

Various investigators have discussed floral microorganisms influence on a host's immune system Most of these statements come from investigations comparing responses of germfree animals and flora-bearing ones. The present authors attempted to analyze the effect of an indigenous floral organisms on the host under a more simplified condition. Bifidobacterium longum (BL) was given per os to germfree mice (GF) of BALB/c background and various aspects of immune responses to the associated organism were investigated first; antibody (mainly IgA) and cell-mediated immune (CMI) responses to BL, translocations of BL into the internal organs, and shift of lymphocyte subsets in the lymphoid organs were found following per os administration of BL. Some activities of BL on in vitro cultured lymphocytes were also found. Additionally, it was shown that the BL-monoassociated mouse (GB) exhibits beneficial effects in respect to specific immune response and non-specific antibacterial defence reactions to unrelated antigenic substances. These non-specific effects were seen on lethal activity of Escherichia coliendotoxin, IgA production to cholera toxin (CT), and induction of oral tolerance to unrelated antigens.