Immunogenicity of Bifidobacterium breve and change in antibody production in Peyer's patches after oral administration.

Immunogenicity in the intestine of Bifidobacterium breve, included in fermented milk, was compared with that of Bacteroides thetaiotaomicron, also predominant in human intestine. In vivo, serum antibody to B. breve was detected first in mice fed the organism for 33 d; antibody decreased in mice fed these for more than 33 d. Serum antibody to Bact. thetaiotaomicron was detected in mice fed the organism for 7 d and was maintained at the same level in mice fed these for more than 7 d. From in vitro tests, the optimal doses of B. breve and Bact. thetaiotaomicron to induce antibody production by Peyer's patch cells, intestinal lymphoid tissue cells, were 5 x 10(8) and 5 x 10(7) bacteria/ml, respectively. Therefore, it was suggested that immunogenicity of B. breve is weaker than that of Bact. thetaiotaomicron. Furthermore, the change of antibody production to the organism by Peyer's patch cells in the mice administered B. breve orally was tested by the Peyer's patch cell culture method. Antibody production against B. breve by Peyer's patch cells in mice given B. breve for 25 and for 33 d increased and decreased, respectively, in comparison with the control. These results suggest that when serum antibody to B. breve increases significantly, anti-B. breve antibody production by Peyer's patch cells is suppressed, and thereafter, serum antibody to B. breve decrease and is not detected. These findings favor the view that serum antibody production to B. breve is regulated in Peyer's patches.