Enhancement of immune response in Peyer's patch cells cultured with Bifidobacterium breve

Bifidobacterium breve, included in fermented milk, was tested for adjuvanticity and mitogenicity using cells of mouse Peyer's patch, one of the gut-associated lymphoid tissues. Addition of B. breve enhanced antilipopolysaccharide antibody production in Peyer's patch cells and also anti-sheep red blood cell plaque-forming cells in Peyer's patch cells cultured with sheep red blood cells. Furthermore, addition of B. breve accelerated proliferation of Peyer's patch cells, particularly B cells. In BALB/c mice, enhancement of proliferation by B. breve was also found in Peyer's patch cells from nude mice and a B cell-enriched fraction, including both the B cell fraction and plastic-adherent cells. Enhancement was not found in the fraction in which Sephadex G10-adherent and carbonyl-iron phagocytic cells were excluded from Peyer's patch cells or in a pure B cell fraction in which plastic-adherent cells were excluded from the B cell-enriched fraction of Peyer's patch cells. The proliferation of B cells was enhanced when the supernatant of plastic-adherent cells cultured with B. breve was added. It is concluded that B. breve activated plastic-adherent cells and that these cells secreted a soluble factor that enhanced proliferation of B cells.