Abstract
Probiotics have been defined as the living organisms that give advantageous effects to host through improving the factors related to the balance of intestinal bacterial flora. Lactobacilli and bifidobacteria are recognized as the representative probiotics. The present report summarizes recent progress in basic studies concerning the probiotic activity, especially immunoregulatory function of L. casei and B. breve according to the following manners. A) Immunoregulatory functions of L. casei. 1) Prevention of methylcholanthrene-induced carcinogenesis in mice and improvement of downregulated immune responses of lymphocytes. 2) Prevention of autoimmune diseases such as diabetes and chronic rheumatoid arthritis in experimental animal models. 3) Prevention of the allergic responses induced by immunization of mice with ovalbumin. B) Immunoregulatory functions of B. breve. 1) Enhancement of antigen-specific immunoglobulin production by B. breve. 2) Antiinfectious activity of B. breve against experimental viral infections in mice. The importance of antigen presenting cells such as macrophages and dendritic cells in the mechanisms of the immunoregulatory functions of probiotics are also discussed.
