Oral administration of Bifidobacterium bifidum G9-1 suppresses total and antigen specific immunoglobulin E production in mice

Recent studies have suggested that oral bacteriotherapy with probiotics might be useful in the management of allergic diseases. We investigated the effect of oral administration of Bifidobacterium bifidum G9-1 (BBG9-1) on immunoglobulin (Ig) E production in BALB/c mice. Live BBG9-1 was orally administered to mice for 2 weeks from I week before ovalbumin (OVA)-immunization. The treatment of BBG9-1 significantly reduced serum total IgE level. In addition, BBG9-1 significantly and largely reduced the serum level of OVA-specific IgE without lowering of the specific IgG1 and increasing of the specific IgG2a. We also examined T helper type (Th)1 and Th2 cytokine production from OVA-immunized splenocytes by restimulation with OVA in vitro. Productions of interferon (IFN)-gamma, interleukin (IL)-4 and IL-5 from the splenocytes of mice given BBG9-1 were weaker than those of control mice. We conclude that oral administration of BBG9-1 selectively and powerfully suppresses total and antigen specific IgE production in mice. It is suggested that BBG9-1 is useful for the prophylactic treatment in IgE-dependent allergic diseases.